Performance of HVDC Ground Electrode in Various Soil Structures

-This paper discusses and compares HVDC ground electrode design methods in various soil structures. A number of cases are selected based on existing HVDC ground electrodes in order to compare the conventional simplified design method (Method A) with a more advanced grounding design method using a specialized engineering software (Method B). Various soil structures considered include horizontally layered soils, vertically layered soils and finite volume soils. In all cases studied, grounding grid resistances, current distributions, earth surface potentials and touch/step voltages are computed and compared. The results of Method B are also compared with measurements. For the cases studied in this paper, it is found that the step voltages computed by Method A are usually lower than those obtained using Method B. This is especially true for a horizontal linear electrode for which the step voltages near the end of electrode could be underestimated by as much as 48%. The results presented in this paper provide useful insight and information for accurately designing DC ground electrodes in various soil structures.