利用地网自身回流的大型接地网冲击接地电阻测试方法  

Testing Method of Impulse Resistance of Large Grounding Grid Using Grounding Grid Itself for Current Return

作　　者：蒙泳昌 张波[1] 王森 李志忠 MENG Yongchang;ZHANG Bo;WANG Sen;LI Zhizhong(State Key Lab of Control and Simulation of Power Systems and Generation Equipments（Dept.of Electrical Engineering,Tsinghua University）,Haidian District,Beijing 100084,China;Shaanxi Electric Power Research Institute,Xi＇an 710054,Shaanxi Province,China)

机构地区：[1]电力系统及发电设备控制和仿真国家重点实验室(清华大学电机系),北京市海淀区100084 [2]国网陕西省电力公司电力科学研究院,陕西省西安市710054

出　　处：《电网技术》2018年第10期3444-3450,共7页Power System Technology

基　　金：国家电网公司科技项目:考虑土壤分层条件下的变电站大尺寸复合接地网暂态全过程仿真技术研究~~

摘　　要：冲击接地电阻是接地网的一项重要指标。由于特高压变电站接地网面积大,传统的接地网冲击测试难以进行。提出了一种接地网的冲击接地电阻试验方法,基于冲击电流有效散流面积较小的原理,该方法将注流点与回流点布置在待测接地网内,利用接地网自身作为回流极,以30°夹角法布置参考点测量注入点的冲击地电位升以得到接地网的冲击接地电阻。通过计算冲击下回流点与注入点之间的导通阻抗、注入点周围的电流分布和注入点地电位升,论证了所提出的试验方法的有效性,并进一步讨论了不同回流点和注入点位置、土壤电阻率、接地网材料等因素对测试结果的影响以及电压参考点的选择。分析表明,对边长大于100 m的接地网,进行冲击接地电阻测试时,可以将回流点布置在待测地网上,并按照30°夹角法选择电压参考点以补偿回流点的影响。该方法大幅缩短了电流引线,减小了测试回路的回路阻抗,间接提高了冲击发生器的输出能力,显著减少了大型接地网冲击试验的准备工作量。Impulse resistance is an important parameter of grounding grid. Due to large area of UHV substation, traditional grounding grid impulse test is difficult to carry out. In this paper, an impulse test method is proposed with both current injection and return points arranged in the test grounding grid and the grounding grid itself used as the reflux pole because of limited effective leaking area of the impulse current. The impulse potential rise of the injection point can be measured with 30° angle offset method. By calculating the conduction impedance between the return and injection points, current distribution around the injection point and the ground potential rise of the injection point, effectiveness of the proposed method is validated. Influence of the positions of the return and injection points, soil resistivity, grounding grid materials and other factors on test results and selection of reference point are also discussed. Results show that it is feasible to arrange the return point within the grounding grid with side length larger than 100 m and the reference point arranged according to 30？ angle offset method. This method can greatly shorten the length of current lead, reduce the impedance of test circuit, improve the output capability of impulse generator and facilitate carrying out of the impulse test.

关 键 词：大型地网 冲击试验 回流 变电站 

分 类 号：TM86[电气工程—高电压与绝缘技术]