| Renewable energy as a new type of energy plays an extremely important role in today's world,but it has very obvious problems that always hinder its development,and DC microgrid technology provides technical solutions for various new types of renewable energy.Compared with AC microgrid,DC microgrid does not need to consider the impact on the system when reactive power and frequency changes.The independent DC microgrid balances the power of the system by coordinating various renewable energy and energy storage units in the control system,and finally makes the independent DC microgrid run stably.With the increasing demand for energy from countries around the world,the depletion of fossil energy and environmental issues have attracted the attention of countries around the world,thereby promoting the development of new energy power generation technologies at home and abroad.Based on the requirements of independent DC microgrids,this paper studies the coordinated control and capacity optimization of independent storage and charging of independent DC microgrids.First,the topological structure of an independent DC microgrid with optical storage and fuel charging is researched,with various loads in the system and distributed power generation as the goal.The basic composition of the DC microgrid is determined,including photovoltaic,fuel cells,hybrid Energy storage(batteries and supercapacitors)and electric vehicles.According to the characteristics of each unit in the system,each mathematical model is established,and the corresponding simulation model is established in Matlab.Secondly,the control strategies of photovoltaic,hybrid energy storage,fuel cell and electric vehicle units are studied.Among them,for the photovoltaic output characteristics,a reasonable control method is adopted to achieve the purpose of maximum output.This paper compares the adaptive variable step size incremental conductivity method with the traditional photovoltaic MPPT control.As the photovoltaic output is greatly affected bythe environment,bidirectional DC / DC is used in the system to control the supercapacitor and the battery to finally smooth the power fluctuations in the system.The control of fuel cells by adopting an adaptive virtual DC generator control method can increase the service life of the fuel cells to a certain extent;for electric vehicles,constant current and constant voltage charge and discharge control methods are used to achieve the power output and absorb.Then,the coordinated control strategy of an independent DC microgrid with optical storage and fuel charging is studied.By adopting reasonable control methods,7 working modes are established,and the appropriate working mode is selected according to the use status of each module in the system,and when the load and photovoltaic output in the system change,the fluctuation of the bus voltage can Keep the system stable within a reasonable range.Finally,for an independent DC microgrid system consisting of photovoltaics,supercapacitors,batteries,and fuel cells,a DC microgrid capacity allocation model is established,and a particle swarm algorithm based on simulated annealing is used to solve the target model to meet the load in the system The power requirements and configuration results can meet the system's power supply reliability and economy. |
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