Patent ID: 8355824

Claim:
A wind turbine generator, comprising: at least one wind turbine blade; a power generator connected to the wind turbine blade and configured to generate power from a rotational force of the wind turbine blade, the power generator being connected to a utility grid to output the power to the utility grid; and a control unit configured to perform an interconnected operation with the utility grid, the control unit including: a detecting unit for detecting an operation state parameter related to an operation state of the power generator; a demand value obtaining unit that stores therein first information containing (i) a relation between the operation state parameter and active power demand value and (ii) a maximum value of an active power set to a rated value, the demand value obtaining unit configured to receive the operation state parameter from the detecting unit and to obtain an active power demand value corresponding to the operation state parameter detected by the detecting unit from the first information; and a changing unit configured to receive a request for changing the maximum value of the active power and a newly defined maximum value of the active power from the utility grid, and change the maximum value of the active power in the first information to the newly defined maximum value of the active power at a change rate determined based on the maximum value of the active power in the first information and the newly defined maximum value of the active power received from the utility grid.