A Dual-Stage Solid-State Fault-Current Limiter for Flexible DC Distribution Networks

For limiting fault currents, accelerating fault-clearance speed, and providing protection for converters with weak transient-stress tolerance, a dual-stage solid-state fault-current limiter (FCL) is proposed, whose main module is based on thyristors, capacitors, and inductors. By building equivalent models, the working principle and the parameter design are analyzed, and the current-limiting effect is validated by a six-terminal ring flexible DC distribution network model in PSCAD/EMTDC. The FCL is compared with typical FCLs in terms of economic and technical performance. The proposed FCL has three main advantages: the reduced cost by sharing one FCL among multiple lines, the fast response speed by the economical thyristor-based topology, and the multiple current-limiting patterns by a dual-stage limiting strategy. The results show that the proposed FCL is favorable for flexible DC distribution networks.