Direct method for transient stability studies in power system analysis

This paper deals with recent advances in developing direct methods for studying the transient stability problem of single-machine and multimachine power systems. The paper starts out with the construction of the mathematical model that is usually employed in the analyis of power system transient stability. Computer simulation methods are then briefly discussed, and it is indicated why accurate direct methods for transient stability investigations would be most welcome. It is shown that the classical direct methods, which are based on energy considerations, can be derived and generalized by means of Lyapunov´s second method. The main purpose of the paper is to give an exposition of the interesting results that have been obtained by applying Lyapunov´s second method to the transient stability problem of single-machine and multimachine power systems. In the final portion of the paper some areas for further research are discussed.