Patent ID: 8167556

Claim:
A method of damping tower oscillation in a wind turbine, comprising: determining a rotor rotational speed of the wind turbine; selecting an input comprising an avoid frequency input parameter, the avoid frequency input parameter being a null value or a critical frequency value; and selecting, according to the input parameter value, an operation mode adapted to control the rotor rotational speed of the wind turbine, when the avoid frequency input parameter is the null value: the selecting of the operation mode is of an auto tuner operation mode, detecting a tower oscillation frequency, calculating a critical rotor speed based on the detected tower oscillation frequency to avoid the calculated critical rotor speed corresponding to the critical frequency value comprised in the avoid frequency input parameter, and controlling the rotor rotational speed to avoid the calculated critical rotor speed; and when the avoid frequency input parameter is not null value: the selecting of the operation mode is of an static frequency mode, and controlling the rotor speed to avoid the avoid frequency input parameter.