地下金属管道对变电站接地网地表电位的影响

摘要

In order to accurately understand influence of underground metal pipelines on earth surface potential of the grounding grid,this paper calculates earth surface potential distribution of the grounding grid considering current distribution of metal pipelines close to the grid based on field-circuit combination. It analyzes influence of changes of lengths and aper-tures of metal pipelines and performs site test on earth surface potential of the grounding grid of one 34 kV substation. Re-sults indicate underground metal pipelines will decrease earth surface potential near the grounding grid and decrease range is related with length or aperture of the metal pipeline. However scope of the influence is limited within 5 m. The research re-sults may provid basis for fault diagnosis of the grounding grid based on earth surface potential.%为准确掌握地下金属管道对接地网地表电位的影响,基于场路结合的思路计算了考虑接地网附近金属管道散流分布时的接地网地表电位分布,分析了金属管道长度及孔径等变化对接地网地表电位的影响;同时,对一实际35 kV变电站接地网的地表电位进行了现场测试.结果表明:地下金属管道会降低接地网附近的地表电位,且下降幅度与金属管道长度或孔径的增加程度有关;但该影响范围通常只限于距离管道5m之内的区域.研究结果可为基于地表电位分布的接地网故障诊断方法提供依据.