摘要
地下高压电缆已是城市电能传输的主要通道,1条隧道内近距离敷设有多条电缆线路,这些线路共用1个接地网。线路之间的电磁感应与共地后护层回路的相互连通导致了护层电流经常超过标准值,但运维人员排查后确认一些线路接地系统连接良好且不存在故障。为此建立了邻近高压电缆线路各状态下护层电流的计算模型,分析了排列方式、共用接地与小段长度对电缆线路护层电流的影响,以护层回路电流平均值与偏差值为评价标准,分析了护层开路、护层间短路与护层对地短路状态下护层电流的分布特征,并构建了故障诊断判据。接地系统无故障状态下,护层回路电流均值接近,偏差值在电容电流范围内。护层开路故障造成回路电流均值减小,护层短路故障造成电流偏差值增大。该故障诊断方法不依赖负荷电流的测量与理论正常值的计算,在现场中具有较高的可行性与泛用性。
Underground high-voltage cables are the main channel for urban power transmission.Tunnels usually contain multiple cable circuits in close proximity that share the same grounding network.Electromagnetic coupling among these circuits and the connection of multiple sheath loops result in the sheath currents that exceed the standard,but maintenance engineers often find that the grounding system is electrically healthy after thorough inspections.Models for cable circuits in close proximity with a shared grounding system in the presence and absence of faults are established in this paper.The sheath currents in the cable circuits with different scenarios of cable layout,sharing of grounding points,and minor sec-tion lengths are analyzed.The distribution characteristics of the sheath currents in the cable circuits containing various faults are evaluated by the mean values and deviation values of the sheath currents.The diagnostic criteria are proposed according to the characteristics of the sheath currents.The results show that the mean values of currents in three sheath loops of the same circuit are relatively close in the grounding system in the absence of faults,and the deviation values are within the range of the capacitive current generated in this segment.Open-circuit faults reduce the average current in the sheath loop,while short-circuit faults increase the difference among currents in the same sheath loop measured at different positions.Fault diagnosis relies only on measurements of sheath currents and does not require measurement of load cur-rents or calculation of theoretical values under normal conditions.The method can be conveniently applied in the field.
作者
李根
周文俊
喻莹
仇龙
杨斌
艾永恒
LI Gen;ZHOU Wenjun;YU Ying;QIU Long;YANG Bin;AI Yongheng(School of Electrical Engineering and Automation,Wuhan University,Wuhan 430072,China;Extra High Voltage Company,State Grid Hubei Power Supply Company,Wuhan 430050,China;Wuhan Power Supply Company,State Grid Hubei Power Supply Company,Wuhan 430024,China)
出处
《高电压技术》
北大核心
2025年第2期698-707,I0018,I0019,共12页
High Voltage Engineering
基金
国家电网有限公司科技项目(5700-202118195A-0-0-00)。
关键词
高压电缆
状态监测
接地系统
护层电流
故障诊断
high voltage cable
condition monitoring
grounding system
sheath current
fault diagnosis
作者简介
李根,1995-,男,博士生主要从事电力电缆状态评估方面的研究工作,E-mail:LEAGREN@foxmail.com;通信作者:周文俊,1959-,男,博士,教授,博导国际电气与电子工程师学会高级会员(SMIEEE),中国电机工程学会高电压专委会委员,中国电工技术学会电工测试专委会副主任委员。研究方向为高电压绝缘与测试技术、防雷与接地技术、环保绝缘气体等,E-mail:wjzhou@whu.edu.cn。
