Modeling And Simulation Of Distributed Cogeneration System Based On Gas-Air Combined Cycle

Combined Cooling,Heating and Power system can realize cascade utilization of energy and achieve higher primary energy utilization rate.Compressed air energy storage technology can store electric energy and realize "peak cutting and valley filling"for power grid.In this dissertation,a new type of coupled cycle system was proposed and studied by combining these two technologies.The system could adjust the ratio of cooling,heating and power flexibly,and had high thermal efficiency under various working conditions.It also made full use of the peak-valley price difference of electric energy,so it had good economy.Firstly,the new gas-air combined cycle system was designed and the initial parameters were set,and the appropriate system assumptions were put forward.GateCycle simulation platform was used to model the key modules of the system,while other components were modeled by some general methods.Then,GateCycle software was used to simulate and analyze the component characteristics and energy supply characteristics of the distributed combined cooling and heating power system under three typical working environments,including the off-design and rated operation characteristics of gas turbine,the off-design operation characteristics of waste heat boiler,the off-design operation characteristics of air turbine,and the rated operating characteristics of the compressor.In the process of decreasing power generation from rated value,the power generation efficiency of gas turbine decreased gradually,and the gas turbine outlet flue gas temperature decreased gradually,which led to the decrease of primary energy utilization rate and the gradual decrease of heat grade of exhaust gas.Therefore,the gas turbine should be operated at rated condition as far as possible in order to obtain the optimal energy utilization efficiency and economy.The gas-air combined cycle system was simulated and three energy supply modes were proposed.The three energy supply modes were used to supply energy under three typical operating environments of an industrial park and a hotel in Shanghai based on the principle of using the operation mode with high energy-price ratio as far as possible.The system operation strategies of the second energy supply mode and the third energy supply mode in different working hours of three typical working days were designed.The running cost of the three modes were calculated and the third mode had the lowest operating cost,the second had the second cost,the first had the highest cost.Further,the variations of the converted energy supply capacity and the energy-price ratio of the system in different seasons with the different operating conditions(i.e.the shunt ratio of the high temperature flue gas distributor)was studied when the energy efficiency ratio floats,and the curve was drawn.For each season,when the shunt ratio to the heat exchanger was fixed,the smaller the energy efficiency ratio of air conditioning refrigeration,air conditioning heating and water heater was,the greater the converted energy supply capacity and the energy-price ratio were.The gas-air combined cycle system had good flexibility and economy,but the system had been simplified a lot.It needs to improve the system design and simulation research,so as to promote the commercial application of the combined cooling,heating and power system.