计及电网参数不平衡的灵活接地系统高阻接地故障选线方法  

A high resistance ground-fault line selection method for flexible grounding system considering unbalanced power grid parameters

作　　者：李晓波[1] 张世乐 谢剑锋 彭超红 刘栩鹏 梁睿[1] LI Xiaobo;ZHANG Shile;XIE Jianfeng;PENG Chaohong;LIU Xupeng;LIANG Rui(School of Electrical Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学电气工程学院,江苏徐州221116

出　　处：《电力系统保护与控制》2025年第5期59-68,共10页Power System Protection and Control

基　　金：国家自然科学基金面上项目资助(52077215)。

摘　　要：灵活接地系统采用的零序过电流保护存在耐过渡电阻能力低的问题,并且现有的选线方法对互感器精度要求较高,也未考虑电网参数不平衡对判据的影响,存在保护误判的风险。针对上述问题,首先在计及电网参数不平衡条件下,探究了并联小电阻投入前后各电气信号变化量与线路对地参数、不平衡电流的关系。研究发现健全线路零序电流变化量与零序电压变化量之比等于该线路对地导纳,故障线路的零序电流变化量与零序电压变化量之比则为线路对地导纳与接地导纳的总和。在此基础上,提出了一种适用于灵活接地系统单相高阻接地故障的选线方法。该方法不受电网参数不平衡与零序CT极性反接影响,能够有效降低保护对互感器精度的要求。此外,该方法还可利用故障信息实现电网参数不平衡条件下对过渡电阻及单条线路对地导纳的测量。最后,在搭建的仿真电路中验证了所述方法的正确性和有效性。Zero sequence overcurrent protection adopted in the flexible grounding system faces the problem of low tolerance to transition resistance.The existing fault line selection methods also require high-precision current transformers and do not take into account the influence of grid parameter imbalances,increasing the risk of protection misjudgment.To address the issues,this paper first explores the relationship between the changes in electrical signals and line-to-ground parameters and unbalanced current before and after the introduction of a small parallel resistance,taking into account the unbalanced conditions of grid parameters.The research finds that the ratio of zero sequence current change and zero sequence voltage change of a healthy line is equal to the line-to-ground admittance,and the ratio of the change of the fault line is the sum of line-to-ground admittance and grounding admittance.On this basis,a method of line selection applicable to single-phase high-resistance ground faults in flexible grounding systems is proposed.This method is not affected by the unbalance of grid parameters and the zero sequence CT polarity reversal,effectively reducing the precision requirements of current transformers.In addition,the method can also utilize the fault information to measure transition resistance and the ground admittance of individual lines under unbalanced grid parameters.Finally,the correctness and effectiveness of the described method are verified in the simulation circuit model.

关 键 词：灵活接地系统 电网参数不平衡 零序电压变化量 零序电流变化量 高阻接地故障 

分 类 号：TM862[电气工程—高电压与绝缘技术]