Reduced order DFIG model based on the singular perturbation method for grid connected wind turbines analysis

It is a common practice to neglect the stator or rotor dynamics of a Doubly-Fed Induction Generator (DFIG) in order to derive a simple model. This reduced order model, however, may not preserve the stability properties of the complete model. To circumvent this problem, we propose in this paper a DFIG reduced order model based on the Singular Perturbation Method. It is shown that a suitable parameter of the machine for the role of a singular perturbation is the dispersion coefficient, and not a time constant as in the usual practice. The result is a model that can be used with confidence for the analysis, that is, the stability conclusions can be extended to the complete order model. A simple numeric example using linear analysis illustrates this property by comparing the proposed reduced order model behavior with both the full and conventional reduced order models.