Study On Optimization Design Method Of The Nearly-Zero Energy Community Energy System With Multi-Energy Storages

Multiple energy storage could improve the utilization capacity of renewable energy and enhance the comprehensive benefit of distributed energy systems.Therefore,the distributed energy system with multiple energy storage had enormous development potential.It could satisfy users’ various load demands,suppressing intermittent and volatility of clean energy output,and improve the overall benefit level of the distributed energy system.The main contents and conclusions of this paper are as follows:First,the variable condition thermodynamic model of the distributed energy system with multiple energy storage was established.The building energy simulation software was used to obtain the load characteristics of a nearly-zero energy community consisting of nearly-zero energy residential,office,and school buildings in a typical year.A distributed energy system with multiple energy storage was constructed lithium battery,water tank,and cold storage tank as the energy storage equipment.For the system,a two-stage collaborative optimization method was proposed to optimize the configuration of the core equipment of the system in the first stage and optimize the energy storage capacity in the second stage.The optimization results,typical daily energy balance,system energy efficiency,and economics when the system supplies energy to a nearly-zero energy community were analyzed and discussed.The results show that compared with the separated production system,the primary energy saving rate of the distributed energy system with multiple energy storage was significantly improved under the system,hybrid and municipal grid operation modes.Then,a distributed energy system with hybrid energy storage was constructed,which combined lithium batteries,supercapacitors,and water tanks.The operation strategy of the low-pass filtering principle or sliding filtering principle combined with secondary feedback adjustment of supercapacitor state of charge was proposed for hybrid energy storage.For the system,aiming at the economy,energy-saving,and environmental friendliness,a two-layer nested collaborative optimization method was proposed for the upper layer optimize the rated power of the core equipment,and the under-layer optimizes the composite energy storage capacity.The system’s optimization results,typical daily energy balance,energy efficiency,economy,and environmental protection in the nearly-zero energy community scenario were analyzed.The results show that compared with the separated production system,the distributed energy system with hybrid energy storage does not increase the annual cost and could effectively improve the system’s primary energy-saving rate and pollutant emission reduction rate.Finality,a distributed energy system with new energy storage was constructed,which combined two new operation modes of power-to-heat and power-to-cold.A two-layer collaborative optimization method was proposed for the equipment configuration of the upper-layer and energy storage operating parameters of the under-layer.The effects of NSGA-II population size and iteration times and total iteration times on the two-level collaborative optimization method’s optimization results were investigated using the parameter analysis method.Analyzed and discussed the comprehensive benefits of the system in terms of economy,energy saving,environmental friendliness,independence,and reliability in a nearly-zero energy community scenario.The sensitivity analysis of electricity price,gas price,solar irradiation intensity,and municipal grid CO2 emission factor was carried out to study the influence of the above critical parameters on the comprehensive benefit of the distributed energy system with new energy storage.The two-layer collaborative optimization method can effectively solve the problem of balancing the accuracy of optimization results and the calculation time.