新型组合式直流断路器拓扑及其性能分析

基于强迫换流原理的混合式直流断路器具有速动性良好、可低损耗经济运行的优点，但应用于大规模的柔性直流电网时造价高、经济性差。组合式直流断路器的拓扑，通过在换流站对应的每条母线上仅采用一个昂贵的主断部分，可以有效降低断路器的一次造价，但现有的组合式断路器在任一线路故障动作时存在主断开关接地过程，同时不具备对快速机械开关的失灵保护功能。为此，提出一种新型的组合式直流断路器拓扑，分别分析了其在正常运行时分闸、合闸，线路故障时分闸、重合闸与快速机械开关失灵时动作过程的工作原理，同时对新型组合式直流断路器拓扑的可靠性、适应性等问题进行了分析并给出相应的应对策略。最后在PSCAD/EMTDC软件上对所提组合式断路器的性能进行了仿真分析与验证。

New Topology and Performance Analysis of Assembly DC Circuit Breaker

Hybrid DC circuit breaker based on principle of forced commutation has advantages of fast action and economical operation with low loss. When it is applied to a large-scale flexible DC grid, however, it is expensive and uneconomical. By using only one expensive main breaker on each bus-bar in converter station, the primary cost of the assembly DC circuit breaker can be effectively reduced. But when this assembly DC circuit breaker is applied in a DC grid, there is a main breaker grounding process when any line fails, and there is no failure protection function for ultra-fast disconnector. This paper proposes a novel assembly DC circuit breaker topology, and analyzes its working principle of opening and closing process during normal operation of DC system, opening and reclosing process under component fault and process when ultra-fast disconnector fails. The reliability and adaptability of the new topology are analyzed and corresponding countermeasures are given. Finally, performance of the proposed topology is simulated and verified on the PSCAD/EMTDC software.