Nonlinear Oscillation Behaviors Analysis of DFIG-WT -dominated System with Transient Control Switches

Same as synchronize generator dominated system, transient oscillation also occurs in doubly fed induction generator-based wind turbine (DFIG-WT) dominated system. However, since DFIG-WTs employ normal/transient vector controls, they have strong nonlinear and discontinuous features. These features lead the oscillation responses of DFIG-WT-dominated system to be significantly changed, especially after large disturbance. The oscillation characteristics would be time-varying and could not be predicted according to pre-fault states as usual. This paper analyzes the transient oscillation characteristics of DFIG-WT-dominated system and discusses the effects of transient control switches. Firstly, the regulation process of transient controllers under fault are analyzed. Then, a series of transient model of DFIG-WT in different fault stages are established. Next, the transient oscillation characteristic of DFIG-WT-dominated system is analyzed. Finally, as a key factor that impact the post-fault initial states, the influence rules of transient control parameters are discussed.