雷击变电站地网引起的地电位干扰及防护措施研究

变电站遭受雷击后,易导致电力系统的微机保护和综合自动化设备损坏,严重影响了电力系统的正常运行。分析了雷击地网干扰侵入自动化系统的途径,利用EMTP软件仿真模型,分析了雷击变电站时地网电位的分布情况以及二次电缆不同接地方式的屏蔽效果。结果表明:采用方孔地网,增加垂直接地极,采用二次电缆屏蔽层两端接地的方式,可以有效地屏蔽雷击引起的地电位干扰,提高变电站运行的安全性和可靠性。

The Study of the Earth Potential Interference by Lightning Stroke in Substation and Its Protective Measure

Lightning strike to substation may lead to damage of microcomputer protection and integrated automation system which impairs the normal service of power system.The invading path of ground grid interference to automation system caused by thunder strike was analyzed.The distribution of voltage along the ground grid and the effect of different grounding modes of secondary cable was also analyzed using simulation EMTP.The result shows that using ground grid of square meshes,increasing vertical grounding electrode number and grounding of shield layer of secondary cable at two ends,the earth potential interference caused by thunder strike can be effectively shielded thus raising the operation safety and reliability.