Optimal coordination for directional over-current relay using differen toptimizatio nalgorithm

Abstract

Short circuits can occur unexpectedly at any time and in any part of a power system due to various issues, causing a significan tamoun to ffaul tcurren tt oflow through the equipment. These faults are harmful and must be quickly isolated by protective devices. The protective system’s role is to swiftly detect faults and remove them from the power network. Among the most important protective components in power networks is the overcurrent relay. Overcurrent relays provide both primary and backup protection for heavily interconnected and multi-source power networks. The pickup value of an overcurrent relay must be set between the maximum load current and the minimum fault current encountered. Directional overcurrent relays (DOCRs) are widely used as primary protection in sub-transmission systems and as backup protection for distance relays in transmission networks. Coordinating DOCRs involves selecting appropriate relay settings, such as plug setting (PS) and time dial setting (TDS), ensuring the primary relay responds faster than any other relays in the system. If the primary relay or its associated circuit breaker fails, backup relays must operate after a set time interval to ensure proper sequential operation. Recently, there has been significan tinteres ti nsolvin gth eDOC Rcoordinatio nproble musing metaheuristic algorithms. Various techniques, including teaching-learning-based opti- mization (TLBO), genetic algorithms (GA), particle swarm optimization (PSO), and the modifie dwate rcycl ealgorith m(MWCA) ,hav ebee npropose dt ofi ndoptimal solutions for DOCR coordination. This research introduces a new formulation and solution for setting and coordinating DOCRs using an efficie ntoptimizati ontechnique called improved AVOA. The main goal of optimal DOCR coordination is to minimize ithe total operating time of all relays while maintaining a time margin between backup and primary relays. Rigorous experiments are conducted on benchmark IEEE 9-bus and IEEE 39-bus test systems to validate the proposed relay coordination method-ology. A comparative analysis of the outcomes with other well-known optimization algorithms conclusively shows that the proposed methodology is superior in meeting coordination constraints, with empirical evidence supporting its effectiveness.