Adaptive droop control strategy considering hybrid energy storage power allocation

To maximize the advantages of hybrid energy storage in reducing frequency deviations, this study proposes a power allocation strategy for hybrid energy storage based on dynamic adjustable droop control. The strategy is demonstrated by utilizing an energy storage station composed of supercapacitors and lithium-ion batteries. Based on the state of charge (SOC) of the energy storage, the droop coefficient is dynamically adjusted using a logistic curve. Subsequently, the power demand of the hybrid power station is calculated. Additionally, an appropriate frequency regulation deadband is set to prevent system frequency from exceeding limits. Within the deadband, SOC self-recovery is considered to prevent frequency excursions. Outside the frequency regulation deadband, power allocation is determined by the state of charge of the hybrid energy storage system. Finally, simulation analyses using MATLAB/Simulink are conducted for step and continuous disturbances. The findings indicate that the devised control approach successfully enhances the performance of frequency control and refines frequency characteristics.