Optimization Of Community Distributed Cogeneration System Configuration

Compared with the traditional separate generation of cooling heating and electricity system,the distributed energy system has obvious advantages in economy,energy consumption and environment related issues,such as improving the comprehensive utilization rate of energy,reducing carbon emissions.It also has great significance in promoting the adjustment of energy structure,energy conservation and the pollutants emissions reduction.With the increasing of energy crisis and the increasingly prominent environmental problems,more and more attention has been paid to the use of renewable energy sources.It is difficult to rely on renewable energy alone to ensure the stability and reliability of energy supply.If we use the non-renewable energy together with the renewable energy,and give full play to the complementary of the two types of energy,the reliability and stability of power supply can be realized and improve the sustainability of the system at the same time.In this paper,a community building in Jinan was choosen as the research object.Based on the analysis of the load characteristics and the external application conditions,combined with the price of local electricity and natural gas,equipment load rate,the community distributed energy supply system is optimized by the comprehensive index of economy,environmental protection and eneygy saving,then the optimal configuration scheme was given.The design principle,the scheme of configuration and the corresponding operation strategy of the energy supply system are affected by the hourly data of the cooling,heating and electricity loads.In order to predict the hourly load of the building in the cooling and heating season,firstly,using the Transient System Simulation Program(TRNSYS)to build the building model.According to the function and the orientation of the room,the building was divided into different hot zones,to simulate the annual hourly cooling and heating load of the building.The hourly electrical load of the building is predicted by the area index combinedwith the hourly opening rate of the electrical equipments.Then take the energy status quo,the energy structure adjustment policy in China as well as the energy conservation and emissions reduction targets into consideration,eventually determine to adopt the renewable and non-renewable energy combined distributed energy supply system,that is,the natural gas trigeneration system and solar photovoltaic power generation system composite system.The CCHP system consists of internal combustion engine,LiBr absorption chiller/heater,photovoltaic(PV)array etc..The PV system and the gas CCHP system can provide the required cooling,heating and electricity for the community building.The system adopts the grid connected operation mode,when the electricity generated cannot meet the needs of the users,the insufficiency is supplemented by the power grid.Waste heat utilization device is the gas-hot water operated LiBr absorption chiller/heater.When the system was determined,considering the cost saving,energy saving and environmental protection,the multi-objective evaluation index was proposed,based on the annual total cost savings rate,the primary energy efficient rate and the carbon dioxide emission reduction rate which were given the same value 1/3.Take the multi-objective evaluation index as the optimization objective function,and the internal combustion engine capacity as the optimization variable,using the optimization algorithm to find the optimal capacity configuration and the corresponding operation strategy of the system based on the load characteristics.On this basis,change the weight coefficient of each evaluation index to analyze the influence of different evaluation index weight coefficients on the system capacity optimization and comprehensive performance.Finally,the whole system is simulated by TRNSYS.Because the TRNSYS built-in modules library does not contain gas-hot water operated Li Br absorption chiller/heater module,based on it's theory knowledge,the gas-hot water operated LiBr absorption chiller/heater module that can be used in the TRNSYS was established.Then the simulation results was analyzed and compared with the traditional cooling,heating and electricity separate supply system.