Research On Coordination Control Strategy Of DC Microgrid Based On Multi Microsource

Energy is important basic natural resource of human existence,economic development,and society progress.As the most convenient form of energy,electricity is the lifeline of national economic development,but the traditional fossil energy has been increasingly depletion,and caused great environmental pollution.DC micro-grid has been received more attention with the advantages of without regard to the frequency and phase,reactive power and simple control structure.In this paper,a DC micro-grid with solar energy,wind energy and hybrid energy system has been studiesd and a energy management strategy based on real-time active power control has been proposed.Then main contents are as follows:First,a DC micro-grid comprising photovoltaic cells(PV),wind turbine with permanent magnet synchronous generator(PMSG),supercapacitor,battery and local load is introduced in this paper,and it can operate in grid-tied or islanding mode according to the different operation status of DC micro-grid.Besides,the transition logic between different operating states have been designed respectively for the local control of each distributed energy source,hybrid energy storage composed of super capacitor and battery,local load and Utility Grid in order to achieve the modes smooth transition of the whole micro-grid,which finally ensure the real-time power balance of micro source,storage system,load and Utility Grid.Second,in view of the disadvantages of the traditional MPPT control strategy,such as slow tracking speed and power fluctuation,this paper presents a MPPT control strategy for PV based on the observation disturbance method of variable power.The perturbation step changes according to the output power of the photovoltaic cell,and the simulation results show that the control strategy is superior to the conventional perturbation observation method(P&O).Finally,aiming at the problem of bus voltage fluctuation frequently and the fluctuation range is large for traditional coordination control based on dc bus voltage signal(DBS)in DC micro-grid,thus,on the one hand,it reduces the power quality of the power grid and on the other hand,it may cause frequent switching between the various operating modes of the system,and reduce the stability and reliability of the system.A new coordination control strategy based real-time power for DC micro-grid has been proposed and the difference between distributed energy output power and load power is designed to regulate the direction of battery charge/discharge,the size of power,and the operation mode of micro-grid and Combined with the super capacitor SOC size to determine the hybrid storage control strategy.which ensure the real-time power balance in micro-grid.The Matlab/Simulink model show that this method is effective and feasible.