Modeling and fault analysis of doubly fed wind power generation systems

Combining current reference PWM (CRPWM) and sinusoidal PWM (SPWM), with the aid of stator-flux-oriented and grid-voltage-oriented vector control strategy, the doubly fed wind power generation system is modeled based on the mathematical model. According to Chinese recent regulations on low voltage ride through (LVRT), this paper proposed a novel LVRT voltage control strategy which can provide reactive power in grid voltage recovery. From the voltage and flux equations of the doubly fed induction generator (DFIG), this paper analyzed transient characteristics of the stator and rotor flux when symmetrical short-circuit fault occurred close to the DFIG, and derived expressions for the short-circuit current. The impact of crowbar protection and grid side converter (GSC) is analyzed. Finally, a simulation model is established in PSCAD/EMTDC. Simulation results verify the correctness of new control strategy and expressions proposed by this paper.