异阻区土壤对接地网接地电阻影响分析

Analysis of the Influence of Abnormal Resistance Region Soil on Grounding Resistance of Grounding Grid

准确模拟接地网周围土壤结构对接地装置优化设计具有重要意义。基于有限元算法,建立了考虑异阻区的土壤结构模型,对接地网散流过程中地中电流密度进行分析;并对异阻区土壤电阻率、截面积、厚度、位置等参数对接地网接地电阻的影响规律进行了定量分析。结果表明:异阻区截面积不大于10 m×10 m时,可以忽略异阻区对接地网接地电阻的影响,否则应考虑其对接地电阻的影响;异阻区土壤电阻率越小、厚度越大,其对接地电阻的影响越大,异阻区土壤电阻率ρ=10Ω·m,厚度h=1 m时,接地电阻下降幅度为36%;异阻区土壤位置在接地网边角(40,40)时其对接地电阻的影响最大;高土壤电阻率地区采用边角换土方式代替传统的整体换土,不仅可以减少施工量还可以有效的降低接地电阻。

Accurate simulation of the soil structure around the grounding grid is of great significance to the optimal design of the grounding device. Based on the finite element method,a soil structure model considering abnormal resistance region was established,current density in soil are analyzed during the process of connecting with the scattered flow of the grounding grid;The effects of soil resistivity,cross-sectional area,thickness,position and other parameters on grounding resistance of grounding grid in abnormal resistance region were analyzed quantitatively. The results show that when the cross-sectional area of the abnormal resistance region is not more than 10 m × 10 m,the influence of abnormal resistance region on the grounding resistance of the grounding grid can be ignored,otherwise,the influence on the grounding resistance should be considered. The smaller the resistivity of soil in the abnormal resistance region is,the greater the influence of the grounding resistivity,as well as the thicker the soil in the abnormal resistance region is,the greater the influence of the grounding resistivity. When the soil resistivity is ρ = 10 Ω·m,thickness is h = 1 m,the decrease of grounding resistance is 36%. When the location of abnormal resistance region is at the edge Angle of the grounding grid( 40,40),its impact on the ground resistance is greatest. In the high soil resistivity area,the method of replacing the traditional whole soil exchange with edge angle can not only reduce the amount of construction but also effectively reduce the earth resistance.