Required damping to assure multiswing transient stability: the SMIB case

The main concern of this paper is to create a methodology that, if incorporated to the Boundary Controlling Unstable Equilibrium Point (BCU) method of transient stability analysis, one can assure, for the single-machine-infinite-bus system (SMIB), the stability of the system and not only the existence of the first swing. The methodology consists of determining, in an iterative way, a critical damping coefficient that should be associated to the system, so that it is assured the saddle points used as the controlling equilibrium points are on the boundary of the corresponding attraction area. That is, with that damping coefficient in the system, the one-parameter transversality condition will be certainly satisfied. The methodology, as developed, is an iterative monotonically convergent process very easy to implement and does not require knowledge of fault trajectory at all. An example showing how the methodology works is also incorporated to the paper. For multimachine systems the paper gives some insight into how the methodology could be extended. However further studies are necessary to solve the multimachine problem.