Reduced order modeling of synchronous machines using singular perturbation

A singular perturbation analysis of the synchronous machine equations in the
(d, q)
reference frame reveals that several reduced order models can be derived systematically from the fundamental machine equations. Some inconsistencies in the classical approach to model reduction are eliminated, and some assumptions commonly overlooked in the literature are clarified. Ways of accounting for armature transients and amortisseur effects in the electromechanical equations of the reduced models are obtained directly from the theory.