A New Type of Hybrid DC Current Limiting Circuit Breaker suitable for HVDC

Multi-terminal DC transmission technology based on voltage source converter is one of the important technical means to solve the problem of grid connection and consumption of renewable energy. In this regard, encountering the fault current during fault period remains an important issue. Thereby, devices and circuits to suppress the fault current have become a hot topic in recent years. In this paper, a new type of current-limiting circuit breaker structure is proposed. Under normal conditions, the load current flows through the low-loss main branch. After the fault occurs, the power electronics based switches are disconnected, and the fault current is shifted to the auxiliary branch of current limiting device. The current limiting device suppresses the rise of the fault current. Finally, the power electronics based switches in the auxiliary branch open, and eventually the residual current is absorbed by the MOA. Moreover, the proposed topology of current-limiting circuit breaker is verified using PSCAD/EMTDC based simulation experiments. In comparison with ABB circuit breaker, the proposed topology has small on-state losses and good damping characteristics under normal conditions, and in the fault state too, Besides, the proposed topology owns the benefit of high reactance, therefore, allow the suppression of fault current effectively and have advantage to cut-off large amount of fault current. (paper)