Generator Stator Winding Ground Fault Location Algorithm Based on Third Harmonic Potential Distribution Characteristic
Wang Yikai1,2, Yin Xianggen1,2, Tan Liming1,2, Qiao Jian1,2, Zhu Lingjin1,2
1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China; 2. Hubei Electric Power Security and High Efficiency Key Laboratory Huazhong University of Science and Technology Wuhan 430074 China
Abstract：Floating nuclear power plant operates in a wet and salty environment. The main equipment in the power system is easy to be corroded, and generator stator winding ground faults occur frequently. To avoid the power loss of the nuclear reactor loads caused by the generator's blind and rapid tripping, the active arc suppression technology is adopted to realize stator ground fault arc suppression and achieve smooth load transfer. The difference between the active arc suppression technology of the generator and the distribution network lies that: the applied voltage in the neutral point is different for ground faults at different fault points on the stator windings. Therefore, reliable fault point location should be realized. For the problem of generator stator ground fault location, the influence of the winding structure and operating condition should be considered. The existing ground fault location methods usually utilize the fundamental zero-sequence voltage. They can obtain accurate location results in most fault scenarios. However, in some fault scenarios, when the fault transition resistance is large or the fault point is close to the neutral point, multiple solutions are easy to be located. And it cannot provide reliable location guarantee for active arc suppression technology. Aiming at the problems of the existing fundamental potential based location methods, a new location algorithm based on the third harmonic potential distribution characteristics is proposed. Based on the 180° phase-band distribution of the third harmonic potential of each coil, the geometric relation between the third harmonic fault potential and the third harmonic phase potential is constructed. Taking the third harmonic fault current as the intermediate quantity, the analytical location equation containing the third harmonic fault potential, neutral grounding voltage and neutral grounding voltage variation is established. Grounding transition resistance is not included in the equation, which is suitable for the generator in the floating nuclear power plant without injection protection equipment. Simulation results show that under different generator stator windings ground fault scenarios, the location error is within ±1%, which has a high accuracy under different fault points and fault transition resistances. Dynamic test results show that the proposed method can realize accurate ground fault location under different load conditions, and it is not affected by operating conditions and excitation regulation. In engineering application, the existing fundamental voltage based method can be combined with the proposed third harmonic based method proposed in this paper. When the fundamental voltage based method has multiple location solutions, the closest solution of the two location methods is taken as the final localization result. The following conclusions can be drawn from the simulation analysis: (1) The existing ground fault location methods based on fundamental zero-sequence voltage have some problems and cannot provide reliable location guarantee for active arc suppression technology. (2) Based on the distribution characteristics of the 180° phase-band of the third harmonic potential of the stator windings, the analytical locating equation including the third harmonic fault potential, the third harmonic neutral point voltage and the third harmonic neutral point voltage variation is established in this paper. It does not include the fault transition resistance and is applicable to floating nuclear power plant generators without injection protection equipment. (3) Simulation and dynamic model test results show that the proposed method has high accuracy and is not affected by fault location, fault transition resistance and operating conditions. This method can cooperate with the fundamental location method to eliminate the location dead zone and solve the multi-solution problem of the fundamental voltage based location method. (4) The proposed method is applicable to generators whose stator windings meet the characteristics of 60° phase-band distribution and whose neutral point is grounded by high resistance.
