At present

the large-scale grid integration of new energy systems may lead to the fluctuation of grid frequency. And the hybrid energy storage system composed of lithium battery energy storage and flywheel energy storage assists thermal power units to participate in secondary frequency regulation of grid

which can effectively improve the active frequency support ability of generation side of power grid and ensure the frequency safety. Aiming at the problem of modal decomposition signal aliasing and the influence of lithium battery life degradation on system economy when hybrid energy storage participates in secondary frequency regulation of power grid

a capacity configuration strategy for hybrid energy storage frequency regulation is proposed based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and considering lithium battery degradation model. Firstly

the area control error (ACE) signal is decomposed and reconstructed by CEEMDAN to determine the capacity configuration scheme under different reconstruction strategies. And then

the net benefit value model of whole life cycle is built based on the semi-empirical degradation model of lithium battery

and the economic evaluation of capacity configuration scheme under different reconstruction strategies is carried out to obtain the optimal capacity configuration scheme. Finally

the effectiveness and economy of the proposed capacity configuration strategy are verified by ACE data of a typical day of a regional power grid.