This invention discloses a
compressed air energy storage system and its operation method based on underground flexible gas storage. The
system includes compression, thermal storage, gas storage, expansion power generation, and control subsystems. The gas storage utilizes an underground flexible
composite material gasbag with an external sliding layer and concrete lining layer, connected in parallel with a
backup rigid gas tank and a
fast switching valve to improve sealing, geological adaptability, and
operational safety. The thermal storage subsystem forms a closed-loop
heat transfer medium circulation with the reheater, achieving efficient
recovery and utilization of multi-stage compression heat. The control subsystem can quickly adjust power according to grid frequency deviations to meet primary
frequency regulation requirements. This invention solves the problems of high leakage risk, poor geological adaptability, low
system efficiency, and slow
frequency regulation response of traditional gas storage devices, offering advantages such as reliable sealing, high efficiency, fast response, and low cost. It is suitable for wind and solar
new energy bases, grid peak shaving and
frequency regulation, and distributed energy scenarios.