Multi-machine near-constant pressure pumping and gas hybrid energy storage system and operation method thereof

Abstract

The present application relates to a kind of multi-machine near constant pressure pumping gas hybrid energy storage system and its operating method, belong to physical energy storage technical field.Solve the problem of insufficient water-lubricated heat transfer performance of large water head amplitude of hydraulic machinery operation, including hydraulic machinery module, compression expansion machinery module and near isothermal compression module, hydraulic machinery module is used for energy supply, near isothermal compression module is used for energy storage, and compression expansion machinery module is used for realizing energy conversion.The present application reduces the pressure amplitude in water-gas co-containment tank under power generation condition by the way of electromagnetic valve control pipeline on-off, and pumping storage unit can generate electricity efficiently and stably;Effectively enhance the heat transfer performance between air and water, can realize air near isothermal compression and expansion.

Description

Technical Field

[0001] This invention relates to a hybrid energy storage system and its operation method, belonging to the field of physical energy storage technology. Background Technology

[0002] Globally, the continuous consumption of fossil fuels has led to increasingly serious environmental problems, making a green and low-carbon transformation of the energy structure imperative. With the rapid and sustained increase in the grid-connected capacity of intermittent wind and solar energy, the grid's regulation capacity is being challenged, and energy storage technology is playing an increasingly important role in the grid. Common energy storage technologies include physical energy storage, battery energy storage, electrochemical energy storage, electromagnetic energy storage, and superconducting energy storage, among which physical energy storage devices account for the largest share of installed capacity and have the highest technological maturity. Pumped hydro storage and compressed air storage are the most common physical energy storage technologies. Pumped hydro storage still accounts for nearly 80% of the market share; while compressed air storage technology has been developed earlier, is mature, and is in a stage of rapid development. However, these two energy storage technologies also have some shortcomings, such as the stringent site selection requirements and low energy density of traditional pumped hydro storage; and the low energy conversion efficiency and site limitations of traditional adiabatic compressed air storage technology, which is restricted to caverns. Therefore, to improve the grid's regulation capacity and promote the consumption of wind and solar energy, new, efficient, low-carbon, and environmentally friendly energy storage technologies urgently need to be developed.

[0003] In recent years, institutions such as Arothron and Augwind in Israel, SustainX in the United States, Oak Forest Laboratory in the United States, and Xi'an Jiaotong University in my country have conducted research on hybrid energy storage technologies combining pumped hydro storage and compressed air storage. They have constructed corresponding pumped hydro-compressed air hybrid energy storage systems, analyzed the composition and operating principles of each system, explored the energy performance of each system, and improved the low operating efficiency of traditional compressors and expanders, thereby enhancing the system's energy conversion efficiency. However, shortcomings remain, such as large head variations during hydraulic mechanical operation and insufficient gas-liquid heat transfer performance.

[0004] Therefore, there is an urgent need to propose a multi-machine near-constant pressure pumped water and compressed gas hybrid energy storage system and its operation method to solve the above-mentioned technical problems. Summary of the Invention

[0005] To address the shortcomings of pumped-water compressed-air hybrid energy storage technology, this invention provides a multi-unit near-constant pressure pumped-water compressed-air hybrid energy storage system and its operation method. A brief overview of the invention is provided below to offer a basic understanding of certain aspects of it. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0006] The technical solution of this invention:

[0007] A multi-machine near-constant pressure pumped water and compressed air hybrid energy storage system includes a hydraulic mechanical module, a compression-expansion mechanical module, and a near-isothermal compression module. The hydraulic mechanical module is used for energy supply, the near-isothermal compression module is used for energy storage, and the compression-expansion mechanical module is used for energy conversion.

[0008] Preferably, the hydraulic mechanical module includes a water tank, a bladder accumulator, a pumped storage unit, a water pump, a third control valve, a fourth control valve, and a fifth control valve. The water tank is connected to the bladder accumulator via the fifth control valve. The outlet ends of the pumped storage unit and the water pump are respectively equipped with the third control valve and the fourth control valve. The water tank is connected to the near-isothermal compression module via the pumped storage unit and the water pump connected in parallel.

