Blade pitch controller, wind turbine generator, and method of controlling blade pitch

Abstract

A hydraulic cylinder is coupled to blades of a wind turbine generator and actuated to change a pitch angle of the blade. A variable displacement hydraulic pump supplies hydraulic oil to the hydraulic cylinder, and a discharge pressure of the pump does not follow a load pressure. When the discharge pressure of the hydraulic pump becomes a set pressure, a pressure control valve is opened to change a discharge amount of the hydraulic pump, and to make the discharge pressure of the hydraulic pump to be a pressure smaller than a cut off pressure. Further, a setting control unit sets the set pressure based on the hydraulic pressure that the hydraulic cylinder requires such that the set pressure becomes a minimum pressure required to change the pitch angle to a predetermined angle by the hydraulic cylinder.