An enhanced fault-ride-through capability of doubly-fed induction generators during grid faults

This paper discusses a new improved fault ride through technique of wind turbines equipped with doubly-fed induction generators (DFIG). The proposed technique replaces the conventional crowbar with a rotor current limiter (RCL) which is inserted to the rotor circuit upon grid faults detection. In additional to inserting a RCL, demagnetizing rotor currents are injected in order to reduce the induced high voltage appears on the rotor side converter. The proposed method allows the rotor side converter to stay connected to the system such that the DFIG can continue its normal operation immediately after the fault clearance. The simulation results show that the proposed technique limits the rotor inrush currents, DC voltage fluctuations, electromagnetic torque pulsations, and reactive power absorption during the fault and after the fault clearance.