Yaw Control Optimization
It is widely believed in the wind industry that improvements in yaw control can only produce a small improvement in output power. This belief simultaneously exists with an acknowledgement that attempting to measure wind characteristics in the turbulent post-rotor wind is problematic.
BlueScout has shown, on a variety of turbines, that power increases can be achieved when improved wind angle information is fed into the yaw control systems of turbines. However, this early work typically uses the legacy control strategy of the turbine. In truth, turbine manufacturers have invested considerable time and thought into developing yaw control strategies that compensate for the errors of the post-rotor measurement system. However, those strategies typically include long averaging times and allow considerable variance in yaw before correcting the yaw angle of the turbine.
Accurately measuring the incoming wind properties, with dramatically reduced noise, means that different control strategies can be considered for yaw control. Put most simply, beyond the gains achieved by simply feeding better information into the legacy control system, how much extra power can really be generated by employing control strategies that take advantage of the improvement in wind information?
This work takes real data from an operating turbine under the yaw control of the BlueScout Optical Control System (OCS). The summary describes the methodology used in the simulation and the results of the parametric study for the two control parameters of wind direction moving average time and yaw direction threshold. Power performance increases and turbine yaw actuation times are presented. For unlimited yaw activity, a power increase of about 6% is demonstrated. If yaw activity is limited to 8%, it was found that an additional 3% power gain may be achieved with settings for the site/turbine installation evaluated in the study at a moving average time for the wind direction of 60 seconds and a yaw direction threshold of 8 degrees.
