FYP Report

Control System Analysis of Existing LIT Wind Turbine

and Anemometer Data Logging.

By

Mr. John Paul O Brien

Supervisor: Mr. K. Moloney

A project submitted in partial fulfilment requirements

For a

B.Sc. Renewable and Electrical Energy Systems

Limerick Institute of Technology

Submitted: April 2016

LIT Wind Turbine Control System Analysis and Anemometer Data Logging

Declaration

I declare that this report is my own work, and has not been submitted in any other form for

another award at any institution of education. Information taken from the published or

unpublished work of others has been acknowledged in the text and a list of references is

given.

Signed: ____________________ Signed: _________________

(Candidate) (Supervisor)

Date: ______________________ Date: ___________________

2K00191430 REES 3 John Paul O Brien


Dedication

I would like to thank my supervisor Mr Keith Moloney, who without he’s support the project

would not of been possible, for he’s guidance and advice on the direction of the project

which helped to keep me focused throughout the course of the project and also he’s belief

and encouragement in my ability to complete the project. He’s knowledge in renewable

energy systems also proved to be of great benefit in helping understanding the system.

I wish to thank Mr Ian Foley also who was of great help in the programming of the HMI and

he’s advice proved invaluable with regards to understanding and programming with the

Visilogic software.

I also wish to thank Dr Frances Hardiman whose advice and guidance in the formatting and

structuring of the report was of enormous benefit.

I wish to thank Nathy Brennan with who I collaborated on testing and erecting the

anemometer.

I also want to thank Mr Pat Grace for demonstrating how to lower the turbine.

And finally Mr Brendan O Heney who helped with the electrical risk assessment.



Table of ContentsDeclaration...............................................................................................................................2

List of Figures...........................................................................................................................6

List of Tables............................................................................................................................8

1 Introduction.......................................................................................................................9

2 Background.....................................................................................................................11

2.1 Components of Small Scale Wind Turbine System.................................................11

2.1.1 Rotor Blades.....................................................................................................11

2.1.2 Generators........................................................................................................13

2.1.3 Tower................................................................................................................14

2.1.4 Power Electronics.............................................................................................15

2.1.5 Battery Banks...................................................................................................15

2.1.6 Dump Load.......................................................................................................16

2.2 Application of Small Scale Wind Turbines...............................................................17

2.2.1 Off-Grid.............................................................................................................17

2.2.2 On-grid..............................................................................................................18

2.2.3 Direct Heating...................................................................................................19

2.3 Anemometer............................................................................................................20

2.3.1 Cup Anemometer.............................................................................................21

2.3.2 Sonic Anemometer...........................................................................................22

2.3.3 Propeller Anemometer......................................................................................23

2.3.4 Data Logging....................................................................................................24

2.3.5 Measuring Wind Speed....................................................................................25

2.4 Speed Control..........................................................................................................26

2.4.1 Pitch Control.....................................................................................................27

2.4.2 Furling...............................................................................................................28

2.4.3 Active Stall Control...........................................................................................28

2.4.4 Coning..............................................................................................................294

K00191430 REES 3 John Paul O Brien


2.4.5 Electronic Torque/Stall Control.........................................................................30

3 Safety..............................................................................................................................31

3.1 Method Statement...................................................................................................31

3.1.1 Electrical Risk Assessment..............................................................................32

3.1.2 Equipment........................................................................................................33

3.1.3 Method..............................................................................................................34

4 Control System Analysis.................................................................................................40

4.1 Conversion Process.................................................................................................40

4.2 Speed Control..........................................................................................................41

5 Anemometer...................................................................................................................45

5.1 Installing Anemometer.............................................................................................45

5.1.1 Testing Anemometer........................................................................................46

5.1.2 Power Supplies.................................................................................................47

5.1.3 Installing Anemometer......................................................................................48

5.1.4 Installing Nokeval 7470 DAC............................................................................49

5.2 Displaying Anemometer Data..................................................................................51

6 Discussion.......................................................................................................................54

6.1 Control System and Components............................................................................54

6.2 Safety.......................................................................................................................55

6.3 Data logging.............................................................................................................55

7 Conclusion and Recommendations................................................................................56

8 References......................................................................................................................57

9 Appendices.....................................................................................................................61

9.1 Appendix A:.............................................................................................................61





List of FiguresFigure 1-1-Turbotricity Wind Turbine.....................................................................................10

Figure 2-1.Wind Turbine Blade Design (Tutorials, Alternative Energy, 2016).......................11

Figure 2-2-Horizontal Axis Wind Turbine (works, 2006)........................................................12

Figure 2-3. Vertical Axis Wind Turbine (Darrieus, 2003)........................................................13

Figure 2-4-Permanent Magnet Generator (Comsol, 2012)....................................................14

Figure 2-5-Tilt Axis Wind Turbine Tower (College, 2016)......................................................14

Figure 2-6-Power Inverter (Abb, 2016)..................................................................................15

Figure 2-7-Wind Turbine Battery Bank (Energies, 2011).......................................................16

Figure 2-8-Dump Load for SSWT (Turbines, 2016)...............................................................17

Figure 2-9-Off Grid SSWT System (Company, 2015)............................................................18

Figure 2-10-On-Grid SSWT System (Piggot, 2012)...............................................................19

Figure 2-11-Direct Heating SSWT System (CO, 2015)..........................................................19

Figure 2-12-Cup Anemometer (edsc, 2015)..........................................................................22

Figure 2-13-Sonic Anemometer (Dame, 2011)......................................................................23

Figure 2-14-Propeller Anemometer (GmbH, 2016)................................................................24

Figure 2-15-Multiple Anemometers Measuring Wind Speed (Pidwirny, 2009)......................26

Figure 2-16-Pitch Control (Dvorak, 2012)..............................................................................27

Figure 2-17-Furling (Ltd., 2013).............................................................................................28

Figure 2-18-Stall Control (Ltd., 2013).....................................................................................29

Figure 2-19-Coning (mareenotmarie, 2009)...........................................................................30

Figure 3-1 Isolation lock Millennium Controller......................................................................34

Figure 3-2 Isolation lock Inverter............................................................................................34

Figure 3-3 Oil level.................................................................................................................35

Figure 3-4 Hose connections.................................................................................................35

Figure 3-5 Connecting motor and hose..................................................................................36

Figure 3-6 Inserting steel pin on bottom of Ram....................................................................36

Figure 3-7 Inserting steel pins at top of Ram.........................................................................37

Figure 3-8-Loosening Nuts.....................................................................................................37

Figure 3-9- Lowering Turbine.................................................................................................38

Figure 3-10 Turbine Lowered.................................................................................................38

Figure 4-1 Block diagram of PVI 7200 electronics topology..................................................40

Figure 4-2 Block diagram of PVI 3.6 electronics topology.....................................................41

Figure 4-3 Three phase resistive load....................................................................................42

Figure 4-4 Single phase resistive load...................................................................................42



Figure 4-5 Resistive load activated on controller...................................................................43

Figure 4-6 Brake setting applied on control...........................................................................44

