Indonesian Journal of Electrical Engineering and Computer Science Vol. 13, No. 2, February 2019, pp. 437~446 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v13.i2.pp437-446  437 Journal homepage: http://iaescore.com/journals/index.php/ijeecs Allocation of distributed generation and capacitor banks in distribution system Oladepo Olatunde 1 , Hasimah Abdul Rahman 2 1,2 Centre of Electrical Energy Systems (CEES), Institute of Future Energy (IFE), Universiti Teknologi Malaysia (UTM), Malaysia 1 Electrical and Electronic Engineering Department, Osun State University, Nigeria Article Info ABSTRACT Article history: Received Jul 8, 2018 Revised Sep 9, 2018 Accepted Sep 23, 2018 Voltage profile and power losses on the distribution system is a function of real and imaginary power loading condition. This can be effectively managed through the controlled real and reactive power flow by optimal placement of capacitor banks (CB) and distributed generators (DG). This paper presents Adaptive Particle Swarm Optimization (APSO) to efficiently tackle the problem of simultaneous allocation of DG and CB in radial distribution system to revamp voltage magnitude and reduce power losses. The modification to the conventional Particle Swarm Optimization (PSO) was achieved by replacing the inertial weight equation (W) in the velocity update equation, based on the particle best experience in the previous iteration. The inertial weight equation is designed to vary with respect to the iteration value in the algorithm. The proposed method was investigated on IEEE 30-bus, 33-bus and 69-bus test distribution systems. The results show a significant improvement in the rate of convergence of APSO, improved voltage profile and loss reduction. Keywords: Adaptive particle swarm optimization (APSO) Capacitor banks Distribution generation Distribution system Inertial weight Voltage profile Copyright © 2019 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Hasimah Abdul Rahman, Centre of Electrical Energy Systems (CEES), Institute of Future Energy (IFE), Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia. Email: hashimahar@utm.my 1. INTRODUCTION The global increase in electrical power demand and the natural depletion in fossil fuel had necessitated the alternative sources of power generation [1]. The conventional method of transmission line upgrading is highly capital demanding with limited expansion in power capacity. In modernized distribution power system planning and operation, (DG) with microgrid (MD) had being a viable alternative and solution to power challenges [2]. DG, equally known as dispersed generation annexes small-scale technologies that can be powered by renewable energy sources for the production of electricity at users’ vicinities. Technical advantages of renewable generation include reduction of pollution, power loss minimization, voltage stability enhancement and reliability improvement in distribution network. It can be modelled as induction and synchronous generators depending on its expected operation mode, either to generate reactive power only or generation of both real and reactive power [3]. DG are modeled at unity power factor to deliver active power sources. The involvement of non-programmable renewable resources raises many technical issues in the operation of modern power distribution networks. With conventional radially structured distribution networks, some technical challenges limit the integration of DG units: increase fault current magnitude, possible reserve power flow, ampacity violations and voltage variation from the operation limit [4]. Conventionally, capacitor banks (CB) are placed on distribution system for reactive power compensation. It is a reactive load generator. Its utilization benefits includes: minimization of power