It is easy to be influenced by randomness and intermittent for wind power outputs meeting the requirements of connecting into the power grid. Equipping suitable energy storage devices in wind farm can not only smooth the output power fluctuation, but also achieve economic benefit. A novel time-frequency analysis based on the variational mode decomposition and Hilbert transform(VMD-Hilbert) was put forward in this paper. First, VMD was used to decompose the HESS reference power which was derived by moving average, and a series of band-limited intrinsic mode functions(BLIMFs) were obtained. Then each BLIMFs was processed by Hilbert transform and the marginal spectrum of each BLIMFs was calculated. It effectively avoided modal aliasing effect compared with traditional HHT. Finally, the so-call gap frequency was identified by marginal spectrum and then high and low frequency components were distributed to super capacitor and battery. Taken economic cycle cost into account, results demonstrate the proposed method is rational and economically efficient, thus it provides a new way of energy storage configuration in renewable energy generation.