System and method for reducing rotor loads in a wind turbine upon detection of blade-pitch failure and loss of counter-torque

摘要

A system and method for reducing rotor loads in a wind turbine (10) that includes a brake (33) and one or more rotor blades (24) coupled to a rotor (18). Upon detection of a loss of counter torque and a blade-pitch failure in at least one rotor blade (24), a processor (42) reduces a generator overspeed threshold value by a predetermined amount and determines a brake-release threshold value. The brake (33) is applied to slow the rotor (18) if the generator/rotor speed exceeds the reduced generator/rotor overspeed threshold value. In addition, the brake (33) is applied to slow the rotor (18) until the generator/rotor speed is below the brake-release threshold value. The rate of change of the pitch angle of the rotor blade (24) may be varied as the blade (24) moves toward feather in response to the detected blade-pitch failure.