土壤电阻率的温度特性及其对直流接地极发热的影响

为了更准确地分析接地极的发热情况,确保接地系统的安全运行,通过土壤温升模拟试验,获得了土壤在一定温度范围内的电阻率与温度、含水量的变化规律,试验结果表明:当温度较高时,土壤水分蒸发加快,土壤电阻率迅速增大,并呈指数上升。基于试验结果,结合电流场理论及传热学原理,建立了简单直线型接地极的发热仿真模型,从仿真结果中发现:土壤电阻率的变化会影响接地极表面的散流分布,从而改变接地极附近土壤的温度分布。对比传统计算模型中将土壤电阻率视为恒定的情况,该模型计算结果说明接地极附近土壤温升速度更快。试验及仿真结果说明,计算时考虑土壤电阻率的温度特性对接地极发热的影响,将有利于接地极的安全设计和维护。

Temperature Characteristic of Soil Resistivity and Its Effect on the DC Grounding Electrode Heating

In order to analyze the soil heating around the grounding electrode more accurately and to ensure the grounding system operation safely,by a simulation experiment of rising in the soil temperature,we analyzed the changing regulation of the soil resistivity with the temperature and water content variation.The experimental results show that,at a higher temperature,the water in the soil evaporates quickly,leading to a rapid increase in soil resistivity with an exponential trend.Basing on the experiment results,we established a heating simulation model of a simple linear electrode with the combination of the current field theory and the heat conduction principle.The results show that the soil resistivity variation can influence the leakage current distribution on the grounding electrode surface,thus change the temperature distribution of the soil around the electrode.Compared with the traditional calculation model with constant soil resistivity,this model is characterized with faster temperature rise.The results of experiment and simulation benefit safer grounding electrode design and better maintenance when considering temperature characteristic of soil resistivity.