Figure 4-7 Turbine Brake switch............................................................................................44

Figure 5-1 Default wiring screw terminal WMT52 (Oyj, 2012)...............................................46

Figure 5-2 Sample Data form WTM52...................................................................................46

Figure 5-3 Lab Testing WMT52............................................................................................47

Figure 5-4 Unitronics PSU.....................................................................................................47

Figure 5-5 WMT52 terminal screw connections.....................................................................48

Figure 5-6 WMT52 Erected....................................................................................................48

Figure 5-7 Terminal blocks supplying 24 VDC +/-.................................................................49

Figure 5-8 Nokeval 7470 default wiring guide (Nokeval, 2015).............................................49

Figure 5-9 Nokeval 7470 DAC...............................................................................................50

Figure 5-10 V200-18-E3XB I/O Module.................................................................................51

Figure 5-11 Linearizing function in Visilogic...........................................................................51

Figure 5-12 Linearized wind speed values.............................................................................52

Figure 5-13 Linearized wind direction values.........................................................................52

Figure 5-14 Menu Display......................................................................................................53

Figure 5-15 Linking pages using memory bits.......................................................................53

Figure 5-16 Wind speed displayed on HMI............................................................................54

Figure 5-17 Wind direction displayed on HMI........................................................................54





List of TablesTable 3-1 Safety and Maintenance Equipment......................................................................33

Table 5-1 Default wiring for WMT52 (Oyj, 2012)....................................................................45



Abstract

The aim of this project was to do a complete analysis of the control system and all components included in that system and their exact role in the system. Previous students have done projects on the wind turbine but those previous students projects were aimed more at the PLC side of the control system whereas this project will give a clear understanding of how the system works and will enable students in the future to have a better understanding of the operational procedure of the system.



1 IntroductionApproximately 18% of electricity generated in Ireland in 2013 was generated by renewable

sources, to meet the EU targets for 2020 Ireland must increase the percentage of electricity

generated from renewable sources to 40%. To meet these targets approximately 32% of all

electricity generated in Ireland by 2020 will be generated by wind energy so it is by far the

most important renewable energy source in Ireland.

Wind turbines generate electricity from the wind by converting the kinetic energy in the wind

(some not all) to mechanical energy using turbine blades which rotate and are connected to

a generator (typically AC generator) which in turn converts the mechanical energy into

electrical energy. The AC voltage generated is known as wild AC as it is of variable

frequency and amplitude and must pass through power electronics before it can be used or

exported to the grid. Firstly the “wild” AC voltage is passed through a rectifier which converts

it from AC to DC voltage and then through an inverter which converts it back to useable AC

voltage. Off Grid wind turbines used for charging batteries and such do not need an inverter

as they can be charged direct from the DC voltage from the rectifier. Anemometers are used

to measure wind speed and the data collected by Anemometer’s is essential in correctly

sizing a wind turbine and the control system that is needed to extract the maximum energy

from the wind and efficiently convert it to electrical energy.

The aim of this project is to fully understand the existing control system in which the wind

turbine and once data gathered from the anemometer is analysed determine if the existing

control system is optimising the available wind energy and if not what improvements, if any,

can be made to the system. The wind turbine in this report is a Small Scale Wind Turbine

(SSWT) and as such the report will concentrate on comparing and contrasting the various

SSWTs and the control systems available today rather than comparing to Large Scale Wind

Turbines.

The turbine in this report was built and installed in 2009 by a company from the Irish called

Turbotricity. Components of the system included a 2.5kW permanent magnet generator,

Aurora Power One Inverter, Aurora Wind Interface Box, Crouzet Millennium 3 Controller. A

Vaisala WMT52 Anemometer will be used to measure and log data which will be converted

using a Nokeval 7470 DAC and transmitted to a Unitronics V200-18-E3XB I/O Module which

will then be displayed on a HMI screen of a Unitronics V1210 PLC.



Figure 1-1-Turbotricity Wind Turbine

The following are the objectives of this project:

Develop a method statement for maintenance of wind turbine

Fully understand and document turbine operation and control system

Install Anemometer and log data

Display Anemometer data on HMI screen



2 Background The Sustainable Energy Association of Ireland (SEAI) classify a wind turbine with a

maximum rating of 11kW or lower with a 3 phase grid connection as a SSWT or when

connected to a single phase supply with a maximum rating of 6kW.The wind turbine featured

in this report has a maximum rating of 2.5kW with a single phase connection so it falls into

this category SSWT also known as micro generation.

2.1 Components of Small Scale Wind Turbine SystemThe main components of a SSWT are as follows.

Rotor blades

Generator

Tower

Power Converters

Battery banks (Off grid and stand-alone application)

Dump load

2.1.1 Rotor BladesRotor blades in a wind turbine are of similar design to aircraft winds and are usually made of

fibre reinforced epoxy or unsaturated polyester. The rotor blades have an aerofoil design

and a curved surface which generates a lift force as the air flows past. Rotor blades can be

connected in 2 different design systems, Horizontal Axis Wind Turbines (HAWT) or Vertical

Axis Wind Turbines (VAWT).

Figure 2-2.Wind Turbine Blade Design (Tutorials, Alternative Energy, 2016).



All HAWT use a lift force to rotate the turbine blades (some more advanced VAWT also use

it but not too common), the lift force is generated by the air flowing perpendicular to the

blade. As the air passes over the curved surface of the blade it creates a pressure difference

above and below which in turn creates the lift force which then rotates the blades. Most

HAWT blades face directly into the wind direction, these are known as upwind wind turbines.

But some HAWT blades face the opposite direction the wind is flowing, these are known as

downwind wind turbines. They extract the energy exactly the same as upwind turbines but

are not as efficient as the wind flow is disrupted by the turbine tower which reduces the wind

speed and thus reduces energy available. Most SSWT have wind vanes which guide the

turbine blades to face into the correct position corresponding to the wind direction depending

on whether they are HAWT or VAWT.

Figure 2-3-Horizontal Axis Wind Turbine (works, 2006).

Some SSWT are of VAWT design which basically means the rotor blades are positioned

horizontal to the wind direction, this creates a drag force which rotates the blades in the

opposite direction that the wind is blowing. These type of devices are seldom used as they

have a very poor efficiency.



Figure 2-4. Vertical Axis Wind Turbine (Darrieus, 2003)

2.1.2 GeneratorsMost SSWT use AC Permanent Magnet Generators which are connected to the rotor blades

by a generator shaft, generators convert mechanical energy into electrical energy.

” Essentially, a wire is wound around a stator made of material with high relative

permeability. Inside the stator you have a wheel, or rotor, which consists of a centre (made

up of the same material as the stator) and permanent magnets that create a strong magnetic

field. These permanent magnets are typically rare-earth elements, such as samarium for

example.

When the rotor is set in motion a current is induced. That is because the electromagnetic

fields (EMF) of the permanent magnets on the rotor move past the coiled stator. As the

magnets are spaced out like teeth on the rotor, the strength of the EMF fluctuates up and

down as the rotor spins. It is this continuous flux that induces the current into the stator wire.

