Multi-objective Optimization And Sensitivity Analysis Of Distributed Energy System

The distributed energy system(combined cooling heat and power,CCHP)is a cascade utilization technology of energy.It can improve energy utilization efficiency,shift the peak load,relief the tension status of power,reduce energy consumption.In recent years it has been paid more and more attention because of the advantages of efficient,flexible,clean and reliable.While it is difficult to CCHP design for an accurate match between the load,and the cooling,heat and power supply.Moreover,in China the manufacturing level is fall behind,and the experience is lack in design,management,operational control and so on,and the policies and regulations is also imperfect,all of above the distributed energy system is limited to be applicated large-scale in China.Based on the problems of the accurately load match and the terrible economy,a distributed energy system consists of gas engine,absorption chiller,electric heat pump and energy storage is numerically studied based on the summer load demand of an office building and a hotel building in Tianjin.It is modeled with the method of three-dimensional and two-dimensional.The operating cost was selected as objective function,the model considered the carbon emissions,carbon tax and the electricity buy-back from on-site(the surplus electricity out of the CCHP system can be sold back to the grid when the generated power exceeds local demands),and analyzed the difference of three-dimensional and two-dimensional model.Then the optimization model with the objective of operating cost saving ratio,carbon emission reduction ratio and primary energy saving ratio by comparing with the conventional system,is conducted in this paper.Aimed at the optimization models,firstly,the author analyzed the influence of the convert coefficient of adding carbon tax to electricity price on the distributed energy system,the results showed that the distributed energy system bring out better economic benefit when the carbon tax added to the electricity price entirely because the environment of the distributed energy is better;Then regarded the operating cost as the objective through comparing the economy of the distributed with traditional coal-fired power plant system,analyzed the economy of the different strategies on the distributed energy system from supply side and demand side respectively,and conducted a sensitivity analysis on carbon tax value and gas price,reached that the economy of the distributed energy system is better than purchasing electricity from the grid,the biggest cost saving is 16875 yuan(office building)and 22106 yuan(hotel building)respectively,the energy storage have positive influence to the economy of the distributed energy system,also obtained the best control field and the relation of carbon tax value and gas price that have better economy on distributed system.Finally,the multi-objective analysis of distributed energy system,is carried out to reached thebest operation strategy which has the best comprehensive properties,compared with the convention system,the results show that when supply the energy for office building(hotel building)by the distributed energy system,the operating cost saving ratio,carbon emission reduction ratio and primary energy saving ratio are(13.70%),63.89%(66.84%),28.57(28.75%),through the comparison of the three indexs,reached the relations among operating cost saving ratio,carbon emission reduction ratio and primary energy saving ratio.