Energy storage system suitable for deep caves and operation method thereof

Abstract

This invention discloses an energy storage system and its operation method suitable for deep caves. The system includes a water storage tank, a water-gas cave, a gas storage cave, a water pump, a water turbine, a booster compressor, a turbine unit, and a compressor. The water storage tank is connected to the inlet of the water pump and the outlet of the water turbine. The outlet of the water pump and the inlet of the water turbine are connected to the water inlet and outlet at the bottom of the water-gas cave. The gas inlet and outlet at the top of the water-gas cave are connected to the inlet of the booster compressor and the outlet of the turbine unit, respectively. The outlet of the booster compressor and the inlet of the turbine unit are connected to the gas inlet and outlet of the gas storage cave. The top port of the water-gas cave is connected to the top port of the gas storage cave, and valves are installed on the pipeline connecting the top ports of the water-gas cave and the top ports of the gas storage cave. An air inlet is opened in the water-gas cave. Both the water-gas cave and the gas storage cave are artificial caves. The construction of a large-scale physical energy storage system using artificial caves can not only realize the reuse of waste resources, but also effectively reduce the overall investment cost of the system.

Description

Technical Field

[0001] This invention belongs to the field of physical energy storage technology, specifically relating to an energy storage system suitable for deep caves and its operation method. Background Technology

[0002] Establishing a new low-carbon energy structure for the future, transforming the century-old fossil fuel-based energy supply and consumption system into a completely different energy system based on renewable energy, is the core of the energy revolution. Energy storage technology, which stores energy through media or devices and releases it when needed, is urgently needed to address the large-scale integration of renewable energy and improve the efficiency, security, and economy of conventional power systems and regional energy systems. It is considered a supporting technology and strategic emerging industry of the energy revolution. Advanced energy storage technology innovation is one of the key tasks of the energy revolution. With the future development of renewable energy, the demand for energy storage will further increase, and various provinces and regions are considering introducing a renewable energy power generation grid-connected energy storage quota system.

[0003] In certain resource-rich areas, quarrying is suitable and mature mining technologies and facilities exist. After quarrying, numerous abandoned man-made caves are created. Furthermore, the construction of large-scale physical energy storage systems, such as compressed air energy storage or pumped hydro storage, requires substantial investment in the construction of storage containers, resulting in high system costs. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides an energy storage system and method suitable for deep caves. Utilizing artificial caves to construct energy storage not only enables the reuse of abandoned artificial caves but also effectively reduces the construction cost of large-scale physical energy storage systems, and also contributes to the promotion and application of large-scale physical energy storage technology.

[0005] This invention is achieved through the following technical solution: an energy storage system suitable for deep caves, comprising a water reservoir, a water-gas cave, a gas storage cave, a water pump, a water turbine, a booster compressor, a turbine unit, and a compressor; the water reservoir is connected to the inlet of the water pump and the outlet of the water turbine; the outlet of the water pump and the inlet of the water turbine are connected to the water inlet and outlet at the bottom of the water-gas cave; the gas inlet and outlet at the top of the water-gas cave are connected to the inlet of the booster compressor and the outlet of the turbine unit; the outlet of the booster compressor and the inlet of the turbine unit are connected to the gas inlet and outlet of the gas storage cave; the top port of the water-gas cave is connected to the top port of the gas storage cave, and valves are installed on the pipeline connecting the top port of the water-gas cave and the top port of the gas storage cave; valves are installed at the inlet and outlet of the water pump, the inlet and outlet of the water turbine, the inlet and outlet of the turbine unit, and the inlet and outlet of the booster compressor; an air inlet is provided in the water-gas cave; both the water-gas cave and the gas storage cave are artificial caves, and an air inlet is provided at the top of the water-gas cave.

[0006] It also includes a compressor, the outlet of which is connected to the top port of the gas storage cave, and a valve is installed at the outlet of the compressor.

[0007] The compressor outlet is also connected to the top port of the water vapor cave.

[0008] The turbine unit is connected to the generator. The turbine unit can be configured as a single turbine unit, two turbine units connected in series, or two turbine units with different expansion ratios connected in parallel.

[0009] The water vapor caves and gas storage caves each have a volume greater than 100,000 cubic meters and a depth greater than 85 meters.

[0010] Pressure sensors were installed in both the water vapor cave and the gas storage cave.

