High voltage ride-through control strategy of grid-side converter for DFIG-based WECS

For doubly-fed induction generator (DFIG)-based wind energy conversion system (WECS), grid voltage swell is harmful to the dc-link capacitor and the grid-side converter (GSC). The grid over-voltage may lead to the reversal of power flow in the GSC, resulting in the uncontrollability of the GSC. In order to handle this situation, the control strategy of the GSC during grid voltage swell needs to be improved. In this paper, the controllability issue of the GSC with limited rating considered during grid voltage swell is firstly analyzed. Then, a high voltage ride-through (HVRT) control strategy of the GSC is proposed with adaptive adjustment of the dc-link voltage reference according to the variations of grid voltage and rotor-side load current. The simulation results verify that, the GSC can always remain controllable under the proposed HVRT control strategy, so that the dc-link voltage can be kept stable and the reactive current of the GSC can be controlled to reduce the grid over-voltage. Therefore, the control strategy can contribute to improve the reliability of both the DFIG-based WECS and the power system during grid voltage swell.