Windpower Engineering & Development APRIL 2016

April 2016www.windpowerengineering.com

The technical resource for wind profitability

BETTER PREVENTION FOR LEADING EDGE EROSION / WindWatch page 16

WINDPOWER 2016 preview

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I N N O V A T O R S & I N F L U E N C E R S I S S U E

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2015

3

HERE’S WHAT I THINK

2015

3

There is a bit of a controversy brewing in Ohio, thanks to First Energy, American Electric Power, and Duke Energy. According to Ohio Citizen Action, those three utilities

have “filed proposals to raise consumer rates and use the profits to cover the costs of their outdated and inefficient coal plants.” This is a bailout, an OCA flier insists, “because they are asking the Public Utilities Commission of Ohio to be allowed to have a ‘Purchase Power Agreement.’” Complete disclosure: I have stock in AEP and FirstEnergy.

First Energy, in TV ads, say the rate hike is to ensure better customer service.

To me, neither arguments pass the smell test. First OCA does not seem to know the difference between profits and expenses. The rate increase, not a profit, would be used to cover the expense of whatever the utilities are planning. Profits are what are left over after paying expenses. The OCA also implies there is something dishonest about a

“Purchase Power Agreement.” Not necessarily so. Power purchase

agreements are common between enlightened utilities and wind-farm owners. The utility agrees to purchase a wind farm’s power at a certain price and for a certain period, often years. Early PPAs stretched for 20 years. Talk about stability. In the end, the OCA comes off sounding anti-business.

Switching focus to the utilities’ argument: They should have been updating their equipment all along. It’s what we pay them for.

Since the recession put the entire economy in a funk, the demand for power has been pretty much flat, about a 1% growth rate over the last eight years. Any facilities manager studying his electric bill must ask, and loudly, “How do we get that figure down?”

The obvious way of reducing power needs has been through greater efficiency, such as switching to LED lights. Imagine millions of homes and businesses making the same swap and it’s easy to see the demand-for-power curve has a low slope.

The utilities certainly don’t help themselves. It’s difficult to sympathize with them because the price of natural gas is so low (On April 2, Bloomberg energy reported $1.94/million BTUs). They should have planned for the shift to natural gas years ago by starting with their least efficient coal plants. We acknowledge that running a vast utility is a bit more complex than writing an editorial. But as wind-power advocates, it’s easy to see solutions to their pollution problems. (A joke from a recent wind conference: Utility executives have a reputation for slooow decisions. So when they saw the EPA planned to shackle them with punishing rules and regulations, a few despaired and decided to end it all. They threw themselves in front of the fastest moving thing they knew of: A glacier.)

Don’t despair, you guys. We have solutions that will make you look good. Instead of fighting the wind industry, work with it. Sign power purchase agreements with wind farms, buy their power, and crow about it. It’s a win-win. You don’t have to build and maintain new plants, the wind guys do that. You just distribute power. You may have to build a gas-fired plant or two that can cycle up and down to accommodate the variable nature of wind power, but you’ll be heroes…unless, of course, you prefer the role of villains.

Another idea: Promote the use of electric cars with a charging station in appropriate places. I know it is early, but would you not like to sell another 18.4 kWh a day to a Chevy Volt owner, or 60 kWh to another EV owner? Now imagine a million EV owners. The game is yours to lose. W

Why can’t Ohio utilities just work with the wind industry?

E d i t o r i a l D i r e c t o r | W i n d p o w e r E n g i n e e r i n g & D e v e l o p m e n t |p d v o r a k @ w t w h m e d i a . c o m

2 WINDPOWER ENGINEERING & DEVELOPMENT www.windpowerengineering.com APRIL 2016

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DAVID CLARK, CEO of CMS wind, has experience monitoring and analyzing wind turbines from 200 kW to megawatt-class units, and from several OEMs. In addition, he has 11 years of condition-monitoring experience in traditional markets, such as nuclear power, steel mills, and mining. Clark frequently writes for Windpower Engineering & Development.

SCOTT A. EATHERTON has worked in the wind industry since 1984 and has held positions including field technician, construction QC manager, technical trainer, gearbox rebuilder, warranty sweep manager, and root-cause analyst on wind sites from Texas to Pennsylvania and Bulgaria. He joined the AGMA 6006 WTG gearbox standards committee in 1994. [email protected]

KARL FATRDLA has a degree in Mechanical Engineering from the Technical University in Vienna, Austria. He started out in the automotive industry as a Project Manager, and even received Project Management Professional (PMP) certification according PMI standards. In 2008, he joined the wind industry as a Director of Sales for Eastern Europe at Vestas. He’s since moved to Switzerland for ROMO Wind, and is now Head of Sales as part of the company’s young and dynamic wind team based at the Swiss ROMO Office. In this function, Fatrdla has built up sales entities for ROMO Wind in all major European countries.

JUSTIN FORBES is Director of Marketing and Business Development for EDF Renewable Services. Prior to this, Forbes held various sales, marketing, and management roles in the consumer products, energy, and industrial fields. Forbes earned his MBA from Duke University, and a B.S. in mechanical engineering from the University of California San Diego.

LARRY FREEMAN serves EDF Renewable Services as Business Development Manager, where he oversees the Asset Administration Development for Wind and Solar O&M Business. Prior to joining Business Development, Freeman was the Regional Manager for Solar O&M Operations, overseeing over 775 MW of solar assets across the U.S. and Canada. Freeman brings 19 years of experience in renewable energy and operations and maintenance. He has a Bachelor of Arts from the Ohio State University.

ALAN GROSS is President of AMG Bolting Solutions, an industrial bolting supply company. His passion is helping plant managers, MRO specialists, and business owners in nearly every industrial vertical market across the United States and Canada, achieve cost savings by improving employee safety and lower downtime.

DAVE HEIDENREICH has 50 years experience improving drive systems in industrial machinery. He founded PT Tech in 1978 and has developed unique torque control solutions, significantly improving the reliability and productivity some of the world’s most extreme machinery. Heidenreich has 27 patents and, since 2010, has focused on solving transient load problems in wind turbines. [email protected]

COLIN MCNICHOLS, a Senior Design Engineer, joined Romax in 2014 after five years of rotating machinery experience at General Electric. He has a degree in Mechanical Engineering from the University of Wisconsin–Madison, and a master’s in Mechanical Engineering from the Georgia Institute of Technology. McNichols’ most recent work has been on wind-turbine gearboxes, with a focus on structural component design and analysis. He specializes in mechanical engineering support of the Romax InSight product, including borescope inspection, vibration monitoring, design and prototyping of field solutions, and drivetrain failure analysis.

EMIL MOROZ has a deep understanding of wind energy from a system perspective, derived from roles in research, industry, development, operations, and consulting since 1992. Among other achievements, he has developed the site suitability evaluation process for two OEMs, played a pivotal role in the definition of the GE1.5sle, and is author on seven wind turbine technology related patents. [email protected]

SHYLESH MURALIDHARAN is the Global Product Manager at Schneider Electric, focused on building products for real-time weather data analytics integration into energy industry applications. He believes that weather-based decision support systems will play a major role in making the energy infrastructure of the future smarter and climate-resilient. Muralidharan has more than 14 years of worldwide experience in product management, consulting, and generating thought leadership in the field of new energy systems, and sustainability. A System Design and Management fellow from MIT, Muralidharan has a bachelor’s degree in Mechanical Engineering and a MBA from University of Mumbai, India.

BRIAN ROTH received a B.S. degree in Electrical and Computer Engineering from California Polytechnic University of Pomona. He has worked in a variety of engineering roles, and is currently the Marketing Product Engineer for industrial networking devices at Antaira Technologies.

DUSTIN J. SADLER has 16 years of mechanical design engineering experience, including co-inventor of AeroTorque’s WindTC RTD device. He brings knowledge and background from multiple industries to the FMEA application and generation along with project management to aid in the creation of this technical document. [email protected]

DR. ZHIWEI ZHANG is VP of Engineering for InSight, and he is responsible for Romax’s InSight business in North America. He joined Romax in 2008, and led dynamic analysis and design work for multiple wind-turbine gearboxes. Dr. Zhang spent three years working in Asia, mainly on gearbox design and testing projects, and began work in the U.S. in 2014. His technical focus is drivetrain re-engineering and refurbishment, RCA, etc. Dr. Zhang has a PhD on dynamics from Loughborough University in the UK.

Contributors 4-16_Vs4.indd 4 4/6/16 2:13 PM

Follow the whole team on twitter @Windpower_Eng

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Work Safer...get Closer to your work

Photos courtesy of TGM Wind Services

Nothing beats a Bronto aerial for safety when inspecting,cleaning and servicing turbines. And, they do it faster and more productively so you save time and money!

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2013, 2014, 2015

Staff page_WIND_4-16_Vs1.indd 5 4/6/16 2:22 PM

Editorial: Why can’t some utilities just work with the wind industry?

Windwatch: Preview of WINDPOWER 2016 in New Orleans, Wikov gears, Guard for leading-edge erosion, Making construction sustainable work, Ask a wind tech, Windwork around North America

Managing assets: Meeting wind targets with proper asset management

Reliability: A better anemometer gives more accurate wind measurements

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Bolting: Lighter weight components and hydraulic torque tools improve wind-industry safety

Internet of things: Talking with turbines through the Internet of Things

Condition monitoring: Where the often-quoted ISO 10861-21 falls short for CMS

Software: Were any of our turbines hit by lightning? This system has clues

Turbine of the Month: GE’s Alston offshore Haliade 150-6MW

Downwind: Accio Energy’s turbine-less wind generator

D E PA R T M E N T S

F E AT U R E S


62ON THE COVERA technician uses a view scope to check a gearbox’s gear teeth for wear. Photo: Romax

FMEA shows that torque reversals damage more than wind-turbine gearboxes

This article is the second of a two-part series in which a Failure Mode and Effects Analysis (FMEA) is used to evaluate how torsional oscillations and reversals can damage many expensive turbine components. It also compares the effects of adding a Reverse Torsional Damping device to mitigate the damage. The FMEA calculates a projected range of cost reductions based on the credibility of evidence, contribution to overall failure mode, and the estimated life extension from the damping device.

Turbines that last: Gearbox re-engineering

Gearbox failure is a chronic issue for the wind industry, but replacements are not always the answer. Not all gearboxes fail for the same reason, so by examining and correcting serial issues there is potential for improved design. Today, re-engineering rather than a simple replacement is becoming the method more commonly applied to improve the reliability of existing gearboxes.

Windpower Engineering & Development Innovators and Influencers of 2016

Welcome to the seventh edition of Innovators and Influencers. This section recognizes four people who had the inspiration to tackle the technical problems unique to wind-turbine design, and two more with the gift to recognize the great value of the wind industry, and then do something to make it grow.

Table of Contents_4-16_Vs4.indd 6 4/6/16 3:41 PM

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DESIGNING SUSTAINABLE INFRASTRUCTURE DESIGNING SUSTAINABLE INFRASTRUCTURE WHEN IT COMES TO ENVIRONMENTAL BUILDING STANDARDS, LEED (Leadership in Energy & Environmental Design) has become the most widely used third-party verification organization for “green” buildings. Developed by the U.S. Green Building Council, LEED-certified projects earn points based on environmental efficiency standards. For example, a building might reduce emissions by using less energy, less water, or creating less waste.

But what about for infrastructure that falls outside of LEED-approved buildings, such as structures that might not house or hold people but still provide a service, such as watersheds…or wind farms?

LEEDs for wind farms Enter the Institute for Sustainable Infrastructure (ISI) Envision rating system, the international benchmark for all types of infrastructure. Per the ISI’s website: “Envision provides a holistic framework for evaluating and rating the community, environmental, and economic

benefits of all types and sizes of infrastructure projects. It evaluates, grades, and gives recognition to projects that use transformational, collaborative approaches to assess the sustainability indicators over the course of a project's lifecycle.”

By the end of 2015, nine projects earned Envision awards across the United States and Canada. Of notable mention to those in the wind industry is the Portland General Electric’s (PGE) Tucannon River Wind Farm, which represents the first energy project to receive an ISI Envision-verified sustainable infrastructure award in North America.

The 267-MW wind farm is located on 20,000 acres near Dayton, Washington, and achieved a Gold rating by meeting many of the highest principles of sustainability. A total of 116 Siemens wind turbines help PGE meet Oregon’s Renewable Portfolio Standard, which requires the utility to supply 15% of the electricity to its customers from qualified renewable resources by 2015 and 25% by 2025.

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APRIL 2016 windpowerengineering.com WINDPOWER ENGINEERING & DEVELOPMENT 9

Portland General Electric’s Tucannon River Wind Farm, shown here, is the first energy project to receive an Institute for Sustainable Infrastructure (ISI) Envision sustainable infrastructure award in North America. Analysis shows that the wind farm will cut carbon-dioxide

emissions by 92% during its lifetime compared to a conventional power plant with the same capacity. It is located near Dayton, Washington.


W I N D W A T C H

1 0 WINDPOWER ENGINEERING & DEVELOPMENT www.windpowerengineering.com APRIL 2016

Construction of the Tucannon River project began in 2013, and the facility went into commercial operation in December of 2014. Before construction began, the design team evaluated ways to reduce the project’s net embodied energy. In this case, that meant turbine foundations were designed to reduce the amount of required concrete and a significant portion of construction materials used in the project was sourced locally. This cut transportation costs and helped boost the local economy.

Even materials excavated during construction were retained and reused onsite where possible, and most of the turbine’s components can be recycled at the end of the project life.

The Envision sustainable infrastructure categories in which the Tucannon River Wind Farm scored highest include:

Quality of Life. The project offers benefits to the community including full-time jobs, income for local businesses, increased county tax revenue, and easement payments to landowners. It also benefits the Oregon economy by helping PGE provide customers with renewable energy at a reasonable price.

Leadership. Prior to construction, PGE established plans and resources necessary

for long-term monitoring and maintenance of the completed wind farm. Additional environmental monitoring is used during wind-farm operation to manage and protect sensitive natural and cultural resources.

Resource Allocation. Tucannon River Wind Farm will provide a net-positive amount of energy to the grid during the next 20 years. This project's infrastructure contributes more than 676,000 megawatt-hours of renewable power to the grid each year, decreasing dependence on fossil fuel energy sources and increasing national energy independence.

Natural World. Tucannon River Wind Farm was sited to avoid all wetlands and surface water, floodplains, steep slopes, and other potentially fragile or hazardous terrain. The project was also designed and constructed to avoid surface waters and contamination of waters. The project team reduced the use of hazardous or potentially polluting materials.

Climate and Risk. Analysis shows that the wind farm will cut carbon-dioxide emissions by 92% during its lifetime compared to a conventional power plant with the same capacity.

The Tucannon River Wind Farm team thoroughly assessed likely hazards and upgraded designs to prepare for direct and indirect impacts of short-term hazards. In addition to securing infrastructure and configuring its systems for resiliency against man-made hazards, designs were implemented to withstand floods, wildfires, and extreme temperatures and winds. Specific protections were also added to address lightning strikes, ice storms, and seismic events.

The rating systemEnvision was created as a joint collaboration between the Institute for Sustainable Infrastructure (the ISI was founded by three national engineering associations: American Society of Civil Engineers, American Council of Engineering Companies, and American Public Works Association) and the Zofnass Program for Sustainable Infrastructure at Harvard University Graduate School of Design.

Similar to LEED, Envision’s rating system includes points or credits that can earn Bronze, Silver, Gold, and Platinum ratings. The program offers 60 sustainability credits that are divided into five main categories: Quality of Life;

A tower and rotor are ready for assembly at the Tucannon River Wind Farm during construction in the summer of 2014. The wind farm was sited so it avoided all wetlands and surface water, steep slopes, and other potentially fragile or hazardous terrain.


W I N D W A T C H

WINDPOWER ENGINEERING & DEVELOPMENT 1 1

Leadership; Resource Allocation; Natural World; and Climate and Risk.

Envision’s sustainable infrastructure rating system can serve infrastructure development or design companies in two ways: as guidelines for a project team to evaluate infrastructure at any stage of the design process, or as means for objective review by ISI verifiers (known as ENV SPs) to assess eligibility for an Envision award.

To help companies better prioritize and meet sustainability goals, Envision also provides evaluation tools so project owners or designers can:

• Assess costs and benefits over the lifecycles of a project,

• Evaluate potential environmental benefits,

• Use outcome-based objectives, and • Reach higher levels of sustainability

achievement.

One example of an educational tool is the Envision Checklist, which helps users familiarize themselves with the sustainability aspects of infrastructure project design. The checklist is structured as a series of “Yes” or “No” questions based on the Envision rating system. It can be used as a stand-alone assessment to quickly compare project alternatives or to prepare for a more detailed assessment.

However, the goal of either the checklist or rating system doesn’t have to be an Envision award. Companies can simply use these tools to measure sustainability in the planning or construction phase of a project for their own purposes, while maintaining full anonymity.

Envision is also updating its program and is currently developing an economic optimization tool, and construction and O&M phase credits.

If interested in submitting a project for an Envision sustainability rating, there are no limits to infrastructure type. For instance, Tucannon River Wind Farm is not the only success story from 2016. The 26th Ward Wastewater Treatment Plant in New York City earned an Envision Silver award last August for its work in upgrading

and expanding its treatment capacity. And Canada’s Vancouver-based company, Low Level Road, earned Envision Platinum back in September for its roadwork. The company sustainably realigned and elevated about 2.6 kilometers of a city road to provide space for two new rail tracks and direct access to major port terminals.

What goes into attaining each Envision credit is described in a two-page report that includes the intent, metric, levels of achievement, evaluation criteria, credit descriptions, and an explanation of how to advance to a higher level.

Visit www.sustainableinfrastructure.org for further tools, rating, and application requirements. W

A large wind-turbine blade is lifted into place onto a rotor hub at the Tucannon River Wind Farm during construction. Special protections have been added to address lightning strikes, ice storms, and seismic events.



W I N D W A T C H

A little flexing and synthetic lube may be better for wind turbines and tidal water gearboxes

A FLEXIBLE-PIN GEARBOX that improves load sharing between the various gear elements makes it valuable for high-peak load applications, such as wind and tidal-power turbines. Furthermore, it enables the use of more than three planets – in some cases up to eight – in one planetary stage, thus allowing for a significant increase in power density.

This should be good news for the wind industry, which has been struggling to extend the life of its gearboxes. Results suggest that the flexing-pin design has a role to play.

“Traditional gearboxes use solid planet-bearing mounts in carriers,” says the Wikov Group Technical Director Jan Vosátka.

