Sliding mode controller for torque and pitch control of wind power system based on PMSG

Recently, the size of wind turbines is increased. As a result, the permanent magnet synchronous generator (PMSG) plays an important role because of its simple structure and high efficiency. This paper proposes a torque and pitch control scheme for variable speed wind turbines. A torque controller is designed to maximize the output power below the rated wind speed and a pitch controller is designed to regulate above the rated wind speed. The controllers exploit sliding mode control scheme considering the rapid variation of wind speed. Since the aerodynamic torque and rotor acceleration are difficult to measure in practice, an observer is designed which estimate them. In order to verify the proposed control strategy, we provide stability analysis and present simulation results.