Analysis and design of topological structure for DC solid-state circuit breaker

Existing mechanical circuit breakers can not satisfy the requirements of fast operation in power system due to noise, electric arc and long switching response time. Moreover the non-grid-connected wind power system is based on the flexible direct current transmission (FDCT) technique. It is especially necessary to research the solid-state circuit breakers (SSCB) to realize the rapid and automatic control for the circuit breakers in the system. Meanwhile, the newly-developed solid-state circuit breakers (SSCB) operating at the natural zero-crossing point of AC system is not suitable for a DC system. Based on the characteristics of the DC system, a novel circuit scheme has been proposed in this paper. The new scheme makes full use of ideology of soft-switching and current-commutation forced by resonance. This scheme successfully realizes the soft turn-on and fast turn-off. In this paper, the topology of current limiter is presented and analytical mathematical models are derived through comprehensive analysis. Finally, normal turn-on and turn-off experiments and overload delay protection test were conducted. The results show the reliability of the novel theory and feasibility of proposed topology. The proposed scheme can be applied in the grid-connected and non-grid-connected DC transmission and distribution systems.