Design of Grounding Grid for Main Substations in High Soil Resistivity Areas Based on CDEGS Software

Abstract

Objective To address the difficulty of reducing the grounding resistance of main substations in high soil resistivity areas, it is necessary to study the design of grounding grids for main substations in such regions. Method Combining the geographical location conditions and soil resistivity characteristics of the main substation, a reasonable quantity of horizontal grounding conductors is determined using single-variable method. The improvement effects of contact potential, step voltage, and grounding resistance are analyzed using CDEGS simulation software when horizontal grounding conductors are arranged in exponential non-uniform distribution. Optimization measures to reduce grounding resistance are proposed. Result & Conclusion After increasing the quantity of horizontal grounding grid conductors to a certain extent, the marginal effect of the conductors decreases significantly. The vertical grounding electrode has little effect on reducing the grounding resistance of the main substation and is not recommended for use in the design. With the use of deep well grounding electrodes, both the contact potential and step voltage of the main substation are significantly reduced, and the grounding resistance is reduced to below 0.5 Ω, meeting the requirements in related specifications.

Keywords

• urban rail transit
• main substation
• grounding grid
• high soil resistivity