Sub-islanding approach to improve the reliability of power distribution systems considering distributed generation

Improving reliability of power distribution systems is an important consideration for utilities especially when high penetration of distributed generation based on renewable energy sources (DGRESs) is considered. Under faults that result in loss of mains, reliability enhancement can be achieved by operating these sources in the islanding mode hence continuing to supply certain customer loads. This paper presents a novel sub-islanding approach based on two algorithms: a backtracking algorithm which is used to detect the exact location of DGRESs to establish sub-islands in the distribution networks, and a protection coordination algorithm which is used to identify the fault location. The IEEE Roy Billinton test system is used for algorithm qualification with several case studies. The failure mode effect analysis technique along with the developed customer interruption cost model is then used to evaluate the reliability improvements. The results presented in the paper indicate that the proposed approach is effective in increasing the reliability of the power distribution systems with high penetration of DGRES.