Grounding grid performance can be measured in
terms of grounding resistance, but it is preferable to include the
distribution of surface potential and, subsequently, the touch
and step voltages over the area above the substation ground grid
and beyond. Two methods are used in this paper to compute the
grounding resistance (Rg) and the earth surface potential (ESP)
due to discharging current into grounding grids. The first one is
the charge (current) simulation method (CSM) and the other is
the boundary element method (BEM). For BEM, commercial software TOTBEM by university of La Cournia, Spain is used for computing ESP and Rg. The owned FORTRAN code is provided to calculate the ESP and Rg. The soil is assumed to
multilayer soil. The paper focuses the comparison between these
two methods for calculating ESP and Rg. In case of grounding
resistance, a comparison between the two methods results and
IEEE Standard formula is presented.