H Nasiraghdam - Department of Electrical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
S. Jadid - Department of Electrical Engineering, Iran University of Science and Technology (IUST), Tehran, Iran

The operation of a distribution system in the presence of distributed generation systems has some advantages and also challenges. Optimal sizing and siting of DG systems haseconomic, technical and environmental benefits in distribution systems. Improper selection of DG systems can reduce theseadvantages or even result in deterioration in the normal operation of the distribution system. DG allocation and capacity determination is a nonlinear optimization problem. The objective function of this problem is the minimization of the total loss of the distribution system. In this paper, the ImprovedHarmony Search (IHS) algorithm has been applied to the optimization problem. This algorithm has a suitableperformance for this type of optimization problem. Active andreactive power demands of the distribution system loads are dependent on bus voltage. This paper verifies the effect ofvoltage dependent loads on system power characteristics. Theload model has an inevitable impact on DG sizing andplacement. The proposed algorithm implemented and tested on 69-bus distribution systems and the impact of voltage dependentload models are demonstrated. The obtained results show that the proposed algorithm has an acceptable performance

Distributed generation, improved harmony search, DG sizing and siting, load model