Analysis on Power Quality of Grid-Connected Direct-Driven Wind Power System with Super Capacitor Storage Energy

Super capacitor energy storage (SCES) device connected in parallel with DC-bus was used to improve the grid-connected power quality of direct-driven wind power system with permanent magnet synchronous generator (PMSG). The system model was analyzed and the control scheme was designed. By controlling the bi-directional DC/DC converter and the grid-side converter, the fluctuation of wind power could be restricted so that the active grid power is smooth. During the grid voltage sags, wing system low voltage ride through (LVRT) could be realized to apply certain reactive power support to power grid. Simulation has been done to test the output power of No.18 wind turbine at Yilan wind farm. The results show that, the grid power quality of the direct-driven wind power system could be improved with the aid of SCES device.