CALCULATION OF THE FAULT LEVEL CONTRIBUTION OF DISTRIBUTED GENERATION ACCORDING TO IEC STANDARD 60909

摘要

Distribution networks are characterized by a design short-circuit (sc) capacity, i.e. a maximum fault current to be never exceeded, related with the rating of switchgear and the thermal and mechanical endurance of all equipment and standardized constructions. Distributed generation (DG) resources are typically connected to distribution networks, at the low or medium voltage level, and therefore contribute to the total fault level of the network, roughly determined by the combined short-circuit contributions of the upstream grid and the various DG sources within the distribution network. Hence, a basic requirement for permitting the interconnection of DG is to ensure that the resulting fault level remains below the network design value, under the most unfavourable conditions.