Within the project LAWINE, partially sponsored by the Dutch government via the program TKI Wind op Zee, research is performed on the application of LiDAR sensing technologies for wind measurements in wind farms. One of the tasks in this project is on the use of LiDAR measurements for improving wind farm control algorithms, such as ECN's Active Wake Control (AWC) concept. AWC is an approach of operating wind farms in such a way as to maximize the overall wind farm power production. It consists of two concepts patented by ECN: pitch-based AWC (called Heat&Flux [HF]), and yaw-based AWC (called Controlling Wind [CW]).
Both these AWC methods require wind speed and direction measurements to operate properly. However, measurements on the research turbines located at ECN Wind Turbine Test Site Wieringermeer (EWTW) indicate that the turbines operate with a significant yaw error of around 4 degree. While this yaw error is not significant with respect to the power production, it constitute a very significant error when it comes to AWC, and especially CW, application. It is shown that such a yaw error completely destroys the benefit from CW. HF proves to be a more robust strategy with this respect and while its benefit decreases under yaw errors, this is much less pronounced than for CW.
Finally, a number of possible applications of LiDARs are discussed in the context of optimizing the performance of a wind farm with respect to its power production. Several options are considered, such as, (1), improving the accuracy of the wind direction measurements, (2), fine-tuning the underlying farm wake modeling, and (3) using LiDAR (nacelle-mounted backward looking or ground-based scanning) to do online model-free AWC optimization driven by wake measurements (rather than using wake simulation models). The last option might be very promising with respect to AWC applications in wind farm in complex terrain, for which no accurate wake models with reasonable computational complexity exist. Also studied are the requirements on the LiDAR measurement equipment necessary to enable application of the proposed model-free AWC strategy.
This work is performed within the project LAWINE, subsidized by the Dutch government within the framework of the TKI Wind op Zee program.