一起35 kV主变压器跳闸事故分析

Analysis of a 35 kV Main Transformer Tripping Accident

配电线路单相接地故障危害巨大,会导致电网事故存在进一步扩大的风险。针对某35 kV主变压器跳闸事故,基于戴维南等效电路原理论述了电力系统铁磁谐振机理。结合故障现象及现场检查结果,发现事故原因为某10 kV线路发生单相接地,进而引起铁磁谐振过电压,造成电压互感器烧毁。同时结合分析结果,给出了消除或抑制电压互感器铁磁谐振的措施,可为今后确保配电网安全稳定运行提供借鉴和参考。

The single-phase grounding fault of distribution lines greatly harms safety of the network,which will lead to the risk of further expansion of grid accidents.According to the tripping accident of a 35kV main transformer,the mechanism of ferro-resonance in power system is discussed based on the Thevenin equivalent circuit principle.Based on fault phenomena and field inspection results,it is found that the cause of the accident is the single-phase grounding of a 10kV line,which caused the ferro-resonance overvoltage and the voltage transformer to be burnt out.According to the analysis,the measures to eliminate or restrain the ferro-resonance of voltage transformers are proposed,which provides reference for the safe and stable operation of distribution network in the future.