小电阻接地配电系统集中式接地保护研究  

Centralized protection for a grounding fault in a low-resistance grounding distribution system

作　　者：吴海江 陈锦荣 廖峰 黎永豪 WU Haijiang;CHEN Jinrong;LIAO Feng;LI Yonghao(Foshan Power Supply Bureau,Guangdong Power Grid Co.,Ltd.,Foshan 528000,China)

机构地区：[1]广东电网有限责任公司佛山供电局,广东佛山528000

出　　处：《电力系统保护与控制》2021年第21期141-149,共9页Power System Protection and Control

基　　金：国家高技术研究发展计划(863计划)重点项目资助(2012AA050213);南方电网公司科技项目资助(030600KK 52200019[GDKJXM20200486])。

摘　　要：为解决小电阻接地配电系统单相高阻接地故障检测困难和两出线同相接地故障时零序电流保护拒动的问题,提出一种基于中性线与各出线零序电流幅值比较的小电阻接地系统集中式接地保护方案。建立小电阻接地配电系统单相接地故障时等效零序网络,结合相量分析法,提取在不同故障位置、过渡电阻和线路对地电容等条件下单出线单相接地故障和两出线同相接地故障的普适性特征。并挖掘两种故障状态下的共性特征,形成适用于单出线或两出线单相接地故障的接地保护判据,准确地进行故障隔离。该方法利用中性线零序电流与各出线零序电流比值的相对差异,明确区分线路或母线侧单相接地故障,过渡电阻高达1500?时依然成立。该保护算法启动值低,灵敏度高,定值裕度较大,稳定性好,适合配电网灵活运行方式。仿真结果表明接地故障特征分析结果的正确性和该保护方案的有效性。In order to solve the difficulty of single-phase high-resistance grounding fault detection in a low-resistance grounding system and the problem of protection rejection when single-phase grounding fault occurs under two feeders,a centralized protection scheme for such a system is proposed based on the comparisons of zero-sequence current amplitudes of the neutral line and each feeder.Combined with phasor analysis,the equivalent zero sequence networks of the system are established for when single-phase grounding faults under a single feeder or two feeders occur.Then the general characteristics under the two fault conditions are analyzed considering the different fault location,transition resistance and line capacitance to ground.The common fault characteristics are extracted to form the grounding protection criterion.This is applicable to single-phase grounding faults under single feeder or two feeders.The faults are isolated accurately.This method can clearly distinguish the single-phase grounding fault of the feeder and the bus side based on the relative difference of the zero-sequence current amplitudes of the neutral line and each feeder.The method remains valid even when the transition resistance is as high as 1500Ω.The protection algorithm has the advantages of low starting value,high sensitivity,large margin of setting value and good stability.It is suitable for the flexible operation of a distribution network.The simulation results show that the analysis of grounding fault characteristics is correct and the protection scheme is effective.

关 键 词：小电阻接地配电系统 高阻接地 两出线同相接地 零序电流 集中式接地保护 

分 类 号：TM862[电气工程—高电压与绝缘技术]