A gravity hydraulic water-pumping and air-compression hybrid energy storage system and a method for operating the same

Abstract

The present application relates to a kind of gravity hydraulic pumping gas hybrid energy storage system and its operating method, belong to energy storage technical field.The problem of large pressure change in gas compression and expansion process, leading to the large pressure change of hydraulic / hydraulic machinery is solved.It includes low-pressure pool, low-pressure oil tank, pumping module, water-oil dual medium pressure boosting module, energy storage module and power generation module, and low-pressure pool, pumping module, water-oil dual medium pressure boosting module are cyclically connected, and low-pressure oil tank, water-oil dual medium pressure boosting module, energy storage module and power generation module are cyclically connected.The present application realizes the switching between the larger pressure amplitude in water-gas co-containment tank and the smaller water head amplitude in hydraulic machinery by water-oil dual medium pressure boosting module, improves the operation stability of water pump and hydraulic motor;The outside of water-gas co-containment cabin is wrapped by water, which can reduce the temperature change in the process of air compression and expansion, without additional power input to control temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to a hybrid energy storage system and a method for operating the same, and belongs to the technical field of energy storage. BACKGROUND

[0002] With the continuous consumption of fossil energy and the increasing environmental pollution, it is imperative to promote the green transformation of energy structure, and the role of energy storage technology in the power grid is increasingly critical. Pumped storage and compressed air energy storage are two common energy storage methods, but the traditional pumped storage technology has harsh site selection conditions and low energy storage density; while the site selection of compressed air energy storage technology is limited by caves, and the operating efficiency of compressors and expanders is not high. In the context of increasingly fierce global energy technology competition, efficient, environmentally friendly and stable new energy storage systems are urgently needed.

[0003] In recent years, some studies have combined pumped storage with compressed air energy storage technology to solve the problem of low operating efficiency of compressors and expanders, and to improve the energy storage efficiency. For example: the patent with the publication number CN106321343A and the invention name of an isothermal compressed air energy storage power generation system based on liquid temperature control and a method thereof, the technical solution of which is to control the temperature of the liquid in the liquid piston through a heat exchanger, and then control the temperature of the gas in the tank, which has the advantages of high efficiency, environmental protection and small friction loss; the patent with the publication number CN115788745A and the invention name of a pumped compressed air energy storage system with adjustable water head and a method for operating the same, the technical solution of which is to store the compression heat generated during air compression when the reversible hydroelectric generator set is used for pumped storage and power generation, and to use the compression heat to warm up the air when the air expands to do work. However, they all have the problem of large operating pressure amplitude of the hydraulic machinery.

[0004] Therefore, it is urgent to propose a gravity hydraulic pumped air mixed energy storage system and a method for operating the same to solve the above technical problems. SUMMARY

[0005] In view of the deficiencies of the existing hydraulic compressed air energy storage technology, the present application provides a gravity hydraulic pumped air mixed energy storage system and a method for operating the same. A brief summary of the present application is given below to provide a basic understanding of some aspects of the present application. It should be understood that this summary is not an exhaustive summary of the present application. It is not intended to determine the key or important parts of the present application, nor to limit the scope of the present application.

[0006] The technical solution of the present application is as follows:

[0007] The gravity hydraulic water pumping and gas compression hybrid energy storage system comprises a low-pressure water tank, a low-pressure oil tank, a water pumping module, a water-oil dual medium pressure boosting module, an energy storage module and a power generation module, the low-pressure water tank, the water pumping module and the water-oil dual medium pressure boosting module are circularly connected, and the low-pressure oil tank, the water-oil dual medium pressure boosting module, the energy storage module and the power generation module are circularly connected.

[0008] Preferably, the water pumping module comprises a variable speed water pump, a bladder accumulator and a ninth control valve, and the outlet of the low-pressure water tank, the ninth control valve, the variable speed water pump and the bladder accumulator are sequentially connected.

[0009] Preferably, the energy storage module comprises a high-pressure oil tank, a gravity piston, a water-gas coexistence cabin, a compressor and an eleventh control valve, the gravity piston is slidably connected with the energy storage container, the energy storage container is divided into the high-pressure oil tank and the water-gas coexistence cabin arranged in an upper and lower manner by the gravity piston, and the water-gas coexistence cabin, the eleventh control valve and the compressor are sequentially connected.

[0010] Preferably, the power generation module comprises a hydraulic motor and a tenth control valve, and the outlet of the high-pressure oil tank, the tenth control valve, the hydraulic motor and the inlet of the low-pressure oil tank are sequentially connected.

