Fault current distribution in HV cable systems

An advanced analytical model is presented for the evaluation of ground return currents at substations fed by both three and single-core cable circuits. The circuit model includes the accurate treatment of an intermediate substation between the source and the faulted substation, unlike Engineering Recommendation EA S.34, which adopts a more simplified approach. Through detailed parametric studies, the differences between the simplified and the more accurate treatment are quantified. The effects that variations in the key parameters — cable length and type, substation earth impedances — have on the magnitude of the ground return current are identified and explained.