Patent ID: 8240990

Claim:
A method for reducing load in a wind turbine having a plurality of blades, each blade having a blade angle, said method comprising calculating a time delay for switching at least one blade toward feather from an initial pitch rate to a final pitch rate upon initiation of a shutdown condition, wherein the initial pitch rate is smaller than the final pitch rate; and switching the at least one blade to the final pitch rate once the time delay has expired, wherein the time delay is calculated by the following equation: Delay( i )=[Angle( i )−Min Angle]/[Final Pitch Rate−Initial Pitch Rate( i )] where, Delay (i)=the time delay for i-th blade to switch from the initial pitch rate to the final pitch rate, Angle (i)=the blade angle of the i-th blade upon initiation of the shutdown condition, Min Angle=a minimum angle for the plurality of blades upon initiation of the shutdown condition, Initial Pitch Rate (i)=the initial pitch rate of the i-th blade under auxiliary power, and Final Pitch Rate=the final pitch rate under auxiliary power.