高压直流接地极电渗透效应及溢流密度限值研究

Research on Electroosmosis Effect and Current Density Limit of HVDC Grounding Electrode

高压直流接地极在单极大地运行方式下,阳极附近土壤会由于电渗透效应导致含水率下降,出现电阻率和温度陡增的现象。为探究焦炭包裹的直流接地附近的土壤电渗透情况及电流密度对水分迁移的影响,设计并搭建了电渗透实验平台,开展了不同电流密度下的土壤电渗透实验,并对各测点含水率及温度进行了监测。实验结果表明,当电流密度在10 A/m^(2)以下时,阳极附近在最初的100 min内,含水率下降较快,100 min后含水率下降减缓达到稳定;电流密度达20 A/m^(2)时会出现土壤电阻率和温度陡增的情况。针对目前国际标准中设定的1 A/m^(2)的溢流密度限制指标,应考虑一定程度的放宽。

When high voltage direct current(HVDC) grounding electrode operates under unipolar mode, water in soil near the anode will decrease due to the electric osmosis effect, and the resistivity and temperature will increase sharply. In order to find out the characteristic of electroosmosis effect of the soil near HVDC grounding with coke bed under different current density, an electroosmosis experiment platform was designed. The soil electroosmosis experiment was carried out under different current densities, and the moisture and temperature of each measuring point were monitored. The results show that when the current density is under 10 A/m^(2), the water content near the anode decreases rapidly within the first 100 minutes, and then decreases slowly to a stable level after 100 minutes. But the soil resistivity and temperature will increase sharply when the current density reaches 20 A/m^(2). According to the limitation index of current density of 1 A/m^(2) in the current international standard, some relaxations of requirements should be considered.