Constant-pressure operation CO2 compression energy storage system

The utility model discloses a constant-pressure operation compressed CO2 energy storage system. The system comprises a low-pressure storage module, a compression module, a constant-pressure storage module and an expansion module, the low-pressure storage module is used for condensing the low-pressure CO2 released by the expansion module into a liquid state and storing the low-pressure CO2; the compression module is used for pressurizing the CO2 in the low-pressure storage module and condensing the CO2 into a liquid state; the expansion module is used for enabling the CO2 released by the constant-pressure storage module to do work for power generation; the constant-pressure storage module is used for storing high-pressure liquid CO2 at constant pressure and releasing the high-pressure liquid CO2 to the expansion module at constant pressure in an energy release stage; the constant-pressure storage module comprises a high-pressure carbon dioxide storage tank, a membrane type pressure compensator, a water turbine