Abstract A high-voltage DC circuit breaker is one of the key equipment that constructs the DC power grid. Therefore, reducing the peak value of the breaking current and shortening the fault removal time are the main research directions for its performance optimization. This paper first analyzes the basic topology and the traditional breaking strategy of a hybrid high-voltage DC circuit breaker with forced current commutation. Then, the theoretical analysis of the fault current, voltage, and the relationship between the withstand voltage level of the fast mechanical switch and the exit time of the transfer branch, is conducted. A new breaking strategy is proposed, which can effectively reduce the peak value of the breaking current by turning off the transfer branch step by step. When a fast mechanical switch reaches the corresponding withstand voltage level, it sends the OFF signals to each sub-module of the transfer branch; thus, the energy consumption of the DC circuit breaker is reduced and the fault removal time is shortened. Finally, the PSCAD/EMTDC simulation platform is used to build the test system, which verified the effectiveness of current limiting and other functions of the proposed breaking control strategy.

中文翻译：

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降低DCCB开断电流峰值的转移支路控制策略

摘要 高压直流断路器是构建直流电网的关键设备之一。因此，降低开断电流峰值、缩短故障排除时间是其性能优化的主要研究方向。本文首先分析了一种强制换流的混合高压直流断路器的基本拓扑结构和传统的开断策略。然后，对故障电流、电压以及快速机械开关耐压等级与转移支路退出时间的关系进行理论分析。提出了一种新的开断策略，通过逐步关断转移支路，有效降低开断电流的峰值。当一个快速机械开关达到相应的耐压水平时，它向转换支路的各个子模块发送OFF信号；从而降低了直流断路器的能耗，缩短了故障排除时间。最后，利用PSCAD/EMTDC仿真平台搭建测试系统，验证了所提出的分断控制策略的限流等功能的有效性。