An Integrated Grounding Resistance Reduction Strategy Using Foundation Piles in Urban Terminal Substations

To address the limited use of traditional grounding resistance reduction measures in urban terminal substation grounding systems, this paper proposes a novel resistance-reduction scheme by forming a combined grounding system that integrates building foundation piles with the main grounding grid. Through simulation analysis, the effects of pile location within the grounding grid, inter-pile spacing, concrete resistivity, pile side length, pile length, and the number of piles on the grounding impedance are systematically investigated. Based on the results, a fitted formula is proposed with grounding impedance as the objective function, providing a quantitative reference for pile arrangement design. Finally, the effectiveness of the proposed scheme is validated through a practical engineering case study.