AN IMPROVED NEWTON METHOD FOR RADIAL DISTRIBUTION SYSTEM LOAD ANALYSIS

Abstract

This paper presents a modified Newton method of load flow analysis for radial distributionsystems. It is derived with the Jacobian matrix is in UDUT form, where U is a constantupper triangular matrix depending solely on system topology and D is a block diagonalmatrix. With this formulation, the conventional steps of forming the Jacobian matrix,LU factorization and forward/back substitution are replaced by back/forward sweeps on radialfeeders with equivalent impedances. The method has advantages over Newton’ s method interms of speed of solution (no. of iterations), and reliability of convergence by inserting a minimization technique (Cubic Interpolation Technique). The algorithm exhibits a control of the convergence. As such the method converges for cases when conventional Newton’ s method and some other popular methods diverge. Two large distribution systems of 490 nodes and 722 nodes with different r/x ratio in line impedance are used to examine the performance of the method. These tests have shown that the proposed method is as robust and efficient as the forward/back sweep method. The proposed method can be extended to the solution of three phase unbalanced representation.