Assessment of Phase Synchronization Stability of DFIG based WTG System under Large Signal Disturbance

The phase synchronization stability of doubly-fed induction generator (DFIG) based wind turbine generator (WTG) system has been analysed in this paper under large-signal disturbance (grid fault). A second-order model capturing the phase dynamics of the synchronizing unit phase-locked loop (PLL) has been derived by applying model order reduction technique on the standard sixteenth-order model of DFIG based WTG system. The derived ROM has been accurately verified by comparing the small-signal as well as time-domain (TD) simulation results with the full-order model. The bounds on the parameters of the PLL gains for stable grid synchronization have also been assessed analytically based on the developed second-order model of DFIG based WTG system. The analysis has been verified with the help of TD simulations. Additionally, the stable as well as unstable phase synchronization conditions under large-signal disturbance (i.e. severe grid fault) have been assessed numerically by conducting case studies on the second-order as well as full-order model of DFIG based WTG system.