Conventional planetary stage

In a conventional gearbox, (above)

an overload deforms the

contact pattern so that a smaller

area is carrying higher than

average load. That leads to

high stresses and early gearbox

failures. Wikov gearboxes (right)

in contrast, use flex pins and

more than three planets.

“In many cases, it is not difficult to optimize these designs for one load, but it can be quite difficult to do so for applications with variable loads, such as wind power.”

Renewable energy applications must commonly withstand variable and high-load peaks. These harsh conditions may lead to deformation in the system, such as radial and angular misalignments that can result in non-symmetrical planet-bearing load patterns in gearing, which reduce gearbox life.

Most gearbox manufacturers address this concern by increasing the stiffness of the system to avoid deformations, usually at the price of weight penalty. “Our philosophy is different. We work with flexibility rather than fight it. We have a design that places the planet gears on a flexible pin on the planet carrier. A hollow sleeve called a spindle, carries the planet bearing and gear, and mounts on a pin, which mounts to the carrier. The pin is allowed to bend in a controlled manner, introducing flexibility to the system. And, thanks to the geometry of the assembly, this design allows for appropriate planet movement.”

As a result, when a load is applied to the gears, the flexible pin lets the planet float mostly parallel to the axis, minimizing gear tilt and improving load sharing among planets. This alternative design allows for increased life of gears and bearings, greater resistance to shock load, and a 30 to 40% gearbox weight reduction in comparison to conventional gearboxes of similar power.

Furthermore, a patented overload stop is usually used to reduce planet movement under critical conditions. “We also have a version available for helical gears in which planet tilt in the gearing must be handled due to thrust forces,” adds Vosátka,

He says the technology has been proven in the field in systems ranging from hundreds of kilowatts to seven-MW gearboxes. In a 350-kW wind turbine that has been in operation for more than 10 years, the turbine’s gears and bearings show no significant sign of wear or damage.

“We have also used this technology in a tidal-power project where we supplied a twin 650-kW main drive for a tidal current turbine. Those gearboxes have been in trouble-free operation since 2008,” he says.

These are significant applications because wind and tidal power turbines are often in remote locations where maintenance is costly. Tidal power, in particular, is an extreme


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“As a result, we had to ensure that the gearboxes could operate maintenance-free for many years to help ensure customer profitability. To address these issues, we looked at lubricants as well. Specifically, we partnered with ExxonMobil, which had recently launched a new synthetic lubricant – Mobil SHC Gear 320 WT – specifically formulated for renewable and wind-energy applications,” says Vosátka.

After running in-house tests on a 3-MW planetary wind gear, the lubricant displayed the right properties, including high-viscosity stability, strong anti-foam properties, and better fluidity at cold temperatures. Mobil SHC Gear 320 WT is now formally approved for Wikov flexible-pin design in wind applications.

Following the positive performance of Mobil SHC Gear 320 WT in wind turbines, Vosátka’s team tested it for tidal-power applications, and found it to be an useful lubricant for this application as well. It offers a higher viscosity index, easier and faster start-up in cold environments due to lower viscosity and thus limited need of oil pre-heating, and higher protection against wear at high temperatures – an important feature when you consider that temperatures can rise to 100ºC in the load area. W

Flexible pin planetary stage

In a flexible pin planetary stage, an overload does not reduce the contact area between gear teeth. Hence, a longer working gearbox.

application in which the gearbox may be fitted in a closed nacelle on the seabed, making it impossible to access for several years, unless you take the whole turbine out of the water.


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Could this easily applied covering be

the fix for leading-edge

erosion?

TOP: The wind tech applies a straight section of the cover. One kit has enough material to

cover three meters of blade edge.

BOTTOM: A wind tech applies the cover to a blade’s leading edge near a tip. The cover

was developed by IER Fujikura.

IF A MAINTENANCE CREW REPAIRS the leading-edge erosion on a wind-turbine blade early enough with the durable cover produced by IER Fujikura, it could be the last time the problem is dealt with. That is the message from the manufacturer of Blaid Protective Sheet, a reinforced polymer material designed for a blade’s leading edge.

The standard kit the company produces covers about three meters of the blade’s leading edge (larger lengths available), and adds only about one pound per turbine collectively to the blades. What’s more, says IER Fujikura Technical Sales Representative Mario Mastroianni, “the material’s adhesive has a wider temperature-tolerance

range than conventional materials, so it extends the working season. That should be good news for crews.”

What’s not so good is the awful beating that blades take. “The tips even on modest 1.5-MW turbines with 77-m rotors easily hit 100 mph along with dust, dirt, salt spray, sand, and in some places abrasive agricultural debris that gets airborne.”

Once the pitting and holes begins, the performance of the blade degrades and eventually, power production suffers. If this damage goes unnoticed the costs of repair could be astronomical,” says Mastroianni. As more large turbines find work offshore, blade problems could well be worse on their larger, faster tip-speed rotors.

When the damage is ignored long enough, suggests Mastroianni, the

most costly repair might be a blade replacement. “One estimate for such an on-shore repair could be $100,000, that includes the cost of the new blade, transport to the site, cost of a crane and crew to install it, and lost production output.”

Most leading-edge repairs are made with an epoxy putty and a gel coat, simple but time intensive. As damage severity increases, so does the required time and cost. The ideal repair would be a one-time task, but most conventional repair materials will require reapplication in a few years at best.

Mastroianni suggests a better material. Although he’s mum on the exact composition, it appears about 1.5-mm thick,

gray on the outer surface with an adhesive on the other. “The advantage here is that a technician need only clean the surface with alcohol, apply the cover which can be removed and repositioned when necessary, roll it tight, and let the bond form.

After a few minutes from the time installed, it will not come off, without applying significant force.

The material’s adhesive has a wider temperature-tolerance range than conventional materials, so it extends the working season. That should be good news for crews.

Most of the turbines in Japan that are flying the IER Fujikura covers are near or on the coast. Weather data for the pictured site is in the accompanying table.


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FROM THE LABA section of Blaid Protective Sheet, the leading-edge cover produced by IER Fujikura, was removed from a turbine after being in service for five years. Cross sections were made and compared to a new piece of material. A cross section of the used piece and new material were magnified 175 times with stereoscopic microscope to observe and measure the thickness of the rubber surface.

The worn material measured 722 µm while the new material measured 711 µm. No significant change in thickness was seen from worn to new. Based on these findings, it was concluded that wear doaes not produce thinning.

The material’s surface was also photographed under a magnification of 175 times with a stereoscopic microscope. The dirty surface was then cleaned and rephotographed.

The picture of the worn surface, (right) shows dirt and grime accumulated after five years in service. Once the surface is cleaned, however, it shows no cracks or roughness. The integrity of the Blaid Protective Sheet has not been compromised.

Turbines in Japan have been flying with the material for over five years and without measurable degradation, he says. Test results from one of the five-year-old covers removed from one of those turbines appears below in From the lab.

The adhesive’s wider temperature tolerance over conventional repair materials let maintenance crews start repair work earlier in the year and work later. However, repair crews that are paid by the job may not be as interested in the development, but crews under contract should find the material a welcome addition to their toolbox. At this writing, Mastroianni says crews are installing the material on turbines in Texas. W

The picture of the worn surface, below (left) shows dirt and grime accumulated after five years in service. Once the surface is cleaned, however, it shows no cracks or roughness. The integrity of the Blaid Protective Sheet has not been compromised.

The weather around a few Japanese turbines flying the Fujikura covering



W I N D W A T C H

Ask a wind tech

WIND TECHNICIANS ARE THE BACKBONE of the wind industry because they climb the towers and keep the turbines running. But where do these dedicated people come from?

In this new series, we’ll interview wind technicians to learn how they got to where they are, and their recommendations for those who would follow in their footsteps. For this first install, we spoke to Paul Ulezko with Diamond WTG Engineering and Services Inc.

Paul, what position do you hold now and what are your responsibilities?I work as an electrical engineer for Diamond WTG Engineering and Services Inc., a group company of Mitsubishi Heavy Industries, Ltd. (MHI). As an electrical engineer, I provide technical support for Wind Turbine Electric Power Systems and work within Diamond’s Wind Turbine Group Engineering Team. My duties include grid compatibility, maintaining turbine performance on the grid, and watching for low-voltage and other transient stability issues. Diamond’s engineering team also drives electrical and power-system improvements, optimizes availability, and eliminates turbine faults. In addition, we work on new product development to enhance wind turbine functionality.

Where did you take your technical training, and how long did it last? I received my bachelor of science degree in electrical and computer engineering from the New York Institute of Technology. I also have a Systems Engineering Certificate from the University of California, San Diego. In addition, I also receive ongoing safety training and practical training in the field. It is the company’s philosophy that one can never have enough training so that when we arrive onsite, we already have an understanding of the issue and how best to tackle it. It isn’t sufficient to just understand the functions of a wind turbine. These are complex machines, combined with the fact that you are working hundreds of feet in the air.

What was your first job in the wind industry, and how did it evolve into your position today? My first wind industry job was designing energy storage that was used at wind farms in Europe. However, I always wanted to use that experience to take me to the next step, which is to work hands-on with these incredible machines. Every day you are challenged to expand your understanding of how motion is converted into electrical energy. It's a constantly evolving process.

If you had the authority and budget, what would you change in the wind industry or on the wind farms you service? Wind farms are going to get smarter. They produce a lot of data and the ability to download that information will allow my company to create more efficient turbines with far longer intervals between maintenance requirements. That means we can offer cost efficiencies which are crucial to our industry.

Lastly, what advice would you give to aspiring wind technicians?My advice is to not let your guard down around a wind turbine. You may get comfortable with your skill in identifying and fixing a turbine but as our training will remind you, safety is first and foremost. Also, work hard to make yourself stand out, and level up technically. W

WHAT DO YOU THINK?

Connect and discuss this and other wind issues with thousands

of professionals online

Paul Ulezko has been a wind technician for four years and with Diamond WTG Engineering & Service for two years.


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Finding a best rotor for a floating vertical axis turbineTHERE ARE STILL MANY ADVANTAGES to Vertical Axis Wind Turbines (VAWTs) over the conventional three-blade designs, especially when considering offshore duty. Engineers at Sandia National Labs are working on models for an offshore VAWT and offered this mid-project report.

“The goal of the project is to advance the rotor technology of large offshore vertical axis wind turbine from concept to lab-scale prototype stage through four major research thrusts,” says project supervisor D. Todd Griffith. The steps include:

1. Innovative aeroelastic rotor conceptual design,2. Deep-water system design and cost analysis,3. Rotor material and manufacturing strategies, and4. Subscale rotor prototype design and testing. The project aims to capitalize on the VAWT advantages for offshore cost reductions while addressing the key VAWT technical, design, and

manufacturing challenges.The overarching project objective,

says Griffith, is to investigate the feasibility of the VAWT architecture for very large-scale deployment in the offshore environment. “The most critical barrier to offshore wind, its high cost of energy (COE), is specifically targeted with the overall goal of achieving a 20% reduction in COE by applying VAWT rotor technology,” he

says. His team will achieve this goal by

• Developing innovative VAWT rotor designs that enable reliable, cost-effective, and easily manufactured rotors for deep-water offshore machines at the 10 to 20-MW scale;

• Demonstrating the potential for greater than 20% reduction in COE for a deep-water, floating VAWT system compared to current shallow-water horizontal-axis wind turbine (HAWT) systems;

• Developing manufacturing techniques, certification test methods, and a commercialization plan for offshore VAWT rotors to accelerate deployment; and

• Testing in a wind tunnel and combined wind-wave tank, a proof-of-concept subscale, deep-water floating offshore wind turbine employing a VAWT rotor.

An initial research focus has been VAWT code development and code coupling, and design studies for VAWT rotor and floating platform. The figure above shows several rotor configurations that Griffith’s team has analyzed. In addition, we have performed structural dynamics and resonance impact analyses to investigate the effect different support structures and number of blades on VAWT vibratory response and vibratory loading, which are key design drivers. Future work includes plans for detailed system design studies and subscale testing. W

VAWTs in deep-water have inherent advantages over HAWTs in deep-water.

The Sandia design studies for VAWT rotors include an assessment of different architectures, numbers of blades, and different material choices.



W I N D W A T C H

This is Generation Wind: A sneak peak at WINDPOWER 2016

WINDPOWER 2016 will include over 100 presentations and sessions for attendees to learn about the latest industry news and technologies.

COLLEGIATE WIND COMPETITION

The inaugural Collegiate Wind Competition took place during AWEA WINDPOWER 2014 Conference & Exhibition,

and it’s back for 2016. The U.S. Department of Energy Collegiate Wind Competition challenges undergraduate students to design and build a wind turbine based on market research, develop a related business plan, and demonstrate knowledge of siting constraints and location challenges for product installation. The theme for 2016 is to design and construct a wind-driven power system that supplies electricity to non-grid connected devices for off-grid applications. Learn more at http://energy.gov/eere/collegiatewindcompetition.

WIND PRODUCED OVER 190 MILLION MEGAWATT-HOURS OF POWER in the United States last year, and the country continues to hold number one spot in the world for wind energy production. Driven by recent tax credit extensions and upgraded transmission infrastructure, current trends point toward meeting the Department of Energy’s first Wind Vision goal of 10% U.S. wind energy by 2020, and more.

As the American Wind Energy Association’s (AWEA) CEO Tom Kiernan said in a recent press statement: “Now more than ever, low-cost, stably priced, zero-emission wind energy is keeping our air clean and cutting costs for consumers. American wind power is well on its way to supplying 20% of U.S. electricity by 2030.” Twenty percent wind power by 2030 is Wind Vision’s second goal, with sights set on 35% by 2050.

To help pave the way in building a stronger wind community and a more successful industry comes the AWEA WINDPOWER 2016 Conference & Exhibition. Enter: This is Generation Wind, the tagline for this year’s event held May 23 to 26 at the Ernest N. Morial Convention Center in New Orleans.

May 23 to 26, 2016Ernest N. Morial Convention CenterNew Orleans, Louisianawww.windpowerexpo.org



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“We have an incredible opportunity to take our industry to the next level and WINDPOWER 2016 is where that happens,” shared Kiernan. “It’s where you generate business and where, together, we generate actionable ideas. This is Generation Wind!”

The focus of this year’s event is education and accessibility. AWEA wants to connect visitors with the latest products, innovations, education, and ideas in the industry, while making it easier than ever before.

Education stations WINDPOWER has always included educational sessions, but for 2016 expect convenience and accessibility unlike past events. This year’s show offers a mix of sessions and individual presentations throughout the week that will take place right in the exhibit hall with access now granted to all registrants.

Five separate stations on the show floor will include:

• Power Station. Here visitors will gain a better understanding of how wind energy experts are pushing for global growth through market expansions and new commercial opportunities.

• Tech Station powered by GE Renewable Energy. Visit the technology station to hear from the top minds in business, academia, and government on innovations in wind that could fundamentally change the industry.

• Operations Station powered by UpWind Solutions. Learn how to analyze management strategies to better address operational lifecycle issues that challenge wind-farm owners and operators.

• Project Development Station powered by AWS Truepower. Exchange ideas and discuss key topics for developing a

DATE EVENT TIME

Monday, May 23 Wind 101: Introduction to 1 to 5pm(Pre-Conference) Wind Energy Opening Reception 5 to 7pm

Tuesday, May 24 Welcome & Opening 9 to 11am General Session

U.S. Wind Energy Market 11:30 to 12:45pm Forecasts Sliding Down the Cost 1:15 to 2:15pm Curve: U.S. Offshore Wind Topics and Trends in Wind 2:15 to 3:15pm Resource & Energy Assessment A Global Buyers’ Market: 4 to 4:25pm New Rules for Component Suppliers

Wednesday, May 25 Advances in 9:30 to 10:30am Interconnection Strategies for Wind Farms

Operation & Planning of the 10:45 to 11:45 am Electric Grid During Turbulent Times

Wind Finance: State of the 12:45 to 1:45pm Art and Where to Next?

International Market Update 2:15 to 3:15pm Poster Reception 4:30 to 6pm

Thursday, May 26 Reliable Ice Detection for 10 to 10:25am Rotor Blades

Renewable Energy Finance 10:30 to 10:55am Emerging Markets

Independent Community 11:30 to 11:55am Engagement Frameworks to Address NIMBYism

HoursTuesday: 11am to 6pm Wednesday: 9am to 6pm Thursday: 9am to 1pm

WINDPOWER 2016: A few conference highlights


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successful wind-power project, including siting, permitting, forecasting, monitoring, connecting to the grid, and more.

• Thought Leader Theater powered by Mortenson. This station brings together industry experts to discuss lessons learned and company successes so others can achieve the same.

Along with educational sessions, WINDPOWER 2016 offers a new forum designed to showcase the latest achievements within the wind industry.


CLEAN THE WORLD At this year’s WINDPOWER 2016, join fellow colleagues in assembling hygiene kits to support the New Orleans Women & Children’s Shelter. Contribute to a positive impact on the local community while networking with fellow attendees!

Five pavilions will showcase contributions made by targeted industry segments that include: Energy Storage, Offshore Wind, Small Business, Distributed Wind, and Product and Innovation Zone.

Emerging leadersThis year’s Generation Wind theme is directed at today’s wind-power professionals — and tomorrow’s. Last year, AWEA unveiled its Emerging Leaders Program, which

uses WINDPOWER as a platform to recognize emerging talent and connect current industry leaders with future wind-power professionals.

The program will expand this year, providing more opportunities for mentorship, knowledge sharing, and skill development. As per AWEA’s site: “Emerging Leaders is designed to help grow and groom the next wave of industry leaders.”

Key features for the 2016 program include:

• Pre-conference seminars where an Emerging Leader can choose one complimentary seminar (such as Wind 101: Introduction to Wind Energy).

• Nearly 20 hours of presentations and panels within the five education stations.

• Meet and greet with AWEA CEO Tom Kiernan and other key AWEA staff, who will provide industry information and contacts from leaders who have volunteered as program Mentors.

• Access to over 100 poster presentations on display with a designated time to connect with the authors to learn more about their work.

• An invitation to an online AWEA Connect community in the works for current and past Emerging Leaders and Mentors to keep in touch and share information.

WINDPOWER registrants and Emerging Leaders will also have access to the Welcome and Opening General Session, which will feature business leaders, political guests, and best-selling author and keynote, Steve Farber.

Listed as one of Inc’s “Global Top 50 Leadership and Management Experts,” Farber is one of the most in-demand speakers and has re-defined what it means to act as a leader of substance and significance. According to his “Extreme Leadership” framework, no matter what is challenging an organization — whether it’s improving customer service, recruiting and retaining talent, building teamwork, or fostering innovation — it all comes down to great leadership.