[1] 尹项根, 王义凯, 李鹏, 等. 海洋核动力平台电网安全问题及保护技术研究[J]. 电力系统保护与控制, 2020, 48(22): 9-17. Yin Xianggen, Wang Yikai, Li Peng, et al.Study on security problems and protection technologies of the floating nuclear power plant grid[J]. Power System Protection and Control, 2020, 48(22): 9-17. [2] 方晓伦, 杨强, 刘国锋, 等. 海上多平台互联电力系统故障后的供电恢复策略[J]. 电力系统自动化, 2021, 45(7): 53-61. Fang Xiaolun, Yang Qiang, Liu Guofeng, et al.Power supply restoration strategy for offshore multi-platform interconnected power system with faults[J]. Automation of Electric Power Systems, 2021, 45(7): 53-61. [3] Wang Yikai, Yin Xianggen, Qiao Jian, et al.Generator stator windings ground fault diagnosis for generator-grid? directly connected system of floating nuclear power plant[J]. Energy Reports, 2021, 7: 460-469. [4] 高俊国, 孟睿潇, 胡海涛, 等. 电机定子绝缘老化寿命预测研究进展[J]. 电工技术学报, 2020, 35(14): 3065-3074. Gao Junguo, Meng Ruixiao, Hu Haitao, et al.Research progress on prediction of aging life of motor stator insulation[J]. Transactions of China Electrotechnical Society, 2020, 35(14): 3065-3074. [5] 郝亮亮, 李佳慧, 段贤稳, 等. 核电多相环形无刷励磁机转子绕组短路故障特征分析[J]. 电工技术学报, 2020, 35(6): 1251-1261. Hao Liangliang, Li Jiahui, Duan Xianwen, et al.Characteristic analysis of short-circuit fault in rotor winding of nuclear power multi-phase annular brushless exciter[J]. Transactions of China Electrotechnical Society, 2020, 35(6): 1251-1261. [6] 田代宗, 孙宇光, 王善铭, 等. 多相整流永磁同步发电机绕组内部相间短路的故障分析[J]. 电工技术学报, 2020, 35(6): 1262-1271. Tian Daizong, Sun Yuguang, Wang Shanming, et al.Analysis of stator internal phase-to-phase short-circuit in the multiphase permanent magnet synchronous generator with rectifier load system[J]. Transactions of China Electrotechnical Society, 2020, 35(6): 1262-1271. [7] 赵洪森, 戈宝军, 陶大军, 等. 大型核电汽轮发电机定子内部短路故障时局部电磁力分布研究[J]. 电工技术学报, 2018, 33(7): 1497-1507. Zhao Hongsen, Ge Baojun, Tao Dajun, et al.Local electromagnetic force distribution study on giant nuclear turbo-generators with stator short-circuit fault[J]. Transactions of China Electrotechnical Society, 2018, 33(7): 1497-1507. [8] 何玉灵, 张文, 张钰阳, 等. 发电机定子匝间短路对绕组电磁力的影响[J]. 电工技术学报, 2020, 35(13): 2879-2888. He Yuling, Zhang Wen, Zhang Yuyang, et al.Effect of stator inter-turn short circuit on winding electromagnetic forces in generators[J]. Transactions of China Electrotechnical Society, 2020, 35(13): 2879-2888. [9] Wang Yikai, Yin Xianggen, Xu Wen, et al.Active arc suppression algorithm for generator stator winding ground fault in the floating nuclear power plant[J]. IEEE Transactions on Power Delivery, PP(99): 1. [10] 蒋顺平, 丁勇, 石祥建, 等. 位移过电压抑制转接地故障消弧的柔性电源控制方法[J]. 电力系统自动化, 2021, 45(20): 140-147. Jiang Shunping, Ding Yong, Shi Xiangjian, et al.Control method of displacement overvoltage suppression switching to ground fault arc-suppression for flexible power source[J]. Automation of Electric Power Systems, 2021, 45(20): 140-147. [11] 康逸群, 宋梦琼. 大型发电机注入式定子接地保护应用与分析[J]. 电气技术, 2020, 21(1): 129-132. Kang Yiqun, Song Mengqiong.Application and analysis of voltage-injection stator ground protection for large-sized generator[J]. Electrical Engineering, 2020, 21(1): 129-132. [12] 毕大强, 王祥珩, 李德佳, 等. 发电机定子绕组单相接地故障的定位方法[J]. 电力系统自动化, 2004, 28(22): 55-57, 94. Bi Daqiang, Wang Xiangheng, Li Dejia, et al.Location detection for the stator single-phase ground fault of a generator[J]. Automation of Electric Power Systems, 2004, 28(22): 55-57, 94. [13] 陈俊, 刘梓洪, 王明溪, 等. 