International Journal of Computer Applications (0975 – 8887) Volume 52– No.17, August 2012 13 An Approach to Quantify the Loss Reduction due to Distributed Generation S B Karajgi Department of Electrical Engineering S.D.M. College of Engineering and Technology, Dharwad,India Udaykumar R.Y Department of Electrical Engineering National Institute of Technology Karnataka, Surathkal,India ABSTRACT Line Loss Reduction is one of the major benefits of Distributed Generation, amongst many others, when incorporated in the Power Distribution System. The quantum of the line loss reduction should be exactly known to assess the effectiveness of the distributed generation. In this paper, the total loss of a practical distribution system is calculated with and without distributed generation and an index, quantifying the total line loss reduction is proposed. Simulation tests have been carried out on a practical distribution system and the proposed index is evaluated for various ratings, locations of distributed generation. Keywords Distributed Generation, System Loss Reduction Index. 1. INTRODUCTION The presence of Distributed Generation (DG) has been shown to be beneficial in many respects like voltage profile improvement, line loss reduction, improvement in reliability etc. [1]-[5]. The evaluation of these benefits is very critical in assessing the merit of DG. The quantification of the benefit of line loss reduction was proposed in [6], which evaluated the line losses both with and without DG and the benefit index was defined as the ratio of line loss with DG and that without DG. The subsequent researches [7]-[10], also defined the quantification in a similar way and the benefits of DG were defined. These works, however, considered only the losses in the lines and the quantification was defined for the line losses only. These indices, therefore, do not indicate the loss reduction of the system itself. A practical distribution system consists of several distribution transformers, supplying consumers at low voltage on the secondary side. The losses occurring in these transformers and the line losses of the secondary low voltage distribution system should also be considered to arrive at the overall loss reduction of the system. In this paper, a practical distribution system, supplying a number of consumers at low voltage, is considered. The losses occurring in the transformers and the low voltage distribution lines have been considered and the benefit of DG in respect of total loss is evaluated. 2. DESCRIPTION OF THE SYSTEM A simple distribution system shown in fig 1, is considered for analysis. The system consists a number of identical distribution transformers, the secondary of which supply power to the consumers at low voltage. The core loss 0f each transformer is represented by Pc. Fig 1: The single line diagram of a standard distribution system. For simplicity, the following assumptions are made.  All loads are modeled as constant current loads, drawing the same current irrespective of the respective voltages.  The core losses of the transformers remain constant at a value depending on the rating.  All loads draw the power at a power factor of 0.8 lagging.  DG unit is capable of supplying power at both leading and lagging power factors.  The copper losses of the distribution transformer are of small value and are neglected 3. LOSS REDUCTION ANALYSIS The total loss of the distribution system without DG is given by Subst ation ∆ Y To loads ∆ Y ∆ Y ∆ Y