Research on Frequency Regulation Strategies for Wind Turbine-Hybrid Energy Storage Systems Considering De-Loading Operation

As the proportion of new energy generation continues to increase, the issue of power system frequency support becomes increasingly prominent. For wind turbines, a combination of virtual inertia control, over-speed control, and pitch control is used to achieve de-loading frequency control functions. Hybrid energy storage participates in frequency regulation using virtual droop control and virtual inertia control, with coordinated control among different energy storage units based on varying frequency deviation values. The paper demonstrates that a wind-storage combined system can enhance the system's frequency regulation capabilities. Based on the frequency control characteristics of direct-drive permanent magnet synchronous generator and hybrid energy storage, this paper studies the frequency control strategy for wind-storage combined systems under various wind conditions, especially during sudden load decreases. Moreover, it proposes a frequency control method based on PI speed reduction and validates it through corresponding simulations. The simulation results indicate that the proposed frequency control strategy effectively enhances the system's inertial response and frequency regulation capabilities.