A novel variable-speed constant-frequency wind power system and the control strategy thereof

Based on the theory of variable-speed constant-frequency, a new control strategy of doubly-fed system with planetary gear and dual-rotor for wind power system is proposed. The constant frequency control is achieved by electromechanical coupling system under the condition of variable wind speed, when the wind speed is under the rating value, speed feedback is adopted to achieve maximum power point tracking, and the torque control and pitch-control are both used in the opposite working condition. The strategies of variable-speed constant-frequency and grid-connected are studied in Simulink. The simulation and experimental results verify the correctness and feasibility of system. Compared with traditional direct-driven permanent magnet synchronous generator, lower capacity is enough for generator and inverter, and the scope of wind speed is broadened.