[0009] Preferably, the near-isothermal compression module includes a water-gas co-containment tank, a gas storage tank, a first control valve, a second control valve, a sixth control valve, a seventh control valve, a first safety valve, a second safety valve, a third solenoid valve, a first pressure sensor, a second pressure sensor, a third pressure sensor, a fourth pressure sensor, a liquid level sensor, a first spare connector, and a second spare connector. The pumped storage unit and the water pump are connected to the water-gas co-containment tank via the third control valve and the fourth control valve, respectively. The sixth control valve is installed at the bottom of the water-gas co-containment tank, a liquid level sensor is installed on the lower side of the water-gas co-containment tank, and a first pressure sensor is installed on the upper side of the water-gas co-containment tank. The water-gas co-containment tank has a sensor, a second pressure sensor, and an opening at the top connected to a first safety valve and a first spare connector. Another opening at the top of the water-gas co-containment tank is connected to an opening in the gas storage tank via a first control valve and a third solenoid valve arranged in parallel. A third pressure sensor is installed at the inlet of the third solenoid valve via a second control valve and is electrically connected to the third solenoid valve. Another opening in the gas storage tank is connected to a second safety valve and a second spare connector. A fourth pressure sensor is installed on the upper side of the gas storage tank. A seventh control valve is installed at the lower end of the gas storage tank. The other opening at the top of the water-gas co-containment tank is connected to the compression-expansion mechanical module.

[0010] Preferably, the compression and expansion mechanical module includes an expander, a compressor, a first solenoid valve, and a second solenoid valve. The expander is connected to another opening at the top of the water-gas co-containment tank via the first solenoid valve, and the compressor is connected to another opening at the top of the water-gas co-containment tank via the second solenoid valve. The first pressure sensor is electrically connected to the first solenoid valve, and the second pressure sensor is electrically connected to the second solenoid valve.

[0011] Preferably, it also includes an eighth control valve and a ninth control valve, and the number of water pumps, the fourth control valve, and the air storage tank are all two. The two water pumps are connected in parallel, and the eighth control valve and the ninth control valve are respectively installed at one opening of the two air storage tanks.

[0012] Preferred configuration: A stainless steel column is installed in the middle of both the water-gas co-containment tank and the gas storage tank. Multiple plastic trays filled with water are installed on the stainless steel columns, arranged along the axial direction of the columns.

[0013] An operation method for a multi-unit near-constant pressure pumped water and compressed air hybrid energy storage system includes the following steps:

[0014] Step 1: Pressure pre-construction process;

[0015] Step 2: Energy storage process;

[0016] Step 3: Power generation process.

[0017] Preferred: In step one:

[0018] Step 1.1: The second solenoid valve and the first control valve are opened, and the other valves are closed;

[0019] Step 1.2: Pre-fill the water-air co-containment tank and the air storage tank simultaneously with the compressor;

[0020] Step 1.3: The second pressure sensor measures the air pressure inside the water-air co-containment tank and transmits it to the second solenoid valve. When the pressure inside the water-air co-containment tank and the air storage tank reaches the pressure of the pumped storage unit P... 1p When the pressure is preset, close the second solenoid valve and the first control valve, and the pressure preset process ends.

[0021] Preferred option: In step two, the energy storage operation involves the continuous pumping operation of two units, which is divided into energy storage stage one and energy storage stage two.

