Abstract：After line break fault without earthing occurs in resonant grounding system, its transient process contains a wealth of high and low-frequency components. The existing research only considers high-frequency transient components, while the more significant low-frequency transient components have rarely been studied, and its low-frequency transient characteristic has not yet been related to conclusions. This study reveals the amplitude characteristics of low-frequency transient components and elucidates the influencing factors of low-frequency transient characteristics in line break fault without earthing within resonant grounding systems, addressing the theoretical gap in low-frequency transient behavior analysis for such fault scenarios. First, the sequence network diagram for the line break fault without earthing in resonant grounding systems was established based on the fault boundary conditions. This model was simplified to derive an equivalent circuit suitable for low-frequency component analysis. Secondly, second-order linear nonhomogeneous differential equations are formulated from the equivalent circuit. Solving this equation yielded analytical expressions for the low-frequency transient zero-sequence currents in both the faulty line and healthy lines. Thirdly, the dominant resonant frequency and attenuation factor of the low-frequency transient components are systematically investigated. Key influencing factors (e.g., load capacitance, fault location) are identified, and their quantitative relationships with transient behavior are established. A comparative study is conducted between the transient characteristics of the aforementioned line break fault without earthing and single-phase high-impedance grounding faults. Finally, the correctness of the theoretical analysis is verified by simulation results. The following conclusions can be drawn: (1) The amplitude of the zero-sequence low-frequency transient component is related to the line parameters, the distance from the fault point to the bus, and the downstream zero-sequence capacitance to ground of the fault point. The zero-sequence voltage at the bus and the zero-sequence currents on each line reach their maximum peaks within the first attenuation cycle, close to and less than twice the power-frequency component's peak value. (2) The dominant resonant frequency of the low-frequency transient component is determined by the compensation degree of the arc suppression coil. Notably, under over-compensation conditions, the system's dominant resonant frequency is observed to be slightly higher than the power frequency. The dominant resonant frequency is virtually unaffected by the attenuation factor, making the influence of fault location, line type, and load parameters negligible. (3) The attenuation factor of the low-frequency transient component is related to the fault distance and the load parameters of the faulty line. The attenuation factor varies with changes in the active and reactive power of the load. Furthermore, the greater the distance of the fault point from the bus, the smaller the damping factor becomes. Due to the larger zero-sequence capacitance to ground in cable lines compared to overhead lines, this variation becomes more pronounced in cable lines. (4) Generally, the attenuation factor of the zero-sequence low-frequency component in single-phase high-impedance grounding faults is significantly larger than that in line break fault without earthing.
