Grounding system of medium voltage network with integrated distributed generation: short-circuit analysis and calculation of the developed potentials

In modern overhead Medium Voltage power networks, with high RES penetration, remote-controlled coupling and protection systems (Load Breakers, Reclosers and Sectionalizers) are increasingly being installed in order to control network's bi-directional power flow and to protect personnel and equipment against short-circuits. Most of those systems consist of a control panel on a metal enclosure that is accessible either by qualified personnel or by passers-by. For this reason, it is necessary to study the adequacy of the grounding system, in order to ensure the reduction of the developed touch and step voltages in case of a short-circuit on the network. In this paper, the performance of a grounding system is being evaluated, considering various scenarios, by using appropriate software tools. Purpose of the present work is to perform risk analysis and identify the worst-case scenario that should be considered during the design of grounding grids on distribution networks as well as to spotlight critical design parameters, taking into account techno-economical criteria. Finally, the results to be extracted from this paper are expected to be a guide for the optimal design of the grounding system of distribution networks.