JEE_V7_N3_RP3 Dr. N Visali M. Satish Kumar Reddy Surendranatha Reddy M. Journal on Electrical Engineering 2230 – 7176 7 3 27 34 Unbalanced Radial Distribution System, Incidence Matrix, Transmission Losses, Branch, Linear Recursive Equators, TCIM (Three-Phase Current Injection Method) Distribution system is the system which supplies electrical power from generating station to consumers. But the practical loads in the radial distribution systems are generally unbalanced in nature. For analysing the system condition and also to forecast the load, the study of power flows is essential. The presence of high R/X ratio of the distribution system poses a challenge to the convergence criteria of commercial load flows such as Newton Raphson Method, Gauss Seidel method and Fast Decoupled methods. For this type of systems, some changes have been incorporated in above methods so as to obtain better convergence which are named as modified Newton Raphson Method, modified Gauss Seidel Method and Forward/Backward Sweep Methods. The pre-assumption of flat node voltage is essential to carry out the load flow solution in all these methods. A new method has been proposed to determine the solution without any preassumptive flat node voltage and also the unbalanced system is modelled as a balanced system using symmetrical components. The solution is obtained by incorporating relationship between node currents and branch currents using a concept of Branch Incidence matrix and thereby eliminating the need for flat voltage profile. The proposed method has been presented in three sections. In First section 1 the formation of the branch incidence matrix by modelling of unbalanced Radial Distribution System comprising of transformers, switches, capacitors etc. using symmetrical components, In section 2 node voltages and power losses are calculated using branch incidence matrix and system parameters. Finally in section 3, the results obtained are compared with the existing methods. The proposed method is solved for three different unbalanced Radial Distribution Systems such as IEEE 13 node, 19 node and 25 node systems and the results are presented. January - March 2014 Copyright © 2014 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=2706