Transient Stability Equivalents Based on Lyapunov Function

Abstract

Owing to the increasing size and complexity in power systems, the study of the stability equivalent is receiving a great deal of attention. This paper describes a systematic method for the recognition of coherent machines by means of the Lyapunov function which is used for the transient stability analysis. A group of generators, whose partial Lyapunov function has a small value compared with that for the whole system, is aggregated into one equivalent generator. This method does not require a long time simulation of the entire system. The parameters of the simplified system are also determined by using the Lyapunov function. The method is applied to 10-machine and 50-machine sample systems and the results are shown.