Maximum power point tracking in variable speed wind turbine system via optimal torque sliding mode control strategy

This paper proposes a novel maximum power point tracking (MPPT) control strategy for variable speed wind turbine system using the optimal torque sliding mode control technique. In this strategy, the generator optimal torque tracking error and its integral are selected as system state variables, and a dynamic sliding mode controller is designed to improve the wind energy capture efficiency and shorten MPPT response time for variable wind speed working condition. The actual control input signal is formed from a first-order integral operation of the original sliding mode control input signal, which makes the generator actual control input reference current signal continuous and smoothing. It also contributes greatly to chattering attenuation and avoiding large fluctuations of the generator output power. The simulation results for a permanent magnet synchronous generator (PMSG) based wind turbine system have proved the validity of the proposed control strategy.