Harmonic mitigation in wind turbine energy conversion systems

Permanent magnet synchronous generators (PMSG applied to wind energy conversion system (WECS) using variable speed operation is being used more frequently i wind turbine application. Variable speed systems have several advantages over the traditional method of operating win turbines, such as the reduction of mechanical stress and a increase in energy capture. To allow the variable speed operation of the PMSG WECS a conventional three-phase bridge rectifier (BR) with a bulky capacitor associated with voltage source current controlled inverter (VS-CCI) is used This simple scheme introduces a high intensity low frequency current harmonic content into the PMSG and consequently increases the total loses in it. Subsequently, decreases the power capability of the system. This paper presents comparative simulation study between three different approaches applied to harmonic mitigation in PMSG WECS The studied techniques are: a) harmonic trap filters (HTF), b single-switch three-phase boost rectifier (PFC) and c) a three phase boost type PWM rectifier (PWMREC).