Small-Signal Stability Region Analysis of Multi-Time Delay Wind Power System Considering Degenerate Hopf Bifurcation

From the perspective of nonlinear dynamics and bifurcation theory, this paper analyzes the impact of time delay on small-signal stability region of doubly-fed induction generator (DFIG) grid-connected power system. Firstly, the differential-algebraic equation model of the system is established. It is theoretically demonstrated that time delay will affect the bifurcation behavior of the system, especially the degenerate Hopf bifurcation (DHB) under a specific time delay. Then, the time delay, the injected DFIG mechanical power, and the load reactive power are chosen as the bifurcation variables. The bifurcation diagram is obtained through bifurcation analysis, which can determine the multi-parameter small-signal stability boundary of the system. Finally, the impact of single and multiple time delays on the stability region is analyzed through the stability boundary. It is found that the DHB due to the time delay variation induces a hole effect in the system stability region. Moreover, increasing the time delay may also improve the system stability margin. The findings of this study have significant guiding implications for multi-time delay system parameter adjustment.