Wind turbine generator and blade pitch angle control method thereof

Abstract

The present invention provides a wind turbine generator and a blade pitch angle control method thereof in which an aerodynamic imbalance of a wind turbine rotor at the time of shutdown is further reduced, the maximum load of a wind turbine is further reduced, and the wind turbine generator can be reduced in weight and cost. The wind turbine generator includes a collective pitch angle controllerthat produces a collective pitch angle demand that is common to blade pitch angles of wind turbine blades, an individual pitch angle producing unitthat produces an individual pitch angle demand inherent in each wind turbine blade, multiplierstothat multiply the individual pitch angle demand by the individual pitch angle gain; an individual pitch angle gain producing unit, and addertothat add collective pitch angle demands to the output of the multiplierstoand supply the same to pitch actuatorstoinherent in the wind turbine blades. When shutdown is performed, the individual pitch angle gain is adjusted such that an individual pitch angle gain is reduced gradually and reaches to zero by the individual pitch angle gain producing unitafter first set time.