[1] 常仲学, 宋国兵, 王晓卫. 基于零序电压幅值差的配电网断线识别与隔离[J]. 电力系统自动化, 2018, 42(6): 135-139. Chang Zhongxue, Song Guobing, Wang Xiaowei.Identification and isolation of line breakage fault in distribution network based on zero sequence voltage amplitude differential principle[J]. Automation of Electric Power Systems, 2018, 42(6): 135-139. [2] 罗国敏, 谭颖婕, 吴梦宇, 等. 考虑电压跌落差异的有源配电网功率差动保护[J]. 电工技术学报, 2025, 40(4): 1287-1306. Luo Guomin, Tan Yingjie, Wu Mengyu, et al.Power differential protection for active distribution networks considering voltage drop differences[J]. Transactions of China Electrotechnical Society, 2025, 40(4): 1287-1306. [3] 李君, 何敏, 黄守道, 等. 基于相位差的小电阻接地有源配电网接地故障保护算法[J]. 电工技术学报, 2024, 39(23): 7418-7429. Li Jun, He Min, Huang Shoudao, et al.Grounding fault protection algorithm of small resistance earthing active distribution network based on phase difference[J]. Transactions of China Electrotechnical Society, 2024, 39(23): 7418-7429. [4] 汤涛, 黄纯, 江亚群, 等. 基于馈线零序阻抗特性的谐振接地故障选线方法[J]. 电工技术学报, 2016, 31(20): 192-201. Tang Tao, Huang Chun, Jiang Yaqun, et al.A method of fault line selection in resonant earthed system based on zero sequence impedance characteristic of lines[J]. Transactions of China Electrotechnical Society, 2016, 31(20): 192-201. [5] 王风光, 杜兴伟, 李力, 等. 母线差动保护电流互感器断线处理逻辑[J]. 电力系统自动化, 2023, 47(14): 167-173. Wang Fengguang, Du Xingwei, Li Li, et al.Processing logic against current transformer disconnection of busbar differential protection[J]. Automation of Electric Power Systems, 2023, 47(14): 167-173. [6] Li Zichang, Liu Yadong, Yan Yingjie, et al.An identification method for asymmetric faults with line breaks based on low-voltage side data in distribution networks[J]. IEEE Transactions on Power Delivery, 2020, 36(6): 3629-3639. [7] 潘本仁, 管廷龙, 桂小智, 等. 不接地系统高阻接地故障特征及选线适用性分析[J]. 电力系统及其自动化学报, 2017, 29(10): 52-59. Pan Benren, Guan Tinglong, Gui Xiaozhi, et al.Characteristics of high-resistance grounding fault in isolated neutral systems and the adaptability analysis of fault line selection[J]. Proceedings of the CSU-EPSA, 2017, 29(10): 52-59. [8] 张利, 杨秀媛, 王丽婕, 等. 中性点不接地系统单相接地故障定位方法[J]. 电网技术, 2017, 41(12): 4069-4076. Zhang Li, Yang Xiuyuan, Wang Lijie, et al.Fault location of single-phase-to-ground in neutral point ungrounded system[J]. Power System Technology, 2017, 41(12): 4069-4076. [9] 王丙东, 蔡蕾, 董旭, 等. 中性点不接地系统非对称短路故障分析[J]. 电力系统保护与控制, 2017, 45(3): 149-153. Wang Bingdong, Cai Lei, Dong Xu, et al.A comprehensive analysis for asymmetrical short-circuit fault of electric power system with neutral-point unground[J]. Power System Protection and Control, 2017, 45(3): 149-153. [10] 薛永端, 陈梦琦, 曹丽丽, 等. 不接地系统单相断线故障电压分析[J]. 中国电机工程学报, 2021, 41(4): 1322-1333, 1539. Xue Yongduan, Chen Mengqi, Cao Lili, et al.Analysis of voltage characteristics of single-phase disconnection fault in ungrounded distribution system[J]. Proceedings of the CSEE, 2021, 41(4): 1322-1333, 1539. [11] 亓志滨, 田君杨, 薛永端, 等. 不接地系统异名相两点接地故障工频电气量及其对选线的影响分析[J]. 电工技术学报, 2023, 38(13): 3539-3551. Qi Zhibin, Tian Junyang, Xue Yongduan, et al.Analysis of power frequency electrical quantity and line selection applicability for two-point grounding faults occurring on different phases in isolated neutral system[J]. Transactions of China Electrotechnical Society, 2023, 38(13): 3539-3551. [12] 薛永端, 李广, 徐丙垠. 利用熄弧后暂态信息测量谐振接地系统的对地电容[J]. 电工技术学报, 2020, 35(7): 1521-1528. Xue Yongduan, Li Guang, Xu Bingyin.Measuring method of capacitance to ground in resonant grounding system based on transient information after arc extinguishing[J]. Transactions of China Electro-technical Society, 2020, 35(7): 1521-1528. [13] 张健磊, 高湛军, 陈明, 等. 考虑复故障的有源配电网故障定位方法[J]. 电工技术学报, 2021, 36(11): 2265-2276. Zhang Jianlei, Gao Zhanjun, Chen Ming, et al.Fault location method for active distribution networks considering combination faults[J]. Transactions of China Electrotechnical Society, 2021, 36(11): 2265-2276. [14] 李辉, 唐轶, 孙常青. 谐振接地系统单相接地故障仿真分析[J]. 工矿自动化, 2012, 38(1): 47-51. Li Hui, Tang Yi, Sun Changqing.Simulation analysis of single-phase grounding fault of resonant grounding system[J]. Industry and Mine Automation, 2012, 38(1): 47-51. [15] 薛永端, 李娟, 徐丙垠. 中性点经消弧线圈接地系统小电流接地故障暂态等效电路及暂态分析[J]. 中国电机工程学报, 2015, 35(22): 5703-5714. Xue Yongduan, Li Juan, Xu Bingyin.Transient equivalent circuit and transient analysis of single-phase earth fault in arc suppression coil grounded system[J]. Proceedings of the CSEE, 2015, 35(22): 5703-5714. [16] 张海申, 何正友, 张钧. 