A modified harmony search algorithm applied to capacitor placement of radial distribution networks considering voltage stability index

Abstract

In power system, capacitor placement of distribution networks is a complex combinatorial optimisation problem. In this paper, in order to effectively solve optimal capacitor placement (OCP), an aggregate harmony search (AHS) optimiser, a stochastic population-based metaheuristic algorithm, is proposed which introduces a new pitch adjustment mechanism for harmony search (HS). The objective function contains three goals: 1) minimisation of the power losses; 2) minimisation of the capacitor installation cost; 3) improvement of the voltage stability index at the weakest bus. On two case studies, 23 kV nine-section feeder and 33-bus radial system, simulation results show that the proposed AHS not only finds more accurate results than the other investigated HS variants and particle swarm optimisation (PSO) techniques but also has the best robustness. Promising performance of AHS makes this technique as an efficient alternative to solve capacitor placement problem.