A reduced-order model for representing the reactive power response of a doubly fed wind turbine during ZVRT

Zero-voltage ride through (ZVRT) is the worst-case scenario of low-voltage ride through (LVRT), which indicates the optimal fault-response capability of wind turbines (WTs). The reactive response during ZVRT shows the dynamic performance of WTs during extreme grid faults, which greatly improves the flexibility and robustness of renewable-rich grids. The reactive response of a doubly fed (type-3) WT during ZVRT depends on the control strategy of the converter and the steady-state and transient-state performance of the doubly fed induction generator (DFIG). This paper proposes a reduced-order model for representing the reactive response of a type-3 WT during ZVRT including the control strategy of the converter and the equivalent electric circuit of the DFIG, which simplifies some complicated equations but is practical for modeling a renewable-rich power system in most cases. Some simplified expressions between the reactive energy and a single DFIG parameter are presented, which could satisfy the demands of designing a DFIG. Finally, the method of model consistency verification, the influence analysis of DFIG parameters on the reactive response, the reasonable ranges of DFIG parameters and the fault-response performance of the WT in the theoretically longest ZVRT period are also obtained for reference.