Improvement of large-scale power systems decomposition-aggregation approach

Abstract

An N-machine power system with uniform damping and with transfer conductances is decomposed in this work into ( N−1)/2 interconnected subsystems, instead of the usual decomposition into ( N−1) subsystems. Each subsystem consists of three machines, one of which is the comparison machine, and is described as a fourth-order multi-nonlinear Lurie-Postnikov system. Six nonlinearities are assumed to be contained in each free (disconnected) subsystem. A vector Lyapunov function is used for aggregating the system, and an aggregation matrix of order ( N − 1)/2 is obtained. Two power systems (with five and seven machines) are used as examples. An estimate of the asymptotic stability domain is determined for the seven-machine system. It is shown that the decomposition scheme presented can lead to a considerable reduction of the conservativeness of the decomposition-aggregation method.