[0022] Step 2.1: Energy Storage Phase 1

[0023] The first, third, and fifth control valves are open, while the other valves are closed. The pumped-storage unit draws electrical energy from the grid to pump water from the pool into a shared water-air tank. At this time, the shared water-air tank and the air storage tank are connected through the first control valve, and the air in both tanks is compressed. When the air pressure measured by the first pressure sensor reaches the pumped-storage unit pressure P... 2p At that time, the first phase of energy storage will end;

[0024] Step 2.2: Energy Storage Phase Two

[0025] The first, fourth, and fifth control valves are opened, while the other valves are closed. The water pump draws water from the pool into the water-air co-containment tank, compressing the air in the water-air co-containment tank and the air storage tank. The air pressure in the water-air co-containment tank and the air storage tank rises synchronously. When the pressure reaches the water pump P3, the second stage of energy storage ends.

[0026] Preferred: In step three:

[0027] Step 3.1: Phase 1 of Power Generation

[0028] The solenoid valve opens, and other valves close; the high-pressure air at the top of the water-air co-containment tank expands, driving the expander to rotate and generate electricity. During this process, the first pressure sensor remains operational. When the pressure inside the water-air co-containment tank drops to the pumped-storage unit P... 2t When the solenoid valve is closed, the first stage of power generation ends.

[0029] Step 3.2: Second Stage of Power Generation

[0030] The second, third, and fifth control valves are open, while the other valves are closed. Air expansion within the water-air co-existing tank generates electricity, and the water at the bottom of the tank is discharged to the pumped-storage unit to generate power. During this phase, the third pressure sensor remains operational; when the pressure it measures is less than the pumped-storage unit's pressure P... 1t When the third solenoid valve is opened, the high-pressure air in the storage tank expands, replenishing the water-air co-containment tank with air. When the pressure measured at the third pressure sensor reaches the P of the pumped storage unit... 2t Afterwards, the third solenoid valve closes; throughout the entire gas replenishment process, the pumped-storage unit continues to generate electricity; after the gas replenishment operation, the air pressure in the storage tank decreases, and when the pressure measured by the pressure sensor drops to the upper limit pressure P of the high-efficiency zone of the pumped-storage unit's power generation operation... 2t After that, the second phase of power generation ended;

[0031] Step 3.3: Three Stages of Power Generation

[0032] When the first, third, and fifth control valves are opened, the air in the water-gas common tank and the gas storage tank expands together to generate electricity. When the water level in the water-gas common tank, as measured by the level sensor, drops to the initial water level, the three stages of power generation end, and the power generation process is completed.

[0033] The present invention has the following beneficial effects:

[0034] 1. This invention enables pumped storage units and pumps to operate near rated conditions, achieving stable and efficient energy storage;

[0035] 2. This invention reduces the pressure fluctuation in the water-gas co-containment tank under power generation conditions by controlling the pipeline opening and closing with a solenoid valve, enabling the pumped storage unit to generate electricity efficiently and stably.

[0036] 3. The present invention adds a number of plastic trays filled with water to the water-air co-containment tank and at least one air storage tank, which can effectively enhance the heat exchange performance between air and water and achieve near isothermal compression and expansion of air.

[0037] 4. The equipment used in the energy storage system described in this invention is relatively mature. It does not consume fossil fuels during charging and discharging, does not produce environmental pollution, and the system site selection is not limited by geographical conditions. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a multi-machine near-constant pressure pumped water and compressed air hybrid energy storage system.

[0039] Figure 2 This is a schematic diagram of a multi-machine near-constant pressure pumped water and compressed air hybrid energy storage system.

[0040] In the diagram: 1-Water tank, 2-Bag accumulator, 3-Pumped storage unit, 4-Water pump, 5-Expander, 6-Compressor, 7-Water-gas co-containment tank, 8-Gas storage tank, 9-Accumulator, 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, 31-First safety valve, 32-Second safety valve, 41-First solenoid valve, 42-Second solenoid valve, 43-Third solenoid valve, 51-First pressure sensor, 52-Second pressure sensor, 53-Third pressure sensor, 54-Fourth pressure sensor, 55-Level sensor, 61-First spare connector, 62-Second spare connector. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0042] Specific implementation method one: Combining Figure 1-2 This embodiment describes a multi-machine near-constant pressure pumped water and compressed air hybrid energy storage system, which includes a hydraulic mechanical module, a compression-expansion mechanical module, and a near-isothermal compression module. The hydraulic mechanical module is used for energy supply, the near-isothermal compression module is used for energy storage, and the compression-expansion mechanical module is used for energy conversion.