Naturally, the faster the rotor spins, the higher the voltage output (Comsol, 2012).”



Figure 2-5-Permanent Magnet Generator (Comsol, 2012)

2.1.3 TowerThe top of a tower in SSWT is where the generator and rotor blades are housed, the blades

need to be raised high up off the ground to access better wind resource. The tower is of a

tubular steel design and in SSWT would vary in size dependant on the generator output and

location but usually wouldn’t exceed a height of 15m.The towers are generally tilt axis tower

which can be easily lowered or raised without the use of a crane and come in one section.

Single phase or three phase cabling, running internally in the tower, transmits the electricity

produced in the generator into the power electronics.

Figure 2-6-Tilt Axis Wind Turbine Tower (College, 2016)



2.1.4 Power Electronics“Power electronics has changed rapidly during the last thirty years and the number of

applications has been increasing, mainly due to the developments of the semiconductor

devices and the microprocessor technology” (F. Blaabjerg, 2006)

The power electronics needed in SSWT depends on whether its grid connected or for off grid

application. The power electronics consists of converters which convert the variable or “wild”

AC voltage into usable AC/DC voltage. In grid connected turbines the “wild” AC voltage first

passes through a rectifier which converts it to usable DC voltage. This DC voltage then

passes through an inverter which inverts the DC voltage back to usable AC voltage which

can be connected to the grid. Off grid turbines which are used to charge batteries don’t need

an inverter as the batteries are charged direct from the DC voltage from the rectifier. Some

systems have separate PLC controllers but it is more commonly to see the control system

inbuilt in the Inverters in SSWT with inbuilt control which can be access from a front panel

with an LED display. The power electronics are usually housed in a separate control nearby

the wind turbine.

Figure 2-7-Power Inverter (Abb, 2016)

2.1.5 Battery Banks“In off-the-grid systems batteries are an essential component used to store the energy

generated by your wind turbine so it can be reused later as needed. Batteries can also be

used as part of a grid-connected system to provide battery backup in the event the grid goes

down for a period of time. Batteries used with wind energy systems do have some unique

requirements and must be properly designed to fit the particular system you are planning to

implement (Bible, 2012).”



“Most battery banks that are used with home energy systems use either 6 volt or 12 volt

batteries though bigger batteries are also available. In a battery bank the individual batteries

are interconnected into a string so that the voltage adds up to 12VDC, 14VDC or even

48VDC. Now you might be thinking in the back of your mind, isn't that a bit low. My home

electric system uses 120 or 240 volts. Don't worry. The thing to keep in mind is that we are

talking about Direct Current (DC) voltage when it comes to batteries. When you are ready to

use the electricity for your home the inverter, a current conversion device that will be part of

your wind energy system, will convert the DC voltage in your battery bank into the 120 or

240 volts of AC current that your home typically uses (Bible, 2012).”

Figure 2-8-Wind Turbine Battery Bank (Energies, 2011)

2.1.6 Dump LoadA dump load is a device that is used to dump excess electricity when it is not needed or

battery banks are full. A typical dump load is usually just a heating element or resistor, dump

loads are especially important in off grid wind turbines as overcharging the batteries

shortens the life span of the batteries. Dump loads are also used to regulate speed in wind

turbines by diverting the excess power generated in high wind speed to stop the turbine

blades from freewheeling and spinning out of control (Solar, Missouri Wind and, 2015)



Figure 2-9-Dump Load for SSWT (Turbines, 2016)

2.2 Application of Small Scale Wind TurbinesSSWTs have typically been used in off-grid and remote location where connection to the grid

would be very expensive but more recently more grid connected SSWT are being installed

as the drive towards clean and sustainable energy supplies increases. SSWTs are broken

down into 3 different application usages which are as follows.

Off-Grid

On-Grid

Heating

2.2.1 Off-GridSSWT are ideally suited for off grid application usually in remote location where there is no

access to grid supplied electricity. They are relatively expensive per kWh compared to grid

supplied energy and usually take a lot longer than LSWT to repay the initial investment but

when compared to the cost of connection to the grid in most remote location they are

financially feasible .Off grid SSWT use battery banks to store electricity generated from the

wind turbine, a converter converts the AC voltage produced by the generator to DC Voltage

from which the batteries can be charged, an inverter then converts the DC voltage from the

batteries to AC voltage which can then be used for domestic or agricultural applications.

Some stand-alone systems such as lighthouse or emergency telephones on the side of a

motorway can be run from an Off-Grid SSWT by storing energy in a battery to run off. Off

grid system also need a charge controller.

A charge controller 20



“Is a device that regulates the current and or voltage that you can put into your battery or

batteries and it will not allow you to over charge and ruin your battery or batteries by

controlling the voltage at the battery level? Once your battery or batteries are charged the

controller kicks in and opens, diverts, or shunts the generator circuit (windpower, 2015).”

Figure 2-10-Off Grid SSWT System (Company, 2015).

2.2.2 On-gridGrid tied SSWT are used to supplement and reduce the electricity supplied from the grid,

they cannot total replace the grid supplied electricity as the energy produced by the wind

turbine is unpredictable and is concentrated in periods of high wind. The SSWT system for

an off-grid and on-grid turbine are pretty similar. The main difference is battery banks are

used to store the power generated in off-grid systems whereas on-grid system are

connected into grid supplied electricity once it has passed through various converters. By

replacing electricity purchased from the grid optimises the value of installing a SSWT and

also excess electricity produced can be sold back to the grid.



Figure 2-11-On-Grid SSWT System (Piggot, 2012)

2.2.3 Direct HeatingDirect Heating is really only suitable for sites that have a high heating demand, it is a

relatively simple system that uses the voltage generated by the turbine to power a heating

element in a large tank thus heating the water. Large well insulated tanks keep the water hot

and usable for periods when the wind isn’t blowing and the turbine isn’t producing energy. As

direct heating becomes more popular the price of the systems are dropping and are

becoming more financially feasible. The system is essentially the same as on grid SSWT

Figure 2-12-Direct Heating SSWT System (CO, 2015)



2.3 Anemometer An Anemometer is an instrument used for measuring wind speed and wind direction both of

which are very important when assessing if a site is suitable for a wind turbine. Accurate

measurements are vital as the wind speed has a cubic relationship with wind power and a

10% error in wind speed results in a 30% error in wind power, when measuring wind speed

the accuracy should be ideally kept to +- 2%. There are 3 main types of Anemometers used

for measuring wind which are:

Cup Anemometer

Sonic Anemometer

Propeller Anemometer

“Remote sensing techniques are now being used to measure the wind speeds at wind farm

sites. The technology available for this is being developed rapidly, and although the use of

remote sensing devices on wind farm sites is not currently widespread, it is expected to

become more widely used in the near future. Remote sensing devices are essentially ground

based devices, which can measure wind speeds at a range of heights without the need for a

conventional mast. There are two main sorts of devices: Sodar (Sound Detection and

Ranging), which emits and receives sound and from this infers the wind speed at different

heights using the Doppler Shift principle; Lidar (Light Detection and Ranging), which also

uses the Doppler Shift principle but emits and receives light from a laser. Sodar has been

used for assessing wind farm sites for some years, particularly in the US and Germany. It is

often used in combination with conventional anemometry and, historically, the results have

been used to provide more information to better understand the patterns of the wind regime

at a site, rather than necessarily using the data in a direct, quantitative way.



