变电站接地网上两点间电位差的特性

随着变电站的智能化发展,大量二次设备分布式布置于高压一次设备附近.这些二次设备的外壳就地与接地网连接.当故障电流注入接地网导致地电位升时,在接地网上两点之间存在电位差.对于2个由二次电缆连接的二次设备,该电位差可以在二次电缆端口感应共模和差模骚扰电压,严重时影响到二次系统的正常稳定运行.针对某220kV变电站接地网,计...

The Potential Difference Characteristics between Two Points on Grounding Grid of Substation

With the intelligentization upgrade of power substations, a large number of secondary equipment are deployed dispersedly nearby the high-voltage primary equipment. The enclosures of these secondary devices are electrically connected to the grounding grid underground. When a fault current injection causes the potential rise in the grounding grid, there is a potential difference between any two points on the grounding grid conductors. For two secondary equipment located at different positions and connected by secondary cable, the potential difference can induce common-mode and differential-mode disturbance voltages at the ports of the secondary cable, which may interfere the normal operation of secondary system. In this paper, the grounding grid of a 220 kV substation is modelled and the corresponding potential difference is calculated by using the CDEGS software. Also, the effects of the grid density and size, soil resistivity, the positions of current injection and potential observation on the potential difference are investigated. The results are helpful for guiding grounding grid design and evaluating the influence of ground potential difference on secondary equipment.