The first independent scientific study into improving wind turbine performance has confirmed that nacelle-mounted LIDAR reduces yaw misalignment.
Collaborative research by Avent Lidar Technology (ALT) and Renwable NRG Systems has shown that the Wind Iris nacelle-mounted LIDAR from ALT is an effective tool for identifying wind turbine yaw misalignment. The study focused on the optimisation of turbine performance using forward-looking wind LIDAR measurements, improving power output by correcting yaw misalignment and a reduction in turbine costs though load mitigation.
Andrew Scholbrock, field test manager at the Energy Department’s National Renewable Laboratory(NREL) where the project was carried out, said: “Wind turbines traditionally rely on a wind vane mounted on the rear of the nacelle to measure the wind direction in order to control the yaw position of the turbine.
“Certain factors, like rotor-induced wakes, can lead the vane to measure the wind direction inaccurately. The principle focus of the project was to use a LIDAR to measure the wind direction ahead of the rotor and derive a correction function.”
The study further validated the notion that energy increases after yaw misalignment correction using a Wind Iris as an external sensor. Improvement in the power curve was found to be identical with wind speeds measured from the LIDAR and NRELS’s meteorological tower. Based on the results, it is estimated that LIDAR-based yaw correction will increase the annual energy production by 2.4% for a 7.5° static misalignment and standard reference wind speed distribution.
Following this research, NREL and ALT will begin a new study that will explore the use of LIDAR measurements to actively control the wind turbine through improved rotor collective pitch and yaw control.