Study on Black-Start Scheme of MMC-HVDC System with a Large Scale Wind Farm

Abstract

Study on soft black-start scheme for MMC-HVDC system with a large-scale wind farm is done in this paper. For a two-terminal MMC-HVDC system, when a fault occurs at one side, the converter station at the other side would be shut down. A three-stage startup strategy is especially given to realize the black start, which recoveries the DC voltage gradually, including uncontrollable and controllable charging process. For a three-terminal HVDC system, when a blackout situation occurs at the passive side with a wind farm, it would cause a DC voltage drop. To realize the black start, a controller is designed, which makes the AC side voltage of the converter stable enough to restart the wind farm without affecting the other converters. To validate it, simulations are built in PSCAD/EMTDC respectively. The result shows that there is a good effect for the black-start of the MMC-HVDC system by the proposed method.