Objective Aiming at the issues of power fluctuations in photovoltaic PV generation double-frequency power fluctuations in single-phase full-bridge grid-connected inverters and the large voltage fluctuations in supercapacitor systems when smoothing PV power fluctuations that may cause over-limit problems a method for smoothing PV gridconnected power fluctuations based on supercapacitors is proposed. Methods Firstly the two-frequency power of the system is separated by inserting a notch filter into the control loop and the fluctuating power is used as the reference value for the supercapacitor response to reduce the impact of grid-connected power fluctuations of the single-phase full-bridge converter on power quality. Secondly a terminal voltage transient recovery control is integrated into the supercapacitor control loop to ensure that the supercapacitor can promptly restore its energy after dynamic response and reserve energy for s v u o b lt s a e g q e ue h n ig t h p - o fr w e e q r ue fl n u c c y tu f a l t u io c n tua s t m io o n oth sm in o g o . th T in h g ird c l o y n tro to l a is dd d r i e r s e s ct t l h y e in h c ig o h rp -f o r r e a q te u d en i c n y to vo t l h t e age du f t l y uc c tu y a c t l i e on o s f o th n e th s e up D er C ca b p u a s c ito a r control loop so as to further improve the power quality of the DC bus voltage. Results The effectiveness and reliability of the power fluctuation smoothing method are verified through the establishment of a grid-connected system simulation model. Conclusion The experimental results show that the grid-connected power fluctuation smoothing control method not only achieves rational distribution of fluctuating power but also effectively avoids over-limit voltage issues in supercapacitors and improves the power quality of the DC bus voltage.