[0043] Specific Implementation Method Two: Combining Figure 1-2This embodiment describes a multi-unit near-constant pressure pumped-storage / pressurized-air hybrid energy storage system. The hydraulic mechanical module includes a water tank 1, a bladder-type accumulator 2, a pumped-storage unit 3, at least one water pump 4, a third control valve 23, a fourth control valve 24, and a fifth control valve 25. The water tank 1 is connected to the bladder-type accumulator 2 via the fifth control valve 25. The outlet ends of the pumped-storage unit 3 and the water pump 4 are respectively equipped with the third control valve 23 and the fourth control valve 24. The water tank 1 is connected to the near-isothermal compression module through the pumped storage unit 3 and the water pump 4 set in parallel. The water tank 1, the air bladder accumulator 2, the pumped storage unit 3 and at least one water pump 4 are connected by pipelines. When storing energy, the pumped storage unit 3 absorbs power from the grid and pumps the water in the water tank 1 into the near-isothermal compression module to compress air for energy storage. When generating electricity, the air in the near-isothermal compression module expands and squeezes the water at the bottom of the water-air co-containment tank to the pumped storage unit 3 to generate electricity.

[0044] Specific implementation method three: Combining Figure 1-2 This embodiment describes a multi-unit near-constant pressure pumped-storage hydro-gas hybrid energy storage system. The near-isothermal compression module includes a water-gas co-containment tank 7, at least one gas storage tank 8, a first control valve 21, a second control valve 22, a sixth control valve 26, a seventh control valve 27, a first safety valve 31, a second safety valve 32, a third solenoid valve 43, a first pressure sensor 51, a second pressure sensor 52, a third pressure sensor 53, a fourth pressure sensor 54, a liquid level sensor 55, a first spare connector 61, and a second spare connector 62. The pumped-storage unit 3 and the water pump 4 are connected to the water-gas co-containment tank 7 via the third control valve 23 and the fourth control valve 24, respectively. The sixth control valve 26 is installed at the bottom of the water-gas co-containment tank 7. The liquid level sensor 55 is installed on the lower side of the water-gas co-containment tank 7. The first pressure sensor 51 and the second pressure sensor 52 are installed on the upper side of the water-gas co-containment tank 7. An opening at the top of the water-gas co-containment tank 7 connects to the first safety valve 8. 1. The first spare connector 61 is connected. The other opening at the upper end of the water-air co-containment tank 7 is connected to one opening of the gas storage tank 8 through the first control valve 21 and the third solenoid valve 43, which are set in parallel. The third pressure sensor 53 is set at the inlet end of the third solenoid valve 43 through the second control valve 22. The third pressure sensor 53 is electrically connected to the third solenoid valve 43. The other opening of the gas storage tank 8 is connected to the second safety valve 32 and the second spare connector 62. A fourth pressure sensor 54 is installed on the upper side of the gas storage tank 8. A seventh control valve 27 is installed at the lower end of the gas storage tank 8. The other opening at the upper end of the water-air co-containment tank 7 is connected to the compression and expansion mechanical module. When storing energy, the first control valve 21 is opened, and the air in the water-air co-containment tank 7 and at least one of the gas storage tanks 8 is compressed simultaneously to store energy. When generating electricity, the high-pressure air in the water-air co-containment tank 7 expands to generate electricity. When the pressure potential energy provided by the air pressure in the tank to the water body below is lower than the lower limit pressure P of the high-efficiency operating zone of the pumped storage unit 3, the power generation is achieved.1t At that time, gas is replenished into the water-gas co-containment tank 7 through at least one gas storage tank 8.

