Abstract
In the intelligent substation, the shell of the secondary equipment is connected to the ground grid locally. When the short circuit fault current is injected into the grounding grid to cause the ground potential rise, the potential difference between the two points of the grounding grid will affect the normal operation of the secondary equipment. In this paper, aiming at the grounding grid of a 220kV substation, the grounding impedance, ground potential rise and ground potential difference between galvanized flat steel and copper grounding grid are calculated by using CDEGS software. The results show that the copper ground grid has a significant effect on reducing the potential difference of the ground grid.
Highlights
With the intelligence of substations, a large number of secondary devices are distributed near primary high voltage devices such as high voltage switches and busbars[1..The shell of secondary equipment is usually grounded nearby and connected through secondary cables
When a grounding fault occurs, the fault current injected into the grounding grid causes the grounding grid potential to rise, and there is a ground potential difference between different points in the grounding grid[2-3
The results show that the copper ground grid has a good performance of limiting the potential difference of the ground grid
Summary
With the intelligence of substations, a large number of secondary devices are distributed near primary high voltage devices such as high voltage switches and busbars[1..The shell of secondary equipment is usually grounded nearby and connected through secondary cables. The disturbance voltage can add noise to the normal signal, which may lead to the misoperation of the secondary equipment in serious case. In order to meet the needs of future intelligent substation planning and construction, it is necessary to study the characteristics of ground potential difference between two points on the conductor of grounding grid. A numerical calculation method of ground potential difference interference based on transmission line frequency domain method is proposed in reference[4. Based on the idea of field-circuit combination, a new method for calculating grounding parameters of grounding grid is proposed in reference[ 5 ., which analyzes and calculates the grounding impedance and ground potential difference of grounding grid under power frequency. The relationship between insulation potential difference of substation secondary system and grounding grid potential rise is discussed in reference[6
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