某大型海底隧道接地网特性计算

Characteristic of a Large-scale Cross-harbor Tunnel's Grounding Grid

鉴于现有的用于计算发变电站地网的解析公式对特殊形状的大型海底隧道接地网并不适用,采用有限元法对某大型海底隧道接地网建立了计算模型,得到该地网的接地电阻、最大地网电位升、跨步电压、接触电压等参数,并参照相关规程对计算结果进行了综合评价。提出通过把隧道两端变电站地网与隧道地网并联的方法来降低隧道内部地网接地电阻并讨论了采用该方法需注意的相关问题。此研究成果对于大型海底隧道的接地网设计具有一定的指导价值。

To design the ground grid of substations, generally some analytic formulations are used, but it is inapplicable to calculate the grounding grids of complicated large-scale cross-harbor tunnel. This paper presents a finite element method （FEM） computating model for designing grounding grids of the complex large-scale cross-harbor tunnel. Some parameters are calculated by using FEM, such as ground resistance, maximum ground potential, maximum step voltage, maximum touch voltage caused by short current. According to some correlated directive rules, the calculated results are evaluated. A way of parallel connecting the ground grid of the substations on both sides of the tunnel with the tunnel is provided, which can reduce the ground resistance of the tunnel simply and applicably, and some stressed attentions are discussed. The FEM model and results are of practical significance to design ground grid of a large-scale cross-harbor tunnel.