Lyapunov stability of multimachine power systems considering the voltage regulator

A new decomposition-aggregation approach is developed, in the paper, to perform transient stability analysis of an N-machine power system. Considering the generator flux decay effect, non-uniform mechanical damping, transfer conductances and the automatic voltage regulator action, the system mathematical model is derived. It is obtained a system aggregation (square) matrix of the order (N - 1)/2, stability of this matrix implies asymptotic stability of the system equilibrium state. As an illustrative example, the developed approach is applied to a 7-machine, 10-bus power system, and it is determined an estimate for the system asymptotic stability domain. A 3-phase short circuit fault (with successful reclosure) is assumed to occur close to a generator bus. Isolating the faulted line clears the fault. The developed approach is used to determine the critical time for reclosing the open line. It is found that the developed approach is powerful (the obtained critical time is about 90% of the exact time computed by using the step-by-step method) and may be used for stability studies of large-scale power systems. (C) 2002 Elsevier Science Ltd. All rights reserved.