An Analytical Investigation Review of DG Impacts on the Relaying Performance in Distrbution Networks

Installing distributed generators (DGs) to the distribution networks has strongly effects on the selectivity of the conventional protection system. Miscoordination, improper operation, or blinding of overcurrent relays would be expected according to the DGs penetration, DGs location and type. In this paper, an analytical fault study on the simple radial distribution network is carried out to test the selectivity of the conventional protection system and impacts of connecting DGs with different penetration levels at different locations on the network are also tested. MATLAB/Simulink package is used to model the network and simulate the test case studies. With different types and levels of penetration, emphasis on changing the location of DGs in relation to the relaying point and its proximity to the fault point is highlighted. Despite the obvious effects of DGs connection on the performance of the protective system, these effects are always related to their types, their penetration levels and their location relative to the relaying point. Recently, a set of solutions has been introduced in the literatures to mitigate the DG impacts. Some of these solutions are discussed and evaluated.