接地网内电势差的计算模型  

Modeling of Grounding Inter-potential Difference

作　　者：张露[1] 黄文武 文习山[1] 姚森敬 潘卓洪[1] 王玮 

机构地区：[1]武汉大学电气工程学院,武汉430072 [2]深圳供电局有限公司,深圳518020

出　　处：《高电压技术》2014年第4期1045-1051,共7页High Voltage Engineering

基　　金：国家重点基础研究发展计划(973计划)(2009CB724500)~~

摘　　要：电力系统不对称短路的故障电流会产生散流网内电势差和导通网内电势差,是影响接地安全的重要因素之一。为此,使用不等电位的节点电压分析法,研究了网内电势差的计算模型和求解方法,分析了不同情况下接地网内电势差的变化规律。研究表明:土壤电阻率越低则网内电势差越小,地网面积越大则网内电势差越大;网内电势差与土壤电阻率/接地电阻呈现饱和趋势,且地网面积越大则饱和趋势越明显;一般情况下,当土壤电阻率>100?·m或者接地电阻>0.3?时,可以近似认为网内电势差已进入饱和区。建议在变电站接地设计的初始阶段估算电缆承受的网内电势差时,可以按最大网内电势差的50%考虑,在网内电势差>1.4 kV时就适当采取降低导体导通阻抗的措施以控制网内电势差。When asymmetric fault occurs in grounding grids, the scattering inner potential and conducting inner potential will be generated, which are important factors on the security of grounding grids. Based on the unequal potential nodal analytical method, we studied the theoretical model of inner potential and its solving method, and analyzed the variation of inner potential. It is obtained that inner potential gets smaller when soil resistivity or the scale of grounding grid decreases. The increase of inner potential due to increasing soil resistivity （or ground resistance） tends to be saturated, and this saturation becomes more obvious with increasing area of grounding grid. Generally, when soil resistivity exceeds 100 Ω.m or the grounding resistance is over 0.3 12, we could consider the inner potential difference to already enter the satura- tion region. It is suggested that, in the designing stage of substations, the maximum potential difference on cables can be set to 50% of the largest inner potential difference of ground grid; meanwhile mitigation of conductor impedance is sug- gested to suppress inner potential once it exceeds 1.4 kV.

关 键 词：接地网 网内电势差 故障电流分布 导通电阻 接地电阻 地电位升高 GPR 

分 类 号：TM938.49[电气工程—电力电子与电力传动]