Grounding system design improvement by compression ratio and ground rod methods in power distribution substation

This paper presents a touch voltage reduction technique for a uniform and two-layer soil by applying grid compression ratio. The design of ground grid is discussed pertinent to its maximum touch and step voltage produced for a given ground potential rise (GPR). The parameters are analyzed to ensure that they conform to the IEEE 80-2000. It is found that, for a given GPR, the maximum touch and step voltages of the rectangle grid with a ground rod, regardless its compression ratio, are lower than the rectangle grid without ground rod. This means rectangle grid with ground rod is safer than without ground rod one. The ground grid with ground rod is therefore one of the crucial factors in grid design, especially when grids are placed close together unconnected. This is the case when a new substation is constructed near one which is still energized. When there is a GPR, the touch voltage will be made worse by the two unconnected grids, and thus harm and damage personnel and sensitive equipment. Modeling and simulation is carried out by using the Current Distribution Electromagnetic interference Grounding and Soil structure (CDEGS) program.