Research On Optimization Design And Operation Control Of The Combined Cooling,Heating And Power Microgrid With Compressed Air Energy Storage

Under the pressure of energy crisis and environmental problems,reforming the traditional energy supply system and establishing a new energy supply mode with high efficiency and environmental protection have become the energy development strategy of all countries.Based on the principle of energy cascade utilization,the combined cooling,heating and power(CCHP)microgrid aims at efficient utilization of distributed renewable energy as well as energy saving and emission reduction.It is the core component of the integrated energy system(IES)and has great development prospects.However,due to the high proportion of renewable energy penetration and the coupling of multi-energy flow,the optimization design and efficient operation control of CCHP microgrid are facing great challenges.Compressed air energy storage(CAES)is a new hybrid energy storage system with multi-energy interfaces of cooling,heating and power,which access to the CCHP microgrid and complement the advantages of each other.Using compressed air energy storage as a bridge to connect renewable energy to CCHP microgrid can not only suppress the intermittence,randomness and fluctuation of wind and solar resources,but also enhance the correlation between thermal and power systems in microgrid,which is conducive to achieving energy cascade utilization,improving the flexibility of multi-energy joint dispatch of CCHP microgrid and the economy,cleanliness and reliability of system operation.However,compressed air energy storage has the characteristics of multi-energy flow coupling,complex structure mechanism and coexistence of multiple laws.Its accessing to the CCHP microgrid has made profound and complex changes in structure,energy flow and operation mode of the new system.There are large number of scientific and technical problems to be solved urgently.Therefore,this thesis focuses on the new distributed integrated energy supply system of CCHP microgrid with compressed air energy storage,deeply reveals the multi-energy flow coupling relationship,proposes a series of optimization design and operation control strategies,realizes energy flow matching and energy cascade utilization.It effectively improves the operation economy,energy saving,environment and reliability of CCHP microgrid,thus providing a relatively perfect theoretical support system for promoting the development of energy storage,distributed renewable energy and CCHP microgrid.Firstly,the basic structure and operation mode of compressed air energy storage and the unified evaluation method of multi-energy flow of cooling,heating and power are expounded,and the variation of efficiency and energy utilization with structural parameters and process parameters are analyzed.And then,the basic coupling mode of CCHP microgrid with compressed air energy storage,the operation characteristics of internal controllable equipment and the variation law of system energy flow are studied,and the operation evaluation index of CCHP microgrid with compressed air energy storage is analyzed.Through the analysis of system mechanism characteristics and parameter sensitivity,it provides a basis for system design and operation control.Secondly,the energy grade correlation law and structure optimization method of CCHP microgrid with compressed air energy storage,the multi-energy coupling system,is revealed.Considering the coexistence of multi-energy flow and multi-grade heat source,as well as aiming at achieving energy cascade utilization and improving energy utilization efficiency,the structure and working mode of CCHP microgrid with compressed air energy storage are optimized from the point of view of process design,and the system performance under different working modes is analyzed.On this basis,a multi-objective optimal operation strategy considering the economy,environmental protection and reliability of the system is proposed.The optimal operation mode of compressed air energy storage and the hourly scheduling plan of islanded CCHP microgrid controllable equipment are solved under different operating conditions.With the data of typical cooling,heating and power loads and renewable energy sources,the change laws of coupling mode and working mode with the operating conditions of the system are studied At the same time,the operation scheduling strategy of off-line CCHP system is put forward.The results show that through the optimization of working mode and equipment scheduling plan,the economic and environmental benefits of the system have been significantly improved,while the refinement of the mode and the reasonable matching of grade have effectively enhanced the cascade utilization of system energy.Thirdly,considering the characteristics of large capacity and multi-dimensional energy interface of compressed air energy storage,as well as the power market policy and the new characteristics of grid-connected microgrid,an active energy storage operation strategy is proposed,which can actively adjust the thermo-electric ratio of the system and the energy interacting with the power grid by optimizing the hourly output(input)energy of compressed air energy storage.Thus,the CCHP microgrid can be transformed from the traditional single-user side to the distributed generation,and play the role of the core unit of the IES.Furthermore,the combined optimization operation strategy of compressed air energy storage and power generating units(PGU)is proposed to further enhance the economy,energy saving and environmental protection of the system.With case studies,the performance of the system under active energy storage strategy and the combined optimization operation strategy are comprehensively analyzed,and the differences of different operation modes are compared,which verifies the effectiveness of the proposed method.At the same time,considering the characteristics of multi-objective coexistence and hierarchical iteration of the combined optimization operation strategy,the influence rule of objective weight coefficient on the cooperative operation of controllable equipment is further explored.Then,for the inherent randomness and fluctuation issues of intermittent renewable energy,a multi-time scale hierarchical operation control method based on operation scheduling,rolling optimization and real-time control is proposed,which can suppress wind and solar fluctuations and improve the renewable energy absorption capacity of CCHP microgrid,and effectively solve the problem of time scale difference of heterogeneous energy flow in the system.At the same time,a hybrid energy storage system with compressed air storage,battery and super capacitor is proposed in rolling optimization layer.For this new hybrid energy storage system,an energy allocation strategy is designed from the perspective of instantaneous frequency analysis,which can effectively suppress the random and fluctuation of renewable energy,as well as ensure the reliability of the optimization results of the dispatching layer.With case studies,the fluctuation law of renewable energy is further studied,and the performance of the system under the hierarchical operation control strategy is comprehensively analyzed,which verify the effectiveness and feasibility of the proposed operation strategy.Finally,the close relationship between system design and operation is deeply analyzed,a integrated design method integrating equipment parameters,system capacity,operation strategy and operation parameters is proposed with abandoning the traditional ideas of dividing design and operation into two parts,in order to fundamentally solve the random and changeable problems of operation mode in CCHP microgrid caused by renewable energy and multi-dimensional energy storage access.With typical case studies,the system performance under different parameters and capacities is analyzed,and the proposed method and the necessity of integrated design are verified.At the same time,regarding the integrated design method as the guiding ideology,the compressed air energy storage access to multi-energy complementary CCHP microgrid test system is designed,and the key parameters are optimized.In general,the conclusions of this thesis provide effective methods for the design and operation control of CCHP microgrid with compressed air energy storage,and have important theoretical value for promoting the development of energy storage and distributed energy.