Enhanced Yaw Stability of Downwind Turbines

It is shown, in a novel experimental study using a sub-scale model of a 5MW downwind turbine, that individual pitch control based on a sinusoidal pitching scheme that is locked to the phase of the rotor rotation further improves the yaw stability of a downwind turbine. The optimum pitching amplitude is observed to be insensitive to yaw angle. Furthermore, a positive pitching amplitude improves yaw stability at negative yaw angles, while at positive yaw angles, negative pitching amplitude improves yaw stability. Thus, individual pitch control further improves the superior yaw characteristics of downwind turbines compared to upwind configurations.