Safety design planning for ground grid of two neighbouring distrubution substation in MEA´s power system

This paper presents construction planning procedures for a new permanent substation to replace an small (temporary) substation that is served to supply the load of the old existing substation while it has not been removed. In the meantime when the ground grids of the two substations are electrically disconnected, the auxiliary grounding system of substation can create steep ground potential rise (GPR) between the ground grids of the two substations so that may be dangerous to personel working nearby. It is therefore important to incorporate safety criteria described in terms of step and touch voltage into electrical designs without any potential electrical hazards. The safety design planning process is demonstrated by the Pathumwan (PM) substation of Metropolitan Electricity Authority (MEA). Modeling and simulation is analyzed by the Current Distribution Electromagnetic interference Grounding and Soil structure (CDEGS) program. A sequential transition process from the small substation to a permanent substation is suggested to comply with the IEEE standard 80-2000.