Order Reduction Method for Doubly-fed Induction Generator Impedance/Admittance Model Based on Singular Perturbation Theory

With the rapid growth of wind power generation, the penetration of large wind farms in the power grid has increased significantly. A large-scale wind farm contains dozens or hundreds of wind turbines, the model order is high, the modeling analysis is difficult, and the analysis needs to be effectively reduced. In this paper, a singular perturbation theory reduction method for impedance/admittance model stability analysis of doubly fed induction generator (DFIG) is proposed. Firstly, the state space model under the working point of the DFIG model is obtained by using the LINMOD function of MATLAB, and then the state variables of the model’s state space equation can be analyzed on the fast and slow time scale, so as to reduce the order of singular perturbation theory. At the same time, the state space model after order reduction is transformed into impedance/admittance model. The model before and after order reduction has good consistency, and can be used for stability analysis of the system.