[0045] Specific implementation method four: Combination Figure 1-2 This embodiment describes a multi-unit near-constant pressure pumped water and compressed air hybrid energy storage system. The compression and expansion mechanical module includes an expander 5, a compressor 6, a first solenoid valve 41, and a second solenoid valve 42. The expander 5 is connected to another opening at the upper end of a water-gas co-containment tank 7 via the first solenoid valve 41. The compressor 6 is connected to another opening at the upper end of the water-gas co-containment tank 7 via the second solenoid valve 42. A first pressure sensor 51 is electrically connected to the first solenoid valve 41, and a second pressure sensor 52 is electrically connected to the second solenoid valve 42. The expander 5 and the first solenoid valve 41 are connected by a pipeline. The compressor 6 is connected to the second solenoid valve 42 via a pipeline. The expander 5 is connected to the water-gas co-containment tank 7 via a pipeline. A solenoid valve 41 is installed in the middle of the pipeline to control the opening and closing of the pipeline. The compressor 6 is connected to the water-gas co-containment tank 7 via a pipeline, and the opening and closing of the pipeline is controlled by the solenoid valve 42 in the middle of the pipeline. During pressure pre-pressurization, the compressor 6 is used to pre-pressurize the water-gas co-containment tank 7 and at least one gas storage tank 8 simultaneously. During later operation, it is used to replenish the water-gas co-containment tank 7 and at least one gas storage tank 8. During power generation, the expander 5 is used to convert the pressure energy of a small amount of high-pressure gas at the top of the water-gas co-containment tank 7 into electrical energy.

[0046] Specific Implementation Method Five: Combining Figure 1-2 This embodiment describes a multi-unit near-constant pressure pumped-storage hybrid energy storage system, which further includes an eighth control valve 28 and a ninth control valve 29. There are two pumps 4, two fourth control valves 24, and two gas storage tanks 8. The two pumps 4 are connected in parallel, and the eighth control valve 28 and the ninth control valve 29 are respectively installed at one opening of each of the two gas storage tanks 8. During energy storage, the pumped-storage unit 3 first pumps water until it reaches its maximum efficient operating head P under pumping conditions. 1P Afterwards, water pump 4 is turned on and pumped water for energy storage; during power generation, power is first generated through expander 5, and after the pressure drops, power is generated only through pumped storage unit 3; the connecting pipe between water-gas co-containment tank 7 and at least one gas storage tank 8 has a dual channel. During energy storage, the first control valve 21 is normally open, and the gas in water-gas co-containment tank 7 and at least one gas storage tank 8 is compressed together; during power generation, the second control valve 22 is opened, and pressure sensor 53 continuously measures the air pressure in the pipe to the left of solenoid valve 43. When the air pressure is lower than the lower limit pressure P of the high-efficiency zone of pumped storage unit 3 during power generation, the pumped storage unit 3 generates power. 1t At that time, the third solenoid valve 43 opens, and at least one gas storage tank 8 replenishes gas into the water-gas co-containment tank 7. This invention achieves near-rated operation of pumped storage units and water pumps by using at least two units to pump water, and can store energy stably and efficiently.

[0047] Specific Implementation Method Six: Combination Figure 1-2 This embodiment describes a multi-unit near-constant pressure pumped water and compressed air hybrid energy storage system. A stainless steel column is installed in the middle of each of the water-air co-containment tank 7 and at least one air storage tank 8. Multiple plastic trays filled with water are installed on the stainless steel columns, arranged axially along the column, to increase the contact area between air and water, thereby enhancing heat exchange and achieving better temperature control.

[0048] Specific implementation method seven: Combination Figure 1-2 This embodiment describes the operation method of a multi-unit near-constant pressure pumped-storage system. The system utilizes the aforementioned multi-unit near-constant pressure pumped-storage system, where the pumped-storage unit 3 operates in the high-efficiency zone of its pumping operation with an upper head P. 2p Approaching or exceeding the lower head limit of at least one of the high-efficiency zones of a water pump, including the following steps:

[0049] Step 1: Pressure pre-construction process;

[0050] Step 2: Energy storage process;

[0051] Step 3: Power generation process.

