中文摘要：

基于柔性直流的多端直流输电和直流电网技术是解决中国新能源并网和消纳问题的有效技术手段之一,而高压直流断路器是构建直流电网的核心设备之一。从多端直流系统发生直流侧短路故障的机理及故障电流的发展趋势入手,以舟山5端柔性直流输电工程为例,分析了发生最严酷短路故障时,直流母线上故障电流的特性,基于分析结果提出了直流电网对直流断路器的需求;结合对现有直流断路器技术路线的对比分析,提出了一种适用于柔性直流输电网的新型快速直流断路器技术方案,并通过仿真分析验证了所提出的新型直流断路器能够满足柔性直流输电网快速切除故障电流的需求。

英文摘要：

Multi-terminal direct current（MTDC） transmission based on flexible direct current（DC） and DC grid technology are one of the most effective means for the interconnection and accommodation of renewable energy generation.The high-voltage DC circuit breaker is a key component in the DC grid.On the basis of an analysis of the mechanism of DC-side short circuit in the MTDC system and the trend of the corresponding short-circuit current,the characteristics of the fault current through a DC bus of Zhoushan 5-terminal flexible DC transmission project under the most severe short-circuit fault are detailed,and the demands for the DC circuit breaker in the DC grid are stated.After a performance comparison of the three types of DC circuit breakers in current use,a novel topology of fast DC circuit breaker suitable for use in the flexible DC transmission grid is proposed.Simulation results have verified the fast action of the novel DC circuit breaker of cutting off the fault current of the flexible DC transmission grid.