WINDPOWER 2016 is destined to offer just that — leadership, education, and more — to rookie and veteran wind industry professionals and event visitors.

“WINDPOWER 2016 provides a host of curated networking opportunities. The result is a collaborative, highly effective forum for the exchange of new and exciting ideas, best and next practices, and concrete business opportunities,” said Kiernan. “It’s an exciting time to be part of the next generation of wind energy.” W

Tom Kiernan, CEO of AWEA, speaking out for wind power.

Best-selling author and WINDPOWER 2016 keynote speaker, Steve Farber.


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Investing in American wind powerACCIONA Energy closed tax equity financing with Bank of America Merrill Lynch and acquired the 93-MW San Roman Wind Farm in Cameron County, near the southeast coast of Texas. The project represents ACCIONA’s renewed focus on building renewable projects in the U.S. The power generated will create a more reliable supply of electricity for Texas’ Rio Grande Valley, an area that has suffered rolling blackouts in recent years.

Oregon joins the “50% renewables’club”Oregon’s recent bipartisan decision raised the state energy law to 50% renewables by 2040. States with similar mandates (lightheartedly referred to as “the 50% renewables’ club”) include Oregon, Hawaii, California, and Vermont. The new renewable portfolio standard puts Oregon on track to meet its goal of reducing carbon emissions 75% below 1990 levels by 2050. Portland General Electric and Pacific Power will now generate 50% of their power from renewables by 2040.

Ontario wins five new projectsOntario’s Independent Electricity System Operator (IESO) has selected five wind energy projects totaling 299.5 MW at an average price of 8.59 ¢/kWh as part of its latest request for proposals through its Large Renewable Procurement (LRP) Program. LRP is a competitive analysis process for procuring large renewable projects over 500 kW. It guarantees a high level of competition for renewable procurement while ensuring early community engagement for projects.

New York waters opened for offshore windThe Bureau of Ocean Energy Management (BOEM) has defined a Wind Energy Area in New York waters of 81,130 acres for potential commercial development. The area is about 11 miles south of Long Island, and is part of President Obama’s Climate Action Plan to cut carbon pollution and address climate change. This designation is based on a 2011 proposal from the New York Power Authority to build 194 wind turbines that could generate 700 MW of power.

Wind work around North AmericaThe United States continues to lead the world in wind-power production, according to data by the Global Wind Energy Council and by the U.S. Energy Information Administration (EIA). If EIA’s predictions are correct, wind capacity is forecast to increase by at least 9% this year and 8% in 2017. The country now has nearly 75 GW of installed wind-power capacity, and produced over 190 million megawatt-hours last year with some notable firsts. For example, Iowa hit an all-time high in 2015, marking the first time wind supplied a state with more than 30% of its annual electricity. What’s more is the offshore wind potential in the U.S. is growing with 21 projects now in the development pipeline. For a quick but detailed guide to almost 6,000 MW of planned offshore wind projects, check out http://tinyurl.com/offshore-summary.

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New winds and transmission in TexasFirst Reserve, a global private equity and infrastructure investment firm, acquired the Mariah North Wind power project in Parmer County, Texas, from Mariah Acquisition. Upon completion at the end of 2016, Mariah North is expected to generate 230 MW of wind power with a 13-year fixed price hedge for its power production. The project will include construction of a 27-mile, 345-kV transmission line to interconnect with the ERCOT CREZ system, which represents the first phase of an expected 600-MW development.

Aloha to floating offshore wind power?The U.S. Bureau of Ocean Energy Management (BOEM) is publishing a call for information and nominations to initiate a competitive planning and leasing process for offshore wind power in Oahu, Hawaii. BOEM received three lease requests from two developers: two from AW Hawaii Wind for the AWH Oahu Northwest Project and the AWH Oahu South Project, and one from Progression Hawaii Offshore Wind for the Progression South Coast of Oahu Project. Each proposal is for about 400 MW of offshore floating wind.

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Doubling up on Kansas wind energyMidwest Energy has signed a purchase-power agreement with Westar Energy of Topeka for 57 MW of wind energy from the Kingman Wind Energy Center, scheduled for completion in early 2017. The agreement will bring Midwest Energy’s total wind energy supply up to 106 MW, and means that more than a quarter of the utility’s customer-owned power will come from Kansas wind.

BlackRock strikes deal in New MexicoEDF Renewable Energy (EDF RE) has sold 50% interest in the 250-MW Roosevelt and the adjacent 49.65-MW Milo Wind Projects in New Mexico to a fund managed by BlackRock Infrastructure. BlackRock operates one of the largest renewable investment platforms in the world. The transaction seals the partnership on the final two of five projects that EDF RE and BlackRock have signed deals for over the past year.

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L a r r y F re e m a nB u s i n e s s D e v e l o p m e n t M a n a g e r

E D F R e n e w a b l e S e r v i c e s

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E D F R e n e w a b l e S e r v i c e s

Meeting wind targets with proper asset management Today’s wind farms are large investments that require more than a routine maintenance plan to ensure optimal performance. Asset management provides a more comprehensive plan, optimizing a project’s lifecycle and profitability through a series of good decisions. The role of asset manager takes skill, and a knack for goal-setting and overcoming challenges. Here we detail how asset management has evolved and illustrate a day in the life of an asset manager at a wind farm.


A S S E TM A N A G E M E N T

Asset management is the process of organizing and maintaining projects. In the past, it was not a specific professional activity like it is today but a loosely organized set of best practices at a company. There were no job titles that reflected the term, nor

were there educational programs or degrees for it. But times have changed. One example of early adoption of asset management happened

during the Korean War when the U.S. Air Force began using barrier analysis to probe the relationship between preventative maintenance and failure in the aviation industry. This slowly gave rise to a new way of thinking about important projects and assets.

Although the wind-power industry has different goals than the aviation sector, both industries stand to lose when assets are down. Any wind-farm owner can attest to the importance of a properly managed fleet of turbines. One broken turbine can cost thousands in repairs and lost production time.

The wind industry learned early on about the value of managing assets, although this hasn’t always been an easy task to do well.

What is asset management exactly? Asset management is the art and science of making the right decisions to optimize lifecycle performance and profitability of a project. Management of physical assets is key to long-term operational performance and profitability, as is the management of the financial, technical, contractual, and regulatory aspects of a project.

An asset manager balances costs, opportunities, and risks against desired performance of assets, to achieve organizational objectives. Two reasons this is

The 175-MW Pilot Hill Wind Project is located 60 miles southwest of Chicago, Illinois, in Kankakee and Iroquois counties. The project is situated on the same electric grid that powers Microsoft’s Chicago area data center. It serves as an example of a wind project where asset management is integral to success. Photo credit: Daniel Peters

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A S S E T M A N A G E M E N T

windpowerengineering.com WINDPOWER ENGINEERING & DEVELOPMENT 2 7

more challenging than it sounds: Resource constraints and goals.

Most resources at a wind farm are devoted to high-capacity turbines. However, because a lot of money is on the line, it’s also worth maximizing the returns of those assets and leveraging the right technology to do so (such as predictive maintenance software and preventative maintenance visits, which both cost money). In this sense, asset management becomes a story of sorts told to decision makers in the form of a business case that leads to sound investments in operations, maintenance, and capital spending.

It’s also imperative to consider a company’s goals. All megawatt hours are created equal but no two projects are the same. Depending on who you are (whether a finance company, turbine supplier, or wind-farm operator), goals vary and may have a short or long-term horizon — and ideally both.

Risk versus cost-centered strategyGoals are imperative to good asset management, and will vary depending on company size and project expectations. Risk and cost scenarios are two common considerations as part of a project’s short or long-term goal.

In a risk-centered strategy, a company is likely to pay more for certainty but have greater exposure to potential market exits and failures (think Satcon or Clipper). If working with a smaller portfolio with fewer resources to spare, then choices are more limited and a risk-based approach is more common.

In a cost-centered strategy, reduced cost equates to increased risk but mitigation can occur through effective asset management. This is often seen in larger companies that have more diverse options where it’s possible to drive costs down by allocating risk. For example, a large-scale wind-farm owner might have the means to store four or five gearboxes for an 80-turbine wind farm just in case one goes down. Here, asset management might show that the upfront cost for the gearboxes is worth the money and time saved in waiting for an order after a turbine goes down.

Timeline: A day in the life of an asset manager.

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An asset manager coordination calls to ensure project challenges are met with ease.

A balance-of-plant manager gets details from a wind farm’s Asset Manager so he can properly address an issue with a turbine without delay.

Physical asset management Physical asset management is a system designed to minimize the cost of operating, maintaining, and renewing assets within resource constraints, while balancing an acceptable life of risk to an organization.

To balance risk, one must fully understand their asset, including:

• Performance demand, • Condition and remaining useful life, • Risk and consequence of failure, • Potential repair or refurbishment

options, and • Cost of risk and repair options.

Imagine you have a 1.5-MW turbine and you’re thinking with some minor adjustments or enhanced methods of operation it’s possible to squeeze a little higher performance out of the machine and, therefore, greater production. Sounds great, but first compare this option to your vehicle. Sure, your car might run comfortably at 70 or 80 miles per hour for a brief period — but you don’t drive it that way every day, and you’re not wearing out the engine in the same way at 50 miles per hour.

Pushing a 1.5-MW turbine to its maximum wears bearings, generators, blades, and more. Proper asset management must account for potential long-term effects in this case. For instance, will the gearbox need replacing more than twice over the lifetime of a turbine, and what are those costs? Will the turbine shave three or four years off of its life because it was run above capacity?

Asset management involves balancing costs, opportunities, and risks against desired performance of assets to achieve organizational objectives, and this balancing act must be considered over time.

An understanding of assets provides greater confidence that

investment decisions are of the lowest lifecycle-cost strategies for sustained performance at an acceptable level of risk.

Case in pointOn paper, asset management might sound simple enough. But the real life of an asset manager — especially of a wind company — is a strategic act of planning for and facing challenges, and finding answers that fit demands and budgets.

Here’s a snapshot of the day in the life of an asset manager based on real events.

A new wind farm was having a typical first six months of commercial operations, which (as most new wind-farm owners might attest) is to say, nothing was going according to plan. There were no show stoppers, just routine “emergencies,” including telemetry interruptions caused by

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a faulty fiber converter installed by the transmission operator.

The project’s energy settlement statement was off because of an issue with a scaling error on the meter agent’s end and an incorrect rollover value. Plus, there was a safety stand down during break-in maintenances because of some questionable documentation provided by the installer of the climb assist.

But these are all typical issues, especially at a new wind farm that an asset manager must manage as part of his or her job.

Among managing day-to-day operations, an upcoming plant outage was also planned at this wind farm to update relay software to meet a more aggressive seasonal voltage schedule. Coincident with this outage, a final points checkout was scheduled with all parties receiving data from the plant. This provided an ideal opportunity to audit the final list of data points to suit specific needs of the counterparties and memorialize the configuration in the plant engineering log.

The outage was scheduled for eight hours with a three-day window, when winds were forecast at their lowest. In preparation, notice was given to the transmission operator, the energy forecast was adjusted accordingly, and assurances were made that everyone would attend as necessary (including the offtaker, turbine OEM, balance-of-plant manager, and the project‘s control-room operator.).

At first, the shutdown went according to plan. The team ramped down the turbines, opened the feeder breakers to isolate the main power transformer from any load, and then proceeded to open the high side air-break switches. But one of the phases arced, resulting in visible damage to the contact jaws. A hole had burned right through the contact plate, and the entire assembly required replacement.

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Unfortunately, no one on the EPC (engineering, procurement, and construction) side was available for repairs for another two days. Despite risking the warranty, the project’s asset manager had another high-voltage company onsite as soon as possible.

A call was also made to the transmission operator to ensure the project’s transmission line was

disconnected from the substation, and to the OEM of the failed switch to find out how soon a replacement part could arrive onsite. The parts were machined and awaiting heat treatment, but could be on route the next day (accompanied by a factory representative).

At this point, the project’s asset manager also had to: estimate the outage and return of service time,

update the most recent wind forecasts, predict the production losses — and call the wind-farm owner with the news. A brief rundown of the event, damage, probable cause, solution, and a summary of the financial impact, and a schedule of activities over the next crucial hours.

Once the wind farm was back online (which successfully happened the

next day), follow up reports, warranty claims, debriefings, and a “lessons learned” session would occur with the affected parties.

As we said, this a typical day in the life of a wind-farm asset manager. Imagine one in which more than a few problems crop up and good asset management becomes key to a wind-farm’s success or failure. W

Goals are imperative to good asset management, and will vary depending on company size and project expectations.

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A better anemometer gives more accurate wind measurements and monitoring

R E L I A B I L I T Y


K a r l F a t rd l aH e a d o f S a l e s

R O M O W i n d A G

Although intended to measure wind speeds, conventional anemometers often provide imprecise data. On a wind turbine, these devices are mounted on

the nacelle behind the rotor. But this placement can provide distorted measurements because of potential for wind effects from the rotor and nacelle. This makes attaining accurate wind speed, direction, and turbulence intensity measurements next to impossible. Reliable detection of yaw misalignment and performance monitoring are important for gaining insight into the wind, which is key to operating efficient and high-performance turbines.

Fortunately, a new ultrasonic device is available that can measure wind parameters that until now have proven difficult or impossible to measure accurately. The Spinner Anemometer (iSpin) measures wind speed and yaw misalignment in all wind sectors, and can increase the energy output of turbines by measuring and correcting yaw errors. iSpin sensors measure wind reaching the turbine at the spinner — where the wind hits the rotor. As such, the sensors can provide precise information about wind speeds, air pressure, and temperature.

The designiSpin consists of three specially designed ultrasonic wind sensors installed at the front of a turbine, where the wind

hits first. Here, wind is only influenced by the induction effect (slowing of the wind) caused by the turning rotor and its passage over the spinner and deflection on the symmetrical spinner body. These effects are predictable and correctable by means of calibration.

Simultaneous measurement of precise wind speed, yaw misalignment, inflow inclination angle, and turbulence intensity at the point of impact with the rotor are unique features of this system, not currently available from other anemometers on the market.

By detecting even small changes in power curves, iSpin can verify performance optimization measures (such as YMA corrections or rotor power-ups by applying vortex generators), and provide a continuous sequence of power-curve comparisons to enable reliable performance monitoring.

In a recent R&D project, together with the utility Vattenfall and the Technical University of Denmark (DTU), iSpin was verified against an IEC-compliant wind met mast to demonstrate that it can measure absolute power curves according to IEC 61400-12-2. The IEC, or the International Electrotechnical Commission, is the global standard and conformity assessment body for all fields of electrotechnology. IEC 61400-12 is the standard measurement procedure when assessing the power curve of a wind turbine.

The iSpin power curve of the investigated turbine showed only a 0.4% difference from the IEC-compliant wind met-mast measurement, based on a calculated annual energy production (AEP) for a site-typical wind climate. Power-curve measurements with the iSpin equipment on the other turbines at the site (unrelated to the met mast) showed an average power-curve deviation of 0.4% from IEC’s met-mast measurements.

The demonstrated reliability of the iSpin’s transfer function means it can transfer to other wind turbines without major losses to measurement data or quality. Through comparison measurements with a met mast (a free-standing meteorological tower), the iSpin showed an ability to measure wind speeds accurately in a 360° range around a wind turbine. Therefore, the device is not limited to undisturbed wind sectors only.

Anemometer comparisons took place on a Vattenfall’s wind farm with this turbine arrangement.

The wind farm

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Wind-speed correlation graphs

Comparison of wind measurement methods


When data was used without filtering for wake directions, the resulting AEP values from the iSpin power curves were still in the range of 0.1 % relative to the IEC-compliant met mast measurement results and with an average deviation of -0.3%.

The testFor the R&D project, evaluations took place at a Vattenfall wind farm that consists of 13 Siemens turbines with 2.3-MW rated power and 80-meter hub heights. The site is characterized by flat terrain and located on the southern coastline of the Limfjord area in Denmark.

All turbines were equipped with spinner anemometers to conduct power-curve measurements, according to IEC 61400-12-2. Additionally, a normal IEC 61400-12-1 power-curve measurement using a met mast was performed for verification purposes on one reference turbine (#4). The distance from the met mast to this reference turbine was IEC compliant at 234 meters.

The data for the IEC verification of the power curve has been limited to the free wind sector of the south (101° to 229°), where the upstream terrain is flat and without significant obstacles.

Sensor calibrationiSpin measures wind speed and direction on the surface of the spinner. This is influenced by the geometry of the spinner itself (deflecting the wind direction) and the induction effect of the rotor (slowing down the wind stream).

The wind direction measurement is easily calibrated without an external reference measurement. The aerodynamics around the spinner provide for self-calibration by introducing a sequence of controlled yaw angle errors to the turbine.

What proved interesting for the IEC power-curve measurement was calibration of the free wind speed measurements. These must be done once for a specific turbine type by conducting a comparison

with a reliable reference measurement from an IEC-compliant wind met mast. This transfer function describes the transition from “rotor wind speed” (as measured

directly by the iSpin sensors) to “free wind speed” (as measured by the wind met mast), and is determined in two steps (see graphsbelow Wind-speed correlation graphs).

Linear calibration of wind speeds for the high and low wind speeds only, and not the induction of the rotor. (Step 1)

Forward looking wind measurement Local wind measurement

Non-linear calibration by the methods of bins calibration, as described in IEC 61400-12-2. (Step 2)

Power curves in undisturbed wind sectorsPower-curve measurements were conducted at the reference turbine (#4) for four wind-measurement systems: Met mast, nacelle-based LiDAR, nacelle anemometer, and iSpin. IEC standards were applied as necessary (for example, nacelle-based LiDAR’s are not part of the IEC standard).

None of the power curves were corrected for turbulence intensity or wind shear, but were measured on the basis of a site-specific wind climate.

In this comparison, the iSpin power curve resulted in approximately 30% less scatter

than all other measurement systems. Based on differences between the IEC met-mast power curve, warranted power curve (provided by the OEM), measured power curves of the LiDAR, and iSpin wind measurements, the results were derived for turbine #4 (see the




Forward looking wind measurement Local wind measurement

(once determined for the turbine type based on a calibration with an IEC-compliant met mast) can reliably transfer to other wind turbines of the same type.

Full-range power curvesIn contrast to met-mast and nacelle-based LiDAR systems, the spinner anemometer has an ability to measure the correct wind at hub height and in wake conditions. Forward-measuring devices, such as met masts or LiDARs face a challenge, especially in wake

effects: the measured wind speed cannot be considered free wind speed (which becomes deteriorated from the turbine in front) and, therefore, are not comparable in non-free wind sectors.

