Evaluation of Over Current Relay Settings Optimization for Multi-infeed DG-connected-grid

Abstract

Increasing the short-circuit current magnitude and bidirectional flow in a multi-infeed DG-connected grid have significant impacts on protection systems based on over-current relays (OCRs). An adaptive protection scheme based on defining the optimal setting of a directional OCR (DOCR) has recently been introduced as a solution for mis-coordination and false tripping issues associated with DG penetration increase. In this paper, this approach is highlighted, and its performance in different operating modes of the DG-connected grid is evaluated. Genetic algorithm (GA), and gray wolf optimization (GWO) have been used to provide optimized values of the time multiplier setting (TMS) of the DOCR scheme. Different faults at different locations with different DG locations and sizes are studied. The international electrotechnical commission (IEC) micro-grid benchmark and different DG units are modeled with MATLAB Simulink and ETAP software to carry out and test all these operating modes and evaluate this scheme. The ability of this scheme to maintain the coordination between the forward and reverse main and backup relays for each fault location is focused on in this study.