Modified setting of overcurrent protection for distribution feeders with distributed generation

Connecting Distributed Generators (DGs) into conventional distribution systems leads the protection design assumptions to become incorrect. These generators are commonly utilized with renewable energy resources including solar photovoltaic (PV) and wind electric conversion systems (WECS). As a result, miss-coordination or improper operation of overcurrent relays in distribution networks can be expected. This paper presents a practical and versatile setting profile for overcurrent protective elements in such networks that have considerable amounts of DG units. For this target, a typical 11 kV underground distribution feeder is modeled while a considerable DG unit is inserted. Different locations and sizes are considered for the utilized DG. For simulation purposes, Matlab/Simulink package is employed with its massive simulation library and broad programming facilities. Different fault type scenarios are constructed and analyzed. The results corroborate a better understanding of the essence of DG problems in distribution systems and assist to realize a better protection coordination, lower fault clearing times as well as optimized selectivity for overcurrent relays with the existence of DG units.