[0011] Valves are installed at the inlets and outlets of both the water vapor cave and the gas storage cave.

[0012] It also provides an operation method for an energy storage system suitable for deep caves, including a pre-compression process, an energy storage process, and an energy release process; the pre-compression process includes a first operation mode and a second operation mode;

[0013] The first operating mode is as follows:

[0014] S11, ambient air enters the water vapor cavity through the air inlet, and the air inlet is then closed;

[0015] S12, open the passage between the water vapor cave and the gas storage cave, the water pump pumps the water in the water tank into the water vapor cave until the water vapor cave is full, and the gas in the water vapor cave is stored in the gas storage cave.

[0016] S13, disconnect the passage between the water vapor cave and the gas storage cave;

[0017] S14, the water pump is turned off, the air inlet is opened, and the water in the water-air cavern uses the drop to drive the water turbine to generate electricity, and then enters the water storage tank;

[0018] S15, turbine shut down;

[0019] S16, repeat S11-S15 above until the gas pressure in the gas storage cave is equal to the gas pressure in the gas storage cave at the end of the energy storage process, disconnect the passage between the water gas cave and the gas storage cave, and close the air inlet at the same time.

[0020] The second operating mode is as follows:

[0021] S21, ambient air enters the water vapor cavity through the air inlet, and then the air inlet is closed;

[0022] S22, open the passage between the water vapor cave and the gas storage cave, and the water pump pumps the water in the water tank into the water vapor cave until the entire water vapor cave is filled, and the gas in the water vapor cave is stored in the gas storage cave.

[0023] S23, disconnect the passage between the water vapor cave and the gas storage cave;

[0024] S24, the water pump is turned off, the air inlet and water turbine are opened, and the water in the water-air cavern uses the drop to drive the water turbine to generate electricity, and then enters the reservoir;

[0025] S25, shut down the turbine;

[0026] S26, repeat S21-S25 above until the gas pressure in the gas storage cavern is equal to the gas pressure in the water gas cavern when the energy release process ends;

[0027] S27, disconnect the passage between the water vapor cave and the gas storage cave, open the air inlet, start the booster to pressurize the gas introduced through the air inlet and store it in the gas storage cave.

[0028] S28, When the gas pressure in the gas storage cavity is equal to the gas pressure in the gas storage cavity at the end of the energy storage process, the booster is turned off and the air inlet is closed;

[0029] After the pre-compression process is completed, the energy release process begins, and then the energy storage process and the energy release process alternate in a cycle.

[0030] Energy storage process: Water in the reservoir enters the water-gas cavern through a water pump. At the same time, air at the top of the water-gas cavern enters the gas storage cavern through a booster. The water pump operates under constant conditions, and the gas pressure at the top of the water-gas cavern gradually decreases. For every 1 meter increase in the liquid level in the water-gas cavern, the gas pressure in the water-gas cavern decreases by 0.0098 MPa.

[0031] Energy release process: Water in the water-gas cave enters the reservoir through the water turbine. At the same time, air in the gas storage cave enters the water-gas cave after the turbine unit does work. The water turbine operates under constant conditions, and the gas pressure at the top of the water-gas cave gradually increases. For every 1 meter the liquid level in the water-gas cave drops, the gas pressure in the water-gas cave increases by 0.0098 MPa.

[0032] Pre-compression is also performed in the following two ways:

[0033] Type A pre-compression: The compressor compresses the air in the environment and stores it in the gas storage cavity. At the end of the pre-compression process, the gas pressure in the gas storage cavity is equal to the gas pressure in the gas storage cavity at the end of the energy storage process.

[0034] Type B pre-compression: The compressor compresses the air in the environment and stores it in both the water vapor cavity and the gas storage cavity. When the pre-compression process ends, the gas pressure in the gas storage cavity is equal to the gas pressure in the gas storage cavity when the energy release process ends, and the gas pressure in the water vapor cavity is equal to the gas pressure in the water vapor cavity when the energy release process ends.

[0035] In the type A pre-compression operation mode, after the pre-compression process is completed, the energy release process begins, followed by the energy storage process and the energy release process in a cycle. In the type B pre-compression operation mode, after the pre-compression process is completed, the energy storage process begins, followed by the energy release process and the energy storage process in a cycle.

