The Design of 220kV Substation Grounding Grid with Difference Soil Resistivity Using Wenner and Schlumberger Methods

This paper presents the design of 220kV substation grounding grid with difference resistivity soil according to horizontal and vertical two layer soil model is structure using the MALT program of CDEGS Software. The target of this paper is to minimize the touch and step voltages when the resistivity soil is high, in 220kV urban substation pending a direct lightning stroke. Also, it is shown that for a sensor located on the ground, close to 220kV substation, the magnetic field component vertical to the structure can also experience a considerable attenuation, perhaps due to the effect of the induced currents in the substation. The results are confirming by numerical simulations, obtained using NEC-4 and IEEE Guide for Safety in AC Substation Grounding. The step by step procedure for designing 220kV substation grounding grid has been presented for which design parameters were obtained by CDEGS Software.