| With the continuous development of microgrids and the improvement of DC load ratio,low-voltage DC microgrids based on energy storage devices have received widespread attention.In DC microgrid systems,DC type units such as photovoltaics and energy storage devices can reduce the use of inverters and improve conversion efficiency.However,in low-voltage DC microgrid systems,there are problems such as large fluctuations in renewable energy output and high light rejection rates.On the premise of meeting the load demand,reasonable configurations of photovoltaic installed capacity and energy storage capacity,improvement of renewable energy consumption rate and improvement of operational economic benefits are key issues currently being studied.This article focuses on the optimization of the low-voltage DC microgrid based on energy storage devices,proposes a capacity allocation method based on photovoltaic multiple output scenarios,establishes an optimal operation model for low-voltage DC microgrid systems that takes into account the service life of energy storage,and uses the multiobjective gray wolf algorithm to iteratively optimize,improving operation economy,reducing system carbon emissions,and improving the service life of energy storage.The main research contents are as follows:Firstly,this paper analyzes the operation optimization of microgrids at home and abroad,expounds the research status and application of energy storage technology in DC micro grids,introduces the structure of low-voltage DC micro grids,analyzes the output characteristics of each unit in the system,and expounds the relevant influencing factors and constraints on the output of each unit.Secondly,an evaluation method for energy storage technology selection based on principal component analysis was established to analyze the adaptability of energy storage in low-voltage DC microgrid.Through processing the relevant index parameters,calculating the characteristic values to find the principal components,forming data dimensionality reduction and scoring,the optimal energy storage technology selection scheme is obtained.Then,research is conducted on the capacity allocation method of the low-voltage DC microgrid.The K-means clustering algorithm is used to cluster the annual output of photovoltaic power,and four typical days of photovoltaic power and corresponding probabilities are obtained.On the basis of different typical days,considering the different operating states of the grid-connected converter,the system operation mode is divided,the annualized total investment cost of the system is the lowest as the objective function,the constraints such as energy storage charge and discharge power,load loss rate and other constraints are set,and the artificial bee colony optimization algorithm is used to solve the problem,and the capacity configuration results of each unit in different operating modes of the system are obtained,and the comparison and analysis are carried out.Finally,aiming at the problems of economy,low carbon and energy storage service life in DC microgrid,an optimal operation model of the low-voltage DC microgrid considering the service life of energy storage is established,and the model includes units such as photovoltaic,grid-connected converter,energy storage and user load.Taking the maximum daily net return,the smallest battery equivalent charge and discharge amount and the smallest carbon dioxide emission as the objective functions,the constraints such as power balance and energy storage state of charge are set,the optimal Pareto solution set is obtained according to the multi-objective gray wolf algorithm iteratively optimized,and the optimal solution is obtained by the TOPSIS algorithm,which realizes the economic and low-carbon optimal operation of energy storage under the low-voltage DC microgrid system,and improves the service life of energy storage. |
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