International Journal of Power Electronics and Drive Systems (IJPEDS) Vol. 15, No. 2, June 2024, pp. 824~834 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v15.i2.pp824-834  824 Journal homepage: http://ijpeds.iaescore.com Distributed voltage unbalance mitigation in islanded microgrid using moth flame optimization and firebug swarm optimization Chakrapani Gandikoti, Shashank Kumar Jha, Bishnu Mohan Jha, Pankaj Mishra Department of Energy Engineering, Central University of Jharkhand, Ranchi, India Article Info ABSTRACT Article history: Received May 7, 2023 Revised Dec 23, 2024 Accepted Jan 5, 2024 In recent trends, hybrid renewable energy sources (HRES) provide a better solution to meet energy demand, maximizing the productivity of electricity network. Due to the above-mentioned features, several researchers have given more attention to PV-wind-based HRES systems. A stable energy supply must be added, including batteries, diesel generator (DG), to meet demand in the event of a grid failure. To meet the voltage unbalance in islanded mode, the sizes of DG have need to be selected sensibly and HRES requires additional energy storage. To examine the voltage unbalance problems of an islanded microgrid, a hybrid optimization approach known as moth flame optimization (MFO) and firebug swarm optimization (FSO) is introduced. Due to various loads, harmonic distortion causes the voltage to unbalance, which can result in voltage collapse. To deliver a quick response in an island mode, a comprehensive algorithm called MFO-FSO control is proposed. MATLAB software is used to validate the results which demonstrate that the proposed MFO-FSO outperforms the conventional decoupling double synchronous reference frame (DDSRF) methods by reducing total harmonic distortion (THD) up to 1.21% and voltage unbalance factor (VUF) up to 1.427%. Keywords: Distributed generation Firebug swarm optimization Hybrid renewable energy sources Islanded microgrid Moth flame optimization Total harmonic distortion Voltage unbalance factor This is an open access article under the CC BY-SA license. Corresponding Author: Chakrapani Gandikoti Department of Energy Engineering, Central University of Jharkhand Ranchi, India Email: Chakrapani.19210201002@cuj.ac.in 1. INTRODUCTION The introduction of the microgrid has received significant interest in a number of nations worldwide in recent years. A microgrid is a configurable system made up of local loads, energy storage appliances, tracking and protection equipment, and several distributed generating. Whenever storage devices and intermittent renewable energy sources are coupled in a hybrid inverter-interfaced distributed generation (DG) microgrid, the network's dependability improves [1]. The microgrid may function in both the islanded and grid-connected modes, giving crucial loads more dependable electricity. The majority of research on islanded microgrids focuses on correction for voltage imbalance, power management for various DGs and forms of energy storage, and parallel-inverter power sharing and circulation limitation [2]. In order to achieve effective functioning of the entire electric power system, distributed generation and the growing penetration of renewable energy sources are characteristics of the continuing transition in the electric power system [3]. Multiple elements have been created to address voltage imbalance compensation and improve the quality of the voltage waveform [4]. An unbalance compensation technique is suggested in the earlier work [5] by providing the local controllers of DGs with the appropriate control signals [6]. Since the voltage imbalance factor whose value is lowered by the positive sequence voltage is the primary control variable used by the microgrid central controller. To solve this problem, a hybrid green energy system that combines many energy