Vertoda wind farmoperations

An Overview of Wind Farm Operations – A White Paper by Vertoda

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Abstract

Wind Farms are a key component of Clean Energy. This paper outlines how Wind Farms work and the data requirements and management systems required by Wind Farm operators.



Table of Contents

Table of Contents....................................................................................................................................5

Glossary...................................................................................................................................................7

1. Introduction ....................................................................................................................................8

2. Wind Turbines.....................................................................................................................................9

3. Transmission of Electricity ................................................................................................................10

4. Data Acquisition & Management Systems........................................................................................12





Glossary

O&M Operations and Maintenance

OLE Object Linking And Embedding

OPC OLE For Process Control

SCADA Supervisory Control And Data Acquisition



1. Introduction

This White Paper outlines the operations of Wind Farms and how the energy generated by Wind Farms is transmitted to the electricity grid. The data produced and the management systemsrequired by Wind Farms is also considered.

Figure 1: A Wind Farm



2. Wind TurbinesA wind turbine uses wind to create energy. Wind causes the blades of the turbine to rotate.A more scientific interpretation is that the kinetic energy in the wind is captured by these blades. These blades in turn are connected to a rotor which is connected to a shaft. The shaft spins a generator to create electricity.

Despite its name, the turbine is only one component of a wind turbine machine. The blades/propellers are the turbine component. The machines also have a gearbox that turns the slow rotation of the propellers into a faster rotation for powering the electricity generator. This is the final key component of a Wind Turbine and is an electromagnetic device that converts kinetic energy into electricity. Sometimes a generator is described as an electric motor running in reverse as a copper coil is being moved inside a magnetic field to generate electricity. A key point here is that energy is not being created. Rather it is being transferred from one medium to another.

The larger the rotor blades, the more energy is captured. Similarly, the taller the machine the more energy is captured as wind speed is much faster when it is clear of obstructions. It is for this reason that Wind Farm location is critically important. Site surveys to determine the appropriateness of a location and the number of turbines required are carried out before a decision to select a particular location is made.

From a commercial perspective, the turbines in a Wind Farm are manufacturers by only one vendor. While a Wind Farm operator may have different manufacturers in different farms only a single manufacturer’s turbines will be present in any one farm. The most well known manufacturers in the Wind Turbine space are the Vestas from Denmark (http://www.vestas.com), Enercon from Germany (http://www.enercon.de), Siemens (http://www.energy.siemens.com) and Nordex also from Germany (http://www.nordex-online.com).



3. Transmission of ElectricityOnce a Wind Turbine generates electricity, this electricity must be transferred to the electricity grid. Typically, a Wind Turbine is connected by powerlines to a collectorsubstation. This substation converts the power generated by the wind turbine and converts it to a higher voltage for the electricity distribution system (the grid) using a transformer. This ensures that wind power is delivered at a consistent voltage. Another consideration is that there is less loss of power at higher voltages. The substation is then connected to the main transmission grid.

Substations are managed by a SCADA system and will also have a power quality meter and mimic panel to display the state of the circuits. O&M support of both the turbines and the substation is carried out by the manufacturer.

Figure 2: A Collector Substation in Ireland



Figure 3: Transmitting from the Wind Farm to the Distribution Grid



4. Data Acquisition & Management Systems

An individual wind turbine is a complex piece of machinery that needs to be managed by itsowners for two key reasons: its operational efficiency and the measurement of the energy and hence revenue being generated by the equipment. There are a number of challenges that Wind Farm operators must meet to achieve these goals.

As noted, an individual wind farm may consist of a number of wind turbines but, in general, the turbines in a given wind farm come from the same manufacturers. If an operator has more than one wind farm, however, they may find themselves in the situation where they have to manage turbines from different manufacturers. Individual wind farms are managed by the turbine manufacturers’ SCADA system offering (SCADA stands for Supervisory Control And Data Acquisition). SCADA systems are powerful systems that supervise the operation of the wind turbines and the wind farm as a whole. Through the use of the SCADA system, operators can assess how much energy a farm is producing and hence how much revenue they are generating.

This situation is complicated where there are wind farms with multiple manufacturers as operators as they then have a situation where they have a SCADA system for each manufacturer. In a worst case scenario, operators may have to manually add up the output of each SCADA system to ascertain the revenue figures. Some SuperSCADA systems have been developed where turbines from multiple manufacturers and hence multiple wind farms can be managed. One such system has been developed by the Technical University of Denmark – see http://tinyurl.com/no2ezs and http://tinyurl.com/mu8269 for more details.

SuperSCADA systems offer one solution to the problem of managing several wind farms with multiple wind turbine manufacturers but Vertoda can offer another solution. Vertoda can aggregate the data produced by different vendors’ SCADA systems and can present maintenance, energy production and revenue information in a unified fashion. Vertoda provides a central data repository for the data generated by wind farms and makes this information available in a timely fashion to the rest of the Wind Farm operator’s IT systems and software. Users can then view this data from both fixed and mobile devices.

A key metric of wind turbine performance is its availability. Unfortunately for operators, different vendors have different ways of calculating availability. Unsurprisingly, given their complexity, wind turbines can be temperamental. A typical service agreement would be 97% availability for 50 weeks of the year with 2 weeks set aside for maintenance, 1 week every 6 months is standard. This is key data regarding wind turbine performance but can be difficult to obtain. Using Vertoda enables a wind farm operator to assess the availability performance of their wind farms at a high level and at an individual turbine level. Revenue is lost when a turbine is unavailable so without this data accountable losses are not accrued correctly and operators can’t quantify how manufacturers are performing.



In addition to availability, the other key metrics for assessing wind turbine performance are production and wind speed. These metrics can be viewed as interdependent. For example, if a wind turbine is unavailable during a period of high wind speed operators lose more revenue than during a time of low wind speed. Metrics therefore need to be correlated and Business Intelligence is required for assessing operational performance using the Vertoda Framework.

Typically, a wind turbine is exposed through a firewall and has an IP Address and port that can be accessed. To access a wind turbine, its OPC interface needs to be opened by the manufacturer, usually for an extra fee (OPC stands for OLE for Process Control, OLE in turn stands for Object Linking and Embedding.). We previously discussed how Vertoda can read output from OPC Servers. OPC hardware exists at the hardware level. Without access to an OPC interface, the only route to accessing a wind turbine’s data is through its manufacturer’s SCADA system. Vertoda can make wind turbine data available by accessing either the SCADA system or the OPC interface.

Access to the OPC interface determines the real-time availability of data. If an operator elects not to open the OPC interfaces for their turbines, real-time data is unavailable. It can take between 6 and 24 hours for performance data to be made available without access using OPC as data is collected for SCADA systems only once a day.

There is a potential alternative here as some wind turbines can send email and SMS text messages. The Vertoda Framework can access, centralise and parse these messages and publish them on Desktop, Web and Mobile User Interfaces. This would be a richer presentation than is possible with an email or SMS client and enables real-time data without an OPC interface.

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Vertoda wind farmoperations