Realization of fault ride through for doubly fed induction generator system with cascade converter

The doubly fed induction generator (DFIG) system is prevalent in the wind power industry due to cost-effective variable speed operation and part size power converter. The DFIG system dynamic performance might be degraded by oscillations of the electromagnetic torque and instantaneous stator power under grid faults. This paper proposes an improved method to augment the dynamic performance of the DFIG system under the aforesaid scenarios, where an additional cascade converter (CC) is serially connected at Y-point of DFIG stator windings. The DFIG performance under low-voltage ride through (LVRT) and high-voltage ride through (HVRT) is improved with the proposed control topology. Additionally, with auxiliary control provision, the proposed method can improve the stability of the DFIG system. The theoretical analysis and Matlab/Simulink simulations validate the effectiveness of the proposed method.