Method for operating a wind turbine, control system for operating a wind turbine and wind turbine

A control system for operating a wind turbine having a rotor with N rotor blades, wherein N≥2, and a pitch setting system for individually setting the pitch angles of the N rotor blades, the control system comprising:

• a sensor system configured to take measurements via which it is determinable whether an edge-wise movement of at least one rotor blade exceeds a threshold while the rotor is rotating with frequency P;
• a control device including at least one processor and a non-transitory computer readable medium having program code stored thereon, wherein said program code is configured, when executed by said processor, to:
• determine first information which is representative for whether an edge-wise movement of at least one rotor blade exceeds the threshold while the rotor is rotating with the frequency P;
• and,
• if the edge-wise movement of at least one rotor blade exceeds the threshold while the rotor is rotating with the frequency P, generate an output signal configured to cause the pitch setting system to individually and periodically change the pitch angles of the N rotor blades each with a frequency of (M*N−1)*P in order to reduce the edge-wise movements of the at least one rotor blade, wherein M is an integer greater than 0;
• said control device being signally connectable to said sensor system in order to provide said control device with the measurements of the sensor system;
• and,
• said control device being signally connectable to the pitch setting system in order to provide the pitch setting system with said output signal of said control device so that the pitch setting system sets the pitch angles of the rotor blades depending on said output signal.

A wind turbine comprising:

• a rotor with N rotor blades, wherein N≥2;
• a pitch setting system for individually setting pitch angles of said N rotor blades;
• a control system including a sensor system configured to take measurements via which it is determinable whether an edge-wise movement of at least one rotor blade exceeds a threshold while said rotor is rotating with frequency P;
• said control system further including a control device having at least one processor and a non-transitory computer readable medium having program code stored thereon, wherein said program code is configured, when executed by said processor, to:
• determine first information which is representative for whether an edge-wise movement of at least one rotor blade exceeds the threshold while said rotor is rotating with the frequency P;
• and,
• if the edge-wise movement of the at least one rotor blade exceeds the threshold while said rotor is rotating with the frequency P, generate an output signal configured to cause said pitch setting system to individually and periodically change the pitch angles of said N rotor blades each with a frequency of (M*N−1)*P in order to reduce edge-wise movements of said at least one rotor blade, wherein M is an integer greater than 0;
• said control device being signally connectable to said sensor system in order to provide said control device with the measurements of said sensor system;
• and,
• said control device being signally connectable to said pitch setting system in order to provide said pitch setting system with said output signal of said control device so that said pitch setting system sets the pitch angles of said at least rotor blade depending on said output signal.