[0036] During the energy release process, the high-pressure gas in the gas storage cavern expands in the turbine unit and then enters the water-gas cavern. In the first operating mode, the turbine unit adopts single-unit variable operating condition regulation. In the second operating mode, when the maximum pressure ratio between the gas storage cavern and the water-gas cavern is greater than 1.44, the two turbine units operate in series. As the pressure difference decreases, one of the turbine units is shut down and switched to the first operating mode of the turbine unit, or the second operating mode of the turbine unit is maintained. In the third operating mode of the turbine unit, two turbine units with different expansion ratios operate in parallel. When the maximum pressure ratio between the gas storage cavern and the water-gas cavern is greater than 1.3, the turbine unit with the larger expansion ratio operates. As the pressure difference decreases, it switches to the turbine unit with the smaller expansion ratio.

[0037] When the maximum pressure ratio in the gas storage cavern and the water-gas cavern is greater than 1.44, the turbine unit operates in the second operating mode. As the pressure difference decreases, it switches to the third operating mode of the turbine unit.

[0038] Compared with the prior art, the present invention has the following beneficial technical effects:

[0039] The system described in this invention utilizes artificial caves to construct a large-scale physical energy storage system. Using this cave for energy storage can effectively save ground space, not only enabling the reuse of waste resources, but also effectively reducing the overall investment cost of the system. The system can also operate normally without the use of a compressor.

[0040] This invention is applicable to energy storage methods with diverse pre-compression modes in deep caves. Compared with traditional technologies, it offers different advantages depending on the pre-compression mode. In both the first and second operating modes, compressor-free pre-compression can be achieved. The second operating mode reduces the performance requirements of the water pumps in the system, especially the maximum head requirement. The system layout in this invention is diverse, allowing for flexible arrangement of the pre-compression device based on the presence or absence of a compressor and its performance. The water pumps and turbines in this system operate under design conditions, clearly defining the pressure control requirements in the water-gas cave during energy storage and release, i.e., P = aH + b, where P is the gas pressure in the water-gas cave, H is the liquid level height in the water-gas cave, and a = -0.0098 MPa / m.

[0041] Furthermore, in the type A pre-compression operation mode, it features a short pre-compression process time and simple operation; in the type B pre-compression operation mode, the requirement for compressor pressure ratio is reduced compared to the type A pre-compression operation mode. Attached Figure Description

[0042] Figure 1a This is a schematic diagram of an energy storage system with a type A pre-compression mode suitable for deep caves, as described in an example of the present invention.

[0043] Figure 1b This is a schematic diagram of the energy storage system of the type b pre-compression mode applicable to deep caves as described in the example of the present invention.

[0044] Figure 1c This is a schematic diagram of the energy storage system with a C-type pre-compression mode suitable for deep caves, as described in the example of this invention.

[0045] Figure 2a This is a schematic diagram of the first operating mode of the turbine unit described in the example of the present invention.

[0046] Figure 2b This is a schematic diagram of the second operating mode of the turbine unit described in the example of the present invention.

[0047] Figure 2c This is a schematic diagram of the third operating mode of the turbine unit described in the example of the present invention.

[0048] In the diagram: 1 is a water storage tank; 2 is a water-air cavity; 3 is a gas storage cavity; 4 is a water pump; 5 is a water turbine; 6 is a booster compressor; 7 is a turbine unit; 81 is the first valve; 82 is the second valve; 83 is the third valve; 84 is the fourth valve; 85 is the fifth valve; 86 is the sixth valve; 87 is the seventh valve; 88 is the eighth valve; 89 is the ninth valve; 9 is the air compressor; 10 is the air inlet. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0050] like Figure 1aAs shown, an energy storage system with a type A pre-compression mode suitable for deep caves includes a water storage tank 1, a water-air cave 2, an air storage cave 3, a water pump 4, a water turbine 5, a booster compressor 6, a turbine unit 7, a first valve 81, a second valve 82, a third valve 83, a fourth valve 84, a fifth valve 85, a sixth valve 86, a seventh valve 87, an eighth valve 88, a ninth valve 89, and a compressor 9; the water storage tank 1 is connected to the inlet of the water pump 4 and the outlet of the water turbine 5; the water pump 4... The outlet and the inlet of the water turbine 5 are connected to the bottom port of the water-air cave 2; the top port of the water-air cave 2 is connected to the inlet of the booster compressor 6 and the outlet of the turbine unit 7, respectively; the outlet of the booster compressor 6 and the inlet of the turbine unit 7 are connected to the top port of the gas storage cave 3; both the water-air cave 2 and the gas storage cave 3 are artificial caves; the outlet of the compressor 9 is connected to the top port of the gas storage cave 3, and a ninth valve 89 is installed at the outlet of the compressor 9; the location of the ninth valve 89 varies depending on the system configuration.