谐振接地系统单相接地故障频谱特征分析[J]. 电力系统自动化, 2012, 36(6): 79-84. Zhang Haishen, He Zhengyou, Zhang Jun.Frequency spectrum characteristic analysis of single-phase grounding fault in resonant grounded systems[J]. Automation of Electric Power Systems, 2012, 36(6): 79-84. [17] 王玘, 何正友, 张姝. 基于零序电荷-零序电压关系的谐振接地系统单相接地故障特征分析[J]. 电力系统保护与控制, 2013, 41(11): 18-24. Wang Qi, He Zhengyou, Zhang Shu.Characteristics analysis of single-phase ground fault in resonant grounding system based on zero-sequence charge-voltage relationship[J]. Power System Protection and Control, 2013, 41(11): 18-24. [18] 薛永端, 张秋凤, 颜廷纯, 等. 综合暂态与工频信息的谐振接地系统小电流接地故障选线[J]. 电力系统自动化, 2014, 38(24): 80-85. Xue Yongduan, Zhang Qiufeng, Yan Tingchun, et al.Faulty feeder identification based on combined transient and power-frequency components in reso-nant grounded systems[J]. Automation of Electric Power Systems, 2014, 38(24): 80-85. [19] 汤涛, 黄纯, 江亚群, 等. 基于高低频段暂态信号相关分析的谐振接地故障选线方法[J]. 电力系统自动化, 2016, 40(16): 105-111. Tang Tao, Huang Chun, Jiang Yaqun, et al.Fault line selection method in resonant earthed system based on transient signal correlation analysis under high and low frequencies[J]. Automation of Electric Power Systems, 2016, 40(16): 105-111. [20] 李高明, 黎皓彬, 卢颖, 等. 基于暂稳态电流幅值比较的谐振接地系统故障选线方法[J]. 电力系统及其自动化学报, 2022, 34(10): 97-103. Li Gaoming, Li Haobin, Lu Ying, et al.Fault line selection method for resonance grounding system based on comparison between transient and steady-state current amplitudes[J]. Proceedings of the CSU-EPSA, 2022, 34(10): 97-103. [21] 吴江雄, 郑茂然, 王欣, 等. 基于暂态零序导纳值的谐振接地系统单相接地故障选线方法[J]. 南方电网技术, 2024, 18(11): 58-66. Wu Jiangxiong, Zheng Maoran, Wang Xin, et al.Single-phase grounding fault line selection method for resonant grounding system based on transient zero-sequence admittance value[J]. Southern Power System Technology, 2024, 18(11): 58-66. [22] 张洪涛, 曹丽丽, 冯光, 等. 谐振接地系统单相断线故障分析[J]. 电力系统及其自动化学报, 2019, 31(2): 58-65. Zhang Hongtao, Cao Lili, Feng Guang, et al.Analysis of single-phase open fault for resonant grounded system[J]. Proceedings of the CSU-EPSA, 2019, 31(2): 58-65. [23] 周斌, 陈梦琦, 郑海涯, 等. 谐振接地系统单相断线并坠地故障电压特征仿真分析[J]. 电力系统保护与控制, 2021, 49(17): 93-100. Zhou Bin, Chen Mengqi, Zheng Haiya, et al.Simulation analysis of voltage characteristics of a single-phase line-broken and grounding fault in a resonant grounded system[J]. Power System Protection and Control, 2021, 49(17): 93-100. [24] 张弛, 王淳, 潘建兵, 等. 谐振接地系统单相断线并电源侧接地故障电压特征分析[J]. 电网技术, 2022, 46(12): 4993-5005. Zhang Chi, Wang Chun, Pan Jianbing, et al.Voltage characteristics analysis of single-phase disconnection with power resource side grounding fault in resonant earthed system[J]. Power System Technology, 2022, 46(12): 4993-5005. [25] Li He, Xue Yongduan, Chen Mengqi, et al.Analysis of voltage characteristics for single-phase line break fault in resonant grounding systems[J]. IEEE Transactions on Power Delivery, 2023, 38(2): 1416-1425. [26] 谢松伟, 薛永端, 吴卫堃, 等. 单相断线坠地故障暂态特征及暂态选线方法适用性[J]. 电力系统自动化, 2022, 46(2): 126-136. Xie Songwei, Xue Yongduan, Wu Weikun, et al.Transient characteristics of single-phase line breaking and grounding fault and applicability of transient line selection methods[J]. Automation of Electric Power Systems, 2022, 46(2): 126-136. [27] 薛永端, 李娟, 陈筱薷, 等. 谐振接地系统高阻接地故障暂态选线与过渡电阻辨识[J]. 中国电机工程学报, 2017, 37(17): 5037-5048, 5223. Xue Yongduan, Li Juan, Chen Xiaoru, et al.Faulty feeder selection and transition resistance identification of high impedance fault in a resonant grounding system using transient signals[J]. Proceedings of the CSEE, 2017, 37(17): 5037-5048, 5223. [28] 谢松伟. 单相断线-坠地故障暂态特征及暂态选线方法适用性[D]. 东营: 中国石油大学(华东), 2022. Xie Songwei.Transient characteristics of single-phase disconnection-grounding fault and applicability of transient line selection method[D]. Dongying: China University of Petroleum (Huadong), 2022.
2026, Vol. 41 
