Hybrid Energy Storage Participation in Secondary Frequency Regulation Control Strategy Based on Hierarchical Adaptive Control

ObjectivesWhen assisting the frequency regulation of the thermal power units, battery energy storage faces difficulties in coping with high-amplitude and high-frequency disturbances. To address these issues, a hybrid energy storage strategy for participation in secondary frequency regulation control, based on hierarchical adaptive control, is proposed.MethodsThe outer layer discusses the relationship between system residual energy and the proportional factor, proposing an adaptive proportional factor control strategy based on mathematical function methods. This strategy reasonably allocates regional control signals based on the system’s current frequency regulation capacity. Meanwhile, the inner layer optimizes the output control of the generation units and energy storage outputs. The unit output is controlled using a variable fuzzy PI controller, and energy storage output is controlled using a two-layer fuzzy control with variable time constant low-order filtering. This ensures that energy storage is not overcharged or over-discharged while adaptively allocating the frequency regulation signals. Simulation analysis is conducted using continuous load disturbances.ResultsCompared with the traditional fixed K method, the proposed adaptive proportional factor control strategy reduces the maximum frequency deviation by 2.2%, reduces the energy storage contribution by 31.7%, and demonstrates better maintenance performance of state of charge.ConclusionsThe proposed control strategy can optimize the system’s frequency control and provide a new approach for maintaining grid frequency safety.