Capacity Optimization Configuration Strategy for Electrochemical-hydrogen Hybrid Energy Storage Based on State-of-charge Self-recovery for Wind Power Fluctuation Smoothing

To address the challenges in wind power fluctuation smoothing using electrochemical-hydrogen hybrid energy storage, a SOC self-recovery-based capacity optimization is proposed. The key issues include extreme high/low SOC states of electrochemical storage due to large charge-discharge disparities and the degradation of hydrogen storage tank SOH caused by its efficiency characteristics, which lead to high configuration costs. First, considering grid-connection lag time and algorithm adaptability, an adaptive weighted filter is designed to suppress wind power fluctuations, to obtain precise active power reference values for hybrid energy storage. The active power is then allocated between electrochemical and hydrogen storage using EMD and HT. Subsequently, a complementary operation strategy for electrochemical-hydrogen systems is proposed, which incorporates equivalent SOC metrics to assess the overall SOC level of electrochemical storage. By defining trigger thresholds for different operational modes, abnormal SOC and SOH states are eliminated. Finally, a full lifecycle economic cost assessment model based on the rainflow counting method is established to evaluate the impact of different threshold settings on the operational lifespan of energy storage and the overall configuration cost. The proposed method is validated through real-data simulations, demonstrating its effectiveness in optimizing hybrid storage configurations and reducing costs compared to conventional strategies.