Research and improvement of voltage stability of grid connected system with doubly fed wind turbine

In order to study the bifurcation mechanism of parameter changes affecting the voltage stability of the system in the doubly fed wind turbine system, based on the 3-node simple power system, taking the reactive power as the bifurcation control parameter, the local continuation method is used to pursue the popularity of the equilibrium solution of the system. The location and type of bifurcation point can be known through the popularity curve of the equilibrium solution. On this basis, combined with the time domain diagram The phase diagram and Jacobian matrix eigenvalue trajectory diagram analyze the dynamic process of the system from stability to instability, reveal the structural change of the solution and the essential reason of voltage stability caused by the change of bifurcation parameters, and analyze the influence of different types of bifurcation points as the initial operating points and different disturbances on the voltage collapse of the system, Finally, the system is analyzed by adding washout filter. The results show that there are saddle node bifurcation, Hopf bifurcation and homoclinic bifurcation in the system, which can lead to the collapse of system voltage, and the addition of washout filter can eliminate the bifurcation point and improve the voltage stability margin of the system.