With the increasing capacity of grid-connected wind power generation， the influence of wind farm power fluctuation on the grid becomes more and more serious. To improve the stability of grid-connected wind farm and regulate the grid-connected power effectively， a new type of environment-friendly vanadium redox flow battery（VRB） energy storage system（ESS） is equipped at the outlet of wind farm. According to the equivalent circuit model of VRB， the change characteristic between the state of charge（SOC） and terminal voltage is analyzed. One-stage bi-directional DC/AC converter is used as the power regulator of VRB energy storage system， and the corresponding control and energy management strategy is developed. The grid-connected wind farm with VRB energy storage system is established and simulated. The simulation results show that the active power fluctuations of wind farm are effectively smoothed under the varied wind， thus the certain reactive power can be provided to system and the operating performance of grid-connected wind farm is improved.