不同土壤分层结构下接地网性能的差异计算

为了尽可能量化不同土壤结构下变电站接地网安全性能的差异大小,基于所得土壤电阻率测量试验数据,对比分析了山地、沿海、丘陵3类地区垂直分层土壤结构和水平分层土壤结构下的变电站接地网接触电压和跨步电压等安全指标,并以两者间的偏差百分比来衡量不同土壤结构与不同地区间差异。结果表明:使用现有的电流分布、电磁场、接地和土壤结构分布(current distribution, electromagnetic field and soil analysis, CDEGS)软件可以比较准确地计算出土壤水平分层和垂直分层结构;各地区两种土壤分层结构下的接触电压和跨步电压的对比说明了考虑土壤垂直分层的必要性;在同一地区垂直分层结构下,靠近土壤分界面部分的接触电压和跨步电压偏差百分比较高;最大值偏差百分比的计算结果说明,土壤电阻率越大, 这种不同土壤分层结构所带来的差异越明显。

Difference calculation of grounding grid performance under different soil layered structures

In order to quantify the difference in safety performance of the substation grounding network under different soil structures as much as possible, based on the measured soil resistivity data, the substation ground network safety indicators, such as step voltage and touch voltage of the mountains, coastal and hilly areas under the vertical layered soil structure and the level layered soil structure were analysed, and the differences between regions in percentage were evaluated. The results showed that the soil vertical layered structure and horizontal layered structure could be accurately calculated by using current distribution, electromagnetic field and soil analysis(CDEGS)software,the necessity of considering vertical layered soil was explained by the contrast of step voltage and touch voltage under two kinds of soil structure in different regions,deviation percentage of touch voltage and step voltage near the soil interface part under vertical stratification structure were higher at the same area, and the calculation results of maximum deviation percentage showed that the difference caused by different soil layers structure was more obvious in the bigger resistivity region