But iSpin wind measurements have proven much less prone to deteriorations from these influences. Why? The calibration procedure with an IEC-compliant met mast first stores the information on a flat site that’s undisturbed by obstacles (and stored in the iSpin controller). So, whenever iSpin is applied to the same turbine type in more complex terrain or higher winds, it is measured in the wake of the stored calibration factors. The transfer function then translates wind hitting the spinner into “free wind.” This explains why iSpin can also determine power curves and turbine performance information in all wind sectors.

For this measurement, power curves for the reference turbine were calculated including data from all wind directions. For illustrative purposes, the met mast and LiDAR results are shown (in Comparison between wind measurement methods in all wind sectors), however, wind-speed measurements are misleading when a turbine or the met mast is in wake of another turbine.

By comparing the iSpin power curve with all wind sectors to the IEC-compliant met-mast power curve using only the free

Comparison of power curves in the undisturbed wind sector

Note: “Wind sectors” refers to the fact that following the IEC standard, it’s only possible to measure power curves in so called “free wind sectors” or “undisturbed wind sectors,” which need to be bare of any obstacle in the 2.5 RD distance from the turbines. So, each wind direction that does have an obstacle (such as trees, buildings, or other wind turbines nearby) must be excluded. Usually the 360° wind rose is segmented in 12 sectors with 30° each. The free wind speed range for this project was determined with 101° to 229° (south-east-east to south-south-west, approximately).

Comparison with other turbines: Undisturbed wind sectors only

Comparison between wind measurement methods in all wind sectors

Comparison of power curves in the undistributed wind sector graph). Note the nacelle-based anemometer was excluded because of high uncertainties.

To demonstrate the reliability of the transfer function of iSpin, it was essential to carefully and accurately employ the calibration factors and transfer function from the reference turbine to other turbines of the same type at the wind farm. The results of this comparison clearly showed that the iSpin transfer function and calibration factors


Roto Clip - 12-2015.indd 1 4/6/16 2:00 PM



Comparison of power curves in all wind sectors

sector demonstrates the unique capabilities of the iSpin system. The spinner anemometer’s power curve does not materially alter when measuring wind speeds in all wind sectors.

In much the same way as for measurements in the undisturbed wind sectors, it’s essential that the transfer function calibrated was reliable enough to be transferred to other turbines of the same type. W

For further readingi Refer to http://romowind.com/en/knowledge-centre/#performancemonitoring for detailed information on the test set-up.

ii See K-alpha calibration method in http://romowind.com/media/Calibration-of-a-spinner-anemometer-for-yaw-misalignment_we.1798.pdf

iii In regard to the LiDAR deviation, refer to the explanations given in http://romowind.com/en/knowledge-centre/#performancemonitoring

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B O L T I N G

Lighter weight components and hydraulic torque tools improve wind power safety


As the wind industry grows and turbines are built larger, safety issues grow right along with them. One way to make turbines safer to work around is to lighten the weight of

components and construction tools that assemble them. In 2013, Windpower Engineering &

Development magazine, wrote about a company called Victrex whose (polyaryletherketone) peek polymers are “said to be a good choice when replacing (some) metal wind-turbine components.” The logic is simple: “the high-performance and light-weight material allows up to a 70% weight reduction,” for some parts [Source: http://www.windpowerengineering.com/design/materials/light-weight-tradeoff-polymer-for-steel/]

Light weight for the wind industry Light-weight components have helped advance turbine technology and led to a more reliable and cost-efficient industry. Light-weight tools and components required for the maintenance of wind farms also enhances safety, which is a growing concern during the assembly of wind turbines. For example, the UK’s Caithness Windfarm Information Forum of 2015 highlighted a steady increase in wind farm accidents. For the complete report: http://tinyurl.com/wind-accidents

NOMINAL PITCH, DIAMETERSDIAMETER MM MM INCHES

M36 4 36 1.4173

M42 4.5 42 1.6535

M48 5 48 1.8898

M64 6 64 2.5197

M100 6 100 3.937

Coarse threads

Companies such as Victrex and AMG Bolting Solutions have taken inspiration from the global shifts in power generation without losing a focus on safety. In a recent blog post, we stated, “While it is important to make lighter weight hydraulic and pneumatic torque-wrench tools to improve ergonomics, it is critical to make light-weight ancillary products such as hydraulic torque pumps and swivel-friendly hoses to help save lives.” The comments continued: “Along with fall protection, you need fall prevention.”

Sadly, fasteners are given little attention in the wind industry. A faulty or improper installation, or both, can lead to major costs and safety risks.

Lighter-weight bolts (they do exist) are easier to install and maintain, and they reduce the stresses placed on the integrity of bolted joints. But here is the problem: There are no required North American

The Dynamic focuses on safety by providing a light-weigh hydraulic torque pump that improves the ergonomics of using hydraulic torque wrenches.

The TTZ low profile cassett series is intended for work that requires the accuracy and joint integrity from tightening bolts in confined space.

Bolting_3-16_Vs2.indd 38 4/6/16 2:58 PM

B O L T I N G


codes for structural-steel connections to correctly install wind turbines with metric bolts. The codes that do exist are solely written for bolts up to 1.5-in. diameter.

Considering that wind turbines require flange splice bolts of M36, M42, M48, and M64 diameter with Grade 10.9, and other segments of a wind turbines and yaw foundations required M100 bolts for installation, no code essentially means – “Houston, we have a problem.”

This is especially challenging in the wind industry, because bolted connections on a wind turbine are exposed to extreme vibrations and dynamic loads.

Matters get worse according to Kulak’s, Fisher’s, and Struik’s, “Guide to Design Criteria for Bolted and Riveted Joints,” (2nd edition: John Wiley, 1987) “Our research found repeated installation of A490 bolts [whose property class is similar to 10.9] achieved the required tension upon initial installation, and one cycle of re-tightening.”

Although the wind industry has strict requirements for annual torque checks on bolts, the study also showed that after repeated tightening, the same bolts showed a sharp decline of induced tension. Fortunately, a group of companies have found an answer.

Light-weight innovations, synergistic solutionsDokka Fasteners has been serving the wind industry for over 30 years. It has developed heavy-duty, yet light-weight bolts for every section of a wind turbine that requires “large bolts.” Furthermore, Nord-Lock, a 100-year old manufacturer, produces specialty

MATERIAL YIELD STRENGTH TENSILE STRENGTH

10.9 MPa ksi MPa ksi 940 136 1,040 150.8

A490 896.3 130 1,034 to 1,192 150 to 173

A brief comparison of bolt material strengths

washers. In 2014, the two companies teamed up to create an innovative, “No Need For Re-Tightening” [NNFR] kit.

The idea is simple, a wedge washer keeps a bolt from slipping over time as long as the bolt stud and nut are lubricated, and accurately torqued and tensioned. The NNFR kit includes pre-lubricated Dokka Fasteners bolts, Nord-Lock wedge washers, and tips on what to tighten with a hydraulic torque wrench versus what requires a bolt tensioner.

For example, you can use a hydraulic torque wrench such as the TTX Square Drive Series on sections of a wind tower such as the nacelle where torque, not pre-load tension is required.

Meanwhile, the kit suggests using Boltight tensioners on areas with wind-turbine base bolts, where stretching the bolt stud is the best practice.

Innovation in light-weight components and fastening tools are contributing to the success the wind industry is experiencing. With a future focus on mass storage technology, and increased vigilance toward personnel safety, wind power can contribute to what some would say is part of “Making America Great Again.” W

TOP: When properly applied, Nord Lock washers keep bolts on wind turbines accurately tightened.

BOTTOM: The Torc TTX Square Drive series is intended for work where accuracy and joint integrity of tightening bolts is the optimal requirement.

Bolting_3-16_Vs2.indd 39 4/6/16 2:58 PM

B r i a n R o t hP r o d u c t M a r k e t i n g E n g i n e e r

A n t a i r a Te c h n o l o g i e s

I N T E R N E TO F T H I N G S

Talking with turbines through the Internet of Things


This diagram shows how industrial networking equipment is used to connect a wind-turbine’s nacelle to the base of a tower and create a redundant network between turbines at a wind farm. If a link fails, data can re-route the opposite direction using the redundant path.

Chances are you’ve heard the term “Internet of Things” (abbreviated as IoT), which refers to a shared network of data and connectivity between devices, software, and even

buildings or structures. IoT can turn off the oven after you’ve left home, remotely switch on or off office lights or computers, and even help you find your keys.

However unlike light switches, failures that occur in remote locations such as at wind farms may result in interrupted power generation that can lead to decreased productivity and increased system downtime and costs. Fluctuating energy prices make optimal project efficiency and uptime critical to a

wind farm’s profit margins and bottom line.Through remote access, IoT can bridge the gap

between a wind farm located several hours or even days away and a local control center with access so attendants might adjust switches, software, or equipment from a distance. IoT gives wind-farm operators control to monitor and regulate much of a turbine’s operation no matter how much distance separates the two.

Why industrial networking?The industrial Internet of Things represents an advanced ability to access information and data from machines, sensors, and controllers connected

IoT_3-16_Vs2.indd 40 4/6/16 3:04 PM

I N T E R N E T O F T H I N G S

WINDPOWER ENGINEERING & DEVELOPMENT 4 1

to the Internet. Connected systems and devices can collect, exchange, monitor, analyze, and act on information to intelligently make changes with little to no human intervention.

IoT is possible in part because of a mass transition of industrial-grade equipment using an Ethernet data medium as a main link to networking infrastructures. Ethernet is the most widely installed local area network (LAN) that lets devices format data for transmission to other devices on the same connection.

Through access links such as Ethernet, but also fiber optics, wireless, and LTE (or “long-term evolution,” which is high-speed Internet), today’s Internet is faster, more affordable, and more widely used than ever before. The result is that even remote locations now have access and connectivity options — and where there’s Internet, IoT is possible.

An industrial-grade network infrastructure offers wind-farm operators many benefits, including improved operational management, access to real-time data, network security features, and automatic system warnings. These features provide real-time data, control, and secure access from remote locations.

IoT gives wind-farm owners or operators an ability to monitor and analyze onsite data on a daily, monthly, and even yearly basis, and can provide a detailed look at individual turbine performance. Based on this data, an optimized maintenance strategy can prioritize turbines that experience less than expected performance losses and therefore minimize downtime.

However, because wind farms are typically situated in extremely remote locations, equipment and networking reliability is critical. Transmission errors or delays could result in unnecessary maintenance delays.

Industrial-grade networking must be designed for rugged environments and support long mean times before failure

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Tree Protocol (RSTP) and an Ethernet Ring Protection Switching (ERPS) ring.

RSTP provides a mesh network topology where individual nodes relay data to the network. This means RSTP is resilient and capable of operating throughout multiple points of failure. But it also has a network recovery time of about 30 seconds. Should that outage delay generate concern for a wind-farm owner because it results in a gap in power production and data collection, ERPS provides another option.

Implementing an ERPS ring in a managed industrial Ethernet switch means it’s possible to achieve recovery times of less than 50 milliseconds during a link failure. Impressive, but the downside is that an ERPS ring is only capable of having a single point of failure.

Fiber-optic supportWind turbines are equipped with a control cabinet that holds a programmable logic controller (PLC), inverter power source, human machine interface (HMI), and I/O devices at the base of each tower. At the top of the tower or nacelle, several sensors detect wind speed, wind direction, and shaft rotation speed.

To maximize wind power, it’s imperative that the data collected from sensors are analyzed quickly and turned into “actionable insights”— meaning each turbine can adjust its settings accordingly, based on data it receives from the system. A reliable connection lets a turbine continually assess and account for changes in wind speed, temperature variations, and vibration to best optimize power generation.

However, the communication path from a nacelle to the base of a turbine has some of the toughest communication challenges to overcome because of the distance. Sometimes it is possible to successfully use shielded Ethernet cables to provide a data link. Ethernet cables can provide communication links for about

rates — typically greater than 100,000 hours. All controls and Ethernet equipment must withstand extreme temperatures, lightning strikes, and potential electrical interference from high-power turbines.

Industrial-grade networking is key because keeping a network up and running at all times is imperative to successful wind-farm operations and production revenues.

A redundant pathFor networks containing multiple end devices (in this case, wind turbines), industrial-managed Ethernet switches with built-in fiber ports provide a ring-redundancy architecture. This design prevents loss of control and data to the wind farm in the event of an unexpected link failure.

Multiple fiber ports on the switch in the control cabinet are found at the base of a wind turbine, and provide at least two connections to the redundant ring. One or more additional fiber ports are usually available to run fiber to the nacelle to connect sensors and other devices.

If a switch fails, a connector disconnects, or someone cuts a cable, or if another unforeseen type of disruption occurs, the system automatically routes data around the problem using the redundant path. The design works to proactively safeguard against potential failures while assuring network uptime.

Network administrators can choose between multiple ring topology standards, depending on their application needs. For example, a wind-farm owner might choose between a Rapid Spanning

This diagram shows IoT at work and just how quickly remote data from a wind farm can reach a technician, regardless of distance.


IoT_3-16_Vs2.indd 42 4/6/16 3:04 PM



330 feet, well within the range of most wind turbine heights.

A fiber-optic link can also offer electromagnetic interference or EMI immunity, which is important in turbines. Considerable EMI often exists in a wind turbine because of the ongoing generation of power. EMI can negatively impact communication and corrupt or completely lose data, especially if only Ethernet cables are used in a network.

Fiber-optic cables are also beneficial in mitigating potential damage caused by lightning strikes and can prevent strike effects from propagating to other pieces of equipment in the turbine.

Advanced management & IoTThe size and remote location of most wind farms are no longer the same concern as before the Internet of Things. An industrial networking system

and remote data collection and communication provides real-time troubleshooting and advanced management at wind sites.

Should issues or equipment failures occur at a wind farm, detection and recovery time is reduced significantly. What’s more, data collection can lead to predictive operations and maintenance — or advanced management — of turbines so failures are caught before causing turbine downtime.

Implementing industrial-grade managed switches at wind farms makes additional software

features available through the switch’s Web interface. This improves data flow, network traffic, and equipment performance.

Some of the more commonly implemented features include:

• IGMP snooping, which monitors traffic on a network, creating and maintaining a map of what pathways use multi-cast traffic streams. Some common pieces of equipment that send out multi-cast traffic are security cameras and PLCs. By learning where network traffic goes, the switch is able to filter multi-cast traffic and send it only to locations that require it rather than sending it all over the network, which greatly reduces bandwidth consumption.

• Quality of Service (QoS) prioritizes network traffic so that when congestion occurs, higher priority traffic takes precedence. QoS can help with error rates and transmission delays.

• Network redundancy is an important system safeguard where a component is duplicated so if it fails there is a backup.

• VLANs are virtual local area networks. These can divide or segment a network through software to create smaller and seemingly isolated networks for better management and security. For example, security and surveillance monitoring, control data, and management overview can flow through separate VLAN’s that are then directed to the appropriate parties. This provides additional control over a site and prevents someone in the surveillance-monitoring department from accessing the control section of the network. VLANs also reduce the amount of network bandwidth consumed. Additionally, if a security threat or denial-of-service attack affects one VLAN, the threat will not spread to other VLANs on the network.

• System warnings from industrial-managed switches let users implement warnings and email alerts for various events, so operators are alerted remotely and can respond faster to important networking issues.

Industrial-grade networking equipment provides a high degree of reliability and control pertinent to smart energy-management systems and offers a variety of solutions to the unique networking challenges at wind farms.

Industrial-grade networking equipment is intended for rugged environments and used at many wind sites because it provides redundancy, fiber optic support, and advanced software management features that make a reliable and easily managed IIoT network possible. W

Antaira’s LMX-0804G-SFP" is a managed Gigabit Ethernet switch with four copper and four fiber ports.

IoT_3-16_Vs2.indd 43 4/6/16 3:04 PM

D a v i d C l a r kP r e s i d e n t

C M S W I N D

C O N D I T I O N M O N I T O R I N G

Where the often quoted ISO 10861-21 falls short for CMS


There is dire need for the system certification of condition monitoring, mostly because current CMS vendors offer at least nine different approaches for basic sensor

selection and placement. This confusion originally prompted the call for a certification for owners to assist in the selection of a viable CMS for wind.

After speaking at recently NREL and UVIG events, I was asked if there was a certification for CMS systems in the wind industry. The answer is yes…and no. To investigate further, we will go through the available standards for CMS in wind to find what is helpful.

The standard for vibration in wind turbines is listed as ISO 10816-21. This ISO standard states it “does not apply to diagnostics or fault detection.” It also states that the vibration “evaluation zone boundary values are not intended for use as acceptance values. These must be agreed upon between the manufacturer and user.” So how does the standard help?

To be clear, if you adhere to ISO 10816-21, there is no guarantee you will have a successful CMS program. Also note that the standard

applies to a rather wide range of wind turbines, from 200 kw up to 3-MW ratings.

So, what does the standard suggest regarding monitoring? It suggests the use of piezoelectric accelerometers and separates equipment into rotating and non-rotating components.

For rotating components, the standard suggests:Sensor placement – For rotating components (drive train is a given), it advises the use of sensors in three axis across the drive train. This is not standard for many reasons. Using accelerometers in three axes is not beneficial in determining a failure component. A single sensor can work except when determining some defects. However, as this standard states, its purpose is not intended to measure specific defects.

The main bearing – Three-axis measurements are recommended but not demodulated readings for detecting early bearing defects, nor time waveform measurements. The standard makes no suggestion for the number of lines-of-resolution in the spectrum, averaging, or overlap.

CMS DIFFERENCES ISO COMMERCIAL CMS Number of sensors on the drive train 17 7 to 8 Number of sensors on non-rotating components 8 0 Number of measurement types 2 5 to 6 Number of sensor axes 3 1 Measurement time 10 min. Much less than 1 min. Measurement parameters (resolution, averaging, overlap) Notclearlydefined Defined Alarm parameters Notclearlydefined Defined Estimated cost per turbine $20,000+ $7,000 to $10,000

How the ISO standard differs from what is usually applied

Condition Monitoring 3-16_Vs2.indd 44 4/6/16 3:06 PM

BACHMANN SUPPORTS ALL ASPECTS OF CONDITION MONITORING

• Integration of condition monitoring to existing Bachmann controllers• Stand-alone condition monitoring• Remote monitoring and analysis• End of warranty vibration inspection

Bachmann electronic Corp. | 529 Main Street, Suite 125 | Charlestown, MA 02129, USAT: +1 (617) 580-3301 | [email protected] | www.bachmann.info

Condition Monitoring

More Profit, Greater Production

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C O N D I T I O N M O N I T O R I N G


Gearbox – Three-axis measurements again but no demodulated reading for early bearing defect detection nor time waveform measurements. No suggestion for lines-of-resolution in the spectrum, averaging or overlap.