[0011] Preferably, the water-oil dual medium pressure boosting module comprises a water hydraulic cylinder, a piston rod, an oil hydraulic cylinder, a first control valve, a second control valve, a third control valve, a fourth control valve, a fifth control valve, a sixth control valve, a seventh control valve and an eighth control valve, both ends of the piston rod are slidably connected with the water hydraulic cylinder and the oil hydraulic cylinder, and the piston rod divides the water hydraulic cylinder and the oil hydraulic cylinder into two inner cavities arranged in a left and right manner, the variable speed water pump is connected with the inlets of the left and right sides of the water hydraulic cylinder through the sixth control valve and the eighth control valve, the inlet of the low-pressure water tank is connected with the outlets of the left and right sides of the water hydraulic cylinder through the fifth control valve and the seventh control valve, the inlet of the high-pressure oil tank is connected with the outlets of the left and right sides of the oil hydraulic cylinder through the second control valve and the fourth control valve, and the outlet of the low-pressure oil tank is connected with the inlets of the left and right sides of the oil hydraulic cylinder through the first control valve and the third control valve.

[0012] Preferably, the acting area of the piston rod in the water hydraulic cylinder is greater than the acting area of the piston rod in the oil hydraulic cylinder.

[0013] Preferably, the surface of the energy storage container in the part where the water-gas coexistence cabin is located is wrapped by water.

[0014] The operation method of the gravity hydraulic water pumping and gas compression hybrid energy storage system comprises the following steps.

[0015] Step one: before the first operation of the system, a pressure presetting process should be performed, and the water-gas coexistence cabin is preset with compressed air with a pressure of p1 through the compressor.

[0016] Step two: when storing energy, the variable frequency water pump pumps water into the right / left side of the hydraulic cylinder, pushes the piston left / right, and extrudes the hydraulic oil on the left / right side of the hydraulic cylinder to the high-pressure oil tank, which pushes the gravity piston up and pushes the water in the water-air coexistence cabin up, compresses the air to store energy; when the piston rod reaches the left / right end, switch to the right / left direction; cycle until the air pressure in the water-air coexistence cabin reaches the set value p2.

[0017] Step three: when generating electricity, the high-pressure air in the water-air coexistence cabin expands, pushes the gravity piston down, and discharges the hydraulic oil in the lower high-pressure oil tank to the hydraulic motor to generate electricity, and the hydraulic oil after generating electricity returns to the low-pressure oil tank, and the air pressure in the water-air coexistence tank is reduced to the set pressure p1, and the power generation process is completed.

[0018] The present application has the following beneficial effects:

[0019] 1. The present application realizes the purpose of water pump water pressure potential energy lifting through water-oil dual medium supercharging module, converts the small water head amplitude of variable speed water pump into a larger pressure amplitude in the water-air coexistence tank, and realizes the stable and safe operation of the variable speed water pump.

[0020] 2. The present application stores energy in the form of gravity potential energy of the gravity piston and internal energy of compressed air, which improves the energy storage density of the system.

[0021] 3. The water body pumped by the variable speed water pump and the hydraulic oil used for generating electricity by the hydraulic motor are not in contact with high-pressure air, the air dissolution amount is small, the variable speed water pump and the hydraulic motor are less affected by cavitation, and it is more safe.

[0022] 4. The energy storage system of the present application does not consume fossil fuels, does not pollute the environment, and is not limited by geographical conditions.

[0023] 5. The energy storage efficiency of the large-scale energy storage system of the present application can reach more than 70%. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a structure diagram of a gravity hydraulic water pumping and air pressure mixed energy storage system.

[0025] Figure 2 It is a flow chart of the energy storage operation process of a gravity hydraulic water pumping and air pressure mixed energy storage system.

[0026] Figure 3 It is a flow chart of the power generation operation process of a gravity hydraulic water pumping and air pressure mixed energy storage system.

