Analysis of strong resonance in power systems with STATCOM supplementary modulation controller

The paper analyzes the behaviour of a pair of oscillatory modes of a power system, essentially a swing mode and an exciter mode, that pass near strong resonance. The method of perturbations suggested by A.P. Seiranyan (see J. Applied Mathematics and Mechanics, vol.58, no.5, p.805-13, 1994) to describe the behaviour of a pair of eigenvalues in the neighbourhood of a multiple point has been suitably modified to make it applicable to systems with feedback controllers. In the case of multimachine systems, the swing mode of interest is isolated by making use of the concept of modal transformation. The knowledge of participation factors helps in identifying the exciter mode that interacts with the swing mode. The illustrative examples comprise a single machine connected to infinite bus (SMIB) system and a 3-machine system with a STATCOM supplementary modulation controller.