接地网设计理念及其工程实践

为适应电网发展对接地网安全性越来越高的要求,安全性分析逐步成为接地网设计的基点。以典型的高土壤电阻率站址220 kV变电站设计和施工为例,结合现场实测和仿真计算,分析不同降阻阶段接地网特性参数的安全性与投资预算的关系,阐明了对于站址土壤条件不理想的情形。在首先满足接地网特性参数（接地故障下地网导体电位升高、场区压差、场区跨步电压和接触电压等）符合一、二次设备运行和人员安全要求的前提下,科学地选择接地阻抗设计值,取得较优的经济性,达到安全性和经济性平衡的设计理念,给出了安全性和经济性分析在接地网设计中的应用评价方法。

Design and Engineering Practice of Substation Grounding

In order to meet the requirements for grounding grid to adapt to developments of power system, the security analysis is becoming the basis of grounding grid design. Taking the design and construction of a typical 220 kV substation with high soil resistivity as an example, based on field measurement and lab simulation, the relationship between the security of grounding grid and investment budget on different stages is analyzed and both security and economic factors are considered into the grounding design. On the premise that the parameters of the grounding grid, such as potential rise of conductors, field potential difference, field step voltage and touch voltage, satisfy the requirements of primary and secondary devices for operating and personal safety, the choice of design values of grounding impedances should be scientific to achieve the economy improvement. Accordingly, the balance of safety and economy of the design is obtained. The method of grounding grid design based on safety and economic analysis is thus developed.