Recently, some wind energy specific Sodar products have come onto the market and

experience is currently being gained from these new devices. Lidar devices have made an

entry into the wind market over the last few years and two main commercial models are

currently widely available with additional models now entering the market. Published papers

on the devices show they are capable of achieving impressive accuracy levels in simple

terrain and it is expected that their use in wind energy applications will increase. The clear

merit of remote sensing devices is that they do not need a mast. However, Lidar devices, in

particular, are relatively expensive to purchase and both devices draw significantly more

power than conventional anemometry, so for remote sites a local, off grid power supply

solution would be needed (EWEA, 2016).”

2.3.1 Cup AnemometerThe Cup Anemometer is the most commonly used anemometer, current industry standard

cup anemometers have 3 hemispherical cups each mounted on a horizontal arm, at equal

distance and angle apart from each other, that rotate on top of a vertical shaft. The passing

wind is captured by the hollow part of the cup which rotates the cups in a horizontal direction

proportional to the wind speed and by counting how many times the cups fully rotate over a

set period of time the wind speed is measured. (Inc, 2015)

Some cup anemometers have tiny magnets attached to the cups and each time they pass a

magnetic detector an electrical pulse, which represents a single rotation is completed, is sent

to a data logger.

Cup Anemometers are relatively simple and cheap and can be easily installed, but

depending on the accuracy needed and climate conditions more expensive high quality cup

anemometers should be used. In colder environments icing can be an issue and heaters are

needed to prevent this occurring, also for measurements over a long period of time heavy

more robust anemometers are needed. Most Cup Anemometers don’t come with a wind

vane, to measure wind direction, so this is another drawback of Cup Anemometers.



Figure 2-13-Cup Anemometer (edsc, 2015)

2.3.2 Sonic AnemometerSonic Anemometers use ultrasonic sound waves to measure wind, pairs of transducers

(sensors) measure how long it takes for sound pulse to travel between them. The

transducers are arranged in 3 pairs on 3 different axis which measures wind speed three

dimensionally and because of this the wind direction can also be determined. Sonic

Anemometers are the most accurate and reliable anemometers which also makes them the

most expensive. The accuracy is mainly due to the much higher sampling rates, some high

quality sonic anemometers are capable of taking measurements approximately every 20

milliseconds. Sonic Anemometers have no moving parts which increases the reliability and

they are capable of operating in extreme conditions but the data quality can be significantly

affected in heavy rain when water droplets on the transducers impair the pulse signals.

When this occurs the affected data is usually discarded to reduce any error in overall data

collected. Most Sonic Anemometers also have heaters to prevent ice building up on the

transducers and affecting the quality of measurements (Science, 2016).



Figure 2-14-Sonic Anemometer (Dame, 2011)

2.3.3 Propeller AnemometerPropeller Anemometers work very similarly to wind turbines, they use propeller shaped

blades which rotate in the wind.

“Propeller anemometers measure the air flow from any vertical and horizontal wind direction.

They are usually applied in Wind Park monitoring by showing how the turbines react to

airflow. A propeller anemometer utilises a fast-response helicoid propeller and high-quality

tach-generator transducer to produce a DC voltage that is linearly proportional to air velocity.

Airflow from any direction may be measured, but the propeller responds only to the

component of the airflow that is parallel to its axis of rotation. Off-axis response closely

approximates a cosine curve with appropriate polarity; with perpendicular air flow, the

propeller does not rotate. The output signal of propeller anemometers is suitable for a wide

range of signal translators and data logging devices (GmbH, 2016).”

Propeller Anemometers output an Analog DC voltage signal which is proportional to wind

speed by using this method the accuracy of the data signals are very high. Some Propeller

Anemometer have screens that display the wind speed as it is being measured. The

Propeller Anemometer differs from other Anemometers as it generates an Analog signal,

usually 0-10v. This means, say for wind speed range from 0-100km/hr for every 0.1 volts it

corresponds to 1km/hr wind speed i.e. If it detects an output of 5.5v the corresponding wind

speed for 5.5v will be 55km/hr, for example:

5.5v.1v

× 1kmhr

=55km /hr



Equation 2-1 Converting Analog signal to Wind Speed

Figure 2-15-Propeller Anemometer (GmbH, 2016)

2.3.4 Data LoggingMost Anemometers have data loggers for storing data and measurements recorded, data

loggers store this data in either a digital or analog format, some anemometers have built in

Digital Analog Converter (DAC)/Analog Digital Converter (ADC) but a separate DAC/ADC

will be needed in most cases. Data can be extracted from the data loggers with various

different methods, ideally data could be sent via a radio transmitter to a Remote Telemetry

Unit (RTU) as the anemometers is actually measuring it and as the RTU would store it there

would be no need for a data logger but this is location dependant as a site with poor radio

signal would not be suitable.

Another method would be to connect to the serial port on the anemometer with a RS-486

cable and transfer the data to laptop. Some anemometers have removable micro-SD cards

which store the data and can simply be removed and inserted into a PC or laptop to transfer

data. Anemometers can also be hardwired to PLC units with built in or removable ADC/DAC

converters dependant on whether the data from the anemometer is analog or digital.



2.3.5 Measuring Wind SpeedWhen measuring wind speed at a site only anemometers covered by IEC-61400 standards

should be used, also each anemometer must be individually calibrated and have an official

ISO 3966 1977 certificate of compliance. Anemometers used for measuring wind speed over

long periods of time should be recalibrated after use to make sure there have been no

changes while measuring (Große, 2016).

“When erecting an Anemometer the impact of the mast (tower), on which the anemometer

will sit, on wind speed measurements should be taken very seriously and proper procedures

should be followed to reduce the impact it has on accurate measurements. Also more than

one anemometer should be used and placed at varying heights to give more accurate and

detailed measurements, below are a list of steps to follow for when installing anemometers.

All wind sensors must be fitted absolutely vertically. Even small deviations lead to

skew winds and therefore to wrong measurements.

Traverses keep the sensors as far away as possible from shaded or turbulent areas.

However, the traverse must not start swinging. This can not only influence the

measurement, but also lead to bearing damage of the transmitter.

The top-anemometer is to be placed centrally on the top of the tower. It must be

streamed on from all directions without obstruction. For the last piece (minimum

0.5 m) of the pillar, one should choose a diameter which is similar to the shaft of the

transmitter and which corresponds to the set-up used during the calibration of the

wind sensor in the wind channel. Next to the anemometer there should only be a thin

lightning conductor.

The lower anemometer(s) should be fitted on a vertical pipe attached to a traverse,

so that the anemometer stays 30 to 60 cm over the traverse. A traverse directly

under the anemometer can influence measuring! The fitting must be such that the

transmitter lies at a 45° angle to the main wind direction, which is usually known

approximately.

