Evaluation the effect of voltage sags due to grid balance and unbalance faults on DFIG wind turbines

This paper demonstrated the dynamic behavior of DFIG wind turbine during grid balance and unbalance faults by using simulation results, the effect of voltage sag on DFIG wind turbine is discussed through comparing of the different voltage sag depth in a type of fault lengthways and comparing one type of fault with another breadthwise. The response characteristics of DFIG wind turbine under PCC voltage sags are summarized by a typical example. Finally it is clear that some countermeasures on the rotor side convertor or the stator side must be taken into account for DFIG wind turbine ride through PCC extreme voltage sag.