In order to improve the inertia of the DC microgrid with wind/energy storage

the back stage converter control strategy of the wind turbine based on virtual DC generator（VDG） is proposed in this paper. A small-signal model of DC microgrid with wind/energy storage is established and an expression of impedance ratio under the charging and discharging modes of battery is obtained. In the range of the moment changes of inertia

some typical values are substituted into the impedance ratio expression for calculation and analysis to reveal that the basic characteristics of mircogrid and the influence of the moment of inertia on stabilization of DC microgrid. In order to minimize the deviation values of the bus voltage and system dynamic response time

the particle swarm optimization solution algorithm（PSO） and flow chart are proposed

and then the optimal moment of inertia is obtained. Simulation results under different working conditions show that the control strategy in this paper can not only improve the system inertia on maximum power point（MPPT） and load power tracking（LPTC）

but also minimize the fluctuation of DC bus voltage when the load and wind speed change and the optimal operation of this system can be realized

thus the correctness and feasibility of the proposed control strategy are verified.