With a cylindrical tower, the length of the traverse should be at least 7-times of the

tower diameter. If a framework structure is used for the mast (width up to 30 cm), the

traverse length should be around 1 m long.



The wind vane should be fitted as high as possible on a traverse, but at least 1.5 m

below the top anemometer. The traverse is to be fitted as described before. For fitting

the vane you need a compass or a good map with a small scale in order to locate a

prominent fixed point on the horizon. Mostly one has to screw the wind vane onto the

tower while it is still lying on the ground. A good angle-measuring tool also helps.

The lightning rod (thickness approx. 2 cm) must have a distance of 50 cm from the

anemometer and must be free from vibrations. The lightning rod should be over the

anemometer at a 60° angle.

The best place for all cables is within the tower. The dead weight of free hanging

cables over 50 m in length has to be secured with an additional rope. If fitting within

the tower is impossible, you must fix the connections to tower and traverses at

intervals of one metre. Be sure that no loose cables are flying in the wind. Also avoid

contacts with sharp edges. Every little stress on the cable can lead to damage in the

course of long-term operations! (GmbH, 2016).”

Figure 2-16-Multiple Anemometers Measuring Wind Speed (Pidwirny, 2009)

2.4 Speed ControlSpeed control is essential in wind turbines for numerous different reasons, the first and most

obvious is to prevent the turbine from being damaged during storms or periods of high wind

speeds. Each turbine has a cut out speed given by the manufacturer, the cut out speed is

the maximum wind speed as recommended by the manufacturer for each turbine to operate

in and where operating above this wind speed is likely to cause damage to the wind turbine.

Wind Turbine blades can rotate at up to 7 times the actually wind speed so measures must

be taken to curtail the speed from exceeding the cut out speed. There are several ways of

doing so which are as follows:



Pitch Control

Furling

Coning

Active Stall

Electronic Torque/Stall Control

Speed control also prevents generating more energy than the system can handle which can

result in overheating or damage to cables and other components. Also speed control is

important for constant speed generators as the shaft and rotor rotational speed must remain

the same for the generator to operate at the optimum efficiency.

2.4.1 Pitch ControlPitch control is mainly used in Large Scale Wind Turbines but some SSWT manufacturers

do offer it. Pitch control uses a mechanism which adjusts the angle the turbine blades are

with regards to the wind direction, when wind speeds exceed the recommended cut out

speed the pitch mechanism angles the blades so they are horizontal to the wind direction

and no lift force is acting on the blades which stops the blades from rotating. Pitch control is

also used for regulating the power output from the turbine by adjusting the angle of the

blades so that they rotate at the same speed as a synchronous generator.

Figure 2-17-Pitch Control (Dvorak, 2012)



2.4.2 Furling“Furling is the process of forcing, either manually or automatically, the blades of a wind

turbine out of the direction of the wind in order to stop the blades from turning. Furling works

by decreasing the angle of attack, which reduces the induced drag from the lift of the rotor,

as well as the cross section. (Darling, 2013). “

Furling is done manually by physically cranking the turbine out of the wind using spring

hinges to adjust the rotor and blade angles relative to the wind direction, this is a simple

method which essentially is folding the turbine rotor and blades to a position so they do not

rotate. Furling can be done either horizontally or vertically and automatic furling uses the

same principle as manual furling but uses sensors and hydraulics to adjust the rotor when

wind speeds get too high.

Figure 2-18-Furling (Ltd., 2013)

2.4.3 Active Stall Control“Stall-regulated wind turbine have their blades designed so that when wind speeds are high,

the rotational speed or the aerodynamic torque, and thus the power production, decreases

with increasing wind speed above a certain value (usually not the same as the rated wind

speed). The decrease in power with increasing wind speeds is due to aerodynamic effects

on the turbine blades (regions of the blade are stalled, propagating from the hub and

outwards with increasing wind speeds). The blades are designed so that they will perform

worse (in terms of energy extraction) in high wind speeds to protect the wind turbine without

the need for active controls. The benefit of stall-regulation over pitch-regulation is limited the

capital cost of the turbine, as well as lower maintenance associated with more moving parts.



Like the pitch-regulated wind turbine, stall-regulated wind turbine also have brakes to bring

the turbine to a halt in extreme wind speeds.” (Chen, 2011).

Stall control doesn’t work on variable speed turbines and also the force acting on the blades,

when in stall-regulation, can be very high leading to high vibration which increases noise and

also can damage the blades.

Figure 2-19-Stall Control (Ltd., 2013)

2.4.4 ConingConing is a very simple method of speed control used on downwind turbines, the blades

have spring hinges and as the wind speed increases the blades simple start to bend back

reducing the force exacted on the blades



Figure 2-20-Coning (mareenotmarie, 2009)

2.4.5 Electronic Torque/Stall ControlAlthough not widely used electronic torque is a very effective way of regulating speed, as the

current increases so does torque. So when high wind speed occur the power electronics can

increase the current being drawn which increases torque on the rotor shaft which in turn

reducing the speed of rotor.



3 SafetyProper safety procedures are vitally important when working on or nearby live electrical

equipment to ensure the health and safety of employees and also members of the public

who could be at risk. Before a method statement is drafted an electrical risk assessment

must be done on the equipment or system in question by trained personnel and once

hazards are identified the following procedures as set out in Chapter 5, Regulation 85 of the

Safety, Health , and Welfare at Work (General Applications) Regulations 2007 Part 3 must

be followed.

“Switching and isolation for work on equipment made dead. 85.

(1) An employer shall ensure that— (a) subject to paragraph (2), where necessary to

prevent danger, suitable means (including, where appropriate, methods of identifying

circuits) are available to switch off the supply of electricity to any electrical equipment

and to isolate any electrical equipment, (b) every switch, circuit breaker or other

control device provided under subparagraph (a) is, where necessary to prevent

danger, (i) clearly marked to indicate the “ON” and “OFF” positions, unless these are

otherwise self-evident, and (ii) readily accessible for authorised persons and in a

suitable and adequately lit location, and 42 (c) adequate precautions are taken to

prevent the operation of any switch while carrying current where that switch is not

capable of safely interrupting normal load current. (2) Paragraph (1) does not apply

to electrical equipment which is itself a source of electrical energy, provided that

adequate precautions are taken to prevent danger (hsa, 2007).”

3.1 Method StatementA method statement is a vital document that informers workers of the potential risks and

hazards in a particular work environment, it also details the correct procedure to follow when

work or maintenance is to be carried out on a particular task or activity. Method statements

are site specific and should be tailored to the environment and job specifications in which the

activity will be carried out.



“Whilst there is no standard format for a method statement, the following aspects may need

consideration:

working systems to be used;

arrangements for access e.g. to roofs;

methods for safeguarding existing structures;

structural stability precautions, e.g. temporary shoring arrangements;

arrangements for protecting the safety of members of the public;

plant and equipment to be used;

health protection arrangements, such as the use of local exhaust ventilation

and respiratory protection, where hazardous dusts and fumes could be

created;

procedures to prevent local pollution;

Segregation of specific areas; (Direct, n.d.).”

