Transient impedance of grounding grids with different soil models

Transient response of grounding systems to lightning or fault currents is fundamental for insulation coordination and safety purpose. This work deals with the computation of the harmonic impedance of grounding grids in the frequency domain by a hybrid method based on electromagnetic field theory in stratified media and circuital approach. We simulate the behaviour of grids buried in homogeneous and layered soils, with constant electrical parameters or modeled as frequency-dispersive. We discuss the influence of different soil models on the time-domain transient ground potential rise, caused by the injection of a subsequent stroke current, with reference to a classical grounding grid.