Generator – Three-axis measurements yet no demodulated reading for early bearing defect detection nor time waveform measurements. No suggestion for lines-of-resolution in the spectrum, averaging or overlap.

Number of sensorsIt is not practical to use the suggested 17 sensors across the drive train. Typically, most commercial CMS systems use 7 to 8 sensors. Seventeen of them are cost prohibitive. They will also generate too much data. Consider that 7 to 8 sensors installed on 100 towers will produce an annual data volume is in excess of two-million measurements based upon once-a-day intervals.

Using three sensors on a generator bearing to find a bad bearing within is simply not practical. Installation costs go up, data volume increases, hardware costs double, and network load increases as well to get the data out. So this portion of the specification is simply not practical.

On Non-rotating equipment:Sensor placement – The standard suggests three axes in two locations to monitor the bedplate of the tower for structural purposes. This is more for a process

and controls purpose than a condition-monitoring function. Most bedplate monitoring I have been involved with is at a prototype level, certainly not at a fleet level.

Number of sensors – The standard specifies installing eight low-frequency sensors. Again, as with 17 sensors on the drive train, adding eight expensive low frequency sensors is not a good suggestion. It is doubtful that any owner would install eight sensors per tower to understand the vibration of the structure.

Measurement parameters – The standard suggest performing evaluations in 10-minute periods. This really requires specialized equipment. It is certainly not something that is fleet advisable. At 10 minutes per tower, the data volume would be significant, and the data storage and analysis substantial.

Vibration levels – The standard suggests measuring only acceleration and velocity. The accompanying chart (above) shows overall vibration levels in velocity measurement units.

Other standardsISO 10816-21 standard does not give the end user guidance for acceptable vibration levels, diagnostics, or fault detection. So what can it offer the owner? It does advise as to structural vibration measurements and parameters as well as sensor types and placement. To be clear, not one CMS system commercially available today, marketed and installed, meets this standard.

However, portions of two other suggested standards might be helpful to owners. They are:

• VDI 3832, for rolling element bearing noise and vibration. This also has a wide range of application in wind turbine size. And,

• ISO 13373-2, techniques for bearing and gearbox defects analysis.

So between rotating and non-rotating components, the suggested 25 sensors per tower is literally three times the amount normally installed. Owners show pause at the current eight-accelerometer pricing per tower. Twenty-five is likely not realistic.

Here is what’s missing and crucial to a successful CMS program:

Quality of the sensors – There are at least 10 to 12 sensor factors that are not covered. Cables are not even discussed.

Ability of the software – There are no specifications on measurement parameters, measurement types, resolution, averaging, and a dozen other measurement factors.

Ability of the analyst – There currently are three companies that certify vibration analysts. It certainly makes sense to have an analyst who is certified but this is no guarantee that the person is a good analyst. Ironically, the certifying bodies that teach the theory and background of vibration analysis measurements, teach very little on actual vibration analysis.

We will discuss these important factors in a following article. We will also look at what makes sense for a standard for CMS installs to benefit the owners, ISPs, and manufacturers. W

Most wind turbines would fall under Class IV. But it is important to note that this is a rather wide classification from 200 kw up to 3 MW wind turbines. This is similar to comparing a small car to a semi-truck. Also understand that the vibration levels in a wind turbine will not indicate a problem especially at indicated vibration levels.

Condition Monitoring 3-16_Vs2.indd 46 4/6/16 3:06 PM

PSI offers expert repair and product upgrades for GE, Vestas, Siemens and Clipper wind turbines. Our highly skilled engineers improve legacy design with newer, more reliable technology for problematic parts like printed circuit boards, pitch drive systems, inverters, and IGBTs, resulting in longer life. The cost-savings don’t stop there, either. PSI also remanufactures unsalvageable and obsolete parts, and manufactures custom-designed products to improve uptime performance.

Extend the life of turbine parts and keep downtime to a minimum.Call PSI today at 800-325-4774, or visit psi-repair.com.

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Were any of your turbines hit by lightning? This system has clues

S O F T W A R ES h y l e s h M u r a l i d h a r a n

G l o b a l M a r k e t i n g M a n a g e r S c h n e i d e r E l e c t r i c


Weather and asset management go hand-in-hand in the energy industry, and especially when monitoring the impact of severe weather. Flooding, high winds, snow, ice

and of course lightning knocks out power delivery to thousands and cost energy companies millions in short and long-term asset repair, replacement, and upgrades.

As the fastest growing source of energy in the world, wind farms face many of the same weather related challenges as utilities. The harmful threat of lightning is no exception. It is the leading cause of turbine blade damage, and often the leading cause of unplanned turbine outages.

Lightning poses a particular challenge for wind-farm operators because its specific geographic impact cannot be forecast, and even when using lightning tracking software, the damage caused by a strike is often nearly invisible without close inspection.

But despite the fact that weather services for the energy industry have significantly advanced in their accuracy and even their ability to forecast weather along with anticipated damage from coming storms, wind farm operators still face the challenge after a storm of deciding whether to manually inspect every turbine in the storm’s path for lightning damage, or risk operating a damaged turbine which leads to more problems down the road.

New weather technology, however, is available to give wind farm operators more specific weather predictions, specifically analyzing the likelihood that the

turbines within a designated radius were struck by lightning. This lets wind farms better assess damage following a storm and enact a more efficient inspection and repair plan, greatly alleviating the guessing game.

Without the assistance of a lightning strike locator, crews might spend their time unproductively inspecting turbines that likely were not hit.

Mother nature has been busy. Each dot represents a lightning strike and location. Maps of this sort, overlaid on wind farms can guide maintenance crews to the turbine most likely hit.

When lightning strikesThe biggest challenge of lightning strikes comes from the fact that damage is often small, but when unaddressed, can grow into

Software_3-16_Vs2.indd 48 4/6/16 3:16 PM

WHAT DO YOU THINK?

Connect and discuss this and other wind issues with thousands

of professionals online

a much bigger problem – one that could result in spending hundreds of thousands of dollars to replace a blade.

Aside from the economic cost, lightning detection effects energy output, as well. The more time it takes to locate which blades were struck by lightning, the longer the turbine will be out of operation. This directly results in a loss of generation. Faster maintenance and repairs from more accurate damage assessments help maximize wind-farm generation output by reducing down time from inefficient maintenance.

The critical development enabling such specific and granular weather-related damage assessments is the overlay of GIS-mapped assets with accurate weather data. An accurate strike assessment can be generated, down to a specific asset, by combining accurate lightning-strike data with turbine locations.

To get started, wind operators would provide a list of all wind turbines across one or more farms. A catalog is created that includes the specific geo-location of each turbine. After a storm, this catalogue can be compared to

Tables of this sort sent to maintenance crews lists the turbines that may have been hit by lightning. An inspection might begin with Crosswind turbine T05.

the recorded latitude-longitude of the lightning strikes, and compiled into a list.

When a strike occurs near a turbine, the system generates a report that provides operators with the exact location and how far, in meters, the lightning was from the turbine, polarity (positive or negative) of the strike, and the amplitude (a measure of electrical current or intensity) of the lightning. The accompanying table provides a report example.

Every 24 hours, the system generates a new list for operators to access. When the O&M manager starts planning the day’s maintenance schedule, that person can now prioritize which turbines to inspect first by noting the proximity of the strike, focusing effort on those turbines most likely to have been damaged.

Looking ahead Asset-specific weather threat assessments are not only critical for wind farm operators but for the utility industry as a whole. Using the same methods as wind farm operators, utilities can work with weather system services and


S O F T W A R E

partners to generate after-action storm damage reports, and pre-storm threat assessments to specific assets to give outage management planners the best information to create safer, faster and more efficient response efforts.

The energy industry can now plan ahead to improve reliability and decrease costs. With increasing weather volatility and pressure on asset management budgets, this capability is critical for understanding weather’s impact on assets and how best to manage them. W

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Alstom Haliade 150-6MW, first utility-scale wind turbine to work in U.S. waters

T U R B I N E O F T H E M O N T H P a u l D v o r a k

E d i t o r i a l D i r e c t o rW i n d p o w e r E n g i n e e r i n g & D e v e l o p m e n t

Wind turbine class I-B IEC-61400-1 / IEC-61400-3

Rated power 6.0 MW, net after transformer

Cut-in wind speed 3 m/s

Cut-out wind speed 25 m/s (10 min average) Grid frequency 50 or 60 Hz

Rotor diameter 150.95m

Blade length 73.5m

Rotor swept area 17,860 m2

Tip speed 90.8 m/s

Generator type Direct drive, permanent magnet

Rated voltage 900V per phase

Number of phases 3 x 3

Protection class IPP 55

Converter type Back to back 3-phase ac/ac

Output voltage 900V

Tower Tubular steel

Hub height 100m,orsitespecific

Power control Variable speed and system independent pitch control by blade

Normal air -10 to 40ºCtemperaturesExtreme air -30 to 50ºCtemperatureLightning protection Class 1 acc. IEC 62305-1

Alstom Halide 150-6 by the numbers

The Haliade™150-6MW is a three-bladed wind turbine. Using 73.5m turbine blades, the 150m diameter rotor combined with6 MW rated power maximizes the capture of energy.

The hub supports the rotor blades and houses their pitch assembly. It is designed in such a way as to provide easy, direct access for technicians working from the nacelle.

The pitch system makes it possible to control the blade angle, which optimises the area exposed to the wind and the speed of rotation to, ultimately, increase the yield.

The rotor bearings directly transfer the unwanted load on the rotor towards the main structure, bypassing the drive train.

The Haliade™150-6MW toweris 100m-high and made of tubular steel.

A helicopter winching area allows for quick rescue in case of emergency at sea.

The generator is key component of the wind turbine because it is the component in charge of generating the electricity. The Haliade™150-6MW is equipped with a direct-drive permanent magnet generator: with no mechanical gearbox coupled to the generator, the turbine consists of fewer rotating parts, which increases reliability, maximises turbine availability and reduces maintenance costs.

The yaw system makes it possible to pivot the nacelle and thus orient the wind turbine in the optimal direction,i.e. facing into the wind.

Made of cast steel, the main structure houses the nacelle inside the central frame, and the PURE TORQUE® system inside the front frame.

ALSTOM PURE TORQUE® This technology was exclusively developed by Alstom and is found in all of its wind turbines. It protects the drive train from unwanted wind buffeting by deflecting it towards the tower. The PURE TORQUE® system improves turbine efficiency and durability.

BLADE

HUB

MAIN FRAME

PITCH

ROTOR BEARINGS

TOWER

NACELLE

INTERMEDIATE FRAME

YAW SYSTEM

GENERATOR

HELIPAD

Built upon ALSTOM PURE TORQUE® proven technology for drive train reliability, Alstom has developed a new generation, 6 MW direct drive offshore wind turbine. Suitable for all offshore conditions -uncompromising on reliability-, the turbine will deliver a leading cost of offshore energy while supplying electric power for up to 5,000 households.

HALIADE™ 150-6MW ROBUST, SIMPLE, EFFICIENT

SLIP RINGS

SECONDARY COOLING SYSTEM

ELASTING COUPLINGKey element of the ALSTOM PURE TORQUE® principle which includes a patended coupling system with rubber elements that avoid any undesired load towards the generator.A hydraulic system embeded in the rubber parts guarantees that misalignements between main rotor and generator rotor are affecting the bearings configuration.

FRONT FRAME

WiththefirstU.S.offshorewindfarm,DeepwaterWind,abouthalfwaythroughconstruction,whatcouldbe more appropriate than to select

Alstom’s(nowpartofGE)Haliade150-6MWturbineas the Turbine of the Month? The turbine design is oneofthelargestintheworld.(Enerconsportsa7.58-MWonshoreturbinewhileVestashasbraggingrightstotheworld’sonly8-MWunit.)DesignersoftheU.S.wind-farmwillcommissionfiveofthe6-MWturbines to provide 30 MWs total and possibly keep thedieselgeneratorsonnearbyBlockIslandofflinefor long periods.

ThefirstHaliade150-6MWsuccessfullyobtainedtheIECpower-performancemeasurement(powercurve)afterthreemonthsoftestinginFrance.TheturbinewasdesignedfollowingClassI-Bspecifications,makingitsuitableforsiteswithareferencewindspeedof50m/s(10-minuteaverage)and a 50-year extreme gust speed of 70 m/s (3-secondaverage).

A few featuresTheturbineboastsarangeofnoteworthyengineeringdevelopments. For instance, like many other offshore units,thisonewilluseadirectdrive–nogearbox.GEsays the generator is more compact and lighter than earlier direct-drive systems.

A feature called Alstom Pure Torque protects the generator and improves its performance by safely divertingunwantedstressesfromthewindthoughthemainframetotheturbine’stower.Itdoessowithaclever rotor-support concept protecting the drivetrain andothercomponentsfromdeflections.Apatentedcouplingwithrubberelementsandanembeddedhydraulicsystemabsorbundesiredloadsthatwouldotherwiseaffectthegenerator.

Otherinnovationskeeppoweroutputsatoptimumlevels.Forinstance,electricpitchandyawsystems control energy production. The system is


TOTM_2-16_Vs3.indd 50 4/6/16 3:23 PM

The Haliade™150-6MW is a three-bladed wind turbine. Using 73.5m turbine blades, the 150m diameter rotor combined with6 MW rated power maximizes the capture of energy.

The hub supports the rotor blades and houses their pitch assembly. It is designed in such a way as to provide easy, direct access for technicians working from the nacelle.

The pitch system makes it possible to control the blade angle, which optimises the area exposed to the wind and the speed of rotation to, ultimately, increase the yield.

The rotor bearings directly transfer the unwanted load on the rotor towards the main structure, bypassing the drive train.

The Haliade™150-6MW toweris 100m-high and made of tubular steel.

A helicopter winching area allows for quick rescue in case of emergency at sea.

The generator is key component of the wind turbine because it is the component in charge of generating the electricity. The Haliade™150-6MW is equipped with a direct-drive permanent magnet generator: with no mechanical gearbox coupled to the generator, the turbine consists of fewer rotating parts, which increases reliability, maximises turbine availability and reduces maintenance costs.

The yaw system makes it possible to pivot the nacelle and thus orient the wind turbine in the optimal direction,i.e. facing into the wind.

Made of cast steel, the main structure houses the nacelle inside the central frame, and the PURE TORQUE® system inside the front frame.

ALSTOM PURE TORQUE® This technology was exclusively developed by Alstom and is found in all of its wind turbines. It protects the drive train from unwanted wind buffeting by deflecting it towards the tower. The PURE TORQUE® system improves turbine efficiency and durability.

BLADE

HUB

MAIN FRAME

PITCH

ROTOR BEARINGS

TOWER

NACELLE

INTERMEDIATE FRAME

YAW SYSTEM

GENERATOR

HELIPAD

Built upon ALSTOM PURE TORQUE® proven technology for drive train reliability, Alstom has developed a new generation, 6 MW direct drive offshore wind turbine. Suitable for all offshore conditions -uncompromising on reliability-, the turbine will deliver a leading cost of offshore energy while supplying electric power for up to 5,000 households.

HALIADE™ 150-6MW ROBUST, SIMPLE, EFFICIENT

SLIP RINGS

SECONDARY COOLING SYSTEM

ELASTING COUPLINGKey element of the ALSTOM PURE TORQUE® principle which includes a patended coupling system with rubber elements that avoid any undesired load towards the generator.A hydraulic system embeded in the rubber parts guarantees that misalignements between main rotor and generator rotor are affecting the bearings configuration.

FRONT FRAME

T U R B I N E O F T H E M O N T H


said to reduce non-torque loads by 90% when compared to conventional designs. Electrical yaw and pitch controls rapidly adapt the rotor alignments to changing wind conditions to keep a nominal and constant power supply to the grid. The braking system is based mostly on pitch control. Each blade is equipped with an independent power supply to ensure safe rotor braking, even in extreme conditions.

Safety Alstom says the Haliade 150-6MW will make maintenance as simple and as safe as possible. The hub is accessible from the nacelle, which is equipped with a 1-ton

capacity crane on a central frame. A maintenance trolley inside the frame eases transport of components. Outside the nacelle, a helicopter winching area allows for quick rescue in case of an on-turbine emergency.

Other design features ensure that the turbine provides high-power production in all circumstances. For instance, three independent generator and converter lines ensure uninterrupted operations. And, the turbine can reach a yawing capacity of 95% with only six of its seven yaw motors. Software-controlled derating strategies guarantee operation in the event of faults in the power line or cooling systems.

More than SCADA No turbine is an island, so a feature called WindAccess monitors and collects wind-farm data from other wind turbines, meteorological masts, and substations letting the facility operate like a conventional power plant. A ring-topology network connects the turbines on a facility to maintain communications even with an isolated cable fault.

Lastly, the system’s web-based interface lets operators access their wind farms from any location at any time. And the system’s open communication protocols lets the operator easily combine the wind farm with all other renewable assets in its portfolio. W

TOTM_2-16_Vs4.indd 51 4/6/16 5:24 PM


Scott Eatherton • President • Wind Driven LLC.

Emil Moroz • President • EM Energy LLC.

Dustin Sadler • Principal Engineer • AeroTorque Corp.

Dave Heidenreich, P.E. • Founder and Retired Chief Engineer of PT Tech, Inc.

shows transient torque events damage

This article is the second in a two-part series in which a Failure Mode and Effects Analysis shows how alternating torque damages more than gearboxes. The first article set the stage for how the FMEA would be conducted while this

part presents further considerations and results.

Feat AeroTorque_3-16_Vs3.indd 52 4/6/16 3:59 PM


more than gearbox bearings

In Part I of this series, the authors described the hazards of torque reversals and hard stops, what causes them, and the damage they inflict on wind-turbine gearboxes and other components in a drivetrain. Part 1 is online here: tinyurl.com/aerotorquepart1The FMEA divides the gear and bearing failure sequence into

three distinct stages, and examines the contribution of transient torsional events (TTEs) to each failure stage: initiation, propagation and failure. This section begins with how cracks propagate.

Propagation Once a crack has been initiated, propagation can begin, driven by cyclic loading, one cause of which is transient torsional events. Fatigue, hence crack growth, is the dominant failure mode in wind-turbine gearboxes. The crack may have been initiated by fatigue, a

flaw, or from other pre-existing damage such as debris denting [9] or scuffing [6]. TTEs are strongly linked to fatigue failure modes in standards and failure analysis texts. TTEs accelerate crack growth because it is a function of loading [7]. Crack-growth rates tend to increase over time and the remaining material available to support loads becomes diminished, increasing the stress levels in the remaining material.

