垂直接地极的降阻性能研究

Research on Vertical Grounding Rod Performance

接地网是保证变电站安全的重要设施,垂直接地极是变电站降低接地电阻的常用措施之一。文章选取110 kV、220 kV、500 kV和1 000 kV电压等级变电站中的典型接地网进行仿真研究。对于均匀土壤,从接地网面积、垂直接地极长度、根数3方面研究了垂直接地极的降阻效果,并引入了垂直接地极长度与接地网对角线长度的比值来描述不同面积接地网中垂直接地极的降阻效果;对于双层土壤,将接地网分为大面积和小面积两类,研究了反射系数和上层土壤厚度对垂直接地极降阻效果的影响。研究结果表明,长垂直接地极对于所在土壤存在下层低电阻率的接地系统尤其有效。

Grounding grid is an important facility to ensure substation safety. The vertical grounding rod is a common measure to reduce the grounding resistance. Typical grounding grids in 110 kV, 220 kV, 500 kV and 1000 kV substation are selected in the paper. For uniform soil, the vertical grounding rod＇s reduction in resistance is studied on grid area, the vertical grounding rod length and the number. The ratio of the vertical grounding rod length and grounding grid＇s diagonal length is proposed to represent a clear description of the link between the vertical grounding rods＇ resistance reducing rate in grounding grids of different sizes. For the double-layer soil, grounding grids are divided into two categories including the large area and the salall area. The paper also studies the effect of reflection coefficient and the upper soil thickness on the resistance reducing rate of the vertical grounding rod. The results show that the vertical grounding rod is particularly effective for the grounding system buried in the soil with a low-resistivity layer down. The results and conclusions of this paper can provide reference for the engineering practice.