一起气体绝缘金属封闭开关设备起动过程中断路器接地故障分析

Fault analysis of circuit breaker grounding during the gas insulated switchgear start-up process

气体绝缘金属封闭开关设备(GIS)气室存在金属异物时容易导致电场畸变甚至绝缘击穿。本文结合一起220kV GIS断路器合闸送电过程中C相断路器发生单相接地故障的案例,通过进行SF6气体成分分析、局部放电在线监测、解体、缩比模型下金属异物模拟试验、螺栓材质分析可知,当GIS气室内部存在金属异物时,分合闸操作会导致在线监测局部放电信号远大于正常信号,但局部放电信号出现的频次少,可能无法满足告警条件。通过模拟试验表明,若GIS气室内部存在金属异物,当GIS受到振动冲击时更易发生内部绝缘击穿。因此,此次故障主要由操作过程中的振动冲击和气流影响下的内部金属异物放电引起。

When there are metal particles in gas chamber of gas insulated switchgear(GIS),it is easy to cause electric field distortion and even insulation breakdown.In this paper,a case of single-phase ground fault of phase C circuit breaker in the process of closing and sending power of 220kV GIS circuit breaker is taken as an example,by using SF6 gas composition analysis,on-line monitoring of partial discharge,disassembly inspection,simulation test of metal particles under scaled model and bolt material analysis,the result shows that when there are metal particles inside the GIS gas chamber,the on-line monitoring partial discharge signal is much larger than the normal signal,but the frequency of the discharge signal is less,and the alarm conditions may not be achieved.The simulation test shows that when there are metal particles inside the GIS gas chamber,the internal insulation breakdown is more likely to occur when the GIS is subjected to vibration shock.The main reason for this failure is the discharge of internal metal particles under the influence of vibration shock and airflow during the start-up process.