Simulation of impact of vertical grounding electrode on impulse grounding resistance of substation grounding network

In order to study the influence of vertical grounding electrode on impulse grounding resistance of substation ground network, the grounding model was built in COMSOL, and the impulse grounding resistances of substation grounding grid in different distribution, length and quantity of vertical grounding electrode were simulated and calculated. The results show that the closer the vertical ground to the lightning current injection point is, the smaller the impact grounding resistance is. The impulse grounding resistance, that has a minimum value, decreases first and then increases with the increase of the vertical grounding electrode length. When the additional vertical grounding electrodes are placed in accordance with the evacuation outside and internal density manner within a certain region ranging from the lightning current injection point, the impact grounding resistance has the best reduction effect.

I. Introduction

Grounding network plays a very important role in the safe operation of the substation, it can not only provide a reference for all kinds of electrical equipment in substation, but also quickly discharge the fault current or lightning current when the system is fault or be struck by lightning and reduce the substation ground potential rise [1], [2]. In recent years, with the continuous improvement of substation capacity and voltage level, higher requirements have been put forward for the design and construction of grounding system [3]–[5]. If the impulse grounding resistance of the grounding system is too large, the transient potential of the grounding network will rise abnormally. In severe cases, the over-voltage will cause the protection device to fail, and the two monitoring equipments such as station monitoring and control will be burned out, which will cause great economic losses.