Simulation Model of Unsymmetrically - Shaped Grounding Grids for Investigation of the Touch Voltages during Lightning Stroke

Lightning activity is a natural hazard. Protection of equipment and people in electrical power systems depends on the effectiveness of the earthing (grounding) and lightning protection systems. Modeling of the earthing systems of electrical power substations is within the scope of the authors' research work. They have developed a computer model based on Matlab. The purpose is to be obtained the possible contact (touch) voltages in the earthing systems caused by a lightning stroke. The model takes into account the specific processes that develop in the soil. The values for the maximum contact voltage have been published for an earthing grid with a regular shape of the cells and without vertical earthing rods. The paper presents a computer model for investigation of the maximum touch voltage in a rectangular - shaped grounding grid in case of a lightning stroke in different points of the grid. The influence of the impulse wave front of the lightning current has also been investigated.