[0027] In the figure: 1 - variable speed water pump, 2 - bladder accumulator, 3 - low pressure water tank, 4 - water hydraulic cylinder, 5 - piston rod, 6 - oil hydraulic cylinder, 7 - low pressure oil tank, 8 - hydraulic motor, 9 - high pressure oil tank, 10 - gravity piston, 11 - water-air coexistence cabin, 12 - compressor, 21 - first control valve, 22 - second control valve, 23 - third control valve, 24 - fourth control valve, 25 - fifth control valve, 26 - sixth control valve, 27 - seventh control valve, 28 - eighth control valve, 29 - ninth control valve, 30 - tenth control valve, 31 - eleventh control valve. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be described below by specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0029] Specific implementation one: combined Figure 1 In this embodiment, a gravity hydraulic water pumping and air pressure mixed energy storage system includes a low pressure water tank 3, a low pressure oil tank 7, a water pumping module, a water and oil dual medium pressure boosting module, an energy storage module and a power generation module. The low pressure water tank 3, the water pumping module, the water and oil dual medium pressure boosting module are cyclically connected, and the low pressure oil tank 7, the water and oil dual medium pressure boosting module, the energy storage module and the power generation module are cyclically connected. The present application realizes the switching between the larger pressure amplitude in the water-air coexistence tank and the smaller water head amplitude of the water power machinery through the water and oil dual medium pressure boosting module, and the operation stability of the water pump and the hydraulic motor is higher. The water-air coexistence cabin is wrapped by water outside, which can reduce the temperature change in the air compression and expansion process without the need for additional power input to control the temperature. The energy storage density is large through the common energy storage of the gravitational potential energy of the gravity piston and the internal energy of the compressed air.

[0030] Specific implementation two: combined Figure 1 In this embodiment, a gravity hydraulic water pumping and air pressure mixed energy storage system includes a low pressure water tank 3, a low pressure oil tank 7, a water pumping module, a water and oil dual medium pressure boosting module, an energy storage module and a power generation module. The low pressure water tank 3, the water pumping module, the water and oil dual medium pressure boosting module are cyclically connected, and the low pressure oil tank 7, the water and oil dual medium pressure boosting module, the energy storage module and the power generation module are cyclically connected. The present application realizes the switching between the larger pressure amplitude in the water-air coexistence tank and the smaller water head amplitude of the water power machinery through the water and oil dual medium pressure boosting module, and the operation stability of the water pump and the hydraulic motor is higher. The water-air coexistence cabin is wrapped by water outside, which can reduce the temperature change in the air compression and expansion process without the need for additional power input to control the temperature. The energy storage density is large through the common energy storage of the gravitational potential energy of the gravity piston and the internal energy of the compressed air.

[0031] Specific implementation three: combined Figure 1The embodiment is explained as follows: a gravity hydraulic water-pumping and air-compressing hybrid energy storage system, the energy storage module comprises a high-pressure oil tank 9, a gravity piston 10, a water-air coexistence cabin 11, a compressor 12 and an eleventh control valve 31, the gravity piston 10 is in sliding connection with the energy storage container, the gravity piston 10 divides the energy storage container into the high-pressure oil tank 9 and the water-air coexistence cabin 11 arranged in an up-down manner, the water-air coexistence cabin 11, the eleventh control valve 31 and the compressor 12 are connected in sequence; during energy storage, the oil hydraulic cylinder 6 draws the hydraulic oil in the low-pressure oil tank 7 into the high-pressure oil tank 9, the gravity piston 10 is lifted upward, the air in the water-air coexistence cabin 11 is compressed to store energy, the high-pressure potential energy provided by the oil hydraulic cylinder 6 is converted into the gravity potential energy of the gravity piston and the internal energy of the compressed air, the energy storage density is large, the gravity piston 10 can move upward or downward, upward compression of the air in the water-air coexistence cabin 11, downward extrusion of the hydraulic oil in the high-pressure oil tank 9; during power generation, the air in the water-air coexistence cabin 11 expands to push the gravity piston 10 to move downward, the hydraulic oil in the high-pressure oil tank 9 is discharged to the hydraulic motor 8 to do work and generate electricity, realizing the function of converting the gravity potential energy of the gravity piston and the internal energy of the compressed air into the pressure potential energy of the hydraulic oil; that is, during energy storage, the grid electricity is finally stored as the gravity potential energy of the gravity piston 10 and the internal energy of the compressed air, during power generation, the gravity potential energy of the gravity piston 10 and the internal energy of the compressed air are converted into electricity.

