Reactive power dispatch with a hybrid stochastic search technique

Reactive power dispatch (RPD) in power systems is concerned with the security and economy of operation of the power system. This is a complex combinatorial optimization problem involving non-linear functions having multiple local minima and non-linear and discontinuous constraints. A number of techniques ranging from classical techniques like gradient-based optimization algorithms to various mathematical programming techniques have been applied to solve this problem. In all these efforts, some or the other simplification has been done to get over the limitation of the solution technique. In recent years, the advantages of evolutionary algorithms in terms of the modeling capability and search power have encouraged their application to the RPD problem in power systems. In this paper, a solution to RPD problem with the help of hybrid stochastic search (HSS) is presented. The hybridization of the standard real-coded GA with ideas from simulated annealing provides the advantages of both. A novel coding scheme is used to consider many of the constraints at the coding stage itself. A local optimization step and concentration of the search in the 'better' areas of the search space further contribute to the utility of the approach. It is shown that HSS method proposed in this paper converges to better solutions much faster than the earlier. reported approaches on the IEEE 30 bus example. The optimization strategy is general and can be used in the solution of other power system problems as well. (C) 2002 Elsevier Science Ltd. All rights reserved.