Feedforward Frequency Deviation Control in PLL for Fast Inertial Response of DFIG-Based Wind Turbines

Inertial response is gradually becoming a mandatory requirement for wind turbine (WT) integrated into power system. However, most inertia control strategies are implemented in the main control system of WT or the power loop of converter control system, resulting in a slow inertial response. To cope with it, this article proposes a feedforward frequency deviation control (FFDC) for doubly fed induction generator (DFIG) based WT to achieve fast inertial response. First, the inertia model of DFIG-based WT is developed, and the effects of different control loops on the inertia characteristics are analyzed. Then, the FFDC method is proposed by introducing the frequency deviation feedforward into the phase-locked loop (PLL). Meanwhile, the inertia characteristics and stability of proposed FFDC method are studied. The results indicate that the proposed FFDC method achieves superior inertial response than the method with reduced PLL bandwidth, while not degrading PLL dynamic performance under normal conditions. Finally, the proposed method is validated by experiments.