[0032] Specific implementation method four: combined Figure 1 The embodiment is explained as follows: a gravity hydraulic water-pumping and air-compressing hybrid energy storage system, the energy storage module comprises a high-pressure oil tank 9, a gravity piston 10, a water-air coexistence cabin 11, a compressor 12 and an eleventh control valve 31, the gravity piston 10 is in sliding connection with the energy storage container, the gravity piston 10 divides the energy storage container into the high-pressure oil tank 9 and the water-air coexistence cabin 11 arranged in an up-down manner, the water-air coexistence cabin 11, the eleventh control valve 31 and the compressor 12 are connected in sequence; during energy storage, the oil hydraulic cylinder 6 draws the hydraulic oil in the low-pressure oil tank 7 into the high-pressure oil tank 9, the gravity piston 10 is lifted upward, the air in the water-air coexistence cabin 11 is compressed to store energy, the high-pressure potential energy provided by the oil hydraulic cylinder 6 is converted into the gravity potential energy of the gravity piston and the internal energy of the compressed air, the energy storage density is large, the gravity piston 10 can move upward or downward, upward compression of the air in the water-air coexistence cabin 11, downward extrusion of the hydraulic oil in the high-pressure oil tank 9; during power generation, the air in the water-air coexistence cabin 11 expands to push the gravity piston 10 to move downward, the hydraulic oil in the high-pressure oil tank 9 is discharged to the hydraulic motor 8 to do work and generate electricity, realizing the function of converting the gravity potential energy of the gravity piston and the internal energy of the compressed air into the pressure potential energy of the hydraulic oil; that is, during energy storage, the grid electricity is finally stored as the gravity potential energy of the gravity piston 10 and the internal energy of the compressed air, during power generation, the gravity potential energy of the gravity piston 10 and the internal energy of the compressed air are converted into electricity.

[0033] Specific implementation method five: combined Figure 1In this embodiment, the water-oil dual medium pressure boosting module of the gravity hydraulic water pumping and compressed air hybrid energy storage system includes a water hydraulic cylinder 4, a piston rod 5, an oil hydraulic cylinder 6, a first control valve 21, a second control valve 22, a third control valve 23, a fourth control valve 24, a fifth control valve 25, a sixth control valve 26, a seventh control valve 27, and an eighth control valve 28. The two ends of the piston rod 5 are respectively in sliding connection with the water hydraulic cylinder 4 and the oil hydraulic cylinder 6, and the piston rod 5 divides the water hydraulic cylinder 4 and the oil hydraulic cylinder 6 into left and right inner cavities. The left and right inner cavities are respectively provided with inlets and outlets. The variable speed water pump 1 is connected with the inlets of the left and right inner cavities of the water hydraulic cylinder 4 through the sixth control valve 26 and the eighth control valve 28. The inlet of the low-pressure water tank 3 is connected with the outlets of the left and right inner cavities of the water hydraulic cylinder 4 through the fifth control valve 25 and the seventh control valve 27. The inlet of the high-pressure oil tank 9 is connected with the outlets of the left and right inner cavities of the oil hydraulic cylinder 6 through the second control valve 22 and the fourth control valve 24. The outlet of the low-pressure oil tank 7 is connected with the inlets of the left and right inner cavities of the oil hydraulic cylinder 6 through the first control valve 21 and the third control valve 23. The oil hydraulic cylinder 6 is connected with the first control valve 21, the second control valve 22, the third control valve 23, and the fourth control valve 24 through pipelines. The water hydraulic cylinder 4 is connected with the oil hydraulic cylinder 6 through the piston rod 5. During energy storage, the water hydraulic cylinder 4 transmits the water pressure potential provided by the variable speed water pump 1 to the oil hydraulic cylinder 6 through the piston rod, and converts it into hydraulic potential with higher pressure. This module overcomes the problem of large friction and leakage loss of the water hydraulic cylinder operating at a pressure greater than 5 MPa. It converts the low-pressure water pressure potential provided by the variable speed water pump into high-pressure hydraulic potential in the hydraulic oil, achieving the purpose of converting the small water head amplitude of the variable speed water pump and the large pressure amplitude in the water-air compatible tank.

[0034] Specific implementation method six: in combination with Figure 1 In this embodiment, the water-oil dual medium pressure boosting module of the gravity hydraulic water pumping and compressed air hybrid energy storage system, the acting area of the piston rod 5 in the water hydraulic cylinder 4 is greater than that in the oil hydraulic cylinder 6. The water hydraulic cylinder 4 in the water-oil dual medium pressure boosting module uses water as the working medium, and the oil hydraulic cylinder 6 uses hydraulic oil as the working medium. The acting area of the piston in the water hydraulic cylinder 4 is larger than that in the oil hydraulic cylinder 6, which can convert the low-pressure potential pressure in the water hydraulic cylinder 4 into high-pressure potential pressure in the oil hydraulic cylinder 6.

