Patent ID: 8880379

Claim:
A method for evaluating performance of a system for controlling pitch of a set of rotor blades of a wind turbine, the wind turbine comprising a hub adapted to carry a set of rotor blades, the method comprising: obtaining load values being indicative of at least one load moment of the hub of the wind turbine using the system for controlling pitch; filtering, by the system for controlling pitch, the obtained load value to obtain a first filtered load value from a first filter and a second filtered load value from a second filter; determining a standard deviation of at least one of the first and second filtered load values; obtaining information regarding wind conditions at a site of the wind turbine; selecting, by operation of one or more processors, a set of predefined, expected values of the load values based on the obtained wind conditions; comparing the obtained load values with the selected expected values; and based on said comparison and the standard deviation, evaluating the performance of the system for controlling pitch.