Restricted by natural conditions， the outputs of renewable energy generation is stochastic. If renewable energy generator unit is connected to a public grid directly， it may cause instability of power grid. Taking wind power as an example， the renewable energy is used as charge power supply for superconducting magnetic energy storage（SMES） systems. SMES devices have such advantages as high efficiency， fast response and good capability of exchanging active and reactive power independently. SMES can regulate outputs on time according to load changes to stabilize fluctuation of frequency and reduce unnecessary power flow among tie lines. Simulation results prove that SMES can improve frequency effectively and inadequate spinning reserve issue.