Damping of edgewise wind turbine blade vibrations

A method for damping an edgewise rotor blade vibration of a rotor blade of a wind turbine, said method comprising:

• quantifying a vibration parameter of the edgewise rotor blade vibration,
• damping the edgewise vibration of the rotor blade of the wind turbine if the vibration parameter exceeds a predetermined entry threshold, the damping comprising:
• measuring at the rotor blade a motion parameter of the edgewise rotor blade vibration, wherein said motion parameter enables determining an edgewise rotor blade vibration velocity,
• generating based on said motion parameter a blade pitch angle control signal,
• damping the edgewise vibration of the rotor blade by pitching the rotor blade according to the blade pitch angle control signal,
• wherein the blade pitch angle control signal is arranged so that a resulting force on a rotor blade pitched according to the blade pitch angle control signal, in a direction of the edgewise vibration of the rotor blade in a coordinate system, which rotates with a rotor of the wind turbine, is opposite and proportional to the edgewise rotor blade vibration velocity.

A wind turbine, comprising:

• a tower;
• a nacelle disposed on the tower;
• a rotor extending from the nacelle and having a plurality of rotor blades disposed thereon;
• a controller configured to perform an operation damping an edgewise rotor blade vibration of at least one of the plurality of rotor blades;
• the operation comprising:
• measuring, at the at least one rotor blade, a motion parameter of the edgewise rotor blade vibration, wherein said motion parameter enables determining an edgewise rotor blade vibration velocity,
• generating based on said motion parameter a blade pitch angle control signal, and
• damping the edgewise vibration of the at least one rotor blade by pitching the rotor blade according to the blade pitch angle control signal,
• wherein the blade pitch angle control signal is arranged so that a resulting force on a rotor blade pitched according to the blade pitch angle control signal, in a direction of the edgewise vibration of the at least one rotor blade in a coordinate system, which rotates with a rotor of the wind turbine, is opposite and proportional to the edgewise rotor blade vibration velocity.