Research On Dynamic Regulation And Control Of Compressed Air Energy Storage System

Under the goal of"carbon peak and carbon neutral",energy storage technology has developed rapidly.Compressed air energy storage technology with the advantages of high efficiency,large capacity,long life,the cost is relatively low and environmental friendly,is considered to be one of the most development prospect of large-scale energy storage technology.In this paper,the 10MW compressed air energy storage system with thermal energy storage is taken as the research object.Based on the characteristics of complex off-design conditions of the compressed air energy storage system in the operation process,the design,operation,off-design conditions performance and regulation and control are studied.Based on modular modeling method,comprehensive off-design thermodynamic models are established for both key components including compressor,expander,heat exchanger,air storage chamber and the valve and the system.Exergy analysis and corresponding evaluation indexes are used for energy analysis and performance evaluation of the system.For the pressure change of air storage chamber during system operation,the variations of key parameters with time in charge and discharge processes are revealed under constant/sliding pressure operation strategy.The system performance under different operation strategies is compared and analyzed.The results show that the overall exergy loss of the system is smaller under the sliding pressure,and the energy storage efficiency and energy storage density increase by 0.98%and 0.06MJ/m~3respectively compared with the constant pressure.Exergy efficiency of charge process increased gradually over time,while exergy efficiency of discharge process decreased gradually over time.The charge and discharge time decreases with the increase of design power.Charge and discharge time,energy storage efficiency and energy storage density all decrease with the increase of ambient temperature.In view of the problems of low control accuracy and large pressure loss by throttling decompression to regulate inlet pressure of expander in the discharge process of compressed air energy storage system,a volume decompression method consisting of on/off valve and expansion tank is proposed.The key parameters,such as pressure and temperature of air storage chamber/expansion tank,flow rate of on-off valve,inlet flow rate of expander and output power are studied and the mechanism and effect of volume decompression regulating inlet pressure of expander is revealed.Also,the influence of volume of expansion tank on air pressure and temperature in air storage chamber and expansion tank is analyzed.On this basis,the control characteristics and system performance of compressed air energy storage system based on volume decompression are further studied under the condition that the load power varies periodically.The results show that the volume decompression can achieve good regulation for constant power and variable power operation of the discharge process.