土壤特性对变电站地网冲击接地电阻的影响

Research on influence of soil characteristics on impulse grounding resistance of substation grounding grid

为掌握土壤电阻率和土壤结构对大型变电站地网冲击接地电阻的影响,指导变电站地网防雷性能评估,采用接地分析软件CDEGS计算了均匀和水平分层两种土壤结构中地网的工频与冲击接地电阻随土壤电阻率的变化关系.结果表明:均匀土壤中,地网的冲击系数随土壤电阻率的增大而减小;水平分层土壤结构中,地网的冲击接地电阻随表层土壤电阻率增加近似呈幂指数函数增加;冲击接地电阻受地表一定范围内的浅层土壤电阻率影响较大,更深层土壤电阻率对其影响较小.

In order to master the effect of soil characteristics on impulse resistance of large substation grounding grid and provide guidance for lightning protection performance assessment of substation grounding grid,impulse grounding resistance and power-frequency grounding resistance of a grounding grid in homogeneous soil and layered soil were calculated based on the software CDEGS.The results show that the impulse coefficient of grounding grid decreases with the increase of soil resistivity in homogeneous soil;and the impulse grounding resistance increases with soil resistivity of shallow layer with power exponent function.Besides,the impulse grounding resistance affected largely by the soil resistivity of a certain depth of shallow layer from the earth＇s surface;and the deeper soil resistivity has less effect on it.