Substation Earthing System Design Of High Soil Resistance Ratio Area

First of all, this paper studied the artificial soil improvement in half spherical earthing conductor grounding resistance and the impact on the ground of the whole system. In combination with the formula to calculate of Level ground net’s grounding resistance and maximum contact voltage in Code for design of ac electrical installations earthing, the calculation formula of Level ground net’s grounding resistance and maximum contact voltage is deduced. We also analyze the influence of the level ground net’s grounding resistance and the maximum contact voltage after soil improvement. The second, based on a specific engineering, we design a 220kv substation grounding system. We determine the final grounding network layout scheme after compare with the equally spaced and nonuniform arrangement. The third, To compare the materials of electrical conductivity, thermal stability and resistance to corrosion, we determine the ground material selection. At last, we calculate the step and touch voltages in Different point of failure in the system by CDEGS software and assess the safety of the substation level ground net.