含直流断路器的多端柔直系统直流保护定值切换策略

DC Relay Protection Setting Switching Strategy for Multi-terminal VSC-HVDC System with DC Circuit Breakers

南澳(以下简称NA)多端柔直系统加装机械式高压直流断路器后,为实现直流断路器连接的故障站能够被快速有效隔离,非故障站能在特定的运行方式下稳定运行,需要对系统直流保护策略进行调整,以适应系统新的运行方式.本文首先介绍了系统加装直流断路器前的直流保护配置,分析了加装直流断路器对直流保护策略的影响,提出了一种非故障站根据故障站差动保护信号进行定值切换,实现直流断路器隔离多端柔直系统故障的直流保护策略.采用PSCAD/EMTDC仿真对该直流保护定值切换策略的可行性进行了验证,现场试验结果也进一步验证了该策略的可行性.

After the mechanical high-voltage DC circuit breakers(DCCBs)are added to an NA multi-terminal VSCHVDC system,to quickly and efficiently isolate the fault station connected with DCCBs and keep the stable operation of non-fault stations in specific mode,the DC protection strategy for the system needs to be adjusted to adapt to the new operation mode.In this paper,the DC relay protection configuration before the application of DCCBs is introduced,and the effects of DCCBs on the DC relay protection strategy are analyzed.Subsequently,a novel DC protection strategy is proposed,under which the non-fault station can perform setting switching based on the differential protection signal of the fault station,thus realizing the isolation of multi-terminal VSC-HVDC system fault by means of DCCBs.Simulations in PSCAD/EMTDC were conducted to verify the feasibility of the DC relay protection setting switching strategy.In addi⁃tion,the results of field tests also validated the proposed strategy.