Steels that lack fracture toughness have lower fatigue lives than tougher materials. Through-hardened bearings, widely used in turbine gearboxes, have low-fracture toughness, which increases the risk of fatigue failure. Without propagation, initiation will not cause failure, so reducing loading will slow and sometimes stop propagation, thereby extending gearbox life.


shows transient torque events damage more than gearbox bearings


E-STOP AN EMERGENCY STOP

FEA Finite-element analysis, a numerical analysisFMEA Failure mode and effects analysisISO International Standards OrganizationPSO Point surface origin – surface initiated damage and at a single pointRPN Risk priority number – the higher the number, the greater the risk of damageRTD Reducing torsional damping TBD To be determinedTTE Transient torsional events

GlossaryThe table provides a guide to the acronyms in the article

Failure This is the third and final stage in the sequence (initiation, propagation, and failure). A clear definition of failure is required for an accurate FMEA. In this analysis, a gearbox or gearbox component is said to have failed when it meets one or more of the following conditions:

1. Fracture has occurred on one or more parts. Common examples are inner rings with through-cracks and broken-off gear teeth.

2. The wind turbine cannot operate until the gearbox has been repaired or replaced.

3. Functional failures. For example, the turbine must be de-rated to operate with a particular gearbox condition, such as overheating or high gearbox vibration at rated power. In the FMEA, functional failure means the asset operates but does not function at a level of performance acceptable to the owner or user [14].

4. The severity of a failure mode is rated as high or severe in a standard or standards-based failure analysis reference.

5. Component failure means repairs can occur up-tower.

6. Gearbox failure means removal of the gearbox from the tower for repair or rebuild.

7. Catastrophic failure means the gearbox cannot economically undergo repairs or a rebuild.

The through-hardened bearings have low crack resistance [7], so suppressing TTEs should extend useful bearing life and reduce the risk of axial cracking. Cyclical loading drives fatigue, but the

relationship is not linear. Halving peak-to-peak amplitude of drivetrain torque transients reduces their fatigue loading by about 75% [17, 19], so it is worth pursuing the life-extending potential of RTD devices.

Fatigue is the dominant failure mode in gearboxes linked to TTEs. Other modes include scuffing and plastic deformation. Fatigue exploits a wide variety of flaws, defects, and prior damage to initiate failure, which is the first of three distinct stages of failure. Initiation is followed by propagation and, finally, failure. Initiation takes the longest of the three stages, propagation is more rapid, and final failure can occur in an instant. The length of time in the initiation and growth stages of fatigue failure modes — ranging from gear tooth bending fatigue to the Hertzian fatigue of bearing elements — is influenced by heavy cyclical loading such as that resulting from TTEs. Analysis of gearbox failure-mode causes and effects suggest that suppressing TTEs has a high potential to prolong the initiation and propagation stages of failure in new, in-service, and previously damaged drivetrains.

Evaluating the impact of TTE on non-gearbox drive components The dynamics of a wind turbine and the consequences of uncontrolled torque reversals on a drivetrain have the potential to create problems on the drive system beyond the gearbox. Some problems may have materialized within the past 10 years of wind-turbine deployments, while others may still exist that can cause failure before the target design life.

To address this topic, the authors reviewed literature along with a sampling of loads documents. A dynamic loads model (FAST) was run for a sub-MW turbine, some load time histories were reviewed, and best judgment was used to draw together initial suggestions to determine which components might be impacted by TTEs. A summary of components likely to have fatigue lives enhanced by use of an RTD device was developed, but in most cases the data was not sufficient for consensus, especially in comparison with other likely causes of failure modes. So, it was decided to leave the benefits as To Be Determined (TBD).

A more complete way of quantifying the benefit is a combination of instrumented wind turbines and use of the latest system models. Also, different configurations of turbines, with different tower heights, rotor diameters, and control strategies may have different design drivers. The trend toward taller towers and larger rotors will likely make the mitigation of drivetrain TTEs more important than it was in older designs.

Cutting-edge system models, such as SAMCEF and the RomaxWIND drivetrain model embedded within BLADED, capture details of a drivetrain integrated into the dynamic and flexible operating environment of a wind turbine. They’ve helped explain what goes on during harsh braking events [2,


Turbine monitoring just got smarter and simpler

New updated SKF @ptitude Observer software At hundreds of windfarms worldwide, SKF WindCon is enabling operators to predict the need for turbine maintenance to reduce downtime and better manage their resources. With newly updated SKF @ptitude Observer software, they can also benefit from an expanded range of diagnostic and communica-tion possibilities, making turbine service even more efficient. Learn more about SKF @ptitude Observer’s intelligent diagnostics and communication at skf.com/wind

New features include:• Event Capture: raw signals acquisition

based on alarms or events • Trigger acquisition on up to parameters • Graphical display improvement based on

wind turbine load classes • Time synchronisation with any external

server • Interfacing with other systems based on

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® SKF is a registered trademark of the SKF Group. | © SKF Group

Come visit us at AWEA WindPower, booth , to learn more!

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3], but such models are not perfect [3]. Ideally, such models will one day provide a comparison of a more commercially relevant wind turbine under various conditions, with and without the benefit of an RTD device in the drivetrain. This kind of analysis (despite acknowledged shortcomings in terms of ability to capture internal deflections and accurately calculate the effect of transients), would broaden understanding of the benefits beyond the current main shaft torque measurements and adoption of Reverse Torsional Damping.

In the context of this paper, TTEs arise primarily from hard-stop protocols, but have also come from normal shut-down stops and may arise out of rarer fault conditions on a turbine — such as when one of the blades gets stuck between fine pitch and full feather in stormy weather, or even from rare wind-driven turbulence events. Hard stops are usually initiated when a turbine is at high risk, say during an over-speed initiated by a loss of generator load when the controller is not available or is being bypassed for some reason.

Typically, these hard stops come from a rapid pitch of blades to feather or stall with

a simultaneous caliper-brake application. The severity of such an event is closely related to the operating point of the turbine. Worst-case loads normally occur near the rated wind speeds, when thrust loads are maximized on a pitch-regulate turbine. In this scenario, the rotor is fully loaded and the tower top is bent downwind by thrust forces. In a hard stop, the tower is suddenly offloaded and typically pulled forward by the negative thrust arising from the pitching blades, before the shaft comes to rest under the influence of the reduced aerodynamic input and the high-speed shaft brake. Real-world recordings have shown the worst torsional loads in the drive system tend to occur during hard stops in high gusty winds, close to cutout speed.

The analysis suggest the following components benefit from lower torque and stresses transmitted through a drivetrain equipped with and RTD:

Rotor blades and related connections An RTD device has demonstrated, through torque measurements on the low-speed shaft, to reduce shaft torsional oscillations during shutdowns.

Because these torsional oscillations are attributed to the drivetrain vibration, with significant participation of the blades, it is concluded that the blades will benefit from additional damping. When the shutdown sequence begins, blades are roughly “flat” to the wind and the edge-wise direction of a blade should benefit most. But as the blades pitch, the reduction in vibrations will move toward a reduction in flap-wise bending. Along with blades, their connection to the hub will likely have a positive effect because the joint probably has a low-design margin related to fatigue.

Main shaft to rotor hub bolts While it is not known if TTEs have a significant effect on the bolted connection between the main shaft and the rotor hub, it is thought that large oscillatory motion and resulting forces could potentially contribute to bolt loosening. In this case, mitigation of TTEs could be beneficial.

Main-shaft bearingsThis FMEA assumes a three-point gearbox suspension with a locating spherical roller main bearing that supports all the rotor’s axial thrust and most of its radial force. Hence, it is intended to take the bulk of the rotor’s non-rotational loads so they do not transmit to the gearbox. The degree to which the main bearing protects a gearbox is a function of the drivetrain configuration: whether a three or four-point suspension, or other configuration. Regardless of configuration, it is believed the main bearing must react significantly to oscillatory side forces during a stop, especially a hard stop. As such, the main bearing will benefit from an RTD device that extracts energy from the torsional vibration and reduces the amplitude of these oscillations. In addition to a reduction in high-cycle fatigue of the bearing elements and fretting

The red plots in both cases show main shaft torque during hard stops and by the indicated braking method. The frequent positive to negative swings are believed to be most dam-aging to bearings. The over laid blue plots are the same stopping protocol, but on a similar turbine equipped with an RTD device.



of the bearing to bedplate interface, a significant reduction is expected in sudden bearing skewing resulting from torque reversals.

Load reversals are known to damage the drive-system bearings. Such reversals are often more damaging when bearings are not rotating. The potential for surface damage is further exacerbated when stationary bearings are subject to simultaneous axial forces and rapid axial motion. Large conventional spherical-roller bearings have a high internal clearance in the axial direction. This limits axial motion and allows a line-contact impact between rollers and raceways. This can happen at the end of an aero and caliper-braking hard stop, when the main bearing is restraining axial load reversals from the high fore and aft oscillations of the tower, and simultaneously with radial-load reversals from the side-to-side tower oscillations.

High-speed shaft coupling The high-speed shaft coupling accommodates small deflections and misalignments. It should withstand bedplate deflections and relative movement between the generator and gearbox arising from a hard stop, and still live with rotational fatigue. Nevertheless, significant misalignment will shorten coupling life, so it is postulated that a reduction in amplitude of large oscillations will have a positive benefit on fatigue life. Some turbines have documented issues of premature coupling failures [15].

Generator bearings and rotor windingsBearings at both ends of a generator “experience high oscillations when the brake is applied due to the flexibility in the coupling and the proximity of the bearings to the brake disc.” [3] An RTD device between the brake disk and the generator is expected to remove

energy from the worst of these oscillations, inferred from the time histories of the 1.6MW and 1.65-MW turbines presented in Part I. It’s also hypothesized that the reduction in oscillatory forces acting on the elements of the generator rotor will help extend its life.

Electronics and electrical systems Thermal issues are considered the primary cause of premature failures in most electronic and electrical components. However, high vibration can also shorten life of components by loosening connections and breaking down insulation. Insulation deterioration can result in thermal failure. It’s suspected that an RTD device’s demonstrated ability to reduce more than 75% of the high-torsional oscillating energy in the drive system during hard stops may reduce the vibration excited in turbine substructures that support electrical

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components. A practical way to learn if this could result in financial benefit is to track failure rates and costs of turbines equipped with an RTD device, as compared to one without an RTD device.

Bedplate“Large transient loads, such as those produced during an emergency stop, will apply large loads to the bedplate (mainly through the low-speed bearing supports and gearbox mountings) causing deflections that effect the whole drivetrain. Unpublished finite-element analysis (FEA) models indicated that these can cause significant deflection of the bedplate and nacelle structure, resulting in potential misalignment. This in turn can cause loads on the drivetrain bearings to significantly increase, most likely resulting in unacceptable damage accumulation” [3]. These deflections are more likely to impact welded bedplates that have a history of suffering from cracking of material, and may not have as much effect on more common cast designs.

Tower repairs, tower bolted connections, and anchor bolts A review of design load time histories show

that oscillatory loads, derived from gearbox torque arm reaction forces during stops, enter the tower and are visible all the way down to the foundation. These reactions manifest themselves, primarily, as rolling moments of higher frequency than the tower’s first natural frequency. The simulations available to support this paper show that occurrences of these oscillations correspond to the oscillation of the blades and drivetrain. Field measurements, however, show that in addition to the oscillations associated with the initiation of the shutdown procedure, torsional reversals occur as the brake activates and rotation stops. These oscillations are also reflected throughout the tower.

Given that the “rolling” oscillations entering the tower correspond to torsional variations on the low-speed shaft, which can be damped by an RTD device, it is clear that the tower system will also benefit from this damping. While the tower shell and flanges can likely accommodate higher loads than may arise from these oscillations, it is unclear whether or not there’s a meaningful impact on the bolted connections from transverse oscillations or resulting deflections. Dynamic modeling,

with and without an RTD device, can help quantify the impact on overall tower fatigue and ultimate loads, but won’t get into the details of the bolted joints. FEA may help in analyzing potential benefits, but it is simpler to monitor bolt checks throughout towers (with and without an RTD device) to see if this results in a reduction of loosened bolts.

Results from the FMEA Results of the FMEA show significant minimum potential savings for the gearbox when the turbine is installed with an RTD device. The gearbox is the focus of substantial industry research because there are many records of failures along with good understanding and documentation of the effects of torsion vibrations, TTEs, and overloads on bearings, gears, and gearboxes systems. The focus recently has been on the chronic axial cracking of high-speed inner rings and its relationship to loading and other factors.

The FMEA shows potential value for installing an RTD device. For instance, the high-speed assembly shows bearing axial inner ring subsurface fatigue, which includes axial cracking. The same failure mode shows

Simplified FMEA results, non critical modes removed



A portion of the simplified FMEA spreadsheet appears here. The full version is available online.

up in the intermediate high-speed assembly, along with an additional four modes of gear failure. The low-speed intermediate assembly shows a few areas for potential moderate improvement related to bearing wear and overload modes. Finally, the low-speed assembly shows several significant potential savings through a combination of bearing and gear-fatigue failure mitigation opportunities. This is driven by the high cost of replacement or repair for these components and assembly systems.

GEARBOX SHAFT ASSEMBLY MINIMUM PROJECTED ANNUALIZED COST REDUCTION ATTRIBUTED TO THE ADDITION OF AN RTD DEVICE/YEAR

High speed (HSS) $741 High-speed intermediate (HSIS) $2,522 Low-speed intermediate (LSIS) $375 Low-speed (LSS) $2,186 Total $5,824

A few cost reductions for frequently repaired components

There is one additional failure mode outside the gearbox identified by the FMEA. Bearing skewing and its resulting damage in the main-shaft bearings is shown to have a significant minimum potential cost savings. Due to insufficient information to show that an RTD device can have a significant impact on other non-gearbox components, there is a challenge in quantifying contribution and life impact in the absence of a dedicated set of loads, with and without an RTD device. Therefore, the potential benefit has been

labeled as TBD. More work or reference material or both are required to bring the non-gearbox contribution to the same level as the gearboxes.

The table A few cost reductions provides a summary of the costs from significant failure modes by gearbox component. The minimum cost does not include crane costs, lost production, or labor reassignment costs. Furthermore, the values in the right-hand column show the most significant cost savings attributed to the mitigation of damage to a wind-turbine gearbox, using only a few of its major failure modes.

For the entire system, the table identifies which components gain most from the cost reductions benefit. The table also summarizes the failure modes highlighted in the table Simplified FMEA, non-critical modes removed. The greatest identified savings of installing an RTD device onto a wind turbine is demonstrated in the gearbox, so this paper focuses on that component, rather than on non-gearbox components. This data indicates that an RTD device would provide a significant minimum

cost savings to the high and low-speed intermediate shaft assemblies, with some additional savings attributed to the high and low-speed shaft assemblies.

The results of the FMEA indicate that an RTD device may produce significant savings to justify installation after evaluating the gearbox alone. Combine that with potential savings from the main-shaft bearings and the RTD value increases further. Once a site has a statistically significant quantity of installed RTD devices it could present further value by tracking costs associated with non-gearbox components identified with TBD. Taking actual failure and cost data from a wind-turbine site further supports the FMEA as a valuable tool, and could show greater potential savings, depending on the frequency and type of failures at that site.

The FMEA model predicts that installing an RTD device could reduce annual gearbox costs by a minimum of 37%, not including crane costs, lost production, or labor reassignment costs. The FMEA further predicts that an annualized gearbox lifecycle cost of $23,750 could reduce to $8,800 with an RTD device installed. This represents a conservative one to two-year payback. Including the other drivetrain components and major turbine components, the FMEA forecasts an annualized lifecycle total turbine cost of over $47,000, but the potential savings from an RTD device is not fully estimated because of insufficient information on the effect of TTEs on most of these systems.


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This analysis has some shortcomings due to the method for simplifying the failure data and frequency. Some scenarios, such as a complete gearbox replacement or rebuild, would affect the uninterrupted linear nature of the projected mean time between failures. This could “reset” the timing of the failure modes’ life with the installation of new bearings and gears. So, following a replacement or rebuild, the failure modes would be delayed, as compared to the linear method that this FMEA uses.

Regardless of the shortcomings, this simplified FMEA uses conservative assumptions to calculate costs and projected savings from the installation of an RTD device. It justifies the installation immediately after or during the repair or replacement of any major drivetrain component to maximize the extension of life by preventing damage.

Final thoughts All wind turbines are subject to a variety of hard stops. Whether they use aero-braking only or combine aero-braking with caliper braking, these transient events can often produce undesirable torque reversals and significant torsional oscillations. RTD devices have proven their ability to reduce these kinds of undesirable transient loads during stops.

A review of the literature provides evidence that, in a gearbox, many premature failures in bearings, gears, and shafts can be attributed to TTEs. For non-gearbox elements, details of the impact of TTEs were not so readily available, but there is evidence and logical arguments can be made to support a conclusion that many of these components are adversely affected by TTEs.

The FMEA presented has made a conservatively framed case that the introduction of an RTD device into a wind-turbine drivetrain can mitigate risk and reduce the cost of operation, and shows a relatively brief one to two-year payback on gearbox savings alone. As more RTD devices are installed and accumulate more run time, the effects on failure modes, reliability, and cost saving benefits are expected to become clearer and estimates of benefits to non-gearbox components will be clarified.

Evidence collected during the

deployment and monitoring of RTD devices is expected to help refine system models and provide designers with better tools to optimize future wind-turbine designs.

Recommendations The data reviewed in this paper encourages site-wise retrofits, while the value per turbine might be even higher for those unit with an above-average number of hard or emergency stops per year. For many wind farms, the conservative one to two-year payback, in the gearbox cost savings alone, can justify fleet-wide installation of RTD devices. Other wind-farm owners may prefer retrofitting a statistically significant number of turbines and tracking the performance and reliability of those turbines, compared with a control set of other turbines. At the very least, wind-farm owners experiencing chronic problems with gearboxes or other major turbine components should look at installing an RTD device when those components are replaced or repaired.

For those wishing to do partial wind-farm retrofits, there are many early indicators that can demonstrate the ability of an RTD device to reduce loads and extend life. For turbine models that have not already demonstrated the load reduction capability of an RTD device, it’s recommended to record side-by-side torsional load graphs during hard stops, and on turbines with and without an RTD device. Examples of these graphs are presented in this article. Within a couple weeks, the recordings can provide valuable evidence of reductions in some of the worst turbine transient load events. However, the strongest benefit is a reduction in O&M costs and unscheduled downtime, with an associated increase in energy production within one year. W

AppendixThe appendix for this article provides extensive background information on the subjects discussed in the article but it is too long to reproduce here. However, it will appear in its complete form online here: www.tinyurl.com/aerotorquepart1 Briefly, the appendix heads include:

• How an RTD device works (through frictional slippage and damping)

• Torsional behavior at the generator with an RTD device. It provides more than a 50% reduction in torsional oscillations and reversals at the generator shaft.

