A Simplified Approach for Load Flow Analysis of Radial Distribution Network

This paper presents a simple approach for load flow analysis of a radial distribution network. The proposed approach utilizes forward and backward sweep algorithm based on Kirchoff’s current law (KCL) and Kirchoff’s voltage law (KVL) for evaluating the node voltages iteratively. In this approach, computation of branch current depends only on the current injected at the neighbouring node and the current in the adjacent branch. This approach starts from the end nodes of sub lateral line, lateral line and main line and moves towards the root node during branch current computation. The node voltage evaluation begins from the root node and moves towards the nodes located at the far end of the main, lateral and sub lateral lines. The proposed approach has been tested using four radial distribution systems of different size and configuration and found to be computationally efficient. Keywords—constant current load, constant impedance load, constant power load, forward–backward sweep, load flow analysis, radial distribution system. List of symbols n N = Total number of nodes in the given radial distribution network b N = Total number of branches in the given radial distribution network l N = Total number of lateral lines in the given radial distribution network sl N = Total number of sub lateral lines in the radial distribution network m N = Total number of minor lines in the given radial distribution network M en = Ending node number in the main line b Z = Impedance of the branch b b R = Resistance of the branch b b X = Reactance of the branch b K. Vinoth Kumar is a research scholar in the department of electrical and electronics engineering, National Institute Technology, Tiruchirapalli, Tamil nadu, India – 620 015. (e-mail: [email protected]). M.P.Selvan is with the department of electrical and electronics engineering, National Institute Technology, Tiruchirapalli, Tamilnadu, India – 620 015. (corresponding author :phone: 91-431-2503262; fax: 91-4312500133; e-mail: selvanmp@ nitt.edu). b y = Line charging admittance of the branch b n V = Voltage at the node n n S = Complex load power at the node n Ln I = Load current injections at the node n b I = Branch current of the branch b cb I = Line charging current of the branch b , bl l I = Branch current in the l th lateral line , bsl sl I = Branch current in the sl th sub lateral line , bm m I = Branch current in the th m minor line Ml n = Node number in the main line from which this l th lateral line begins lsl n = Node number in the lateral line from which this sl th sub lateral begins slm n = Node number in the sub lateral line from which this th m minor begins Ml b = Branch number connecting the main line with the l th lateral line lsl b = Branch number connecting the lateral line with the sl th sub lateral line slm b = Branch number connecting the sub lateral line with the th m minor line l snl = Starting node number of l th lateral line sl snsl = Starting node number of sl th sub lateral line m snm = Starting node number of th m minor line l enl = Ending node number of l th lateral line sl ensl = Ending node number of sl th sub lateral line m enm = Ending node number of th m minor line l = denotes a lateral line, l = 1,2,3,.................. l N sl = denotes a sub lateral line, sl =1,2,3................ sl N m = denotes a minor line, m = 1,2,3................... m N