WIND TURBINE ROTOR BLADE PITCH CONTROL FOR TOWER FATIGUE REDUCTION

The invention relates to adjusting collective pitch of the wind turbine rotor blades. A sensor signal is received, from wind turbine sensors, indicative of wind turbine rotor loading in a fore-aft direction. A first component is determined, based on the received sensor signal, in the fore-aft direction, the first component including high frequency collective content, greater than 2P frequency content, from the received sensor signal. A second component that is orthogonal to the first component is generated. The first and second components are rotated about a phase angle to obtain first and second phase-shifted components. A collective pitch reference offset value is determined for the three rotor blades based on the first or the second phase-shifted component. A control signal is transmitted to adjust collective pitch of the rotor blades based on the determined collective pitch reference offset value.