[0052] Specific implementation method eight: Combination Figure 1-2 This embodiment describes the operation method of a multi-unit near-constant pressure pumped water and compressed air hybrid energy storage system. In step one:

[0053] Step 1.1: The second solenoid valve 42 and the first control valve 21 are opened, the eighth control valve 28 and the ninth control valve 29 are opened, and the other valves are closed;

[0054] Step 1.2: Pressurized air is simultaneously pre-filled into the water-air co-containment tank 7 and at least one air storage tank 8 via the compressor 6;

[0055] Step 1.3: The second pressure sensor 52 measures the air pressure inside the water-air co-containment tank 7 and transmits it to the second solenoid valve 42. When the pressure inside the water-air co-containment tank 7 and at least one of the air storage tanks 8 reaches the lower limit pressure P of the high-efficiency zone of the pumping operation of the pumped storage unit 3, the pressure will be released. 1p When the pressure preset process ends, the second solenoid valve 42 and the first control valve 21 are closed.

[0056] Specific Implementation Method Nine: Combining Figure 1-2 This embodiment describes the operation method of a multi-unit near-constant pressure pumped water and compressed air hybrid energy storage system. In step two, the energy storage operation involves the continuous pumping operation of at least two units, which can be divided into energy storage stage one and energy storage stage two.

[0057] Step 2.1: Energy Storage Phase 1

[0058] The first control valve 21, the third control valve 23, and the fifth control valve 25 are open, the eighth control valve 28 and the ninth control valve 29 are open, and the other valves are closed. The pumped storage unit 3 absorbs electrical energy from the grid to pump water, drawing water from the water tank 1 into the water-air common tank 7. At this time, the water-air common tank 7 and at least one air storage tank 8 are connected through the first control valve 21, and the air in the water-air common tank 7 and the air storage tank 8 are compressed together. When the air pressure measured by the first pressure sensor 51 reaches the upper limit pressure P of the high-efficiency zone of the pumping operation of the pumped storage unit 5, the pumped storage unit 3 operates at full capacity. 2p At that time, the first phase of energy storage will end;

[0059] Step 2.2: Energy Storage Phase Two

[0060] The first control valve 21, the fourth control valve 24, and the fifth control valve 25 are open, the eighth control valve 28 and the ninth control valve 29 are open, and the other valves are closed. The water pump 4 draws water from the water tank 1 into the water-air co-containment tank 7, compressing the air in the water-air co-containment tank 7 and at least one air storage tank 8. The air pressure in the water-air co-containment tank 7 and the air storage tank 8 rises synchronously. When the pressure reaches the upper limit pressure P3 of the high-efficiency zone of the water pump 4, the second stage of energy storage ends.

[0061] Specific Implementation Method Ten: Combining Figure 1-2 This embodiment describes the operation method of a multi-unit near-constant pressure pumped water and compressed air hybrid energy storage system. Step three can be divided into three operation stages:

[0062] Step 3.1: Phase 1 of Power Generation

[0063] Solenoid valve 41 opens, eighth control valve 28 and ninth control valve 29 open, and other valves close; the high-pressure air at the top of the water-air co-containment tank 8 expands, driving the expander 5 to rotate and generate electricity. During this process, the first pressure sensor 51 works continuously. When the pressure inside the water-air co-containment tank 7 drops to the upper limit pressure P of the high-efficiency zone of the pumped storage unit 3's power generation operation, the pressure sensor 51 will open. 2t When the solenoid valve 41 is closed, the first stage of power generation ends;