[0051] A first valve 81 is installed at the inlet of the water pump 4; a second valve 82 is installed at the outlet of the water pump 4; a third valve 83 is installed at the inlet of the water turbine 5; a fourth valve 84 is installed at the outlet of the water turbine 5; a fifth valve 85 is installed at the inlet of the booster compressor 6; a sixth valve 86 is installed at the outlet of the booster compressor 6; a seventh valve 87 is installed at the inlet of the turbine unit 7; and an eighth valve 88 is installed at the outlet of the turbine unit 7.

[0052] Both water vapor cave 2 and gas storage cave 3 are man-made caves, with a single volume of more than 100,000 cubic meters and a depth of more than 85 meters.

[0053] To monitor pressure in real time, pressure sensors are installed in both the water-gas cavern 2 and the gas storage cavern 3, and the pressure sensors are connected to the system's control center.

[0054] like Figure 1b As shown, a type B pre-compression mode energy storage system suitable for deep caves is presented. Compared with the type A system, in the type B system, the outlet of compressor 9 is connected to the top port of gas storage cave 3 and the top port of water-gas cave 2, respectively. A ninth valve 89 is provided at the outlet of compressor 9. The rest of the layout of the type B system is the same as that of the type A system.

[0055] like Figure 2a As shown, turbine unit 7 is configured as a single turbine unit in the first operating mode.

[0056] like Figure 2b As shown, turbine unit 7 is configured as two turbine units connected in series in the second operating mode.

[0057] like Figure 2c As shown, turbine unit 7 is configured as two turbine units connected in parallel in the third operating mode.

[0058] To enhance the separate control of air intake in water-gas cave 2 and gas storage cave 3, valves are installed at the inlet and outlet of both water-gas cave 2 and gas storage cave 3.

[0059] like Figure 1c As shown, a type C pre-compression mode energy storage system suitable for deep caves is presented. Compared with type A or type B systems, type C systems do not require a compressor 9. In type C systems, the top of the water-air cave 2 has an air inlet 10 connecting to the external environment. The pipeline containing the ninth valve 89 connects the top port of the gas storage cave 3 and the top port of the water-air cave 2. The rest of the layout of type C systems is the same as that of type A or type B systems.

[0060] Based on the system described in this invention, there are various operating methods for pre-compression modes applicable to deep caves, specifically as follows: including a pre-compression process, an energy storage process, and an energy release process; after the pre-compression process is completed, the energy release process begins, and then the energy storage process and the energy release process are carried out alternately in a cycle; the pre-compression process (i.e., C-type pre-compression) includes a first operating mode and a second operating mode;

[0061] First operating mode:

[0062] S11, ambient air enters the water vapor cave 2 through the air inlet 10, and then the air inlet 10 is closed;

[0063] S12, open the ninth valve 89, open the first valve 81 and the second valve 82, the water pump 4 pumps the water in the water tank 1 into the water vapor cave 2 until the water vapor cave 2 is filled, and the gas in the water vapor cave 2 is stored in the gas storage cave 3.

[0064] S13, close the ninth valve 89;

[0065] S14, the first valve 81 and the second valve 82 are closed, the third valve 83 and the fourth valve 84 are opened, the air inlet 10 is opened, the water in the water-air cave 2 uses the drop to drive the water turbine 5 to generate electricity, and then enters the water storage tank 1;

[0066] S15, third valve 83 and fourth valve 84 are closed;

[0067] S16, repeat steps S11-S15 above until the gas pressure in the gas storage cave 3 is equal to the gas pressure in the gas storage cave 3 at the end of the energy storage process, then close the ninth valve 89 and the air inlet 10.

