一起变电站直流串入交流回路的异常分析与处理

针对某500kV变电站2号主变复役操作过程中,当拉开2号主变220 k V侧接地闸刀后,出现直流接地报警,合上该接地闸刀,直流接地告警消失的异常情况,经过分析查找,发现与该主变220 k V侧接地闸刀有联闭锁关系的2号主变2号电容器3221闸刀机构箱内的热继电器F1两副接点间内绝缘异常,导致直流串入闸刀交流控制回路。阐述了具体的故障处理过程,并给出了变电站在设计、施工、运维过程中防止直流接地的注意事项。

Abnormal Analysis and Processing of a Direct Current String into Alternating Current Circuit in Substation

In the process of #2 main transformer recommision operation of certain 500kV substation, after the grounding switch blade of #2 main transformer at 220 kV side was pulled open, the direct current grounding alarm occurred; while the grounding switch blade of #2 main transformer was closed, the direct current grounding alarm disappeared. After analysis and search, the abnormal insulation between two pairs of contact in thermal relay F1 was the cause of alarm events in 3221 switch blade operation box of #2 main transformer, which has elec-tric locking relationship with the grounding switch blade at 220 kV side. The concrete fault treating procedure was expounded. This paper gave the matters need attention to prevent direct current grounding in the process of substation design, construction, operation and mainte-nance.