Series Voltage Compensation for DFIG Wind Turbine Low-Voltage Ride-Through Solution

This paper introduces a new solution for doubly fed induction generators to stay connected to the grid during voltage sags. The main idea is to increase the stator voltage to a level that creates the required flux to keep the rotor side converter current below its transient rating. To accomplish this goal, a series compensator is added to inject voltage in series to the stator side line. The series converter monitors the grid voltage and provides compensation accordingly to accomplish this aim. Since the turbine and converter stay connected, the synchronization of operation remains established during and after the fault and normal operation can be resumed immediately after the fault is cleared. To keep the current at its minimum, a control strategy has been developed to keep the injected voltage and line voltage in phase during and after the fault.