A Decomposed Two-Port Network Impedance Modeling Method of Type-3 Wind Generation System with Grid-Forming Control

The doubly-fed induction generator (DFIG) has been widely used in the field of wind generation. However, due to the couplings on both dc-side and ac-side, the full-order small-signal impedance model of the DFIG system is hard to build. To solve this problem, this paper proposes a decomposed two-port network impedance modeling method. With this method, the total admittance of the DFIG system is decomposed into four components, and each of them can be calculated independently. Then, a full-order small-signal admittance model can be obtained accordingly. The proposed modeling method has three main advantages: 1) high accuracy; 2) low complexity of the modeling process; 3) the impact of the dc-link coupling can be analyzed intuitively. Finally, this paper provides the ac terminal admittance calculation and measurement results of the DFIG system with grid-forming control for cross-validation.