Determining the optimal size of energy storage systems for wind farm ramp-rate control

Short-term power fluctuations from grid-connected wind farms pose challenges to grid reliability and stability, particularly in terms of ramp-rate compliance. To address these issues, new regulations require integrating energy storage systems with renewable generators. This paper presents a method for determining the optimal power and energy capacity of storage systems specifically designed to ensure wind farm compliance with ramp-rate constraints. The proposed approach is validated using three strategies originally developed for photovoltaic applications, demonstrating their effectiveness when adapted to wind energy. Validation is based on high-resolution real-world data recorded at 1-second intervals and averaged over 5 s, covering one year at a wind farm in northern Spain with five 3 MW wind turbines. Additionally, the annual cycling degradation of the storage system is analyzed. The effectiveness of the ramp-rate control strategies is further validated through experimental testing on a real system comprising two lithium-ion batteries: a 1 MW/0.39 MWh power battery with a fast response and a 0.7 MW/0.7 MWh energy battery with a slower response but greater autonomy. These batteries are connected to a 3 MW wind turbine, where a commercially available power converter is adapted for use as a battery charger. • A methodology to determine energy storage requirements for wind power ramp-rate control is presented. • Ramp-rate control is simulated for smoothing Wind farm power fluctuations. • Ramp-rate control is validated with real operational data. • Ramp-rate control strategy is validated at a real wind farm with energy storage system.