基于暂态电流概率分析的PT二次多分支电缆中性线接地故障辨识研究  

Research on Neutral Line Ground Fault Identification of PT Secondary Multi-Branch Cable based on Transient Current Probability Analysis

作　　者：温才权 韦鑫 闫茂华 熊小伏[2] 荣浩 李大川 WEN Caiquan;WEI Xin;YAN Maohua;XIONG Xiaofu;RONG Hao;LI Dachuan(Wuzhou Bureau of the UHV Power Transmission Company,China Southern Power Grid Co.,Ltd.,Wuzhou 543000,Guangxi,China;School of Electrical Engineering,Chongqing University,Chongqing 400044,China)

机构地区：[1]中国南方电网有限责任公司超高压输电公司梧州局,广西梧州543000 [2]重庆大学电气工程学院,重庆400044

出　　处：《电网与清洁能源》2024年第12期45-53,共9页Power System and Clean Energy

基　　金：国家自然科学基金项目(52277079);中国南方电网公司科技项目(CGYKJXM20220115)。

摘　　要：变电站(potential transformer,PT)二次回路健康状况会影响继电保护动作的可靠性,对PT二次回路电缆接地故障的识别及接地分支电缆的选线较为困难。针对这一问题,提出利用分支电缆接地电流的暂态信息识别接地故障和PT电缆接地分支的选线方案。利用Hilbert变换获取滤除基频量的暂态信息,并计算衰减直流分量、高频能量、分支电缆电流相似度3个随机变量的估算值,利用Copula函数计算3个指标的联合概率分布密度函数,计算各分支电缆发生接地故障的风险,选出接地分支。搭建仿真模型对二次回路电缆分支接地选线方案进行验证,结果表明,所提基于Copula的融合故障判据不受故障类型的影响,能准确辨识多分电缆故障支路,验证了所提方案的有效性和适应性。The health status of the potential transformer(PT)secondary circuit in a substation is crucial for the reliability of relay protection actions,making it difficult to identify grounding faults in PT secondary circuit cables and select the grounding branch cable.To address this challenge,this article introduces a line selection scheme for identifying grounding faults and PT cable grounding branches using transient information of branch cable grounding current.The Hilbert transform to is employed to obtain the transient information that filters out the fundamental frequency component,and the estimated values of three random variables-decaying DC component,high-frequency energy,and branch cable current similarity-are calculated.The Copula function is used to calculate the joint probability distribution density function of the three indicators,and the risk of grounding faults in each branch cable is calculated to select the grounding branch.Finally,a simulation model is built to verify the secondary circuit cable branch grounding selection scheme.The results show that the fusion fault criterion based on the Copula proposed in this paper is not affected by fault types,and can accurately identify multiple cable fault branches,verifying the effectiveness and adaptability of the scheme.

关 键 词：PT二次回路 故障选线 基频移位 联合概率分布 COPULA函数 

分 类 号：TM77[电气工程—电力系统及自动化]