General nonlinear modal representation of large scale power systems

In this paper an approach is devised to represent, and study the behavior of, nonlinear dynamic systems using general nonlinear modal representation. This approach is shown to compare favorably to the normal form of vector field technique, the other methodology used for this purpose, in that it is valid under resonance conditions and it does not require nonlinear transformation. By representing the system more accurately and in terms of its modes and their interactions, it would be better suited to be used for understanding and analyzing complex behavior of stressed power system and also in designing various controls for the system. This method can represent a nonlinear system with any order of nonlinearity and provides the solution to the system nonlinear differential equation employing Laplace transformation. The accuracy and robustness of the method has been validated using three systems, two of which model realistic utility power systems under stressed conditions.