基于多端口混合直流断路器的LCC-VSC混合多端直流输电系统故障清除方案

混合多端直流输电系统是解决大规模新能源送出和消纳的有效手段之一,快速有效的故障清除方案是保证其安全稳定运行的关键。然而,已有的基于换流器自清除的故障清除方案会导致健康换流站短时停电,而借助直流断路器的故障清除方案存在实施成本过高的问题。为此,提出一种二极管桥式多端口混合直流断路器拓扑,以一个三端混合直流系统为例设计了基于该多端口混合直流断路器的故障清除方案。所提出的故障清除方案在送端采用LCC移相控制实现故障的清除和换流器重启,在受端汇流母线处采用二极管桥式多端口混合直流断路器实现直流故障快速清除和重合闸。通过PSCAD/EMTDC仿真验证了该方案的有效性,并与已有的技术方案进行了对比。结果显示,所提方案在保证故障快速有效清除的同时,能够减少在混合多端直流系统中使用断路器的经济成本。

Multi-port DC circuit breaker-based fault clearing scheme for LCC-VSC hybrid multi-terminal HVDC systems

A hybrid multi-terminal DC system is an effective solution to the problem of large-scale renewable energy transmission and consumption.A fast and effective DC fault clearing scheme is key to ensuring its safe and stable operation.However,the commonly used self-clearing converter-based fault clearing scheme will cause a short-term power failure in a healthy converter station.However,a DC circuit breaker-based fault clearing scheme carries a high implementation cost.This paper proposes a novel diode bridge-type multi-port hybrid DC circuit breaker and designs the fault clearing scheme of a three-terminal hybrid DC system based on the proposed multi-port DC breaker.The proposed fault clearing scheme adopts LCC phase shift control at the rectifier station to clear the fault and restart the converter.Then,the proposed multi-port hybrid DC circuit breaker is installed at the busbar to achieve rapid DC fault clearing and reclosing.The proposed scheme’s effectiveness is verified using PSCAD/EMTDC simulation,and compared with the existing schemes.The results show that the proposed scheme can significantly reduce the cost of using DC breakers in hybrid multi-terminal DC systems while ensuring fast and effective fault clearing.