考虑人身安全的地网跨步电压降低方法研究  

Reducing Step Voltages of Grounding Grid in a Substation Considering Personal Safety

作　　者：李鑫 朱俊澎 刘立平 胡婷 LI Xin;ZHU Junpeng;LIU Liping;HU Ting(Power Supply Service Center(Metrology Center)of State Grid Hunan Electric Power Co.,Ltd.,Changsha 410004,China;College of Energy and Electrical Engineering,Hohai University,Nanjing 211100,China;Hunan Province Key Laboratory of Intelligent Electrical Measurement and Application Technology,Changsha 410004,China)

机构地区：[1]国网湖南省电力有限公司供电服务中心(计量中心),长沙410004 [2]河海大学能源与电气学院,南京211100 [3]智能电气量测与应用技术湖南省重点实验室,长沙410004

出　　处：《电瓷避雷器》2021年第4期35-40,共6页Insulators and Surge Arresters

基　　金：国家自然科学基金项目资助(编号:51807051)。

摘　　要：合理的变电站地网设计对于降低地网跨步电压、确保人身安全至关重要,有必要详细研究地网接地导体网格布置。通过EMTP软件输电线路和变电站地网模型,考虑接地体雷击暂态特性和人体高频电路模型,计算地网跨步电压。利用自适应遗传算法确定地网采用不等间距等比布置时中心网孔最佳尺寸,分析不等间距布置对于降低跨步电压效果。最后讨论满足人体容许跨步电压安全标准前提下地网所需最少接地导体数量。研究结果表明:输电线路遭受雷击后,临近变电站地网会产生幅值相对较高的暂态过电压,且过电压波形呈现明显振荡衰减;利用自适应遗传算法优化地网网孔尺寸和导体布置后,地网均压效果明显,地网跨步电压能够得到有效降低;满足人体容许跨步电压限值条件的地网布置所需最少接地导体数量随着土壤电阻率的增大呈现出先降低后增大的趋势。Proper design of a substation grounding grid is crucial to reduce step voltage and ensure personal safety,so it is necessary to study the grid arrangement of grounding conductor in detail.Equivalent circuit models of transmission lines and the substation grounding grid were built in EMTP to calculate step voltages which takes transient characteristics of the single grounding electrode and high frequency circuit model of the human body into consideration.The best dimension of the central mesh in the grounding grid according to exponential law was calculated byadaptive genetic algorithm(SGA),and the effect of unequal space arrangement on reducing step voltage is analyzed.Finally,the minimum number of grounding conductors is discussed on the premise of satisfying the safety standard of human body allowable step voltage.Research results show that:After the transmission line is struck by lightning,a relatively high amplitude transient overvoltage will be generated in the grounding grid near the substation,and the overvoltage waveform shows obvious oscillation attenuation.When the mesh size and conductor arrangement are optimized by SGA,the voltage sharing effect is obvious,and the step voltage of the grounding grid can be effectively reduced;The minimum number of earth conductors needed for the layout of earth grid which meets the allowable step voltage limit of human body shows a tendency of decreasing first and then increasing with the increase of soil resistivity.

关 键 词：自适应遗传算法 地网 雷电 跨步电压 人身安全 EMTP 

分 类 号：TM862[电气工程—高电压与绝缘技术] TM63