自适应工况的大型水轮发电机定子接地故障定位方法  

An Adaptive Load-Based Location Method of Stator Ground Fault for Large Hydro-Generators

作　　者：谭力铭 尹项根[1,2] 王义凯 乔健[1,2] 徐雯 Tan Liming;Yin Xianggen;Wang Yikai;Qiao Jian;Xu Wen(State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology,Wuhan 430074,China;Hubei Electric Power Security and High Efficiency Key Laboratory Huazhong University of Science and Technology,Wuhan 430074,China)

机构地区：[1]强电磁工程与新技术国家重点实验室(华中科技大学),武汉430074 [2]电力安全与高效湖北省重点实验室(华中科技大学),武汉430074

出　　处：《电工技术学报》2022年第17期4411-4422,共12页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金资助项目(51877089)。

摘　　要：定子接地故障是大型水轮发电机中最为常见的故障类型,有效的接地故障定位方法能够缩短故障排查时间,提高供电可靠性。现有定位方法未考虑负载工况下电枢反应对绕组电压分布的影响,该文基于对电枢反应机理的深度研究,得出不同负载工况下定子绕组电压与空载情况下定子绕组电动势分布规律相同的结论。据此,该文提出自适应工况的大型水轮发电机定子接地故障定位方法。根据空载情况下发生接地故障时中性点电压和故障绕组电压间的幅值相位关系构建故障评价函数,并依据机端电压的实际测量值确定实时工况下的故障绕组电压分布形式,对故障评价函数进行调整。在故障绕组上设置虚拟故障点并计算各点对应的故障评价函数,将其极小值对应的点定义为故障定位结果。在PSCAD/EMTDC中搭建水轮发电机的准分布参数模型进行仿真验证,仿真结果表明所提定位方法在不同的故障场景和运行工况下均能准确定位故障位置,为故障检修提供参考。Stator ground fault is the most common fault in large hydro-generators,and effective ground fault location methods can shorten the troubleshooting time and improve the reliability of the power supply.Existing location methods ignore the influence of armature reaction on the winding voltage distribution under load condition.Based on the in-depth study of the armature reaction mechanism,it is concluded that the voltage distribution of the stator winding under different load conditions is the same as the electrical potential distribution under no-load condition.On that basis,an adaptive load-based location method of stator ground fault for large hydro-generators is proposed in this paper.The fault evaluation function is constructed according to the amplitude and phase relationship between the neutral voltage and the fault winding voltage when a ground fault occurs under no-load condition.Then the fault winding voltage distribution under the real-time load condition is determined and the fault evaluation function is adjusted according to the actual measured value of terminal voltage.Virtual fault points are set on the fault winding and the fault evaluation function value is calculated for each point,and the point corresponding to its minimal value is defined as the fault location result.A quasi-distributed parameter model of the hydro generator is built in PSCAD/EMTDC for simulation verification.Simulation results show that the proposed method can effectively determine the fault location under different fault scenes and load conditions,which provides a reference for fault maintenance.

关 键 词：大型水轮发电机 定子接地故障 电枢反应 故障绕组电压分布 故障评价函数 

分 类 号：TM312[电气工程—电机]