A Piecewise Method for Optimal Load-Flow Problem

Abstract

Power utilities are increasingly being interconnected to improve the reliability of power supply and achieve economy of operation. Optimal load-flow analysis of such interconnected power systems, in general, results in complex large scale nonlinear programming problem, the direct method of solution of which requires huge amounts of core and computer time. Decomposition techniques have been extensively investigated in the power system literature to alleviate these difficulties. A piecewise method based on graph theoretic concept is proposed in this paper. The decomposition of the optimal load-flow into an additively separable nonlinear programming problems is achieved through the artifact of equivalent networks which were introduced in the piecewise load-flow problem. Lasdon’s decomposition technique is adapted for its solution. The optimization of subsystems is carried out using a shifted penalty function algorithm imbedded with a recent Fletcher’s unconstrained function minimization routine. Few examples are presented to demonstrate the effectiveness of this approach over the others.