Optimal Configuration And Operation Of An Energy Hub Considering Off-design Characteristics Of Generation Units

Building a multi-energy system(MES),which is integrated with the electric power system,natural gas system and heat system,is an important direction for the future energy development.By co-optimizing the MES,the overall efficiency of energy utilization will be improved and the pollution emissions will be reduced.Energy hub(EH)plays an important role in implementing the integrated energy system as an interconnection point between various energy components and networks.The simulation model is one of the key points affecting the optimal planning and operation of the EH.Since treating the efficiencies of generation units as constants would significantly simplify the calculation,only constant efficiency(CE)model is adopted in most research works.In this paper,we investigate the impacts of off-design characteristics of generation units on the design and operation of an EH.(1)The general mathematical model of the EH is introduced firstly,then we establish a typical EH system configuration.The off-design characteristics based(ODCB)models of gas turbine,heat recovery steam generator,absorption chiller and electric chiller are detailed analyzed.(2)Aiming at evaluating the impacts of off-design characteristics on the accuracy of the optimal operation of an EH,two test cases are conducted respectively on the fixed and variable load conditions.In addition,the individual effect of off-design characteristics of each equipment on the optimal operation cost of the EH is also investigated through 4 optimization runs.(3)In order to optimize the capacity configuration of an EH,we analyze the impacts of off-design characteristics of generation units on the sizing problem.Furthermore,a two-stage planning method is proposed to solve the optimal capacity configuration problem of the EH.Group Search Optimizer(GSO)is used to determine the optimal size in the first stage,and a mathematical programming method is applied to obtain the optimal operation of the EH in the second stage.Life cycle cost of the EH is considered as the objective function to be minimized.Comparative studies using the ODCB model and the CE model are performed to examine the impacts of equipment off-design characteristics on the sizing results.Simulation results indicate that the ODCB model appears to have a better economic performance than the CE model.