Voltage Compensation Scheme for DFIG Wind Turbine System to Enhance Low-Voltage Ride-Through Capability

This paper proposes a control strategy of the voltage compensation based on a nine switch converter (NSC) to enhance a low-voltage ride-through (LVRT) capability for a doubly fed induction generator (DFIG) wind turbine system. The nine switch converter connected to a stator-side of the DFIG can enable to compensate the voltage response of the system during the grid faults. For series voltage source converter (VSC), a control algorithm consisting of dual voltage controllers is implemented for the two sequence components in the dq synchronous reference frame. As for shunt voltage source converter (VSC), a control algorithm is carried out in the dq reference frame and incorporates both an inner current control loop and an outer voltage control loop. The effectiveness of the proposed methods is verified by the simulation results for the 2 [MW]-DFIG wind turbine system under unbalanced grid voltage conditions.