Analysis on voltage stability of power system with doubly fed induction generator wind turbine based on bifurcation theory

In order to study the mechanism of the voltage instability of the power system including doubly fed induction generator wind turbine (DFIG WT), the simplified model of a three-node power system with doubly fed induction generator wind turbine was developed, and the equilibrium manifold was tracked using the locally parameterized continuation method. Based on the bifurcation theory and the simulation, the processes of going from stability to voltage instability and voltage collapse were analyzed. From the nonlinear dynamics point of view, the nature of the voltage instability and the solution structure variation caused by varying the system parameters were illustrated. The critical points of the bifurcation and voltage collapse at different wind speeds were identified and the impact of the wind speed on the voltage collapse point was presented. The results show that Hopf, homoclinic, static and saddle-node bifurcations have been observed and they essentially induce the voltage instability even the voltage collapse of the studied system. Moreover, the wind speed can have influence on the voltage stability margin of the system.