不依赖注入式原理的定子单相接地故障定位方法[J]. 电力系统自动化, 2013, 37(4): 104-107. Chen Jun, Liu Zihong, Wang Mingxi, et al.Location method for stator single-phase ground fault independent of injection type principle[J]. Automation of Electric Power Systems, 2013, 37(4): 104-107. [14] 贾文超, 黄少锋. 水轮发电机定子单相接地故障定位新方法[J]. 电力自动化设备, 2017, 37(2): 134-139. Jia Wenchao, Huang Shaofeng.Stator single-phase grounding fault location for hydro-generator[J]. Electric Power Automation Equipment, 2017, 37(2): 134-139. [15] 尹项根, 王义凯, 谭力铭, 等. 故障机理深度关联的大型发电机保护新原理探讨[J]. 电力系统保护与控制, 2021, 49(22): 1-7. Yin Xianggen, Wang Yikai, Tan Liming, et al.Discussion on a new principle of large generator protection deeply associated with fault mechanisms[J]. Power System Protection and Control, 2021, 49(22): 1-7. [16] 王育学, 尹项根, 张哲, 等. 基于接地电流的大型发电机定子接地保护及精确定位方法[J]. 中国电机工程学报, 2013, 33(31): 147-154, 18. Wang Yuxue, Yin Xianggen, Zhang Zhe, et al.A novel protection and precise location method based on grounding currents for stator ground faults of large generators[J]. Proceedings of the CSEE, 2013, 33(31): 147-154, 18. [17] 黄少锋, 贾文超. 大型汽轮发电机定子单相接地故障定位新方法[J]. 电力系统保护与控制, 2017, 45(9): 35-40. Huang Shaofeng, Jia Wenchao.A new fault location method for stator single-phase ground fault in large turbine generator[J]. Power System Protection and Control, 2017, 45(9): 35-40. [18] 殷林鹏, 桂林, 张琦雪, 等. 基于基波电势分布特征的大型发电机定子接地故障定位方法[J]. 电力自动化设备, 2019, 39(7): 141-146. Yin Linpeng, Gui Lin, Zhang Qixue, et al.Stator grounding fault location method based on distribution characteristics of fundamental wave potential[J]. Electric Power Automation Equipment, 2019, 39(7): 141-146. [19] 王义凯, 尹项根, 乔健, 等. 海洋核动力平台发电机定子绕组单相接地故障风险分析与实时定位[J]. 电力自动化设备, 2022, 42(4): 178-183. Wang Yikai, Yin Xianggen, Qiao Jian, et al.Risk analysis and real-time locating of single-phase grounding fault of generator stator winding for offshore nuclear power plant[J]. Electric Power Automation Equipment, 2022, 42(4): 178-183. [20] 王维俭. 电气主设备继电保护原理与应用[M]. 2版. 北京: 中国电力出版社, 2002. [21] 党晓强, 邰能灵, 刘俊勇, 等. 绝缘状况原理在大型水轮发电机3次谐波量接地保护中的应用[J]. 中国电机工程学报, 2012, 32(34): 129-134, 19. Dang Xiaoqiang, Tai Nengling, Liu Junyong, et al.Application of ground insulation state to improve ground fault protection using third harmonic voltage for huge hydraulic generator[J]. Proceedings of the CSEE, 2012, 32(34): 129-134, 19. [22] 桑建斌, 包明磊, 李玉平, 等. 大型汽轮发电机3次谐波电压定子接地保护方案的研究与改进[J]. 电力自动化设备, 2017, 37(10): 177-183. Sang Jianbin, Bao Minglei, Li Yuping, et al.Research and improvement of stator grounding protection based on third-harmonic voltage for large-scale turbine generator[J]. Electric Power Automation Equipment, 2017, 37(10): 177-183. [23] Fulczyk M, Mydlikowski R.Influence of generator load conditions on third-harmonic voltages in generator stator winding[J]. IEEE Transactions on Energy Conversion, 2005, 20(1): 158-165. [24] 谭力铭, 尹项根, 王义凯, 等. 自适应工况的大型水轮发电机定子接地故障定位方法[J]. 电工技术学报, 2022, 37(17): 4411-4422. Tan Liming, Yin Xianggen, Wang Yikai, et al.An adaptive load-based location method of stator ground fault for large hydro-generators[J]. Transactions of China Electrotechnical Society, 2022, 37(17): 4411-4422.
2023, Vol. 38 
