The Research On DC Micro-grid Optimization Control Strategy And Energy Management

At present,the main sources of new energy in China are photovoltaic power generation and wind power generation.However,the instability of power generation caused by external factors poses a great challenge to the utilization of new energy.With the development of micro-grid technology,these problems have been solved effectively,and the process of human being to enter into "digital society" is the process of increasing DC load,and the solar power generation is direct current.Therefore,the research on DC micro-grid is increasing day by day.At the same time,it is found that the photovoltaic power generation is easy to be disturbed by the external environment,which will lead to the phenomenon of light abandonment.The shortcomings of traditional storage devices such as small capacity and short storage time are increasingly prominent.The combination of hydrogen energy with clean energy can effectively solve the problems of light abandonment and energy storage in photovoltaic power generation.The production of hydrogen requires directly current electrolytic water,while hydrogen can be stored in large quantities because of its high density and large capacity,which solves the problem of photovoltaic power storage.In this paper,the energy of DC micro-grid system based on hydrogen production environment is managed and controlled reasonably,the operation efficiency of DC micro-grid is improved,and the stability and reliability of the system are enhanced.In this paper,firstly,mathematical analysis and modeling of photovoltaic cells in DC micro-grid system are carried out,and three working modes of photovoltaic cells,such as: MPPT mode,CVC mode and shutdown mode,are determined.In addition,the model and external characteristics of the battery are analyzed for the energy storage unit in the system,and a control strategy is proposed to control the charge and discharge of the battery according to the combination of the charge and discharge current from the battery and the charged state of SOC.Three working modes of battery are determined,such as,charging mode,discharge mode and cut-off mode.Secondly,according to the system characteristics of this paper,the DC bus voltage control strategy is adopted.Six modes of energy supply and demand are put forward to manage the energy in DC micro-grid system.According to the strategy of DC bus voltage stratified control,the photovoltaic subsystem and energy storage subsystem are coordinated to realize the stability of bus voltage.Finally,the simulation model of DC micro-grid system is established under the PSCAD environment,according to the DC bus voltage stratification control strategy,the DC micro-grid system operates efficiently and stably when the energy supply and demand change,at last,the simulation model of DC micro-grid system is established under the PSCAD environment.The maximum power point tracking of photovoltaic array,battery SOC,charge / discharge current and system operation mode are verified by simulation.The results show the feasibility and effectiveness of DC micro-grid operation and energy management mentioned in this paper.