A PSO-based Multi-objective Method for Optimal Weight Factors, Placement and Sizing of Multiple DG Units in a Distribution System

Minimization of a single-objective-function (SOF) and a weighted-sum multi-objective-function (MOF) is aimed at obtaining optimal placements and sizes of multi DG units in distribution systems. The indices of the MOF are related to characteristics of the distribution system. The weight factors were assumed arbitrarily or determined according to the preferences of the decision maker. To the authors' knowledge, this paper presents -for the first time- a Particle-Swarm-optimization (PSO) -based-method for computing the weighting factors while minimizing the SOF or MOF of the distribution system. The index priority of the MOF is always given to the deviation of bus-voltage from nominal-value in conformity to power-quality features regarding no sag or swell of bus-voltage. The computed optimal placements and sizes of the DG units agreed reasonably with those reported in the literature. The dependency of optimal placements and sizes on the load type is investigated for the IEEE 33-bus radial distribution system.