High quality mains power from variable-speed wind turbines

Variable-speed operation of wind turbines can improve energy capture and reduce mechanical stress and audible noise levels. Conventionally, the power-electronic interfaces providing the necessary frequency conversion return power to the network through line commutated inverters (LCI). These deliver poor quality power with high levels of harmonics and a varying power factor. This paper reviews the possible control strategies for variable-speed operation and shows how a new power electronic interface can provide high quality sinewave power in both the generator and the power network