3.1.1 Electrical Risk AssessmentAn electrical risk assessment was carried out with Mr Brendan O Heney, Senior Electrical

Technician from LIT, who was responsible for installing the control system for the wind

turbine.

The control system has 2 separate power sources feeding it and these must be isolated or

made dead before any work can be carried out.

1. The first source of electrical supply was 3 phase 0-600 Variable AC voltage and

variable frequency from the turbine generator which was connected to the Wind

Interface Box (Rectifier) and Millennium controller in the control room. An isolation

switch directly between the 3 phase supply and Wind Interface Box cuts this supply

when switched to the OFF position, properly electrical locks and tags are to be used

when doing so.

2. The next electrical hazard identified was the 230 V AC Main supply to the Aurora

Inverter, this also had an isolation switch to cut supply, once switched to the OFF

position proper electrical locks and tags are to be used to ensure cutting off the

electrical supply safely.

3. The control system also contained an isolation switch that activated the hand brake

on the wind turbine, which prevents the turbine blades from rotating and thus



generating electricity, this must be switched to the ON position before any work is

carried out.

4. Once these 3 steps have been implemented a multi-meter is used to carry out tests

to ensure all electrical supply have been isolated and are safe to work on.

3.1.2 Equipment

Table 3-1 Safety and Maintenance Equipment

Safety Equipment/PPE Electrical Isolation Turbine Lowering

Equipment

Steel Toecap Safety

Boots

HI-Visibility

Vest/Jackets

Hard Hat

Barriers or tape to

cordon off area

Safety Tagout Kit

Multi Meter

Flowfit Hydraulic

Cylinder/Ram

TEC 1.5 Kw Electric

Motor

Hydraulic Hoses

Hydraulic Oil

Extension Lead

1m Tommy Bar

41mm Socket Set

30mm Diameter

300mm Steel Pins



3.1.3 Method1. Ensure area is clear of unauthorised personnel before work can commence, lock

gate and cordon off work area.

2. Bring turbine to a stop using

3. Carry out Electrical Isolation as set out in Electrical Risk Assessment locking out and

tagging isolation and hand brake switches as seen in figures 3-1 and 3-2



Figure 3-21 Isolation lock Millennium Controller

Figure 3-22 Isolation lock Inverter

4. Uses multi meter to check if electrical supply is killed.

5. Check Oil levels in hydraulic ram are sufficient (as seen in figure 3-3), if below

required level refill.



Figure 3-23 Oil level

6. Connect hoses to motor and hydraulic ram, hose connected to bottom fitting of motor

must be connected to bottom fitting on hydraulic ram and vice versa for top fitting.

Figure 3-24 Hose connections

7. Move hydraulic ram into position flat on ground next to wind turbine.



8. Connect motor to extension lead and plug extension lead into mains supply turning

on motor as seen in figure 3-5.

Figure 3-25 Connecting motor and hose

9. Tilt hydraulic ram up using control levers until pin holes match up on turbine and ram.

10. Place steel pins through pin holes at top and bottom of ram and ensure they are

secure before continuing as seen in figures 3-6 and 3-7.

Figure 3-26 Inserting steel pin on bottom of Ram



Figure 3-27 Inserting steel pins at top of Ram

11. Use 41mm socket fitting and 1m tommy bar (for extra torque) to loosen nuts on

turbine stand (as seen in figure 3-8), do not remove fully until sure hydraulic ram is

operating correctly, then remove nuts 1 at a time.

Figure 3-28-Loosening Nuts



12. Slowly lower wind turbine, using control lever, until it is flat on the ground. See figures

3-9 and 3-10.

Figure 3-29- Lowering Turbine

Figure 3-30 Turbine Lowered

13. Maintenance check and work can now be carried out if needed.

14. Slowly raise turbine up using control lever until it is flush on turbine stand and reinsert

nuts and retighten.

15. Once turbine is secure remove steel pins and lower hydraulic ram, plug out and

disconnect hoses.



16. Remove isolation locks and tags from switches, and turn ON isolation switches for

inverter and millenium controller.

17. Do not switch handbrake OFF for at least 5 minutes after inverter has been initialized

as no current will be drawn and turbine blades will rotate uncontrolled and may cause

damage to turbine.

18. Release hand brake switch and observe system is running correctly before leaving

and locking up control room.



4 Control System AnalysisThis section of the report will examine the process and components involved in converting

the variable 3 phase AC voltage generated by the turbine generator to the 230 AC voltage

which is exported to the grid and also how the system is controlled.

4.1 Conversion Process1. The 2.5kW permanent magnet generator, which sits at the hub of the wind turbine,

produces 3 phase variable VAC which is connected to an Aurora Power One

Interface Box PVI 7200 (Rectifier).

2. The PVI 7200 has a maximum input of 400 VAC and maximum output of 600 VDC,

the 3 phase VAC is converted to VDC by the PVI 7200 using a system of power

electronics such as diodes, capacitors and transistors (as seen in figure 4-1) which

then must undergo another conversion process in the Aurora Power One Inverter PVI

3.6.

Figure 4-31 Block diagram of PVI 7200 electronics topology

3. The PVI 3.6 Inverter has a maximum input value of 600 VDC and by using a complex

configuration of electronic components such as capacitors, diodes and transistors (as

seen in figure 4-2) converts the inputted VDC to 230 VAC 50 Hz for export to the

grid.



Figure 4-32 Block diagram of PVI 3.6 electronics topology

4.2 Speed ControlThe system comes with 2 resistive loads or dump loads as mentioned in section 2.1.6., a

three phase load figure 4-3 which is used for speed control and a single phase load figure 4-

4 which is used for dumping excess energy generated (if any). These resistive loads are

basically just heating elements as can be seen from figures 4-3 and 4-4 and any excess

energy generated is dissipated as heat through the single phase dump load. The three

phase resistive load is used for controlling the speed, when the DC voltage from the rectifier

reaches a certain value the three phase load is activated which increases the resistance in

the circuit which in turn forces the generator to draw more current which causes it to stall

and rotor shaft to stop turning.

The system also has a brake switch which when turned to the ON position shorts out the

generator, this is only to be used when the turbine has been already brought to a stop

through the controller, and prevents the rotor from turning when lowering or raising the

turbine.



Figure 4-33 Three phase resistive load

Figure 4-34 Single phase resistive load

The manufacturer pre-programmed the controller to active the three phase resistive load

once the voltage from the rectifier hits 530 VDC and disconnect the load once the voltage

drops below 430 VDC. But since installation the program has been modified numerous

times, by previous students, and now the resistive load will activate once the voltage

exceeds 200 VDC which is only 1/3 of the rated output of the rectifier and by limiting the



voltage from going above 200 VDC the power output and overall efficiency of the system is

greatly reduced.

This is set using a 0-10v analog signal for the voltage range 0-600VDC, this linearizes the

voltage range with the analog value. So when the output voltage is at 0v (min value) this

corresponds with 0.00v (min value) on the analog scale, and when the voltage reaches 600v

(max value) this will correspond to 10v (max value) on the analog scale.

