Decomposition Techniques Applied to the Nonlinear Programming Load-Flow Method

A recent paper introduced a load-flow method based on the minimization of a function made up of the sum of the squares of the load-flow equations. The Fletcher-Powell method, which was used to perform the minimization, becomes very inefficient for large systems. Large systems require excessive core and prohibitive computer time. This limits the method's applicability to systems of not more than about 50 nodes. This paper presents a decomposition technique that can be used in conjunction with the Fletcher-Powell method to extend the application of the nonlinear programming method to large systems. The method makes very efficient use of computer storage and has been found to reduce computation time by a factor of 90 percent for a 57-bus system. Results of the IEEE 14-, 30-, 57-, and 118-bus systems are given. The computer program that has been written can handle systems of 500 nodes without external storage.