A two stage fault current limiter and directional overcurrent relay optimization for adaptive protection resetting using differential evolution multi-objective algorithm in presence of distributed generation

Abstract

This paper presents a two stage optimization approach for solving the excessive network fault currents and resetting of overcurrent relays based on Adaptive Protection Scheme (APS) concept. The first stage consists of Fault Current Limiter (FCL) optimization to restore fault currents within Circuit Breaker (CB) thermal capacity whether caused by Distributed Generation (DG) or not. The second stage consists of Directional Overcurrent Relay (DOCR) coordination based on the adaptive protection concept to reset DOCR in order to function properly in presence of FCL and DG. This is of great importance since FCL may cause over limitation of fault current during minimum load operation which may degrade DOCR performance. The optimization process has been achieved by formulating both the FCL sizing and location problem and DOCR coordination problem using Differential Evolution Multi-Objective (DEMO) algorithm. The proposal has effectively re-coordinated the DOCRs contemplating the effects of FCLs and DGs which mitigated the faults surpassing CB thermal limit, DOCR miscoordination and degraded performance caused by FCL over limitation.