Modelling of DFIG-Based Wind Turbine for Transient Synchronization Stability Analysis

Transient synchronization stability (TSS) of DFIG-based wind turbines (DFIG-WTs) exhibits much more complicated characteristics compared with that of full-power-converter-interfaced renewable energy generation (REG) units. This paper discovers that, for grid-connected DFIG-WT during the post-fault reactive current injection (RCI) period, although the dynamic process of fast current control (CC) loops can be ignored, their initial values do have non-negligible influence on TSS. This influence, named as a newly proposed concept of “quasi-step” characteristics of dominant slow state variables, is analytically calculated, and a 2nd-order simplified model of grid-connected DFIG-WT during RCI is accordingly proposed. Time-domain simulations verify the proposed concept of “quasi-step” and 2ndorder simplified model.