Control of DC Grid for Fault Current Limiting and System Fast Recovery

DC circuit breaker is one of the alternatives for clearing DC faults in flexible DC power grids, and its cost is closely related to its volume and its breaking current. In this paper, starting from the level of reducing the breaking fault current of the DC circuit breaker (DCCB), a dual adaptive controller suitable for MMC fault current limiting and rapid system recovery is designed. By adjusting the reference value of the MMC DC voltage and the capacitor voltage of the bridge arm sub-module, the development speed of the fault current can be automatically limited, and the system recovery after the fault can be accelerated. The design method and structure of the dual adaptive controller are introduced, and the mechanism of action is theoretically analyzed.