A natural commutation current topology of hybrid HVDC circuit breaker integrated with limiting fault current

The high-voltage direct current (HVDC) power transmission short-circuit fault protection is a big challenge, and it is the main obstacle to promote the HVDC multi-terminal networks. A natural commutation current topology (NCCT) of hybrid HVDC circuit breaker (DCCB) integrated with limiting fault current is proposed in this paper, which shares several obvious merits, such as lower peak fault current, shorter fault isolation time and low turn-off loss. The main contributions in this paper are made as follows. (1). A second-order RLC circuit in novel NCCT circuit breaker is utilized as the current limiting circuit to dramatically reduce the fault current rising slope and its peak value. (2) A asynchronous NCCT circuit breaker has been investigated to broaden the proposed NCCT circuit breaker's optimal working area. (3) By taking China Zhangbei 500 kV four-terminal DC grid as an example, an optimization design technique of the asynchronous NCCT-DCCB is developed to demonstrate the process of the theoretical analysis and parameter design. The correctness of the proposed NCCT-DCCB and the feasibility of the optimization design technique are confirmed by EMT simulation on PSCAD/EMTDC and hardware-in-loop experiment on PLECS-RtBox.