Primary Frequency Regulation Strategy for Combined Wind-storage System Based on Improved Virtual Inertia Integrated Control

The increased penetration of wind power causes a decrease in the equivalent rotational inertia of the system and a serious challenge to the system frequency stability. For this reason, this paper proposes a wind-storage cooperative participation in grid primary frequency regulation (PFR) strategy based on the ability of a doubly fed induction generator (DFIG) to participate in frequency regulation at different wind speeds, taking DFIG and battery storage system as an example. The fuzzy logic controller is designed considering the wind speed and frequency change rate to achieve a new DFIG virtual inertia integrated control, which uses the limited rotor kinetic energy of the wind turbine to stop the rapid frequency drop in the inertial response phase. According to the state of charge (SOC) of energy storage for adaptive control, as the DFIG exits the PFR, the energy storage system (ESS) gradually churn out powers and maintains the steady-state recovery process of the frequency. Finally, the simulation verification of the wind-storage cooperative frequency regulation strategy shows that the proposed strategy can effectively improve the frequency response characteristics of the system under different wind conditions, realize the reasonable distribution of wind-storage frequency regulation power, and avoid the occurrence of secondary frequency drop (SFD) accidents, and ensure the frequency stability of high proportion of wind power to the grid.