A Study On Optimal Power Flow Problem Based On Trust-Region Interior Point Method

Study of optimal power flow problems(OPF), combining the economic dispatch with the security supervision perfectly, has resulted from power flow calculation and classical economic dispatch. The strongly convergent, polynomial-time inteior point method is a potentially powerful one among many tools for OPF. However, the global astringency of the interior point method for nonconvex problems is doubtml theoretically. With the persistent development of the power system, OPF methods are increasingly becoming difficult and nonconvex ones among the large-scale nonlinear programming algorithm.Trust-region and line-search methods are two strategies to ensure the global convergency of the optimization algorithm. Combining the inerior point method with trust-region or line-search method, has become a fashion in the mathematical programming.This paper deals with two kinds of OPF methods based on the modern interior point method.Firstly, an improved trust-region interior point method is presented. This method needn't cooperate with power flow calculation to enhance the currency trait and introduces a parameter variable into the trust-region subproblem to insure the continuity; Meanwhile, the model of the trust-region subproblem is improved to heighten the precision of the calculation and the tolerances are adjusted to speed up the computation; The modern interior point method is used to resolve the trust-region subproblem and a reduced correction equation is derived to reduce the expenses of the computation. Two kinds of OPF problems are resolved by the improved algorithm. Numberical computation on IEEE test systems that range in size from 14 to 300, has shown the correctness and validity of the method. Main fault of the method is that both the speed and precision of the proposed mothod are not satisfactory in large scale systems.