雨季对发变电站接地系统安全性能的影响

采用数值计算方法分析了雨季对地网安全性能的影响。地网接地电阻随地表低阻层的厚度的增加而减小。当受影响的地表层的厚度从小于地网埋深变化到大于地网的埋深时 ,接地电阻的减小有一个跃变 ,接触电压将急剧减小 ,低于正常情况时的对应值。地表低阻层的厚度小于地网埋深时 ,将导致接触电压高于正常情况时的对应值 ,低阻层的电阻率越小 ,影响的程度也越大。低阻层将导致地表跨步电压小于正常情况时地网的跨步电压 ,有利于人身安全。但雨季形成的地表低阻层有可能导致接触电压的增加 ,必须综合考虑雨季对地网安全性能的影响。分析结果将为电力部门提供参考。

Influence of rain on safety of grounding systems

Influence of rain on the safety of grounding system was analyzed numerically. The grounding resistance of the grounding system decreases with the increasing thickness of the low resistivity soil layer. When the thickness of the low resistivity soil layer increases from the top of the grounding grid to the bottom of the grounding grid, the grounding resistance will increase dramatically and the touch voltage quickly decrease. If the thickness of the low resistivity soil layer is smaller than the burial depth of the grounding grid, the touch voltage will be higher than the value for normal conditions, with the effect increasing as the soil resistivity decreases. The low resistivity soil layer normally results in the reduction of the step voltage, but the touch voltage may increase due to low resistivity in some condition, so the influence of rain on the safety of grounding systems must be studied further. The analysis results provide a reference for power system design.