Active Power Control of Wind Turbine Generators via Coordinated Rotor Speed and Pitch Angle Regulation

Abstract

With increased wind power penetration in modern power systems, wind turbine generators (WTG) are expected to provide the active power control (APC) for tracking a desired power reference from system or wind farm operators. In practice, the pitch angle control (PAC) and the rotor speed control (RSC) methods can be used for APC in variable-speed variable-pitch WTGs, but the latter using turbine inertia as energy buffer is more attractive due to less pitch activation and higher wind energy production. For existing RSC methods, when the rotor speed reaches the upper speed limit at high wind speed or low power reference, they will actually become PAC to follow active power command, which also results in frequent pitch angle manipulation and considerable fatigue on the pitch servo system. To overcome this drawback, this paper proposes a new APC strategy integrating the rotor speed and pitch angle regulation. By utilizing the kinetic energy of rotor inertia at any pitch position (zero as well as non-zero pitch angle), this strategy can effectively avoid frequent action of pitch actuator while sustaining dispatched active power. The proposed method is verified by the fatigue, aerodynamics, structures, and turbulence-based simulations and wind turbine simulator-based experiments.