Study On Optimization And Performance Of Multi-renewable Energy Complementary Distributed Co-production System

The energy demand in rural areas is increasing,but the energy utilization efficiency of its traditional energy supply is low,and the energy consumption structure still shows the characteristics of high carbon and non-clean,which is not conducive to China’s energy-saving planning and the realization of the goal of"double carbon".Renewable energy is a widely distributed clean energy in rural areas,so it is imperative to explore its efficient energy supply technology.Single renewable energy has a bottleneck in technological development because of its inherent nature,and the multi-renewable energy complementary distributed energy system can not only overcome the instability of single renewable energy,but also achieve efficient and clean energy supply.Therefore,this paper takes 50 new rural buildings in Lanzhou area of Gansu Province as the object.Firstly,the hourly heat and power load of users is calculated by De ST software.According to the load characteristics,resource endowments and technical characteristics,a multi-renewable energy complementary co-production system is proposed,and the energy,economic and environmental evaluation indexes are constructed.Secondly,a multi-objective optimization model is established based on Matlab platform,and an improved non-dominated sorting in genetic algorithm is used to solve the optimization model.The optimal capacity allocation of the system is determined by using the entropy weight-technique for order preference by similarity to ideal solution.Finally,the operating status and annual performance of the optimal capacity allocation system are analyzed,the performance of the system with different operating strategies is compared,the sensitivity of each performance index to the changes of technical and economic parameters is analyzed,and regional adaptability is studied.The conclusions are as follows:(1)The electricity load of rural residential buildings basically does not fluctuate with the season,but it will change frequently within one day,and the cumulative electricity load of the whole year is 85472.05kW·h.The domestic hot water load is relatively stable in the whole year,and the total heat load in the heating season is much larger than the electricity load,and the cumulative total heat load in the whole year is 3.89×10~5kW·h.(2)The weights of primary energy saving rate,annual cost saving rate and carbon dioxide emission reduction rate obtained by entropy method are 0.7,0.21 and 0.09 respectively.The final result of entropy weight-technique for order preference by similarity to ideal solution is that the system is equipped with 405 photovoltaic-photothermal integration component and 30kW internal combustion units.The system has good performance in energy,economy and environment.(3)The primary energy efficiency of the co-production system is 32.02%,and the primary energy saving rate is 33.85%.The annual cost saving rate is 45.71%,the investment payback period is 6.08 years,and the net present value is 2.4057 million yuan.The annual carbon dioxide emission reduction is 542.67 tons,and the carbon dioxide emission reduction rate is 75.3%.It shows that the system is economically feasible and can realize efficient and clean energy supply.(4)When the co-production system implements the operation strategy of following the thermal load in heating season heat following,anaerobic and fermentation system and biogas internal combustion engine not running in non-heating season,the annual cost saving rate and carbon dioxide emission reduction rate of the system are reduced to 28.61%and 73.01%.In order to improve its economic and environmental performance,the anaerobic fermentation system and internal combustion engine cogeneration system should be fully utilized to reduce the idle rate of the equipment.(5)Hydraulic retention time is the technical parameter that affects the annual cost saving rate of the system most,and the thermal efficiency of soil stove is the technical parameter that affects the primary energy saving rate and carbon dioxide emission reduction rate of the system most;the price of biogas slurry and cow dung is the operation economic parameter that affects the economic performance of the system most,and the unit cost of anaerobic reactor is the cost economic parameter that affects the economic performance of the system most.In order to promote the popularization and application of co-production system,the anaerobic fermentation system with high conversion efficiency of biogas should be selected as far as possible and the government subsidy policy for biogas project should be paid close attention to.In order to promote the popularization and application of co-production system,the anaerobic digestion system with high conversion efficiency of biogas should be selected as far as possible,and the government subsidy policy for biogas projects should be paid close attention to.(6)When the system is used in the hot summer and cold winter area of Nanjing,equipped with fewer photovoltaic-photothermal integration component and air source heat pump,it can not only meet the user load,but also obtain relatively better energy,economic and environmental benefits.The economic benefit of the system applied in Nanjing is better than that in Lanzhou,and the payback period of investment is shortened to 4.11 years.The research results show that Multi-renewable energy complementary co-production system can not only realize the local consumption and efficient utilization of renewable energy to meet the various energy needs of users,but also improve the rural ecological environment,so as to achieve the coordinated and sustainable development of rural energy,resources and environment.