[0064] Step 3.2: Second Stage of Power Generation

[0065] The second control valve 22, the third control valve 23, and the fifth control valve 25 are open, the eighth control valve 28 and the ninth control valve 29 are open, and the other valves are closed; the air in the water-air co-containment tank 8 expands to generate electricity, and the water at the bottom of the water-air co-containment tank 7 is discharged to the pumped storage unit 3 to generate electricity; during this stage, the third pressure sensor 53 is always working, and when the pressure it measures is less than the lower limit pressure P of the high-efficiency zone of the pumped storage unit 3's power generation operation... 1tWhen the third solenoid valve 43 is opened, the high-pressure air in at least one of the air storage tanks 8 expands, replenishing the water-air co-containment tank 7 with air. When the pressure measured at the third pressure sensor 53 reaches the upper limit pressure P of the high-efficiency zone of the pumped storage unit 3 during power generation... 2t Afterwards, the third solenoid valve 43 closes; throughout the entire gas replenishment process, the pumped-storage unit 3 continues to generate electricity; after repeated gas replenishment operations, the air pressure in at least one of the gas storage tanks 8 decreases, and when the pressure measured by the pressure sensor 54 drops to the upper limit pressure P of the high-efficiency zone of the pumped-storage unit 3's power generation operation... 2t After that, the second phase of power generation ended;

[0066] Step 3.3: Three Stages of Power Generation

[0067] The first control valve 21, the third control valve 23, and the fifth control valve 25 are opened, and the eighth control valve 28 and the ninth control valve 29 are opened. The air in the water-gas common tank 7 and at least one gas storage tank 8 expands together to generate electricity. When the water level in the water-gas common tank 7, as measured by the liquid level sensor 55, drops to the initial water level, the three stages of power generation end, and the power generation process is completed.

[0068] Example 1

[0069] like Figure 1 As shown, this embodiment provides a multi-machine near-constant pressure pumped water and compressed air hybrid energy storage system, including a hydraulic mechanical module, a compression and expansion mechanical module, and a near-isothermal compression module;

[0070] The hydraulic mechanical module includes a water tank 1, a bladder-type accumulator 2, a pumped storage unit 3, at least one water pump 4, a third control valve 23, a third control valve 24, and a third control valve 25; the water tank 1, the bladder-type accumulator 2, the pumped storage unit 3, and at least one water pump 4 are connected by pipelines; during energy storage, the generator motor in the pumped storage unit 3 absorbs electrical energy from the grid, drives the water pump turbine to rotate, draws water from the water tank 1 into the water-air co-containment tank 7 to compress air, converts the water pressure potential energy into the internal energy of the compressed air and stores it in the water-air co-containment tank and at least one air storage tank; during power generation, the compressed air in the water-air co-containment tank and at least one air storage tank expands, squeezing the water at the bottom of the water-air co-containment tank to the pumped storage unit 3, driving the water pump turbine to rotate, which in turn drives the generator motor to rotate and generate electricity;

[0071] The compression and expansion mechanical module includes an expander 5, a compressor 6, a first solenoid valve 41, and a second solenoid valve 42. The expander 5 is connected to the first solenoid valve 41 via a pipeline, and the compressor 6 is connected to the second solenoid valve 42 via a pipeline. During pressure pre-pressurization, the compressor 6 is used to simultaneously pre-pressurize the water-gas co-containment tank 7 and at least one gas storage tank 8. During later operation, it is used to replenish the water-gas co-containment tank 7 and at least one gas storage tank 8. During power generation, the expander 5 is used to convert the pressure energy of a small amount of high-pressure gas at the top of the water-gas co-containment tank 7 into electrical energy.

