Low Voltage Ride-through Strategy for Wind Farm and VSC-HVDC

The fault ride-through performance of the wind farm and the control strategy of the wind farm modular multilevel converter (WFMMC) have a significant effect on the transient voltage stability of the system. In this regard, the transient characteristics of VSC-HVDC system are studied in case of different degrees of failure at the point of connection (POC) and then low voltage ride-through strategy (LVRT) that coordinated with software and hardware is proposed in this paper. In terms of wind farm, crowbar circuit is added in order to protect the safe operation of wind turbines. In the aspect of VSC-HVDC, an additional reactive current control is proposed to improve the transient voltage characteristics. By detecting the voltage of POC, when the bus voltage exceeds the limit, the WFMMC provides reactive current support. Finally, simulation results show that the strategy effectively suppresses the rotor overcurrent and improves the transient characteristics of voltage.