同步发电机励磁变压器低压侧单相接地故障识别与定位方法  

Method for identifying and locating single-phase grounding fault at low-voltage side of excitation transformer in synchronous generator

作　　者：吴玉璋 嵇兴康 李华忠[1] 张琦雪[1] 李建春[1] 马启超 徐金[1] WU Yuzhang;JI Xingkang;LI Huazhong;ZHANG Qixue;LI Jianchun;MA Qichao;XU Jin(Nanjing NR Electric Co.,Ltd.,Nanjing 211102,China;Zhejiang Zheneng Electric Power Co.,Ltd.,Hangzhou 311100,China)

机构地区：[1]南京南瑞继保电气有限公司,江苏南京211102 [2]浙江浙能电力股份有限公司,浙江杭州311100

出　　处：《电力自动化设备》2024年第10期165-171,共7页Electric Power Automation Equipment

摘　　要：同步发电机励磁变压器低压侧未配置零序电压接地保护,当发生单相接地故障时会造成转子接地保护动作,从而误导故障排查方向。为实现励磁变低压侧单相接地故障准确识别与定位,利用叠加原理分析发生单相接地故障时转子对地电压的故障特征,提出当转子对地电压工频分量与励磁变高压侧相电压之比超过判据门槛,且转子对地绝缘电阻值较低时,判定故障点在励磁变压器低压侧。进一步地,通过分析转子对地电压工频分量与励磁变高压侧相电压的相位关系,实现励磁变压器低压侧接地故障相判别。通过仿真模型和动模实验验证了所提方法的正确性和有效性。The low-voltage side of the excitation transformer in synchronous generator is not equipped with zero-sequence voltage grounding protection.A single-phase grounding fault at low-voltage side of the excita⁃tion transformer would trigger the rotor grounding relay protection,which might misdirect fault diagnosis.For accurately identifying and locating single-phase grounding fault at the low-voltage side of the excitation transformer,superposition theorem is used to analyze the fault symptoms of rotor-to-ground voltages during single-phase grounding fault.Then it is proposed that,when the ratio of the rotor-to-ground voltage’s funda⁃mental frequency value to the excitation transformer’s high-voltage-side phase voltage exceeds the threshold criterion,and the rotor-to-ground insulation resistance value is low,the fault point can be concluded to be on the low-voltage side of the excitation transformer.Furthermore,by analyzing the phase relationship between the fundamental frequency component of rotor-to-ground voltage and the excitation transformer’s high-voltage-side phase voltage,the phase discrimination of the low-voltage side grounding fault is achieved.The correct⁃ness and effectiveness of the proposed method is proved by simulation and dynamic experiment.

关 键 词：励磁变压器 单相接地故障 转子电压 叠加原理 故障特征 故障识别 

分 类 号：TM772[电气工程—电力系统及自动化]