Exploiting bidirectional power flow control to capture wind gust power in small and medium wind turbines

Among renewable energy sources, wind energy is one of the most promising ones. However, small and medium wind turbines need to cope with the natural intermittent nature of wind speed at lower altitudes. This imposes challenges on optimally tracking the Maximum Power Point (MPP) of the turbine. Up to now, various MPPT techniques have been proposed. However, most of these algorithms have poor performances in gusty weather conditions exhibiting sudden changes in the wind speed. Conventional Tip Speed Ratio (TSR) control fails to track the MPP under these strong wind variations. Therefore, it is not able to capture the energy contained in wind gusts. To tackle this problem, this paper proposes and experimentally validates a bidirectional power flow controller, where a permanent magnet synchronous machine acts both as a generator and as a motor. The performance of the proposed bidirectional controller is validated through simulations and experimental results on a 7.5 kW wind turbine drivetrain to verify the improvements in terms of captured wind energy.