Crowbar hardware design enhancement for fault ride through capability in doubly fed induction generator-based wind turbines.

A crowbar circuit used in doubly fed induction generator (DFIG)-based wind turbines protects the system during transient stability. However, in a large power system, crowbar protection may be insufficient due to over-voltage and inrush currents occurring during balanced and unbalanced faults. Hence, in this study, a crowbar circuit was enhanced for fault ride through capability against balanced and unbalanced faults in a DFIG. The stator and rotor dynamic modeling used a crowbar hardware circuit design with rotor active impedance. Electromotive force voltages were used for the stator-rotor dynamics in the DFIG. Furthermore, crowbar resistance units were designed to meet the fault ride through DFIG requirement. The DFIG behaviors with and without the crowbar hardware circuit design were compared. The balanced and unbalanced faults were also compared in terms of behavior. Results showed that the circuit design of the crowbar hardware enabled the system to promptly become stable and eliminated the oscillations.