Control and interfacing of a grid-connected small scale wind turbine generator

An ac/dc/ac power converter is an important component to extract power from a variable speed permanent magnet wind generator and feed into the grid. This paper describes such a converter incorporating maximum power point tracking based on power fed to the grid at different wind speeds. Using the permanent magnet generator voltage, the grid current and the grid voltage samples, the proposed system achieves an enhanced dynamic behavior. This feature effectively prevents the grid from ¿boost¿ charging the dc side of the H bridge inverter at the beginning of operation. Since small wind turbines normally do not have expensive pitch control mechanisms, a thyristor based ¿dump-load circuit¿ is employed to protect the turbine from high wind speed operation when disconnected from the grid. The thyristor controller also protects the inverter from high dc voltage input from the wind generator at high wind speed. Preliminary results are included based on a laboratory 2 kW prototype converter.