Large-scale grid-connected new energy will cause great fluctuation of power system and even endanger the stability of it. Energy storage technology with reasonable control logic can balance the fluctuating power and enhance the stability of power system. By using constant power control, a hybrid generation system including wind, solar and lithium batteries is proposed in this paper to overcome the uncertainty in the output power of new energy. Perturbation and observation method is employed to track the maximum power point of photovoltaic (PV) array and wind turbine, electric vehicle (EV) energy storage system with bi-directional DC-DC control logic is conducted to constantly adjust the unbalanced power. Voltage source converter (VSC) with d-q decoupling control is used to maintain the DC bus voltage. The simulation results of Simulink verify the feasibility and effectiveness of the proposed system.