一起隐蔽的直流接地故障分析处理

Analysis and treatment on a concealed DC ground fault

针对某换流站验收过程中出现的直流系统接地事件,分析出故障原因是断路器合闸过程中交直流短时搭接接地。通过分析此次接地可能导致的危害,提出了针对性的解决措施。应用结果表明:提高出口中间继电器动作电压及功率、改善对地分布电容有利于降低直流接地导致保护误动的风险,提高直流系统及二次设备的稳定运行。

Aiming at a DC system grounding fault occurred in the acceptance process of a converter station,analyzed the cause of the fault is that the AC-DC short-circuit short-time grounding during the closing process of the circuit breaker.By analyzing the possible damage caused by the grounding,the solutions were proposed.The application results show that increasing the operating voltage and power of the outlet intermediate relay,and improving the distributed capacitance to the ground are beneficial to reduce the risk of protection misoperation caused by the direct current grounding,and which can improve the stable operation of the direct current system and the secondary equipment.