Objective The grounding devices of the traction power supply system in urban rail transit play a crucial role in ensuring the normal operation of equipment and personal safety. Grounding grids, buried in soil environments for long periods, are susceptible to corrosion, leading to reduced electrical conductivity and deterioration of grounding performance. To enhance the corrosion protection of grounding grids in urban rail transit lines, it is essential to conduct an in-depth analysis of the impact mechanisms and variation laws of grounding grid performance under corrosion.

Method By analyzing the mechanism of corrosion affecting metal conductivity, a soil-simulating solution is prepared to test the resistance, oxide layer thickness, and equivalent resistivity of Q235 steel under varying degrees of corrosion. Coatings are used to simulate the corrosion of grounding metals, grounding grid models for 35 kV and 110 kV substations are established in CDEGS to simulate and analyze the impact of changes in the degree of corrosion on grounding resistance.

Result & Conclusion Soil corrosion generates metal oxides on the metal surface, which is the main reason for the increase of metal resistance value. When the corrosion mass is less than 0.6%, the influence on metal resistance and grounding resistance value is relatively light. When the corrosion mass exceeds 2.0%, with the increase of corrosion mass, the metal resistance value increases linearly, accompanied by grounding resistance increases. If the corrosion mass of the 35 kV substation grounding grid reaches 4.7%, or the corrosion mass of the 110 kV substation grounding grid reaches 4.2%, the grounding resistance values will both exceed standard requirements.