| With the implementation of the Carbon Peaking and Carbon Neutrality strategy,the trend of energy structure transformation with clean energy as the mainstay has been formed.Integrated energy supply system is the most important development direction,which couples multiple energy resources in the region,and through coordinated planning,interactive response and collaborative management among heterogeneous energy sources,it can efficiently meet multiple energy demands.In recent years,the integrated energy supply system based on carbon dioxide has started to receive attention.It is easy to integrate advanced energy technologies in the system and realize the integrated energy gradient utilization and deep utilization of waste heat within the system,which has the significant advantages of integrated heating and cooling,high efficiency,environmental protection and zero carbon emission.In order to promote the application of the integrated energy supply system based on carbon dioxide,it is necessary to deeply analyze the working characteristics and operation mechanism of each energy conversion technology equipment inside the system,and combine the quantitative characterization of energy resources and demand to reveal the efficient coupling mechanism of multiple energy resources,and evaluate the cost reduction and large-scale promotion potential of this energy supply system.Therefore,the paper proposes to conduct a study on the optimization of integrated energy systems based on CO2 networks,which is divided into the following three aspects.(1)The model construction of the integrated energy supply system based on CO2 network.It includes the following modules:CO2 heating and cooling network,CO2 state conversion,renewable energy power supply,electricity to gas(P2G)technology,and energy storage module.The operating characteristics of the energy conversion technology equipment and its energy flow connections in each module are analyzed and mathematically modeled separately,such as heat pumps,heat exchangers,photovoltaic panels,solid oxide fuel cells,and solid oxide fuel electrolysis cells.(2)Quantitative characterization analysis of energy resources and energy demand.Based on the horizontal irradiation intensity data and other light-related parameters,the annual time-series tilted surface irradiation intensity is calculated.A multi-subject modeling approach is used to predict the energy demand of a residential community in Beijing,and the Monte Carlo method is used to obtain the annual time-series electricity,heat and cooling demand with uncertainty.Finally,the k-means clustering method is used to extract typical days with energy resources and end-use demand as the characteristic variables,and eight typical days that can represent the whole year are obtained.(3)Analysis of integrated optimization results of integrated energy supply system based on CO2 network.The mixed integer linear programming model is constructed to optimize the system capacity allocation and operation strategy with the lowest total cost,lowest investment cost and lowest operation cost as the objective functions,respectively.With the lowest total cost as the objective function,the system efficiency reaches 92%,and the total annual cost is 70%to 85%of the remaining objective functions.With the lowest investment cost as the objective function,the system increases the capacity of heat pumps in the heating and cooling network,and can directly meet the cooling and heating needs of customers without additional heat utility projects.When the lowest operating cost is the objective function,the renewable energy generation reaches 58%of the total generation capacity,and the electricity-togas technology with larger capacity is configured to consume renewable energy well. |
