Analysis and simulation of wide-area frequency oscillations in doubly-fed induction generator grid-connected system

The rapid restoration of power systems is a critical task in responding to large-scale blackout events. Wide-Area Frequency Oscillations (WAFOs), a common issue during the restoration process, can pose a significant threat to system stability and recovery efficiency. To mitigate the impact of WAFOs on power systems, this paper focuses on the sequence impedance model of doubly-fed induction generators (DFIGs), considering the effects of frequency coupling. The Nyquist stability criterion, based on impedance analysis, is then employed to analyse the wide-area frequency oscillations in the wind turbine grid-connected systems. It is emphasized that two factors—namely the dynamic characteristics of the DC bus and the coupling effect of grid impedance—must be considered when building model. Finally, the theoretical analysis is validated through simulation results.