The Short-Circuit Fault Current Impact Mechanism and Adaptive Control Strategy of an MMC-HVDC

A modular multilevel converter (MMC) is voltage-sourced and can supply fault currents to an AC system. To clarify the current impact mechanism of MMC, this paper examines control capacitor discharge processes MMC when system has a three-phase short grounding fault. The theoretical analysis shows that outer loop MMCs changes injection. In different modes, nonzero reference value forces inject absorb into occurs. limiter determines final injecting MMC. help adjust system’s current, adaptive strategies are also proposed, which include control, control. On basis proposed strategies, could be increased or decreased within MMC’s capacity. simulations verify analysis.