Patent ID: 7205676

Claim:
A wind turbine generator system including switching means arranged on a stator side of a doubly fed generator for linkage with a grid and a converter for exciting a secondary winding of the doubly fed generator, a rotor of the doubly fed generator coupled to a wind turbine for generating electric power, comprising: first detection means for detecting a stator voltage at the switching means on the stator side of the doubly fed generator; second detection means for detecting a grid voltage at the switching means on the side of the grid; third detection means for detecting a rotation phase of the doubly fed generator; equalizing means for equalizing, when the switch is open, the stator voltage generated by excitation on the secondary side with the grid voltage; and controlling means for decreasing a difference in phase between the grid voltage and the stator side voltage with the converter when the switch is open after the equalizing means equalizes the stator voltage generated by excitation on the secondary side with the grid voltage.