[0035] Specific implementation method seven: in combination with Figure 1 In this embodiment, the water-oil dual medium pressure boosting module of the gravity hydraulic water pumping and compressed air hybrid energy storage system, the acting area of the piston rod 5 in the water hydraulic cylinder 4 is greater than that in the oil hydraulic cylinder 6. The water hydraulic cylinder 4 in the water-oil dual medium pressure boosting module uses water as the working medium, and the oil hydraulic cylinder 6 uses hydraulic oil as the working medium. The acting area of the piston in the water hydraulic cylinder 4 is larger than that in the oil hydraulic cylinder 6, which can convert the low-pressure potential pressure in the water hydraulic cylinder 4 into high-pressure potential pressure in the oil hydraulic cylinder 6.

[0036] Specific implementation method eight: in combination with Figures 1-3This embodiment describes the operation method of a gravity-hydraulic pumped water-compressed air hybrid energy storage system, which includes the following steps:

[0037] Step 1: Before the system is run for the first time, a pressure pre-setting process should be performed by supplying compressed air with a pre-set pressure of p1 into the water-air co-containment chamber 11 through compressor 12;

[0038] Step 2: During energy storage, the variable frequency water pump 1 draws water into the right / left side of the hydraulic cylinder 4, pushing the piston inside to move left / right, squeezing the hydraulic oil in the left / right side of the hydraulic cylinder 6 into the high-pressure oil tank 9, pushing the gravity piston 10 upward, pushing the water in the water-air co-containment chamber 11 upward, compressing the air to store energy; when the piston rod 5 reaches the leftmost / rightmost end, it switches to the right / left direction; the cycle repeats until the air pressure in the water-air co-containment chamber 11 reaches the set value p2;

[0039] In step two, the energy storage process can be divided into two operating states: left-hand and right-hand, as follows:

[0040] 2.1 Left-hand driving state:

[0041] like Figure 2 As shown, when moving to the left, the second control valve 22, the third control valve 23, the fifth control valve 25, and the eighth control valve 28 are opened. The variable frequency water pump 1 draws water into the right side of the hydraulic cylinder 4, pushing the piston inside to the left. This forces the hydraulic oil on the left side of the hydraulic cylinder 6 into the high-pressure oil tank 9, pushing the gravity piston 10 upward and pushing the water in the water-air co-containment chamber 11 upward, compressing air to store energy. When the piston rod 5 reaches its minimum stroke (i.e., L≤L), min When determining the gas pressure p inside the water-gas co-containment chamber. t Has the set maximum pressure p2 been reached? If it has, the energy storage process ends; otherwise, switch to the right-hand direction.

[0042] 2.2 Right-hand movement:

[0043] like Figure 2 As shown, when moving to the right, the first control valve 22, the fourth control valve 24, the sixth control valve 26, and the seventh control valve 27 are opened. The variable frequency water pump 1 draws water into the left side of the hydraulic cylinder 4, pushing the piston inside to the right. This forces the hydraulic oil on the right side of the hydraulic cylinder 6 into the high-pressure oil tank 9, pushing the gravity piston 10 upward and pushing the water in the water-air co-containment chamber 11 upward, compressing air to store energy. When the piston rod 5 reaches its maximum stroke (i.e., L≥L), max When determining the gas pressure p inside the water-gas co-containment chamber. t Has the set maximum pressure p2 been reached? If it has, the energy storage process ends; otherwise, switch to the leftward direction.

[0044] Step three: when generating electricity, the high pressure air in the water-gas coexistence cabin 11 expands, pushing the gravity piston 10 to run downward, discharging the hydraulic oil in the lower high pressure oil tank 9 to the hydraulic motor 8 to generate electricity, and the hydraulic oil after generating electricity returns to the low pressure oil tank 7. It is judged whether the pressure of the air in the water-gas coexistence cabin is reduced to the set minimum pressure p1 (i.e. p t ≤p1), if it is satisfied, the electricity generation process is ended, otherwise, the electricity generation process is continued.

[0045] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined. Those skilled in the art can exhaust all possibilities according to the mathematical knowledge of arrangement and combination, so the invention will not be described one by one after the arrangement and combination of the technical solutions, but it should be understood that the technical solutions after the arrangement and combination have been disclosed by the invention.