[0068] Second operating mode:

[0069] S21, ambient air enters the water vapor cave 2 through the air inlet 10, and then the air inlet 10 is closed;

[0070] S22, open the ninth valve 89, open the first valve 81 and the second valve 82, the water pump 4 pumps the water in the water tank 1 into the water vapor cave 2 until the water vapor cave 2 is filled, and the gas in the water vapor cave 2 is stored in the gas storage cave 3.

[0071] S23, close the ninth valve 89;

[0072] S24, the first valve 81 and the second valve 82 are closed, the third valve 83 and the fourth valve 84 are opened, the air inlet 10 is opened, the water in the water-air cave 2 uses the drop to drive the water turbine 5 to generate electricity, and then enters the water storage tank 1;

[0073] S25, third valve 83 and fourth valve 84 are closed;

[0074] S26, repeat steps S21-S25 above until the gas pressure in gas storage cave 3 is equal to the gas pressure in water gas cave 2 when the energy release process ends.

[0075] S27, close the ninth valve 89, open the air inlet 10, open the fifth valve 85 and the sixth valve 86, start the booster 6 to pressurize the gas introduced into the air inlet 10 and store it in the gas storage cave 3;

[0076] S28, when the gas pressure in the gas storage cave 3 is equal to the gas pressure in the gas storage cave 3 at the end of the energy storage process, the booster 6 is turned off, and the fifth valve 85 and the sixth valve 86 are closed at the same time, and the air inlet 10 is closed.

[0077] Energy storage process: valves 83, 84, 87, 88, and 89 are closed, while valves 81, 82, 85, and 86 are opened; water in reservoir 1 enters water-air cavern 2 through pump 4, and at the same time, air at the top of water-air cavern 2 enters gas storage cavern 3 through booster 6.

[0078] During the energy storage process, water pump 4 operates under constant conditions. To ensure a constant pressure at the outlet of water pump 4, the gas pressure at the top of water-gas cavern 2 gradually decreases. For every 1 meter increase in liquid level in water-gas cavern 2, the gas pressure in water-gas cavern 2 decreases by 0.0098 MPa.

[0079] Energy release process: First valve 81, second valve 82, fifth valve 85, sixth valve 86, and ninth valve 89 are closed; third valve 83, fourth valve 84, seventh valve 87, and eighth valve 88 are opened; water in water-gas cave 2 enters water storage tank 1 through water turbine 5; at the same time, air in gas storage cave 3 enters the top of water-gas cave 2 through turbine unit 7.

[0080] During the energy release process, turbine 5 operates under constant conditions. To ensure a constant pressure at the inlet of turbine 5, the gas pressure at the top of water-gas cavity 2 gradually increases. For every 1 meter decrease in the liquid level in water-gas cavity 2, the gas pressure in water-gas cavity 2 increases by 0.0098 MPa.

[0081] In addition to the above-mentioned Type C precompression operation mode, the system equipped with compressor 9 can also operate in Type A and Type B precompression operation modes, as detailed below:

[0082] Pre-compression process: First valve 81, second valve 82, third valve 83, fourth valve 84, fifth valve 85, sixth valve 86, seventh valve 87, and eighth valve 88 are closed, and ninth valve 89 is opened;

[0083] Type A pre-compression: Compressor 9 compresses the air in the environment and stores it in the gas storage cave 3. When the pre-compression process ends, the gas pressure in the gas storage cave 3 is equal to the gas pressure in the gas storage cave 3 when the energy storage process ends.

[0084] Type B pre-compression: Compressor 9 compresses ambient air and simultaneously stores it in water vapor cavity 2 and gas storage cavity 3. At the end of the pre-compression process, the gas pressure in gas storage cavity 3 is equal to the gas pressure in gas storage cavity 3 at the end of the energy release process, and the gas pressure in water vapor cavity 2 is equal to the gas pressure in water vapor cavity 2 at the end of the energy release process.

[0085] In the type A precompression system, after the precompression process ends, the energy release process begins, followed by an alternating cycle of energy storage and energy release. In the type B precompression system, after the precompression process ends, the energy storage process begins, followed by an alternating cycle of energy release and energy storage.

