一起330kV变压器间隙保护动作行为分析

Analysis of 330kV transformer gap protection action

针对一起在系统连续发生单相接地故障状态下,变压器中性点间隙被多次击穿,最终导致变压器中性点间隙过流保护动作的事故过程,根据故障录波图详细分析了中性点零序电压及间隙电流产生的原因,并对双回线路不同运行方式下非全相运行状态时零序电流进行了理论分析和仿真计算。根据理论分析及仿真计算结果,论证了在非全相状态下所产生的持续零序电压和零序电流是变压器间隙零序电流保护动作的主要原因,并提出了避免类似事故的切实可行的防范措施。

In view of the system with continuous single-phase grounding fault condition, the transformer neutral ooint gap is breakdown for many times, eventually lead to the accident of the transformer neutral noint gap over-current protection action. The causes of the neutral gap zero seuuence voltage and gad current are analyzed in detail by the fault oscillograph. The theoretical analysis and simulation calculation of zero seuuence current in the non-full nhase running state are carried on under different operation mode for double circuit lines. It is demonstrated that the continuous zero seuuence voltage and zero seuuence current in the condition of non-full nhase is the main reason for the zero sequence current nrotection action of transformer gap. The feasible preventive measures to avoid similar accidents are nut forward.