Research On Battery Operation Strategy And Capacity Optimization Of Building Photovoltaic Energy Storage System

Building photovoltaic energy storage system s are widely used in net/nearly zero energy buildings.As a typical energy storage technology,the battery can directly store electric energy and adjust the balance between supp ly and demand.Appropriate battery capacity and operation strategy can improve the system’s technical-economic characteristics and self-consumption ability.However,there are still some problems in the research of battery capacity optimization,such as ig noring battery aging,challenges in solving the model,and poor operation strategy.As for the current lack of research,considering the effect of battery degradation on the system operation,a new optimization method and a novel operation strategy are pro posed to optimize battery capacity for building photovoltaic energy storage system s.The primary study and conclusions are as follows:Firstly,considering the effect of battery degradation on the operation of the system life cycle,the photovoltaic power generation model and battery energy storage model are built.According to the system evaluating indicators and constraints,a mixed integer nonlinear programming model is employed to optimize the capacity and operation of battery.Secondly,based on the mixed integer nonlinear programming model,a new t wolayer optimization method is proposed to optimize the battery capacity and system operating.The life cycle costs and self-consumption ratios with and without battery degradation are compared when the feed-in tariff is flat and time of use,respectively.The effects of different feed-in tariffs,feed-in limits,and PV degradation on optimization are analyzed.The results show that the proposed two-layer optimization method is effective,and ignoring battery aging can lead to the non-optimal battery capacity and underestimation of life cycle cost.Thirdly,to solve the problem of high computation cost of the mixed-integer nonlinear programming model,considering the function of self-consumption improvement,peak shift,and price arbitrage,a new operation strategy that is MF strategy,is proposed.The optimization results based on the MF strategy are compared with that based on the mathematical programming model and SCM strategy.In addition,based on the MF strategy,the influence of parameters on system performance is studied by applying local sensitivity analysis and global sensitivity analysis.The results show that MF strategy h as a low calculation cost and can achieve good performance in building photovoltaic energy storage system.Finally,to further analyze the differences of different operation strategies applied to battery capacity optimization,the single-objective optimization results of battery based on SCM strategy,TOU strategy,MF strategy,and the mathematical programming model under different feed-in tariff and building load are compared.Besides,the pareto fronts of multi-objective optimizations based on SCM strateg y,TOU strategy and MF strategy under different cases are compared.The results show that the mathematical programming model has the best economy,and among the three rule-based operating strategies,the MF strategy has the best economy.Considering the effect of battery degradation on system operation,a new two-layer optimization method is proposed to optimize the battery capacity and system operating of building photovoltaic energy storage system.This method tackles the complex problem of solving the model.In addition,a new system operation strategy proposed,which simplifies the system operation optimization and reduces the calculation cost of battery optimization,can achieve good performance of photovoltaic energy storage system.