[0086] During the energy release process, the high-pressure gas in the gas storage cavern 3 expands in the turbine unit 7 and then enters the water-gas cavern 2. Optionally, the first operating mode of the turbine unit 7 adopts single-unit variable operating condition regulation; the second operating mode of the turbine unit 7 operates the two turbine units in series when the pressure difference between the gas storage cavern 3 and the water-gas cavern 2 is large. As the pressure difference decreases, one of the turbine units can be selectively shut down and switched to the first operating mode, or the second operating mode of the turbine unit 7 can be maintained; the third operating mode of the turbine unit 7 consists of two turbine units with different expansion ratios connected in parallel. When the pressure difference between the gas storage cavern 3 and the water-gas cavern 2 is large, the turbine unit with the larger expansion ratio operates. As the pressure difference decreases, it switches to the turbine unit with the smaller expansion ratio.

[0087] Preferably, when the pressure difference between the gas storage cavern 3 and the water vapor cavern 2 is large, the turbine unit 7 operates in the second operating mode. As the pressure difference decreases, it switches to the third operating mode of the turbine unit 7.

[0088] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. An operation method for an energy storage system suitable for deep caves, characterized in that, It includes a pre-compression process, an energy storage process, and an energy release process; the pre-compression process includes a first operating mode and a second operating mode; The first operating mode is as follows: S11, ambient air enters the water vapor cave (2) through the air inlet, and the air inlet (10) is closed; S12, open the passage between the water vapor cave (2) and the gas storage cave (3), and the water pump (4) pumps the water in the water tank (1) into the water vapor cave (2) until the entire water vapor cave (2) is filled, and the gas in the water vapor cave (2) is stored in the gas storage cave (3); S13, disconnect the passage between the water vapor cave (2) and the gas storage cave (3); S14, water pump (4) is turned off, air inlet (10) is opened, water in water-air cave (2) uses the drop to drive water turbine (5) to generate electricity, and then enters water storage tank (1); S15, turbine (5) shut down; S16, repeat S11-S15 above until the gas pressure in the gas storage cave (3) is equal to the gas pressure in the gas storage cave (3) at the end of the energy storage process, disconnect the passage between the water gas cave (2) and the gas storage cave (3), and close the air inlet (10). The second operating mode is as follows: S21, ambient air enters the water vapor cave (2) through the air inlet, and then the air inlet (10) is closed; S22, open the passage between the water vapor cave (2) and the gas storage cave (3), and the water pump (4) pumps the water in the water tank (1) into the water vapor cave (2) until the entire water vapor cave (2) is filled, and the gas in the water vapor cave (2) is stored in the gas storage cave (3); S23, disconnect the passage between the water vapor cave (2) and the gas storage cave (3); S24, the water pump (4) is closed, the air inlet (10) and the water turbine (5) are opened, the water in the water-air cave (2) uses the drop to drive the water turbine (5) to generate electricity, and then enters the water storage tank (1); S25, shut down the turbine (5); S26, repeat S21-S25 above until the gas pressure in the gas storage cave (3) is equal to the gas pressure in the water gas cave (2) when the energy release process ends; S27, disconnect the passage between the water vapor cave (2) and the gas storage cave (3), open the air inlet (10), start the booster to pressurize the gas introduced by the air inlet and store it in the gas storage cave (3); S28, when the gas pressure in the gas storage cave (3) is equal to the gas pressure in the gas storage cave (3) when the energy storage process ends, the booster (6) is turned off and the air inlet (10) is closed; After the pre-compression process is completed, the energy release process begins, and then the energy storage process and the energy release process alternate in a cycle. Energy storage process: Water in the reservoir (1) enters the water-air cave (2) through the water pump (4). At the same time, air at the top of the water-air cave (2) enters the gas storage cave (3) through the booster (6). The water pump (4) operates under constant conditions, and the gas pressure at the top of the water-air cave (2) gradually decreases. For every 1 meter increase in the liquid level in the water-air cave (2), the gas pressure in the water-air cave (2) decreases by 0.0098 MPa. Energy release process: Water in the water-gas cave (2) enters the reservoir (1) through the water turbine (5), and at the same time, air in the gas storage cave (3) enters the water-gas cave (2) after doing work through the turbine unit (7); the water turbine (5) operates under constant conditions, and the gas pressure at the top of the water-gas cave gradually increases. For every 1 meter decrease in the liquid level in the water-gas cave, the gas pressure in the water-gas cave increases by 0.0098 MPa; pre-compression is also carried out in the following two ways: Type A pre-compression: The compressor (9) compresses the air in the environment and stores it in the gas storage cave (3). When the pre-compression process ends, the gas pressure in the gas storage cave (3) is equal to the gas pressure in the gas storage cave (3) when the energy storage process ends. Type b pre-compression: The compressor (9) compresses the air in the environment and stores it in the water vapor cave (2) and the gas storage cave (3) at the same time. When the pre-compression process ends, the gas pressure in the gas storage cave (3) is equal to the gas pressure in the gas storage cave (3) when the energy release process ends, and the gas pressure in the water vapor cave (2) is equal to the gas pressure in the water vapor cave (2) when the energy release process ends. In the type A pre-compression operation mode, after the pre-compression process is completed, the energy release process begins, followed by the energy storage process and the energy release process in a cycle. In the type B pre-compression operation mode, after the pre-compression process is completed, the energy storage process begins, followed by the energy release process and the energy storage process in a cycle.

