Efficiency optimization of optimum torque maximum power point tracking based on gradient approximation for wind turbine generator system

The efficiency of the conventional optimum torque maximum power point tracking (MPPT) algorithm is reduced by large rotational inertia, and the transient time of the control system becomes longer. The problem was analyzed by studying the mechanism of wind turbine. A novel optimum torque MPPT optimization algorithm was proposed to reduce the transient process time caused by high rotational inertia. The solution presented here used gradient estimation to compensate electromagnetic torque reference. A small signal model was presented with a doubly-fed induction generator based wind turbine for the performance analysis of closed-loop poles, step response and frequency-domain characteristics. From the analysis and simulation results, the novel algorithm combines stability of conventional method and high response rate of tip-speed ratio method, and has good stability, dynamic behavior and high efficiency. ©2015 Chin. Soc. for Elec. Eng.