Patent ID: 9528495
Filing Date: 2016-12-27
CPC Classification: F03D,F05B,Y02E

Claim Text:
1. A method of reducing mechanical load in a wind turbine when facing a grid voltage dip, the wind turbine having a drive train, a converter control unit, and a wind turbine generator controller, the method comprising: receiving an indication signal by the wind turbine generator controller from the converter control unit, the indication signal indicating a voltage dip in the wind turbine; commanding to move the pitch angle of the blade towards a feather position with a specific rate; delivering a maximum active power generation value by the converter control unit to the wind turbine generator controller after the grid recovers; setting a saturation value of the set points for the drive train to assure a correct Drive Train Damper action application, the saturation value set by the converter control unit depending on the maximum active power generation value; ramping up the power or torque set points with different rates according to the Drive Train Damper action to come up with a ramped value of the power taking into account network operators settling time restrictions; applying a first order filter to the ramped value of the power to reduce the torque overshoot; and applying the drive train damper torque command to the ramped value of the power in order to reduce the mechanical load in the wind turbine and to damp the oscillation in the wind turbine generator.