Topological analysis of HVDC circuit breaker with coupling transformer

The rapid progress of large-scale clean energy accessing to the grid promotes the development of DC grid technologies. HVDC (high voltage direct current) circuit breaker as one of the key equipment of the DC grid has gradually attracted more and more attentions. Direct current is more difficult to be interrupted comparing to alternative current because of without natural zero-crossing, especially in the high voltage and large capacity system. This paper briefly reviews the research status of DC circuit breaker firstly. Then a novel topology of DC circuit breaker with coupling transformer is proposed. Its topology is presented and operating principle is analyzed. The equivalent model for different stages is established, and the key component parameters are designed. Operating characteristic of the HVDC circuit breaker is simulated relying ZhouShan 5-terminal flexible HVDC project. Simulation results have verified the correctness of theoretical analysis and the effectiveness of the novel HVDC circuit breaker interrupting the fault current in the flexible HVDC transmission grid. This provides a basis for HVDC circuit breaker design.