Abstract: In order to improve the frequency modulation effect of battery energy storage system under different working conditions,an adaptive frequency control strategy of battery energy storage system considering frequency regulation dead zone is proposed. Firstly,the primary frequency regulation model of power system with energy storage is established,and the influence of frequency regulation dead zone,virtual inertia coefficient and virtual droop coefficient on the frequency regulation ability of energy storage system is analyzed.Secondly,the adaptive frequency control strategy of battery energy storage system considering the frequency regulation dead zone is designed. The frequency regulation dead zone range is set according to the frequency change rate and the state of charge. The fuzzy theory is introduced to adaptively adjust the input coefficient and feedback coefficient of the control link to optimize the output power of the energy storage system. Finally,the effects of different control strategies are compared and analyzed under Matlab/Simulink. The results show that the proposed control strategy can effectively improve the frequency quality of the power grid under different working conditions.