Adaptive control strategy for primary frequency modulation of hybrid energy storage considering state of charge recovery

Abstract

When high-penetration new energy is connected to the grid, it has a huge impact on the frequency stability of the system. In this paper, an adaptive control strategy for hybrid energy storage based on state-of-charge recovery is designed. Firstly , the operation timing and range of each kind of energy storage is determined according to the different frequency regulation dead band of the two kinds of energy storage and their respective SOC ; Secondly , energy storage frequency adjustment is divided into frequency modulation period and SOC recovery period according to whether the frequency deviation is greater than the frequency modulation dead band . During the frequency modulation period , the action depth of virtual droop and virtual positive/negative inertia is determined by SOC and frequency deviation ; In the period of SOC recovery , a self recovery method of SOC is proposed based on the grid limit coefficient determined by frequency deviation and the energy storage demand coefficient determined by SOC . Finally, by establishing a frequency modulation model to conduct simulation experiments on different types of interference, it is verified that the proposed strategy can effectively maintain the stability of the system frequency.