Available active power estimation for the provision of control reserve by wind turbines

The available active power (AAP) is equivalent to the power a wind farm could produce if it had not been curtailed. The AAP is relevant information in the case of congestions management, down-regulation due to negative prices at the spot market or for the provision of control reserve. Until now only few methods for the estimation of the AAP are available. In this paper five different methods are described and compared. Therefore four criteria are defined: accuracy under normal operation, accuracy under curtailment, consideration of changes in the wind farm's composition and costs. For the test 10-minutes averaged data from a wind farm in Brandenburg (Eastern Germany) that were measured over 21 months was used. Four of the five methods show high accuracy under normal operation, only the last measured value method is less accurate. Under curtailment the accuracy of the adjusted power curve method and the site-specific power curve decreases with increasing curtailment leve ls whereas the reference wind turbine method's and physical model's accuracy stays the same. Under additional consideration of the two other criteria the physical model seems to be most suitable for the estimation of the AAP. Further research will test the most promising methods also with three seconds data which is crucial for the provision of control reserve by wind farms. The provision of control reserve by wind farms using the AAP will be shown in a field test in the middle of 2013.