Coordinated Frequency Regulation Strategy for Wind-Power–Hydrogen Coupled Systems Considering the Equivalent State of Charge

To address the frequency stability challenges arising from the high penetration of renewable energy, this study proposes a coordinated frequency regulation strategy for wind-power–hydrogen coupled systems, considering the Equivalent State of Charge (ESOC). While wind-power–hydrogen integration offers significant regulation potential, frequent ESOC excursions toward operational limits may lead to power interruptions and increased durability-related stress on hydrogen units. To resolve this, a refined mathematical model comprising wind turbines, electrolyzers, and fuel cells is first established to characterize system dynamics. The proposed method adopts an ESOC-based partitioning control logic: within normal ESOC ranges, the hydrogen storage system provides rapid frequency support via virtual inertia control; when ESOC reaches operational thresholds, the hydrogen unit seamlessly transitions out of service to prolong its lifespan, while the wind turbine dynamically compensates for the power deficit through adaptive droop control. Compared with other methods, the strategy proposed in this paper, implemented via DIgSILENT/PowerFactory simulations, improves the frequency nadir by 0.02 Hz during load increases and reduces the frequency peak by 0.04 Hz during load shedding. Under stochastic disturbances, the absolute steady-state frequency error is maintained below 0.02 Hz, while frequency deviations are strictly confined within ±0.5 Hz. These improvements significantly enhance both grid resilience and the operational safety of hydrogen units.