[0046] It should also be noted that the terms "first", "second", etc. are only used for differentiation and description, and cannot be understood as indicating or implying relative importance. The terms "up", "down", "left", "right", etc. indicate the orientation based on the orientation shown in the drawings, and are only used for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device must have a specific orientation, be constructed or operated in a specific orientation.

[0047] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An operation method for a gravity-hydraulic pumped water-air hybrid energy storage system, characterized in that: The application discloses a gravity hydraulic water-pumping and air-compression combined energy storage system, which comprises a low-pressure water pool (3), a low-pressure oil tank (7), a water-pumping module, a water-oil dual-medium pressure boosting module, an energy storage module and a power generation module. The water-pumping module comprises a variable-speed water pump (1), a bladder accumulator (2) and a ninth control valve (29), and the outlet of the low-pressure water pool (3), the ninth control valve (29), the variable-speed water pump (1) and the bladder accumulator (2) are sequentially connected. The energy storage module comprises a high-pressure oil tank (9), a gravity piston (10), a water-air coexistence cabin (11), a compressor (12) and an eleventh control valve (31), the gravity piston (10) is slidably connected with an energy storage container, the energy storage container is divided into the high-pressure oil tank (9) and the water-air coexistence cabin (11) arranged in an upper and lower mode by the gravity piston (10), and the water-air coexistence cabin (11), the eleventh control valve (31) and the compressor (12) are sequentially connected. The power generation module comprises a hydraulic motor (8) and a tenth control valve (30), and the outlet of the high-pressure oil tank (9), the tenth control valve (30), the hydraulic motor (8) and the inlet of the low-pressure oil tank (7) are sequentially connected. The water-oil dual-medium pressure boosting module comprises a water hydraulic cylinder (4), a piston rod (5), an oil hydraulic cylinder (6), a first control valve (21), a second control valve (22), a third control valve (23), a fourth control valve (24), a fifth control valve (25), a sixth control valve (26), a seventh control valve (27) and an eighth control valve (28), both ends of the piston rod (5) are slidably connected with the water hydraulic cylinder (4) and the oil hydraulic cylinder (6), the piston rod (5) divides the water hydraulic cylinder (4) and the oil hydraulic cylinder (6) into two inner cavities, the variable-speed water pump (1) is connected with the water hydraulic cylinder (4) through the sixth control valve (26) and the eighth control valve (28), the inlet of the low-pressure water pool (3) is connected with the outlet of the water hydraulic cylinder (4) through the fifth control valve (25) and the seventh control valve (27), the inlet of the high-pressure oil tank (9) is connected with the outlet of the oil hydraulic cylinder (6) through the second control valve (22) and the fourth control valve (24), and the outlet of the low-pressure oil tank (7) is connected with the inlet of the oil hydraulic cylinder (6) through the first control valve (21) and the third control valve (23). The method comprises the following steps: Step one: Before the system is first run, a pressure preset process should be carried out, and the water-gas co-container (11) is preset with pressure by the compressor (12) to be p 1 compressed air; Step two: when storing energy, the variable frequency water pump (1) pumps water into the right / left side of the hydraulic cylinder (4), pushing the piston left / right, and the hydraulic oil in the left / right side of the oil hydraulic cylinder (6) is squeezed into the high-pressure oil tank (9), lifting the gravity piston (10) upwards, pushing the water in the water-air coexistence cabin (11) to run upwards, and compressing the air to store energy; when the piston rod (5) reaches the left / rightmost end, switch to the right / left direction; cycle and repeat until the air pressure in the water-air coexistence cabin (11) reaches the set value p 2; Step three: when generating electricity, the high-pressure air in the water-gas coexistence cabin (11) expands, pushing the gravity piston (10) to descend, discharging the hydraulic oil in the lower high-pressure oil tank (9) to the hydraulic motor (8) to generate electricity, and the hydraulic oil after generating electricity returns to the low-pressure oil tank (7). When the air pressure in the water-gas coexistence tank (11) drops to the set pressure p 1, the electricity generation process ends.

2. The operating method of a gravity-hydraulic water-pumping and air-compression hybrid energy storage system according to claim 1, characterized in that: The acting area of the piston rod (5) in the water hydraulic cylinder (4) is larger than the acting area of the piston rod (5) in the oil hydraulic cylinder (6).

3. The method of operating a gravity hydraulic water pumping and gas storage hybrid energy system according to claim 2, wherein: The surface of the energy storage container, in which the water-air coexistence cabin (11) is arranged, is wrapped by water.

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