配电网中性点改造为小电阻接地方式的安全性分析研究  

Safety Analysis and Research on Transforming Neutral Point of Distribution Network to Low Resistance Grounding Method

作　　者：田凤兰 景中炤 迟渊泓 李景丽[2] 徐铭铭 时永凯 杨旭晨 TIAN Fenglan;JING Zhongzhao;CHI Yuanhong;LI Jingli;XU Mingming;SHI Yongkai;YANG Xuchen(Zhengzhou Power Supply Company,State Grid Henan Electric Power Company,Zhengzhou 450000,China;College of Electrical Engineering,Zhengzhou University,Zhengzhou 450001,China;Electric Power Research Institute,State Grid Henan Electric Power Company,Zhengzhou 450052,China)

机构地区：[1]国网河南省电力公司郑州供电公司,郑州450000 [2]郑州大学电气工程学院,郑州450001 [3]国网河南省电力公司电力科学研究院,郑州450052

出　　处：《电瓷避雷器》2022年第4期66-74,共9页Insulators and Surge Arresters

基　　金：国网河南省电力公司科技项目(编号:521710210002);国家自然科学基金(编号:51307152)。

摘　　要：我国大中城市配电网出线数量增加及线路电缆化率提高,消弧线圈难以满足电容电流补偿要求,在用电量集中的工商业区开展配网小电阻接地改造及系统安全性研究对其安全稳定运行具有重要意义。首先基于单相接地故障电路模型对中性点小电阻接地系统单相接地故障短路电流进行了理论计算;其次在Matlab-Simulink中搭建消弧线圈接地系统(NES)向小电阻接地系统(NRS)进行负荷倒切的暂态仿真模型,模拟10 kV/380 V配电变压器高压侧外壳保护与低压侧工作保护共用接地背景下的高压侧碰壳故障,其中为准确计算流过人体的电流,将人体等值电阻与接地极及接地极外0.8 m的土壤接地电阻并联,计算典型接地电阻下入地故障电流、地电位升、流过人体的电流;最后采用电磁场有限元分析模型计算入地故障电流下地电位分布,并分析配变接地电阻对接触电压、跨步电压和流过人体电流的影响规律。研究表明:表层土壤电阻率满足规程要求的1000Ω·m时,接地电阻低于30Ω欧时接触电压、跨步电压均满足安全限值;断路器跳闸时限可根据典型接地电阻下人体电流及对应流过人体电流值下各生理效应区域所对应的时间范围来设定。With the increase in the number of outgoing lines and the rate of line cableization in distribution network of large and medium cities in China,the arc suppression coil is difficult to meet the requirements of capacitive current compensation,in the industrial and commercial districts with concentrated power consumption,the small resistance grounding reform of the distribution network and the system safety research are significant.First,based on the single-phase ground fault circuit model,a theoretical calculation of the single-phase ground fault short-circuit current of a small resistance grounding system is carried out;secondly,a transient simulation model of load reversal is built in Matlab-Simulink that arc suppression coil grounding system(NES)to a small resistance grounding system(NRS),simulating the high-voltage side shell fault under the background of the common grounding of the high-voltage side shell protection and the low-voltage side working protection of the 10 kV/380 V distribution transformer,in order to accurately calculate the current flowing through the human body,the human body equivalent resistance is connected in parallel with the grounding electrode and the 0.8 m soil grounding resistance outside to calculate the ground fault current,the ground potential rise,and the current flowing through the human body under the typical grounding resistance;finally,the electromagnetic field finite element analysis model is used to calculate the ground fault current ground potential distribution,and analyze the influence of distribution transformer grounding resistance on contact voltage,step voltage and current flowing through the human body.Studies have shown that:the surface soil resistivity meets the regulatory requirements of 1000Ω·m or less,when the ground resistance is less than 30Ω,the contact voltage and step voltage meet the safety limits;the circuit breaker tripping time can be based on the human body current under the typical ground resistance and the corresponding flow time range correspondi

关 键 词：配电网 小电阻接地 接地方式改造 安全性研究 碰壳故障 负荷倒切 

分 类 号：TM862[电气工程—高电压与绝缘技术]