• Real world concerns, such as flaws in blades that surface with TTEs.

• Gearbox assembly definitions clearly identify components on each shaft assembly.

• FMEA header definitions provides more supporting detail on each, and

• Wind turbine design standards, such as IEC 61400-1,and its four editions

For further reading 2. Heege, A, et al, Fatigue Load Computation

of Wind Turbine Gearboxes by Coupled Structural, Mechanism and Aerodynamic Analysis, DEWI Magazine No. 28, February 2006.

3. Scott, K., et al, Effects of Extreme and Transient Loads on Wind Turbine Drive Trains, 50th AIAA Aerospace Sciences Meeting, Nashville, TN, Jan 10-12, 2012.

6 Baker, P. and Eatherton, S., Adhesive and abrasive Wear of Roller Ends and Ribs in Wind Turbine Gearbox Bearings, Gearbox Reliability Collaborative, 2014.

7. Errichello, R. L., Gear & Bearing Failure Analysis, Geartech, 2011.

9. Errichello, R. L., Hewette, C., Eckert, R., Point-Surface-Origin, PSO, Macropitting Caused by Geometric Stress Concentration, American Gear Manufacturers Association, 2010.

14. Moubray, John, Reliability-centered Maintenance, second edition, Industrial Press, 1997.

15. Sheng, Shuangwen, Report on Wind Turbine Subsystem Reliability – A survey of Various Databases, National Renewable Energy Laboratory, 2013.

17. Jackson, Kevin. NREL Technology Exchange Workshop, October 1993.

18. Errichello, Budny and Eckert, Investigations of Bearing Failures Associated with White Etching Areas (irWEAs) in Wind Turbine Gearboxes, STLE, Detroit, May 2013.

19. Meyer, Haydn, Schuller et al, Very High Cycle Fatigue Properties of Bainitic High Carbon-Chromium Steel, International Journal of Fatigue, September 2008.




Turbines that last:By examining and minimizing the sources for frequent gearbox failures, there is potential for an improved design.

Today, re-engineering the gearbox, rather than just replacing it, is the method more likely to improve turbine reliability.

Zhiwei Zhang • VP Engineering • InSight • North America • Romax Technology, Inc.

Colin McNichols • Senior Design Engineer • Romax Technology, Inc.

I t’s well known in the wind industry that gearboxes don’t often meet their original intended design life before requiring replacement or refurbishment. In the U.S., over 65,000 megawatts of wind capacity is installed and most of

it comes from turbines with gearboxes. Such a large fleet means there’s great potential for improved design and cost savings for wind-farm owners and operators.

Noting and correcting serial issues to ensure a reliable gearbox makes good, economical sense during turbine upgrades. This means examining how and why gearboxes fail, and re-engineering them to last. Significant savings and lifetimes are possible through proper simulation, testing, and monitoring of gearboxes currently operating in the field.

Cost analysis A large number of gearboxes in the U.S. is ready for refurbishment.

Proper analysis of these gearboxes can increase longevity and lead to insight and future cost savings for the industry. For example, a gearbox life-extension plan that provides for one instead of two replacements over a 20-year wind-farm life can save owners $500,000 per turbine. That adds up quickly at a multi-turbine wind farm.

The comparative study in Gearbox scenarios shows three potential choices when a gearbox is removed from a turbine for repair or upgrades.

A wind-farm owner can replace a failed gearbox:

1. Completely but without a design upgrade,2. With a refurbished box but no other upgrades, or3. With a refurbished and re-engineered gearbox for a longer life.

Parameters for this high-level cost model will vary by technology and location, but the study shows that after the first failure, a rebuilt

A back-to-back arrangement tests Romax Technology designed 2-MW gearboxes.

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Protect your main shaft bearings

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Turbines that last:

A cost study produced these cost figures and savings when a gearbox is replaced twice with original equipment, twice with refurbished units, versus just once with a re-engineered design.

gearbox with a higher lifespan can lead to significant cost savings at site level and across an entire wind farm.

Why gearboxes fail earlyTypically gearboxes are designed for each bearing and gear to maintain 20 to 25 years of calculated life.

The main drivers for a drivetrain design fall into these categories:

• High reliability• Low mass• Low turbine cost• Low cost-of-energy (CoE)• Ease of maintenance• Ease of installation

Each category can separate further to fit other design features or requirements. Some common challenges include:

• Planet bearing life. Planet bearing failures are costly to repair and usually lead to full gearbox replacement. An ongoing industry challenge is to design a gearbox to maximize planet-bearing life (especially at the low-speed stage) within the available design space (dimensional envelope, load capacity, cost goals, and others). Attempts have led to spherical roller bearings (SRB), cylindrical roller bearings (CRB), taper roller bearings (TRB), and integral bearing raceways (where the outer race is part of the gear). Some newer gearboxes are even using journal bearings.

The main reason for new bearing designs is to extend life, but many changes haven’t met expectations. Designs

to remove failure modes may bring new challenges. For example, integrating the outer race of a bearing eliminates the possibility of outer ring fretting or creeping, and potentially increases the torque density and overall envelope of the planetary sections. But these changes also add complexity to manufacturing and assembly. Journal bearings greatly reduce the number of parts, but provide difficulties for maintaining sufficient hydrodynamic lubrication in all operating conditions.

• Gear failure modes. Although most gears are designed to meet ISO standards (ISO 6336 series), not all failure modes are covered under these standard. Only bending and contact fatigue, static capacity

(strength), and scuffing are considered in standard calculations. Issues such as micropitting and TIFF (tooth interior fatigue fracture) are still in research stages without a common standard.

Additionally, there isn’t a “catch all” model for these failure modes — each has different underlying physical mechanisms. Good design, therefore, must avoid many potential issues, maintain material quality, and simplify manufacturing practices.

• White etch cracking (WEC). It is a prevalent issue that causes premature bearing failure through spalls or axial cracks. WEC is characterized by irregular micro-structural alteration in the subsurface material.

Root causes of WEC are highly debated within the wind industry, and no specific calculation or procedures are currently available to remedy it. Reports show that case-carburized bearings tend to resist WEC, but they are expensive. Case carburizing provides residual compressive stresses in the rings, which is believed to help against cracking.

Other failure modesThere are many ways a gearbox can fail and some reasons are not solved with a computer model. Here are two examples

Planet bearing failure. An example of roller skewing.



White etch cracking. The Inner-ring axial crack has grown from a white etched area.

of failure modes from a root-cause analysis project that proves good design goes a long way:

1. Proper fit counts. In this case, a high-speed bearing raceway fit proved insufficient. Bearing rings started to spin on the shaft, the end cap bolt came unwound and a bolt dropped in the oil feed. This led to a blocked oil feed that overheated the gear. Eventually, the gear lost all its teeth. A good design approach would have meant ensuring the right fit and reverse-threading the end cap bolt.

2. Watch for wear. Here, an intermediate bearing wore excessively during run-in. The feed took oil to the torque tube bearing and carried the hard wear particles to the contact surfaces of the bearing. Eventually, the torque tube bearing failed due to abrasive wear. A good design approach would add a separate oil feed to the bearing from the manifold.

When it comes to predictive maintenance, one method does not solve all problems. Good re-engineering means each failure mode is analyzed and understood for best results.

System simulation Today’s software can help design and analyze gearboxes and drivetrain systems. An ideal program will also simulate behavior and performance of different components to ensure optimal design.

For example, RomaxWIND is an all-in-one system level software analysis program used in gearbox and drivetrain design. This software analyzes a full drivetrain from hub load to generator inertia, as shown in the Many possible problems illustration. Flexibility of structural components, such as housings and planet carrier, are considered in the program and used to more accurately calculate potential bearing misalignments.

Non-linearities, such as gear backlashes and bearing internal clearances, are also included in the static analysis and solved simultaneously by numerical iterations. Capturing the whole system deflection is especially important in a wind turbine where the drivetrain is lightweight (compared to a gearbox designed to sit in a factory).

A RomaxWIND system model of a gearbox provides key information, including planet-load share, a distribution of gear-face contact stresses, maximum bearing contact maximum, and fatigue lives. Additionally, running sensitivity studies on manufacturing tolerances and operating conditions can validate the robustness of a design against manufacturing and operation. Gear geometry and bearing arrangement can also undergo optimization against multiple targets such as durability, static strength, vibration, and efficiency.

Gearbox re-engineeringRe-engineering, or a design upgrade, is becoming more commonly applied to improve the reliability of existing gearboxes. It is often a more cost-effective alternative when compared to a complete gearbox replacement that incorporates an original design.

Successful re-engineering involves learning as much as possible about a gearbox’s performance from its operation and failure history. All design enhancements should undergo validation testing before production. One challenge is in obtaining load data for proper re-engineering of a gearbox. Even without the original design loads, it is possible to develop loads based on experience or use of load-measurement equipment. This lets users obtain site-specific loads to process into a redesign load set — rather than relying on the OEM load set.

Case study This case study involves a megawatt-class turbine gearbox re-engineering effort for wind-farm owner, Eurus Energy America. Romax Technology was asked

The diagram shows a level of analysis pos-sible when using Ro-maxWIND software.



Turbines that last:

Planetary stage model. The planet gear teeth (lower illustration) show a distribution of face contact stresses.

to carry out a thorough design upgrade and provide gearbox re-manufacturing support.

With a proactive program to minimize long-term O&M costs currently in place, Eurus Energy expects to overhaul more than 200 wind-turbine gearboxes over a period of approximately 15 years.

According to Joe Stevens, Vice President of Operations and Asset Management at Eurus Energy America, timing of the overhaul is important and long-term gearbox is essential. “It’s imperative that we ensure drivetrain efficiency and reliability to optimize the lifecycle of our wind turbines. The end-of-warranty with our OEM was the ideal time to upgrade the gearbox design going forward across two of our important projects. The agreement with Romax enables us to proactively achieve optimization with a high degree of confidence that our fleets will be able to continue operating in challenging wind environments for years to come.”

So far, Romax has undertaken a full bearing analysis, selection, assembly, and gearbox redesign concept assessment, complete with a detailed design and CAD (computer-aided design) analysis using RomaxWIND software and other packages. Full manufacturing and test support is provided during this process, with the goal of improving

gearbox life and reliability. Two major design

upgrades implemented in this effort include a planet-bearing change and gear micro-geometry modification. The planet bearing has been changed from SRB to CRB. Bearing fatigue lives have also been improved, as shown in SRB vs CRB graph. The original SRB design does not meet the 20 years requirement (about 175,000 hours).

Flow chart of Romax Technology’s typical re-engineering process

In this case, gear microgeometry was optimized in the planet stage. The original contact pattern was printed based on a measured gear chart and the optimized contact pattern is shown in Combined tooth loading (A and B). In this graphic, the tip or root contact and end contact are all considerably reduced. Furthermore, the hard contact line at HPSTC (highest point of single-tooth contact) and LPSTC (lowest point of tooth contact) were removed after optimization. The maximum contact stress across the gear face were also reduced to prolong gear life.

Prototype gearbox testingModeling and simulation is important for gearbox design but they cannot substitute for reliability testing nor predict the day a component will fail. Instead, the analysis compliments and reduces testing and the number of prototype designs. One of the goals of simulation is to save money on prototypes.

Drivetrain testing is a key responsibility of a systems integrator, and a company should also have an established engineering practice for the re-engineering process. This includes a cross-functional approach with several key areas, including:

1. Identification of potential failure points during redesign and analysis,

2. Realistic drivetrain testing to represent operating conditions,

3. Reliability and performance data gathered during field operation, and

4. Test data and field data used to drive better design practice and better drivetrain testing methods.

Predictive maintenance that combines engineering with analytic simulation capabilities can reduce costs of gearbox failures and extend turbine life. By reviewing hundreds of gearboxes in service, serial issues can emerge that provide insight for design and redesign processes. The best practices that develop will result in reduced O&M costs for manufacturers and wind-farm owners. W

Calculating contact stresses



The graph compares spherical roller bearings (SRB) to cylindrical roller bearings when used in planet gears.

The original contact pattern is based on measured data. Note that the gear contact goes all the way to the tip and root (and over the ends) when the gear rolled through contact.

Using RomaxWIND, the graphic shows an optimized contact pattern when incorporat-ing the influence of the system deflection of the drivetrain under load. Note that the gear contact no longer extends to the tip and root or edge.

Fatigue life versus bearing design

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On the next few pages you will be introduced to four

people who had the inspiration to tackle the technical

problem unique to the wind industry and two more with

the gift to recognize the great value of the wind industry,

and then do something to make it grow.

»to Windpower Engineering & Development’s Innovators and Influencers of 2016

T H A N K YO U

» Because we work with inspired people, our gratitude goes to:


Massachusetts U.S. Senator, Edward Markey, for his support in the recent effort that

successfully passed the PTC through Congress.

Markey also had a hand in shaping what could

have been a National Renewable Energy Standard.

Wind pioneer Palmer Carlin, who worked

at NREL in its early days to help establish what

eventually became the Lab’s National Wind

Technology Center. Carlin’s early work provided

guidance on electrical systems and variable-

speed turbine technology.

Founder of Romax Technology Ltd and bearing specialist Dr. Peter Poon, for

building the company that provides independent

bearing and gearbox analysis. Recently, NREL

announced testing on an advanced drivetrain

that was made possible with input from three

companies, Romax among them.

These innovators and influencers have had such a

significant impact on the wind industry that the staff of

Windpower Engineering & Development would like to

recognize and celebrate their success in this Seventh

Annual Innovators and Influencers special section.

Engineer and software developer, Liz Walls, for

creating a new and more accurate approach to wind-

flow modeling. She recently launched Version 2.0 of the

Continuum software, which differs from other wind-flow

models in that it incorporates all met data simultaneously

into one model.

Founder of the Wind Engineering, Energy, and Environment (WindEEE) Research Institute, Dr. Horia Hangan is a Professor in the Faculty of Engineering at

Western University and the Director of the WindEEE Dome.

The Dome is the world’s first 3D testing chamber that can

reproduce and study the impact of complex wind systems.

Wind advocate, Karen Conover, who has served on

the AWEA Board of Directors since 1995, and is VP of DNV

GL, a global risk-management company with multiple wind-

energy advisory and certification offices. Conover has also

acted as a Board Member for Women of Wind Energy since it

first incorporated in 2005.

Intro_Influencers_Innovators_Vs2.indd 68 4/6/16 4:21 PM

» M a s s a c h u s e tt s S e n a to r E d wa rd J. M a r ke y

2 0 1 6 I N F L U E N C E R

When Edward Markey moved over to the Senate in 2013 in a special election, one of his first acts was to author a bill that would require utilities to distribute power of which at least 25% came from renewable sources. Had the bill passed, it would have set a national renewable-energy goal. More recently and successfully, Markey worked for the five-year extension of the PTC, a significant milestone for the U.S. wind industry. It is significant in part for the length of the extension and because it was a bipartisan effort. What’s more, the effort also spurred wind-farm development

in coastal waters. For that work, we recognize Senator Edward J. Markey as a Windpower Engineering & Development Influencer of 2016.

Sen. Markey can boast of a long list of environmental and renewable energy accomplishments. For instance, he has been a consumer champion and national leader on energy and environmental protection. He is the principal House author of the 2007 fuel economy law,

which increases fuel-economy standards to 54.5 miles/gal by 2025, the first increase in a generation. And he is the author of a competition encouraging law that requires electricity regulators to open up the wholesale electric power market for the first time, legislation that promotes growth of independent power producers such as wind farms

More recently, in 2014, Markey was first of about 28 to sign a letter to Senators Ron Wyden and Orrin Hatch, chairmen of the U.S. Committee on Finance that encouraged the extension of the Production Tax Credit (PTC). The

signees recognized that in 2012 the wind sector alone drove $25 billion in private investment and led to the installation of more than 13,000 MW of clean power production.

Actually, at the latest U.S. Offshore Wind Leadership Conference, Markey said he was working to extend the investment tax credit until 2025. The policy in part grants a 30% credit for the costs of developing renewable-energy projects.

“We have an opportunity to provide a long-term extension of this tax policy, Markey said at the conference. “Offshore wind is poised to take off in the United States.” He acknowledges that it needs assistance because unlike land-based wind farms, those offshore are much closer to load centers and so need much less transmission infrastructure, an expensive addition.

Sen. Markey previously served for 37 years in the U.S. House of Representatives. He has also served on the Energy and Commerce Committee, where he was Chairman of the Subcommittee on Energy and the Environment. Markey was co-author of the American Clean Energy and Security Act (ACES) of 2009, an earlier but unsuccessful effort to encourage the growth of the renewable energy industry.

According to a spokesperson for the senator, competition remains his economic mantra, in his words, “ruthless Darwinian competition that would bring a smile to Adam Smith.” He has been instrumental in breaking up anti-consumer, anti-innovative monopolies in electricity, telephone services, and others. His pro-competition policies have directly benefited job creation throughout the country. W

We have an opportunity to provide a long-term extension of this tax policy. Offshore wind is poised to take off in the United States.


Ed Markey_Influencer 2016_Vs2.indd 69 4/6/16 4:26 PM

» Pa l m e r Ca r l i n , N R E L w i n d e n e rgy p i o n e e r

2 0 1 6 I N N O V A T O R


The man who assisted in establishing what is now the National Wind Technology Center in 1977, now part of NREL, still comes to work at the Center most days. Palmer Carlin grew up in the 1920s on a prairie farm in Wiley, Colorado, where he tinkered with spare engine parts, a hobby that provided useful training for a coming engineering career. Not surprising, Carlin’s early training is similar and common to many wind pioneers.

His route to the Center had its share of twists and turns. For instance, WWII took him off the farm and to the Colorado University Boulder campus as part of the second class of CU’s Naval Reserve Officer Training Corps. The group often started the day performing “calijumpic” exercises at dawn before getting cleaned up and dressed in uniform for class. Gas and food were rationed so travel was a luxury because nobody had a car. Carlin’s student days weren’t focused on wind research, though he was interested in electrical engineering—but it was the overall campus experience that had the most impact.

“Meeting new people from all over was educational for me,” he said. After all, his high school graduation class had only 19 members. He graduated with an electrical engineering degree in 1945.

