| In recent years,with the increasingly serious problems of energy security and environment,accelerating the development of new energy industry has become a general consensus and objective demand for promoting energy transformation and development and coping with climate change.However,the randomness and volatility of new energy sources have always been the main problems restricting their large-scale application.Energy storage technology can effectively enhance the power grid's ability to absorb new energy,and at the same time,it has shown a strong effect and irreplaceable role in improving the stability and reliability of the system and the comprehensive utilization efficiency of energy.Compressed air energy storage has the advantages of large capacity,long time and long life compared with other energy storage methods.It has got rid of the limitation of geographical conditions and has more flexible structure and more abundant application methods.It has become a new research and development hotspot.Relying on the important international cooperation research project of the National Natural Science Foundation of China,this research takes the electromechanical coupling wind compressed air energy storage system as the research object.Through the analysis of the structure and efficiency of the system,the corresponding control strategy is designed and the practical application of the control strategy is realized through LabVIEW platform.Comparing with the traditional compressed air energy storage system,the electromechanical coupled compressed air energy storage system adopts the bi-motor control structure,which can realize the compressed energy storage under the two modes of electrical coupling and mechanical coupling.It increases the flexibility of the system and improves the energy conversion efficiency of the system.At the same time,it puts forward higher requirements for the control strategy of the system.How to formulate a reasonable control strategy according to the structure and energy conversion characteristics of the system has become a difficult problem to be solved urgently.It is also a scientific problem to be solved in this paper.In order to define the energy conversion efficiency of the system and locate the weak links of energy utilization,the paper first analyzes and tests the work efficiency of the scroll compressor's compression mode and expansion mode.Then,thermodynamic analysis method based on exergy efficiency is used to analyze the total efficiency of the system under the whole cycle of compression and expansion.and the ideal thermal and cooling efficiency is obtained.At the same time,the energy loss of mechanical and pneumatic parts under different modes of the system is analyzed,and the optimal working region is obtained,which provides theoretical support for system control.On this basis,a mode selection strategy based on logic threshold method is designed,which enables the system to select the most efficient mode of work under different working conditions,and enhances the adaptability and flexibility of the system to the changeable environment.Considering the smooth transition of the system in the mode switching process and minimizing the start-stop time,this paper designs the start-stop control strategy of electromechanical coupled wind compressed air energy storage system under three operating modes of independent wind power,compression storage and expansion assistance by means of speed pre-synchronization and differential pressure compensation,designs experiments and verifies the rationality and feasibility of the control strategy.Finally,a monitor program based on LabVIEW is designed,and the control strategy is docked to the practical application.The system runs independently and stably in each mode.The reliability of the control strategy is verified by the experimental design.The experimental results show that the efficiency of each mode of the system has been greatly improved,which verifies the validity of the theory. |
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