Auxiliary Wind Power Frequency Modulation Using Flywheel Energy Storage Based on Array Charge State Consistency

This paper focuses on the flywheel energy storage array system assisting wind power generation in grid frequency regulation. To address the issue of unstable power output due to energy imbalance among individual flywheels within the storage array, a balanced and coordinated control strategy is proposed. This strategy considers both the state of charge (SOC) consistency across the energy storage system and the remaining frequency regulation capacity of the array. By applying a variable-scale weighted consensus algorithm, the flywheel's power output is optimized and managed according to its SOC. The energy storage array employs a hierarchical master-slave control strategy: The upper layer sets the operating modes and output power for each group based on SOC, grid and wind power constraints, while the lower layer distributes the power to individual flywheels within each group according to the SOC deviations and the upper layer's power commands. A simulation model of the wind-storage hybrid system is developed in MATLAB/Simulink. The results show that when the rotational speed deviation of any flywheel exceeds the preset limit within the frequency dead band, the system restores SOC consistency. Additionally, the two groups' priority order for frequency regulation tasks is optimized, improving response efficiency and reducing energy losses during frequency output changes. Simulation results confirm that the proposed control strategy effectively meets frequency modulation (FM) power demands, reduces energy discrepancies among flywheels within the same group, maintains both group-level and overall SOC, and enhances the system's FM efficiency and continuous FM capability.