Research On Design And Operation Of CCHP System Including Compressed Air Energy Storage System

Since energy crisis and environment pollution have become a global problem,it has attracted worldwide attention to develop renewable energy and energy-efficient way,However,despite the rapid development of renewable energy,it is affected by instability factors such as volatility and randomness,and there are still many problems to associate the renewable power with the grid,which leads to serious waste of wind and light in Northwest China.Compared with other energy storage technologies,compressed air energy storage has advantages of long life,large capacity and flexible location and has been developed rapidly both domestic and overseas in recent years.Furthermore,the natural cold,hot and electric interface of the compression and expansion process can be combined with the conventional triple supply system through the multi-energy complementary pattern.The principle of energy cascade utilization in the triple supply system can greatly improve the energy utilization ratio.After coupling the two systems,a reasonable planning and operation strategy can give full play to their advantages,reduce costs and use energy more efficiently.Based on previous research,a combined cooling,heating and power system with compressed air energy storage is proposed in this paper.The CAES system and the conventional tri-generation system with the internal combustion engine as the core are coupled through various interfaces to supply energy for users,while the grid,gas boilers and other supplement equipment to ensure adequate supply of energy.The internal combustion engine is the main source of energy supply for the system.CAES is used as the peaking equipment for both the Grid and the internal combustion engine,it absorbs the excess energy from the Grid to charge in the valley time and discharges during the peak hours of the electricity consumption.The mathematical models of key equipment such as internal combustion engines,heat exchangers,compressors,and expanders were established.Based on the models,the cold,hot and electric output characteristics of the two major subsystems were analyzed,including the output ratio of electric and heating,efficiency,etc.,which indicates that the system has a wide range of output and.can meet different load requirements of users,and it is a good theoretical pave for late operation control.For there are different combinations of energy sources,the working modes of CCHP system were studied.It must begin with the construction of equipment selection in the early stage,if the system wants to achieve global optimization.The appropriate equipment model capacity is the basis for operation optimization,and it will restrict the later optimization of the operation.Meanwhile operation control strategy in the later stage will also affect the equipment of the system.This is a class of multi-time scale optimization problems.In this regard,a bi-level optimization method is adopted to optimize the solution in this paper,by setting different levels of optimization functions to resolve the contradictions in the previous period and the later,the overall goal has a higher priority,and on this basis,the optimization of the lower level operation is performed.A bi-level optimization algorithm is compiled under the consideration of the development level of the algorithm and the actual requirements,the upper layer takes the internal combustion engine off the shelf,CAES capacity and the maximum input power of the Grid as variables,the lower layer uses genetic algorithms to optimize output scheduling.Finally,on the basis of the energy model and the compiled algorithm,a bi-level optimization model for the analysis of system economics is presented.The upper level aims to optimize the overall investment including equipment costs and various costs during operation,while the lower level uses the operating cost as the objective function.Taking the load data of a hotel in Beijing as an example,the analysis of the model and algorithm was carried out,the results show that the optimal capacity configuration required by the upper and lower levels is different.At this time,the optimal value of the upper level is adopted.After the optimal capacity of the upper level is determined,the lower level optimal operation plan at this time can be obtained from the top down.Compared with other energy supply systems with established control strategies,the system proposed in this paper has obvious economic advantages.The work done in this paper has important reference significance for algorithm research and practical engineering construction.