Research On Operation Of Solar-Battery-Charge DC Micro Grid System

With the development of the world economy and industry,the contradiction between economy,environment and energy is also very prominent.When General Secretary Xi talked about environmental issues,he pointed out:"We need green mountains and green mountains and gold mountains and silver mountains.We would rather green mountains and green hills than gold mountains and silver mountains,and green mountains and green mountains are the Jinshan silver mountains."Therefore,reducing the dependence of industrial and economic development on fossil energy is an effective way to solve this problem.The cleanliness and regenerability of photovoltaic power generation,the flexibility of electric vehicles and the characteristics of V2G,coupled with the rapid development of energy storage technologies and charging technologies,research on optical storage charging stations has become a hot spot,compared to AC microgrids,DC micro Due to the advantages of simple control and few influencing links,the grid has attracted attention from domestic and foreign scholars.This topic focuses on the structure,operation,and coordination of the light-storage-charging-DC microgrid.Firstly,this paper designs the structure of the light-storage-charging DC microgrid,and analyzes the characteristics of each module,including photovoltaic power generation units,hybrid energy storage units composed of batteries and super capacitors,and electric vehicle charging units.The bidirectional DC/DC topology used by each module to access the DC microgrid was analyzed and the conduction state was analyzed.Secondly,this paper designs a hybrid energy storage coordination control strategy for storage batteries and super capacitors,and designs high-pass,band-pass,and low-pass filters to make the bus capacitance respond to high-frequency power fluctuations in DC microgrid systems,respectively.Supercapacitors respond to DC power grids.In the medium-frequency power fluctuations,the battery responds to low frequency power fluctuations in the DC microgrid,which improves the stability of the DC microgrid.And use Matlab/simulink for simulation verification.Then,the coordinated control strategy of DC micro grid is designed,and the control flow chart is drawn.The control mode and the switching of each module at different voltage levels are designed,including the MPPT and CVC of the photovoltaic,the mixed energy storage of the battery and the supercapacitor to control the stable parent line voltage,the droop control of the battery and the constant current charge and discharge of the electric vehicle.A communication mode based on bus voltage signal is used to judge the operation mode of each module,so as to ensure the stable operation of DC microgrid.The hierarchical frequency division control of the whole DC micro grid system is modeled and simulated in Matlab/simulink,and the feasibility of the control method is verified.Finally,the experiment platform of light storage and charge DC microgrid is built in this paper.The feasibility of the hierarchical control proposed by this topic is verified by changing the switching of the resistance load on the DC bus and the output power of the photovoltaic power unit.