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  

Analysis of Power Frequency Electrical Quantity and Line Selection Applicability for Two-Point Grounding Faults Occurring on Different Phases in Isolated Neutral System

作　　者：亓志滨 田君杨 薛永端[1] 蔡卓远 徐丙垠[3] Qi Zhibin;Tian Junyang;Xue Yongduan;Cai Zhuoyuan;Xu Bingyin(New Energy CollegeChina University of Petroleum(East China),Qingdao 266580 China;Guangxi Power Grid Power Dispatching Control Center,Nanning 530023 China;Research Center for Smart GridShandong University of Technology,Zibo 255049 China)

机构地区：[1]中国石油大学(华东)新能源学院,青岛266580 [2]广西电网电力调度控制中心,南宁530023 [3]山东理工大学智能电网研究院,淄博255049

出　　处：《电工技术学报》2023年第13期3539-3551,共13页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金项目(52077221);南方电网公司科技项目(046000KK52220008)资助。

摘　　要：中性点不接地系统异名相两点接地且至少一个故障点过渡电阻较大时,故障电流较小出线保护不能直接切除,仍需依赖接地故障选线装置实现保护。根据故障边界条件建立不接地系统异名相两点接地故障复合序网,利用节点阻抗矩阵分别推导出两个接地点故障电流、系统零序电压等工频电气量随两个接地点过渡电阻的变化规律,并进一步分析了其对现有选线技术的影响。结果表明,异名相两点高阻接地时工频电气量总体特征与传统小电流接地故障特征相近,零序电压一般介于两个故障点单独接地时的零序电压之间,其中两个故障线路出口的零序电流既不符合故障线路特征也不符合健全线路特征,已有稳态选线原理并不完全适用。最后,利用数字仿真和现场数据验证了理论分析的正确性。In isolated neutral system,when two-point grounding faults occurring on different phases take place and at least one of the transition resistances is large,the outgoing protection with the small fault current can not be directly removed,it still need to rely on the line selection device to achieve protection.At present,there are some problems in the research on the two-point grounding fault of the small current grounding system,such as lack of quantitative analysis,lack of line selection effect analysis,and difficult to be applied in practice et al.To address these issues,based on the fault equivalent circuit,this paper analyzes the power frequency fault characteristics for two-point grounding faults occurring on different phases in isolated neutral system.Based on the fault characteristics,the adaptability of the existing power frequency line selection methods to the two-point grounding fault of the different phase is analyzed and the development suggestion of line selection technology is put forward.Firstly,Setting up the compound sequence network of two-point grounding faults occurring on different phases,using the nodal impedance matrixes to respectively deduce the expressions of power frequency components,such as two grounding fault point currents,zero-sequence voltage,and so on.Secondly,analyze the characteristics of two-point grounding fault power frequency electrical quantity with the change of the transition resistances in ungrounded systems and compare them with the characteristics of single-point grounding faults.Finally,according to the fault characteristics,the limitation of the existing line selection methods are analyzed,and the development ideas of two-point grounding fault line selection technology are put forward.The results show that,when the transition resistance of at least one fault point is large,the amplitudes of zero-sequence voltage and zero-sequence current of power frequency in two-point grounding of the different phase show the characteristics of single-point grounding.At least one fa

关 键 词：中性点不接地系统 异名相两点接地 工频电气量 稳态选线 

分 类 号：TM713[电气工程—电力系统及自动化]