Performance Evaluation of Grounding System of MV/LV Outdoor Compact Substation

The commitment of many countries worldwide to reduce their carbon footprint in the next few decades, has led to increased penetration of Renewable Energy Sources (RES) into power distribution networks. The connection of those RES to the MV power grid requires the installation of more compact and reliable MV/LV substations that would be easily accessible on the site of the PV Park or Wind Farm. Compact substations consist the preferred option for the connection of RES and LV loads on a power distribution grid since they provide key benefits compared to the conventional overhead substations. However, since they are made of a metal enclosure that is easily accessible, either by qualified personnel either by passers-by, 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 efficacy of two grounding grids, under various scenarios, is being evaluated by using the appropriate software tools. Purpose of the present work is to provide comprehensible data on the most common faults of power distribution networks and identify the worst-case scenarios that should be considered during the optimal techno-economic design of grounding grids of MV/LV outdoor compact substations.