Research On Optimal Capacity Allocation Of Electrothermal Gas Coupled Microgrid Based On Hydrogen Energy

With the depletion of fossil energy and environmental pollution becoming increasingly prominent,it has attracted extensive attention to construct multi-energy coupling,low-carbon,flexible and efficient micro-grid.Hydrogen energy has the advantages of low carbon,environmental protection,flexibility and efficiency,wide range of sources and uses,etc.With the continuous development of technologies such as electrolytic water hydrogen production,hydrogen fuel cell,hydrogen methanation and natural gas pipeline hydrogen doping,hydrogen energy has gradually become a coupling link between electric power,gas and thermal energy systems.It needs to be intensively researched on the optimal allocation of electrothermal gas coupling micro-grid structure and capacity based on hydrogen energy,due to the uncertainty of wind power generation and electric load,the high cost of electrolytic water hydrogen production and hydrogen fuel cell electricity generation,and the complex coupling relationship between electricity,heat and gas.What is studied in this paper is the electrothermal gas coupling microgrid structure based on hydrogen energy,the uncertainty of wind power and electrical load,and the optimal capacity allocation.The specific research contents are as follows:(1)Combined with the electric-thermal conversion function of electric boiler and ORC and the electrothermal gas coupling characteristics of hydrogen energy storage system,an electrothermal gas coupling micro-grid structure based on hydrogen energy is proposed.The mathematical model of the electric-heat conversion element in the micro-grid was established,and the waste heat recovery system structure of electrolytic cell and hydrogen fuel cell,and the thermoelectric coupling system structure including ORC were built,which both laid a foundation for the research of capacity optimization allocation.(2)Considering the uncertainty of electrical load and wind power output,a typical day selection method of electrical load and wind power output based on ordered clustering and fuzzy C-means clustering is proposed,using small probability events to remove abnormal data or extreme scenes.Membership function has been used when extracting the daily load curve trend and peak-valley period information.The electrical load scene extraction model is established based on the ordered clustering and the improved inter-class and intra-class division index,and the typical day of electrical load under each scene is estimated by combining the average method.In order to ensure the timing of typical days of wind power and electrical load,the typical days selection model of wind power output is established based on fuzzy C-means clustering and inter-class and intra-class division index within the effective time of electrical load.(3)An optimal allocation model of electrothermal gas coupling micro-grid capacity based on hydrogen energy is established under comprehensively considering wind curtailment rate,economy efficiency,reliability and environmental benefits.With the minimum annual total cost taken as the optimization objective,and the power balance constraints,constraints of equipment capacity,equipment operation,hydrogen storage system and natural gas pipeline taken into consideration,the optimization model is constructed,and the corresponding mixed integer linear programming problem is obtained.An evaluation index characterizing the efficiency,reliability and environmental benefits of micro-grid is proposed to evaluate the micro-grid performance.Finally,with the actual data of an industrial park taken as an example,the MATLAB platform has been used to invoke the YALMIP toolbox to solve the problem and carry out the sensitivity analysis,which has verified that the proposed method can effectively reduce the total cost of micro-grid,reduce carbon emission and improve the comprehensive efficiency.