OPTIMAL POWER-FLOW USING THE REDUCED NEWTON APPROACH IN RECTANGULAR COORDINATES

This paper presents a simplified technique for solving the optimal pow er flow (OPF) problem with particular reference to transmission loss m inimization. The approach is based on the second-order Newton method i n rectangular coordinates. The key idea behind the use of a rectangula r coordinate formulation far the OFF is to achieve certain computation al advantages stemming from a constant second-order matrix. The charac teristics of typical power system problems are highlighted in connecti on with the solution approach using the full hessian matrix. Then the systematic development of a sparsity-oriented reduced Newton approach is described The Newton method is used as a concept, the implementatio n technique is modified. The concept and the technique together compri se the given approach. A two-state optimization has been performed by decoupling the two sets of control variables, i.e. the voltages at the control buses and the tap settings of the OLTC transformers. Efforts have been made to achieve such decoupling of the hessian matrix withou t sacrificing its positive definiteness which is, quite often, a probl em. The way of handling the inequality constraints is also simplified. Satisfactory performance of the algorithm was observed when applied t o the test systems, for which results are presented. (C) 1998 Elsevier Science Ltd. All rights reserved.