So for every 1v of an increase in output voltage will mean an increase of 16.67mv on the

analog scale, this was calculated using the following formula.

1v output¿analog rangevariable range

=10v600

=0.01666∨16.67mv

Figure 4-5 shows the resistive load activating at 3.3v on the analog scale which correspond

to 200 VDC on the output. The value of 167v in the display can be disregarded as the output

voltage dropped from 200v while the picture was being taken.

Figure 4-35 Resistive load activated on controller

Figure 4-6 shows the brake being applied, which is the generator being stalled, this happens

after the resistive load is applied and as can be seen it also activates at 3.3v analog which

again is 200 VDC, again the output voltage in the picture can be disregarded for the same

reason as mentioned for figure 4-5.



Figure 4-36 Brake setting applied on control

Figure 4-37 Turbine Brake switch



5 Anemometer A Vaisala WMT52 Anemometer was installed to log wind data, the WMT52 is an ultra-sonic

anemometer that uses 3 ultrasonic transducers to measure wind speed. And as mentioned

in chapter 2.3.2 ultra-sonic anemometers measure the time it takes for sound pulses to

travel between the transducers and thus measures the wind speed and also the wind

direction. The data out from the WMT52 is a digital signal so to convert wind speed and wind

direction to an analog signal a Nokeval 7470 Digital to Analog converter was used which

would in turn transmit the analog signal to a Unitronics V200-18-E3XB I/O (input/output)

module and could be displayed on V1210-T20BJ HMI touch screen. An RS-485 cable was

hardwired to the screw terminals of the WMT52 (as there was no 8-pin M12 connector on

the WMT52) to connect to the Nokeval 7470 for power and data transfer. Both the Nokeval

7470 and WMT52 were sent off to be professionally calibrated before project commenced.

5.1 Installing Anemometer Before the Anemometer was installed it was tested in the lab (see figure 5-1) to ensure it

was powering up correctly and data was being transmitted, as mentioned in chapter 1 this

was done in conjunction with 3rd year Electronic Engineering student Nathy Brennan, using

the RS-485 default configuration as seen in table 5-1 and figure 5-1.

Table 5-2 Default wiring for WMT52 (Oyj, 2012)



Figure 5-38 Default wiring screw terminal WMT52 (Oyj, 2012)

5.1.1 Testing Anemometer The testing was carried out by connecting wires to the screw terminal (as configured in

figure 5-1) of the WMT52 to an Arduino ATMega 2560 microcontroller, HTerm software

package was used to open up a COM port between the microcontroller and laptop and a

USB cable used for sending and receiving data (see figure 5-3). The sample data received

from the anemometer is in digital Hexadecimal form which is converted into m/s for wind

speed and degrees for wind direction by the HTerm software. Figure 5-2 shows a sample of

the data received where Dm corresponds to direction in degrees, relative to North, i.e. 90 =

East, Sm refers to wind speed in m/s.

Figure 5-39 Sample Data form WTM52



Figure 5-40 Lab Testing WMT52

5.1.2 Power SuppliesBoth the WMT52 and Nokeval 7470 require 24 VDC power supplies, the Unitronics PLC

power supply is 230 VAC from the grid but its Power Supply Unit (PSU) can provide 24 VDC

out from its terminals so 2 x 24 VDC power supplies on din rail mounted terminal blocks

were generated for the WMT52 and Nokeval 7470 respectively. To do this the Unitronics

was stripped of all wiring from previous projects with the 230 VAC grid supply to the PSU

established 1st, once the PSU was receiving power the 2 x 24 VDC power supplies (figure 5-

4) were created and now the Nokeval 7470 could be installed.

Figure 5-41 Unitronics PSU



5.1.3 Installing AnemometerThe anemometer was hardwired to the screw terminals as per default wiring guide (see

figure 5-1) and mounted on a steel pole before being raised, anemometers should ideally be

raised at the same height of the hub of the wind turbine but in this case was not possible as

the length of the RS-485 cable provided was not long enough. Once the RS-485 cable was

wired to the screw terminals of the WMT52 (see figure 5-5) and an earth cable was also

connected for grounding the anemometer was raised.

Figure 5-42 WMT52 terminal screw connections

Figure 5-43 WMT52 Erected

Next the brown and yellow wires from the RS-485 were connected to the 24VDC + din rail

mounted terminal blocks power supply from the PSU and the pink and red wires connected

to the 24VDC – terminal blocks from PSU also, Figure 5-7.



Figure 5-44 Terminal blocks supplying 24 VDC +/-

The blue and grey wires for data in and data out were connected to the Nokeval DAC (see

chapter 5.1.4) and the remaining 2 wires white and green, from the RS-485 cable, were

terminated as they are of no use in the RS-485 default wiring configuration.

5.1.4 Installing Nokeval 7470 DACThe Nokeval 7470 was mounted on a din rail inside the Unitronics PLC and was connected

up as per default wiring guide RS-485, see figure 5-8, on the input side the grey wire (data in

from WTN52) connected to terminal 1 and blue wire (data out from WMT52) to terminal 2

Figure 5-45 Nokeval 7470 default wiring guide (Nokeval, 2015)



24 VDC + connected into terminal 12 and 24 VDC – connected to terminal 11 also. As

previously mentioned the DAC was sent away to be calibrated before use, the analog

outputs are a 4-20mA range. Channel 1 of the analog output was calibrated for a wind speed

range of 0-60 m/s meaning an output of 4mA= 0m/s and 20mA= 60m/s and as the range is

16mA/60m/s for every increase of 266.7μA current signal is equal to a 1m/s increase in wind

speed. Terminals 13 + and 14 - were connected to Analog input 0 + and – on the V200-18-

E3XB I/O module (see figure 5-9).

Figure 5-46 Nokeval 7470 DAC

Analog out channel 2 on the DAC was calibrated for wind direction, again 4-20mA was the

signal range which corresponded to 0-360° for direction with 0°= North. As the range is

16mA/360° as the signal increases by 44.44μA = 1° change in wind direction clockwise.

Terminals 16 + and 17 – (see figure 5-10) from the DAC were then connected to Analog

Input 1 +/- on the V200-18-E3XB (see figure 5-11).



Figure 5-47 V200-18-E3XB I/O Module

5.2 Displaying Anemometer Data.The data from the anemometer is displayed on a Unitronics V1210 HMI in conjunction with

a V200-18-E3XB snap in I/O module which connects into the V1210 as seen in figure 5-10.

The snap in I/O module receives the 4-20 analog signals from the DAC into analog inputs 0

and 1 and these inputs are assigned to Memory Integers which are internally addresses in

the I/O list. To display this data a ladder and HMI program had to be created using

Unitronics Visilogic V9.8.22, to convert the 4-20mA signals to values that can be displayed

the first step done is what is called linearizing.

Figure 5-48 Linearizing function in Visilogic



Linearizing is converting the analog signals to bit values which allows the actual measured

values then to be displayed, in this case wind speed in m/s and wind direction in degrees.