Carlin eventually returned to CU to pursue a master’s degree and Ph.D.—but he was fueled by a new interest in physics, which he began teaching to undergrads. “The atom bomb had been developed, so all at once, it was interesting to go into particle physics,” he said. And as he

pursued his doctoral degree in 1955, he was involved in several of the major historic scientific events of the day.

Carlin built an early prototype turbine while at CU Boulder as an electrical engineering professor—a gizmo that had magnets around the outside. “It never worked very well,” he admits. Despite his initial vision, he never dreamed he would see the giant megawatt-scale turbines towering 90 meters and more.

In the fall of 1977, Carlin took a three-semester leave from his professorship to help create at the time as Wind Energy Test Site south of Boulder in a buffer zone adjacent to the former Rocky Flats Atomic Energy Installation. The Site was later renamed the NWTC. He recalls the only things on site were a couple trailers, and he would travel with other early pioneers to work with developers on small 10 and 20-kilowatt wind turbines. But Carlin was more than an observer.

Eventually, the lure of NREL (then called the Solar Energy Research Institute, or SERI) proved too strong, so in 1986 he retired from CU and joined SERI. As the organization pushed for wind’s future, Carlin’s role was perhaps a bit more complex than he lets on. Colleagues heap praise on him. “We worked together in the 1970s to set up the small wind systems research efforts here at what was then the Rocky Flats Small Wind

Systems Test Center,” said NREL Research Fellow Bob Thresher.

Thresher also noted that Carlin consulted with the staff on electrical systems analysis. “He authored some of the seminal analysis papers on variable-speed technology and collaborated with many small wind companies of that era on the development of variable speed electrical topologies.”

Today, three afternoons a week, 91-year-old Palmer Carlin still comes into the Energy Department’s National Wind Technology Center to begin the continuation of his career. W

NREL Senior Engineer Palmer Carlin (left) collaborates with other NREL wind pioneers. At the board, Bob Thresher, Sue Hock, Darrell Dodge, and Peter Tu. Photo: Warren Gretz

NREL Senior Engineer Palmer Carlin at the National Wind Technology Center, flanked by some of the massive turbines he says early wind technology pioneers only dreamed of seeing. Photo: Dennis Schroeder

Palmer Carlin_Innovator 2016_Vs2.indd 70 4/6/16 4:29 PM

» D r Pe te r Po o n , Fo u n d e r o f Ro m ax

Te c h n o lo gy L i m i te d

2 0 1 6 I N N O V A T O R

How could the wind industry ever improve its complex and high-load gearboxes unless they were modelled with sufficient detail to allow a proper analysis? Dr. Peter Poon, the founder and now Non-Executive Director of Romax Technology Limited, did not set out to answer the question, but in the end, he did and in the process, developed an engineering firm and the software for the design, analysis, and improvement of large gearboxes. The company has also developed detection systems that can sense an ailing rotating component, such as a main bearing, and months in advance of it becoming critical. For these contributions to the wind industry, we recognize Dr. Peter Poon as a Windpower Engineering & Development 2016 Innovator.

Dr. Poon was born in China, and educated in Hong Kong, Taiwan, and the U.K. An interest in rolling element bearings sparked his interest in mechanical engineering where he established himself as an industry authority. Although he was an R&D head at a leading bearing company, he was dissatisfied with the way the industry performed its performance calculations and decided to improve on them.

He left that company in 1983 to become an independent consultant. In that role he advised governments on industrial policies both in UK and for the United Nations Industry of Development Organisation. Later recognition brought

him to the attention of the Department of Industry of the Korean government as a gear and bearing industry adviser.

Eventually he founded Romax, which stands for ROtating MAchinery eXpert. The company’s first product was a software program, RomaxDesigner, which significantly changed the way that the gearbox industry performs calculations. That led to software for designing gearboxes and rotating machinery across many industrial sectors.

Another an more recent product the company has developed offers insight into wind turbines’ mechanical conditions. And that gives the ability to manage and reduce the cost of component failures through a combination of predictive maintenance and practical solutions. Gearbox Express, a gearbox repair firm in the U.S., has used the software to improve upon repaired gearboxes so they are more durable and reliable than when new.

Throughout his career, Dr. Poon has served as a consultant and expert witness to the court for clients in the UK, U.S., and Far East. Since founding Romax Technology in 1989, he has worked alongside the world’s leading transmissions and engineering companies, developing bespoke software solutions

and providing engineering consultancy services to meet their growing needs.

Today, Dr. Poon holds a PhD in Mechanical Engineering from Bristol University and a Research Fellowship from Cambridge University. Company clients include Honda, Caterpillar, Samsung,

and E.ON. He is recognized as a world-leading expert on rolling element bearings and his work has been rewarded with the prestigious James Clayton prize, Institute of Mechanical Engineers for Tribology and The British Design Council Award for his rolling bearing design. The company boasts that 19 of the top 25 of the largest global operators are Romax InSight clients. W

Dr. Peter Poon examines an automobile transmission in his UK office.

Dr. Poon has been recognized by the Queen for his technical accompishments.


Peter Poon_Innovator 2016_Vs2 needs your edits Matt.indd 71 4/6/16 4:33 PM

» I n n ova to r a n d w i n d - f low s o f twa re d e ve lo p e r

L i z Wa l l s

2 0 1 6 I N N O V A T O R


Engineer and software developer, Liz Walls, didn’t start her career in the wind industry. She grew up in Calgary, Alberta, near the center of the oil and gas industry of Canada. So it was no surprise that after graduation she landed a job in the field, and in 2002 began her career as a reservoir engineer in the Alberta oil sands division of Petro-Canada. She found the work challenging and interesting, but Walls was slowly becoming aware of serious environmental issues concerning fossil fuels and oil sands.

“There was one book in particular, From Naked Ape to Superspecies by David Suzuki, which really got me thinking and pushed me in the direction of renewables,” she shares. “I also started to become fascinated with wind power. I saw how quickly the industry was growing at the time, and I wanted to be a part of it.”

Not one to hold back in pursuing her dreams, Walls decided that if she wanted to enter the wind industry, she would have to go back to school. “I had a degree in mechanical engineering with a minor in petroleum engineering,” she laughs. “But my dad once told me that if I was ever unsure in life to do the ‘Rocking Chair’ test. You know, where you picture yourself as an old woman or man sitting in the chair, thinking back on your life? You then have to ask yourself if you feel proud or have regrets.”

Walls knew that if she dedicated her career to wind energy, she would one day pass that Rocking Chair test. So she researched the best schools to master wind power, and in 2005 wrote her Graduate Record Exam for U-Mass’ Renewable Energy Research Laboratory (RERL) — the longest-running wind-energy research laboratory in North America. She got accepted, but there were limited spaces that year.

“To show how much I wanted in, I flew to Massachusetts to visit RERL’s Director, Dr.

James Manwell,” says Walls. “He loved that I was ‘coming from the dark side,’ as he put it, in reference to the oil and gas sector. He also liked that I knew how to code in terms of computer programming.” Late that summer, Walls left her job at the Alberta oil sands and moved down to Massachusetts.

“I started my Master’s degree that fall and was immediately given a research project. For the next two years, I studied advanced mechanical engineering and conducted various experiments with SODAR units,” Walls explains. SODAR is a meteorological instrument that profiles wind by measuring the reflection of sound waves by atmospheric turbulence. The experience landed her a job at Second Wind (now owned by weather-measurement company, Vaisala), developing the company’s Triton wind profiler.

By 2010, however, Walls took a proverbial seat back in the ‘Rocking Chair,’ and began assessing what she wanted to do next in the wind industry. As fate would have it, she met Jack Kline, who was a well-known pioneer of the American wind industry. “His work revolved around resource assessment and designing wind farms, which was exactly what I wanted to do.” It didn’t take long before Walls joined his meteorological consulting firm, RAM, in California.

For the next few years, she worked alongside Kline, developing the wind-flow modeling software, RAMWind. “Eventually, I decided that I wanted to branch out and continue software development on my own, so I formed

Cancalia Engineering & Consulting, acquiring the IP from RAM.”

Walls released Continuum 1.0 wind-flow modeling software in the spring of 2014 and version 2.0 in the fall of 2015. “In 2015, I also published a paper in the peer-reviewed journal, Wind Engineering, which presented the model theory and a case study where Continuum was used at a site with 11 met masts. The wind-speed estimate error was very low at 0.9%. In May 2015, I submitted a U.S. patent application that encompasses the Continuum wind-flow model methodology.”

Although she’s already looking at her accomplishments with pride, Walls says there’s more yet to come. “I’m proud of what I’ve done so far, but I’ve only just begun,” she states. “The transition from fossil fuels to renewable energy is happening, and I am very grateful to be a part of it.” W

My dad once told me that if I was ever unsure in life to do the ‘Rocking Chair’ test. You know, where you picture yourself as an old woman or man sitting in the chair, thinking back on your life? You then have to ask yourself if you feel proud or have regrets.

Liz Walls_Innovator 2016_Vs3.indd 72 4/6/16 4:53 PM

» U n d e r t h e d o m e : Pro fe s s o r H a n ga n a d va n ce s w i n d re s ea rc h

2 0 1 6 I N N O V A T O R

At a lecture a few years back at Ontario’s Western University, Dr. Horia Hangan, Professor in the Faculty of Engineering, discussed the challenges of measuring wind. “Wind is invisible and so we have to make it visible in some way,” he said.

He then displayed a graph with a single line that zigzagged up and down to demonstrate the variability of wind. “The engineer’s way of looking at the wind, and making it visible, is as a time series. We look at the variation of the velocity as a function over time,” he explained. “But engineers are often accused of not having imagination.”

One look at the world’s first 3D, hexagonal wind-measurement dome, located about 25 minutes away from Western

University’s campus, and engineers might earn a new reputation. Along with his work as a Professor, Hangan is also Founding Director of the Wind Engineering, Energy, and Environment (WindEEE) Research Institute, an organization with a vision “to be a global leader in wind research and innovation.”

In 2009, Hangan received a CDN$30 million grant by Canadian federal and provincial funding agencies to design and build the WindEEE Dome. WindEEE is intended to reproduce and study the impact of any and all types of wind systems in a controlled environment. The 25-meter

diameter inner dome (40-m diameter for the outer return dome) lets researchers simulate wind conditions over extended areas and in complex terrain on a large scale.

By manipulating the outflow and direction of over 100 powerful fans mounted on the dome’s ceiling, the facility can produce time-dependent, straight, sheared, or swirl winds of variable directionality. Hangan likes to refer to it as “the tornado-generating wind dome.”

Hangan received an Engineering Degree in Aeronautics from the Polytechnic University of Bucharest, Romania back in 1985, and continued his graduate studies at Ecole Polytechnique Federale de Lausanne in Switzerland before obtaining his Ph.D.

in Wind Engineering at the Western’s Boundary Layer Wind Tunnel Laboratory in 1996. After post-doctoral studies at Universite de Poitiers in France he rejoined Western in 1997 as a faculty member with the Boundary Layer Wind Tunnel Laboratory and the Department of Civil and Environmental Engineering.

Hangan has also authored more than 200 journal and conference publications, and is part of the Editorial Board of several international journals including ASME Journal of Solar and Wind Energy, the Journal of Wind Engineering and Industrial

Aerodynamics, and many others.Despite his work in establishing a

3D wind dome, Hangan always intended WindEEE to act as more than just a wind measurement facility. He envisioned a network that serves the wind industry and academia on a national scale. Before the facility had finished construction in 2013, the Wind Energy Strategic Network of Canada (WESNet) declared it a national research network facility. WESNet is the first wind-related network in Canada. It’s comprised of 39 Canadian researchers from 16 universities that work in close collaboration with industry, wind institutes, and governments.

As per WindEEE website, “The Institute acts as an enabler of industry-academic

partnership in wind-related research in which commercial funding is

matched with academic research funds to multiply the initial investment.”

“WindEEE is to serve as the physical facility for a network that entails most everything done in wind-energy research,” said Hangan, whose goal from the beginning of this project was to connect industry to research and education. “This is a huge investment for Canada, but we’re opening it to the world. We want to make this an international wind facility.”

Now who said engineers don’t have imagination? W

Wind is invisible and so we have to make it visible in some way.


Horia Hangan_Innovator 2016_Vs2.indd 73 4/6/16 4:41 PM

» D e vo te d to w i n d : M e e t i n f lu e n ce r, Ka re n Co n ove r

2 0 1 6 I N F L U E N C E R


A 25-year-plus wind energy veteran, Karen Conover barely remembers a time when she wasn’t interested in or researching renewable energy. It all started at a community science and energy event she attended in forth grade. She remembers going with her dad who, at the time, worked for the New Jersey Department of Environmental Protection and was an advocate for conservation and the environment.

“We went to a local event that included a booth focused on energy conservation and renewables. It was so engaging and

interactive,” she shares. Conover recalls pedaling a bicycle to energize a light bulb. “From that point on, I always chose something related to renewable energy for my science projects.”

In high school, Conover told her career counselor that she wanted a job in renewables and was told to pursue engineering. “I’m not even sure she knew what renewables were back then!” she laughs. But Conover was already well informed. She even wrote her college application essay on the benefits of recycling and renewable energy, not common topics for the early 80s.

After receiving her undergraduate degree at Duke University in Mechanical Engineering and Material Science, she sought a graduate program that specialized in renewables. Conover obtained a Masters

in Science and Engineering from University of Arizona in Renewable Energy Systems where she focused on wind, solar, and clean-power generation.

After some time at an energy consulting firm, Conover decided to venture out on her own and started Global Energy Concepts (GEC) in 1992. A wind-focused consulting company, GEC provided a range of services such as wind-resource assessment and due diligence. Clients included developers, equipment manufacturers, investors, government agencies, and utilities.

“GEC thrived, despite a challenging market for wind in the U.S.,” she shares. Those in the industry took notice. In 2002, the America Wind Energy Association (AWEA) recognized GEC with an award for “building one of the world’s leading wind consultancies.” The company grew to over 100 employees.

In 2008, GEC was acquitted by DNV, a global-risk management company headquartered in Norway. Conover then served as their global Wind Segment Director and moved to London for a few years to better interact with European customers. DNV subsequently acquired and merged with other renewable organizations, including KEMA, BEW, and GL, and today Conover is a company Vice President. “My current employer, DNV GL, is the largest provider of renewables’ advisory and certification services

in the world,” Conover says with pride. And she’s fully earned her title and success.

Back in 1995, she was nominated by a client for a position on the AWEA Board of Directors and continues to serve to this day. Although she’s often mistakenly labeled as the first female AWEA board member, Conover won’t take credit.

“When I joined AWEA’s board in the mid 90s, Audrey Zimmelman was already there and represented Northern States Power,” she claims. “However, she was only there a short time and, after she left, I was the only

woman on the board for the next decade or so.” Conover was also one of the youngest ever nominated and is currently the longest serving board member with just over 20 years under her belt.

As if that isn’t enough, Conover was a steering committee member and has acted as a board member for Women of Wind Energy (WoWE) since it first incorporated. WoWE promotes the education and advancement of women in wind power. In 2012, Conover was honored as WoWE’s Women of the Year.

“There’s so much research indicating the value of diverse work teams, yet the number of women in technical and management positions isn’t increasing significantly,” she explains. “And I’d like my legacy to include helping women to take charge and raise their voices to change our energy landscape for the better.” W

There’s so much research indicating the value of diverse work teams, yet the number of women in technical and management positions isn’t increasing significantly.

Karen Conover_Influencer 2016_Vs2.indd 74 4/6/16 4:54 PM

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ALTHOUGH THE COMPANY NAME is based on magic (named after the summoning spell in the Harry Potter series), Accio Energy’s wind-power technology is rooted in science. The science of lightning.

The basic elements used to create lightning are wind, water droplets, and charge separation. Accio’s electrohydrodynamic (EHD) wind-energy generation system uses all three, albeit producing much less power than an actual thunderstorm: wind separates positive and negative charges as it moves charged water droplets away from the source panel. The continuous separation of charges creates a flow of electrons as high-voltage, direct-current electricity.

According to the company, the concept of using charged water droplets to harness wind energy dates back to the late 1960’s. Researchers at the time had the theoretical physics down, but were unable to demonstrate a net energy positive system. Much like a good magic spell, precision is important. The key to EHD wind energy is precisely controlling the complex electric fields that form between charged droplets, the droplet source, and the ground. Failure to do so prevents the generator from creating electricity.

It took a couple of years to viably produce net positive energy and another couple to increase efficiency, but Accio Energy maintains it is the first company to have identified how to control electric fields and produce commercially

attractive power. The result? A first-of-its-kind generator with no blades or moving parts, but instead wind-permeable flat panels (that from a distance resemble solar panels).

The panels, composed of mass-produced tubes with tiny holes (where water droplets are released), can combine into several arrays to scale kilowatts of generated power or gigawatts. Because the number of water droplets and charge on the droplets can adjust

Casting a spell: Accio Energy’s turbine-less wind generator gets offshore funding

instantaneously based on weather conditions, the company says its wind system can operate at peak efficiency in all wind speeds.

EHD generators offer several advantages over conventional wind turbines. Without moving parts, they are bird, bat, and radar friendly. The technology is also scalable and easy to transport. Composed of common materials, Accio Energy says a single wind panel that’s the height and length of a standard shipping container could produce 2.5 to 3 kW of rated power as part of a utility-scale array.

The company estimates a single manufacturing facility (the size of an automotive assembly plant) could produce at least 4,000 panels each day, resulting in 10 to 12 MW of wind-generated capacity. This is equivalent to delivering four 3-MW wind turbines every day of the year from a single plant.

What makes EHD generators even more magical is their potential in the offshore wind market. Because of the modular design and a higher capacity factor (Accio pegs the factor 40% higher than conventional turbines), it estimates that EHD systems can eliminate up to 50% of the costs of offshore wind farms. Through such savings, Accio says EHD wind-generated energy could achieve unsubsidized cost parity with U.S. coal and natural gas plants.

The U.S. Department of Energy has taken notice. In late 2015, the DOE’s Advanced Research Projects Agency-Energy awarded $4.5 million in funding to support Accio Energy’s work in developing utility-scale EHD wind-power generation systems, specifically for the offshore market. With a little magic, the U.S. might soon have another good reason to develop offshore wind power. W

TOP: Accio Energy’s EHD wind-power system generates electricity using wind and charged water mist. The wind separates positive and negative charges as it moves the mist, creating high-voltage, direct-current electricity.

BOTTOM: Accio Energy says its wind-energy generation systems have up to a 40% higher capacity factor than conventional turbines.

Downwind 3-16_Vs2.indd 76 4/6/16 4:56 PM

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Windpower Engineering & Development APRIL 2016