Behaviour of Grounding Systems: a Quasi-Static EMTP Model and its Validation

The main approaches used to study the transient behavior of grounding systems subject to lightning strokes are based to simple and approximated circuit models or to the more rigorous electromagnetic field theory. Both philosophies have pros and cons. In the paper, it is illustrated a circuit model developed by the authors in the past years and suitable to describe with sufficient accuracy the behavior of complex and realistic grounding systems under surge condition. In particular, the peculiarity of this model is the inclusion of current controlled voltage sources into the classical RLC circuit, in order to take into account the resistive coupling among the elementary electrodes of a complex grounding system. Simulation results have been compared to ones based on electromagnetic field theory to identify the frequency range of validity of the proposed model.