An EMTP-Compatible Frequency-Dependent Model for Vertical Grounding Rods for Transient Studies

This paper proposes an extended RLC circuit model for grounding rods that incorporates the frequency-dependent nature of both the grounding input impedance and the soil electrical parameters. The accuracy of the model, in terms of its predictions for Ground Potential Rise (GPR) waveforms and impulse impedance values, is demonstrated through comparisons with results obtained using an accurate electromagnetic model, assuming both first and subsequent return stroke current waveforms. The model is fully compatible with EMTP-type simulation programs, requiring only the grounding rod's geometry and the soil resistivity as input parameters. Given the characteristics of the proposed model- its demonstrated accuracy and EMTP compatibility-it can be a useful tool for modeling the typical grounding systems of distribution line poles in time-domain simulations of lightning-induced voltages.