Behaviour of grounding systems: A quasi-static EMTP model and its validation

The transient behaviour of grounding systems subject to lightning strokes may be studied by means of approaches based to simple and approximated circuit models or to the more rigorous electromagnetic field theory. Both philosophies have pros and cons. In the paper a circuit model, developed by the authors in the past years and implemented with modern simulation software, is presented. The model is suitable to describe with sufficient accuracy the behaviour of complex and realistic grounding systems under surge condition, and, 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. In order to validate the model and to identify the frequency range of applicability, simulation results have been compared to ones based on electromagnetic field theory available in literature