2. The operating method according to claim 1, characterized in that, During the energy release process, the high-pressure gas in the gas storage cave (3) expands in the turbine unit (7) and then enters the water-gas cave (2); in the first operating mode of the turbine unit, the single turbine unit is used for variable operating condition regulation; in the second operating mode, when the maximum pressure ratio in the gas storage cave and the water-gas cave is greater than 1.44, the two turbine units (7) are connected in series. As the pressure difference decreases, one of the turbine units is shut down and switched to the first operating mode of the turbine unit, or the second operating mode of the turbine unit is maintained; in the third operating mode of the turbine unit, the two turbine units with different expansion ratios are connected in parallel. When the maximum pressure ratio in the gas storage cave (3) and the water-gas cave (2) is greater than 1.3, the turbine unit with the larger expansion ratio is in operation. As the pressure difference decreases, the turbine unit with the smaller expansion ratio is switched to operation. When the maximum pressure ratio in the gas storage cave (3) and the water-gas cave (2) is greater than 1.44, the turbine unit operates in the second operating mode. As the pressure difference decreases, it switches to the third operating mode of the turbine unit.

3. An energy storage system suitable for deep caves, characterized in that, To implement the operating method described in claim 1 or 2, the energy storage system includes a water storage tank (1), a water-gas cavern (2), a gas storage cavern (3), a water pump (4), a water turbine (5), a booster compressor (6), a turbine unit (7), and a compressor (9); the water storage tank (1) is connected to the inlet of the water pump (4) and the outlet of the water turbine (5); the outlet of the water pump (4) and the inlet of the water turbine (5) are connected to the water inlet and water outlet at the bottom of the water-gas cavern (2); the gas inlet and outlet at the top of the water-gas cavern (2) are connected to the inlet of the booster compressor (6) and the outlet of the turbine unit (7); the outlet of the booster compressor (6) and the inlet of the turbine unit (7) are connected to the gas inlet and outlet of the gas storage cavern (3); the water-gas cavern (2) The top port of the water-gas cave (2) is connected to the top port of the gas storage cave (3). Valves are installed on the pipeline connecting the top port of the water-gas cave (2) and the top port of the gas storage cave (3). Valves are installed at the inlet and outlet of the water pump (4), the inlet and outlet of the water turbine (5), the inlet and outlet of the turbine unit (7), and the inlet and outlet of the booster (6). Both the water-gas cave (2) and the gas storage cave (3) are artificial caves. An air inlet (10) is installed at the top of the water-gas cave (2). The turbine unit (7) is connected to the generator. The turbine unit (7) is configured as a single turbine unit, two turbine units connected in series, or two turbine units with different expansion ratios connected in parallel. The volume of each water-gas cave (2) and the gas storage cave (3) is greater than 100,000 cubic meters and the depth is greater than 85 meters.

4. The energy storage system suitable for deep caves according to claim 3, characterized in that, It also includes a compressor (9), the outlet of which is connected to the top port of the gas storage cave (3), and a valve is installed at the outlet of the compressor (9).

5. The energy storage system suitable for deep caves according to claim 4, characterized in that, The outlet of the compressor (9) is also connected to the top port of the water vapor cave (2).

6. The energy storage system suitable for deep caves according to claim 3, characterized in that, Pressure sensors are installed in both the water vapor cave (2) and the gas storage cave (3).

7. The energy storage system suitable for deep caves according to claim 3, characterized in that, Valves are installed at the inlet and outlet of both the water vapor cave (2) and the gas storage cave (3).

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