10 kV电磁式电压互感器高压侧熔断器频繁熔断事故的诊断分析及改善措施

Diagnostic Analysis and Improvement Measures on Frequent Fusing of High VoltageFuses of 10 kV Electromagnetic Potential Transformer

恩施某220 kV变电站10 kV母线电压互感器(PT)频繁发生单相、两相、三相熔断器熔断事故,并伴随着PT谐振告警、母线接地告警现象。结合现场对PT进行的绝缘、励磁特性等诊断性试验及对10 kV系统电容进行的电流测试,得出了系统发生铁磁谐振及超低频振荡,产生过电压及饱和过电流,导致电压互感器高压熔断器频繁熔断的结论。最后提出了改善PT励磁特性及加装消弧装置等有效防范措施,并进行了相应的整改实施,取得了良好的应用效果。

This paper focuses on accidents of single-phase,two-phase and three-phase fusing as well as the accompanying PT resonance alarms and busbar grounding alarms encountered frequently by a 10 kV busbar potential transformer(PT)of a 220 kV substation in Enshi.Combining on-site diagnostic tests of PT such as insulation and excitation characteristics with current test of 10 kV system capacitance,it is concluded that the system occurs ferroresonance and ultra-low frequency oscillation,resulting in overvoltage and saturation overcurrent,and consequently frequent fusing of high-voltage fuse of PT.Effective preventive measures such as improving PT excitation characteristics and installing arc suppression devices are proposed,and corresponding rectification and implementation have been carried out achieving satisfactory results.