Research On Impedance Modeling And Resonance Suppression Strategy Of Voltage Source Doubly-fed Wind Power System Under Weak Grid

Although voltage source doubly-fed wind turbines are more adaptable to weak power grids than traditional current source doubly-fed wind turbines,medium and high frequency resonances still occur under the conditions of parallel compensation for weak power grids.The main reason is that the impedances of the two are different.Caused by the match.In order to improve the stability of voltage source doubly-fed wind turbines under parallel-compensated weak grids,this paper will establish a sequence impedance model for voltage-source doubly-fed wind turbines and explore their stability in parallel weak grids.Finally,a corresponding resonance suppression strategy is proposed based on the resonance mechanism of the voltage source doubly-fed wind turbine in the parallelcompensated weak grid.This paper uses the method of harmonic linearization to establish the sequence impedance model of the voltage source doubly-fed wind power generation system,and analyzes the medium and high frequency of the voltage source doubly-fed wind power generation system under weak grid conditions through the Thevenin system equivalent model.At the same time,according to the generalized Nyquist stability criterion,the gridconnected stability of the doubly-fed wind power generation system under different control modes and under weak grid conditions is analyzed,and the D-division method is used to analyze the stability of the voltage source doubly-fed wind power generation system.The parameter stability region is analyzed,and the stable region and the unstable region of the voltage source doubly-fed wind power generation system are obtained.Finally,combining the resonance mechanism,a broadband resonance suppression strategy based on low-pass filtering,a broadband resonance suppression strategy based on Kalman filtering and a broadband resonance suppression strategy based on improved Kalman filtering are proposed,and their performance and resonance suppression effects are analyzed.Simulations and experiments are used to verify the proposed broadband resonance suppression strategy,and the results show the effectiveness of the abovementioned resonance suppression strategy.