Visilogic has an option to use 12 bit or 14 bit ,the 12 bit option gives quicker measurements

but the 14 bit option is more accurate so the 14 bit. When selecting the bit resolution it is

very important to select the correct bit range and the correct baud rate, from the manual the

bit range for 14 bit goes from 3277-16383 and a baud rate speed 115200. If the correct bit

range and baud rate are not configured the actual measured values displayed on the HMI

will be incorrect. For wind speed 0 m/s will be equal to 3277 bits and 60m/s will be equal to

16383 and for the wind direction 0° is equal to 3277 and 16383 is equal to 360°, once

linearized the display range values are stored in memory integers which are then used to

program the measured values on the HMI. Figures 5-12 & 5-13 show the configured ranges

for both wind speed and direction, the wind speed for display are stored in memory integer

MI 20 and wind direction MI 21, these are the memory integers that are used to program

display in HMI. Note that there is a 1 decimal offset for the max measures values so Y2 in

figure 5-12 is 60.0 m/s not 600m/s and in figure 5-13 Y2 is actual 360.0° not 3600°.

Figure 5-49 Linearized wind speed values

Figure 5-50 Linearized wind direction values

Four display pages were then created for the HMI display, a Menu page from which the 3

other pages Wind speed, Wind direction and Trends) could be accessed by buttons which

linked the pages. While creating the pages each page was assigned a memory bit address

that are used to link buttons to pages and thus navigate through the HMI display also on

each page a back button was created which when pressed jumps back to the menu page.



Figure 5-51 Menu Display

Figure 5-52 Linking pages using memory bits



Figure 5-53 Wind speed displayed on HMI

Figure 5-54 Wind direction displayed on HMI



6 DiscussionOne of the aims of this project was to fully understand how the control system and

components of the system work and to analysis whether the system is configured to extract

the optimum energy available and optimizing maximum efficiency.

Another aim was to carry out a safety assessment and produce a method statement which

would be of use for further work carried out on the system.

And also erect an Anemometer and log and display data from the Anemometer on a HMI

screen. This chapter will discuss and highlight issues that arose over the course of the

project.

6.1 Control System and Components While analysing the system the most obvious issue in the design was the variation in rated

power between the generator, rectifier (wind interface box) and inverter. The permanent

magnet generator has a power rating of 2.5kW while the rectifier has a power rating of

7.2kW and the inverter has a power rating of 3.6kW, meaning the rectifier can handle just

under 3 times the power generator by the generator which seems to be greatly oversized

and just adds to the initial capital cost of the system unnecessarily.

Another issue was the Crouzet Millennium 3 Controller and its role in the system, the original

design of the system as set out in the manufacturers manual does not include this controller.

The manual states that the Aurora inverter can be used to programme the control setting in

the system from its control panel so it seems to be an unnecessary addition to the system

and also the fact the controller has a very complicated program and the programming

language its self is a combination of ladder logic and function block which further

complicates matters.

On the software side of things the controller has a brake setting which activates when the

output from the rectifier reaches 200 VDC while the rectifier itself has a maximum output

voltage rating of 600 VDC. This setting prohibits the system from utilizing anywhere near the

maximum energy output from the available energy resource and dramatically reduces the

efficiency of the system.

As mentioned in section 4.2 the system uses a three phase resistive load as a braking

mechanism, when this three phase load is activated the rotor and turbine blades stop turning

almost immediately. This sudden stop could in theory cause damage to the rotor and turbine

blades if it has not done so already.59



6.2 SafetyThe system has two electrical isolation switches which when turned to the OFF position

isolate power supply from the grid and also the power supply from the generator but the

system also has a brake switch for the turbine which looks very similar to the isolation

switches. In the event of maintenance being carried out or the turbine needs to be lowered

the two isolation switches need to be in the OFF position but the brake switch must be

switched to the ON position which may cause some confusion and become a safety hazard.

6.3 Data loggingThe anemometer was sent away to be calibrated before this project commenced and was

calibrated for a wind speed range of 0-60 m/s and for wind direction 0-360°. While the

calibration for wind direction is not an issue the calibration for wind speed caused some

problems when displaying it on the HMI screen. 1m/s is equal to 3.6 km/h so the

anemometer was calibrated up to a wind speed of 216 km/h which is excessively high.

The Visilogic software had two options of establishing communication between the I/O

Module and laptop which are USB to mini USB cable and a serial to USB cable which needs

a special adapter supplied from Unitronics. Initially the chosen method of communication

was the USB to mini USB cable as this was the method previous students had used. But

during the course of the project this method of communication failed, replacement cables

were tried, different versions of driver software were tried but to no avail. Eventually after a

lot of time spent trying to remedy the issue it was established that the mini USB port on the

V1210 was the problem and once the adapter for the serial to USB cable was located this

was the method of communication used for the duration of the project.



7 Conclusion and Recommendations As previously mentioned the system is very inefficient, one way of improving the efficiency

and increasing the output power is by adjusting the brake setting from 200VDC to a

recommended setting of 400 VDC on the Crouzet Millennium Controller, however this is a

complicated piece of software, and due to time constraints it was not possible to do so but is

advisable to do so in the future.

The addition of the Millennium Controller in the system, in the opinion of this student, seems

unnecessary and just overcomplicates the system. Further investigation as to why the

manufacturer chose to include this piece of equipment would be advised and if it is possible

to remove the controller without affecting the operational capacity of the system, however

the manufacturers Turbotricity have closed down since the system was purchased and the

technician responsible for sourcing and installing the system is not an employee of LIT

anymore. So due to the fact that little or no information is available with regards to the role of

the controller it is advisable not to remove from the system as it may cause unforeseen

problems to the system.

With regards to braking mechanism employed a variable resistive load could be used to

slowly increase the resistive load and thus bringing the rotor and the rotor blades to a

gradual stop instead of a sudden stop. However these variable resistor are expensive and as

the system has a very small energy output it is not financially feasible to do so unless it was

for educational or demonstration purposes.

Regards the safety issue of the brake switch it is recommended that a sign be erected

directly beside the switch stating its exact purpose as to differentiate it from the two electrical

isolation switches.

The calibration of the Anemometer is probably twice the range of what it needs to be, a 0-

30m/s calibration would be sufficient and would also increase the accuracy of the

measurements as the range is reduced by half.

Also it cannot be overstated the importance of establishing communications between

devices at the initial stage of the project, it is recommended that all methods of

communication be tested as early as possible that way if one method of communications fail

another method can be used without the loss of time.



Overall the system is inefficient especially considering the location is far from ideal as it is

surrounded by building which creates turbulence and a reduction in available wind energy

and as a result will never produce enough energy to even come near to repaying the initial

cost of the system but as a demonstration model this student found the experience and

knowledge gained during the course of the project invaluable and as a teaching aid the

system may have an important role for future students also.



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regulated-Wind-Turbine.html


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9 Appendices

9.1 Appendix A: Data sheet Aurora PVI 3600

9.2 Appendix B: Data sheet Aurora PVI 7200



9.3 Appendix C: Data sheet WMT52

9.4 Appendix D: Data sheet V200-18-E3XB


