Study on impulse characteristics of 35kv substation grounding grids

Abstract

In order to analyze the impulse characteristics of substation grounding grids correctly, a grounding grids model is designed and custom-made based on a 35kV substation grounding grids. The impulse characteristics of grounding grids are studied through simulating corrosion, breakage and sealing-off. Meanwhile, the impact of different impulse points and lightning impulse are also analyzed. The result shows that, with the same current injection point, the impulse grounding resistance rises with the front time of lightning impulse declines. With the same lightning current, when the lightning impulse is injected through the corner of grounding grids, the impulse grounding resistance is bigger than that when the lightning impulse is injected through the center of grounding grids. If the grounding grids has fault, the impulse grounding resistance will increase, but the growing rate has close relation with fault type and lightning current. The study may provide a basis for grounding grids design and evaluation.