Modeling and Analysis of DFIG-WT-Dominated Power Systems in Electromagnetic Timescale Considering Negative Sequence Control

The requirement for negative sequence control introduces time-varying coupling between the positive and negative sequences in a doubly fed induction generator (DFIG). The potential risk of electromagnetic oscillation in DFIG-based wind turbine (WT)-dominated power systems (DFIG-WTPS) necessitates small-signal modeling and stability analysis considering time-varying characteristics. However, the traditional linear time-invariant (LTI) modeling method based on Park transformation is no longer suitable. Therefore, this paper applies the linear time-periodic (LTP) modeling method based on trajectory linearization to the small-signal modeling of DFIG- WTPS in electromagnetic timescale. Floquet theory is further introduced to calculate the L TP eigenvalues. Then, the influence of series capacitor and control parameters on small-signal stability is analyzed. Finally, the results from the nonlinear DFIG- WTPS model demonstrate the effectiveness of the proposed analysis.