[0072] The near-isothermal compression module includes a water-air co-containment tank 7, at least one air storage tank 8, a first control valve 21, a second control valve 22, a sixth control valve 26, a seventh control valve 27, a first safety valve 31, a second safety valve 32, a third solenoid valve 43, a first pressure sensor 51, a second pressure sensor 52, a third pressure sensor 53, a fourth pressure sensor 54, a liquid level sensor 55, a first spare connector 61, and a second spare connector 62. During energy storage, the first control valve 21 opens, and the air in the water-air co-containment tank 7 and at least one air storage tank 8 is simultaneously compressed to store energy. During power generation, the high-pressure air in the water-air co-containment tank 7 expands to generate electricity. When the pressure potential energy provided by the air pressure in the tank to the water below is lower than the lower limit pressure P of the pumped storage unit 3 for efficient operation, the power generation is achieved. 1t At the same time, gas is replenished into the water-gas co-containment tank 7 through at least one gas storage tank 8; the sixth control valve is used to drain the water in the water-gas co-containment tank during maintenance, and the seventh control valve is used to discharge the small amount of water that may remain at the bottom of the gas storage tank after multiple operations; the first safety valve is used to exhaust and reduce pressure in emergency situations such as when the gas pressure in the water-gas co-containment tank exceeds the set pressure; the second safety valve is used to exhaust and reduce pressure in emergency situations such as when the gas pressure in the gas storage tank exceeds the set pressure.

[0073] This invention also provides an operation method for a multi-unit near-constant pressure pumped water / compressed gas hybrid energy storage system. Based on the aforementioned multi-unit near-constant pressure pumped water / compressed gas hybrid energy storage system, its operation includes a pressure pre-control process, an energy storage process, and a power generation process, which can be specifically divided into the following steps:

[0074] (1) Pressure pre-setting process

[0075] The second solenoid valve 42 and the first control valve 21 are open, while other valves are closed. Compressor 6 simultaneously supplies pressurized air to the water-air co-containment tank 7 and at least one air storage tank 8. During air compression, the second pressure sensor 52 measures the air pressure in the water-air co-containment tank 7 in real time and transmits it to the second solenoid valve 42. When the pressure in both the water-air co-containment tank 7 and at least one air storage tank 8 reaches the lower limit pressure P of the high-efficiency zone of the pumped storage unit 3, the pressure is released. 1p At that time, the pressure preset process ends at the second solenoid valve 42 and the first control valve 21;

[0076] (2) Energy storage process

[0077] The energy storage operation involves the continuous pumping operation of at least two units and can be divided into energy storage stage 1 and energy storage stage 2.

[0078] 1) Energy Storage Stage 1: Open the first control valve 21, the third control valve 23, and the fifth control valve 25, and close the other valves; the pumped storage unit 3 absorbs electrical energy from the grid, drives the generator motor to rotate, and drives the water pump turbine to pump water from the water tank 1 into the water-air common tank 7. At this time, the water-air common tank 7 and at least one air storage tank 8 are connected through the first control valve, and the air in the two tanks is compressed together. When the air pressure measured by the pressure sensor 51 reaches the upper limit pressure P of the high-efficiency zone of the pumping operation of the pumped storage unit 3, the pressure is increased. 2p At that time, Phase 1 of energy storage will end;

[0079] 2) Energy storage stage 2: Open the first control valve 21, the fourth control valve 23 and the fifth control valve 25, and close the other valves; the water pump 4 draws water from the water tank 1 into the water-air co-containment tank 7, compressing the air in the water-air co-containment tank 7 and at least one air storage tank 8. The air pressure in the two containers rises synchronously. When the pressure reaches the upper limit pressure P3 of the high-efficiency zone of the water pump 4, the energy storage stage 2 ends.

[0080] (3) Power generation process

[0081] The power generation process can be divided into three operating phases;

[0082] 1) Generation Stage 1: The first solenoid valve 41 is opened, and other valves are closed. The high-pressure air at the top of the water-air co-containment tank 7 expands, driving the expander 5 to rotate and generate electricity. During this process, the first pressure sensor 51 works continuously. When the measured pressure inside the water-air co-containment tank 7 drops to the upper limit pressure P of the high-efficiency zone of the pumped storage unit 3's power generation operation, the pressure will be measured. 2t When the first solenoid valve 41 is closed, the first stage of power generation ends;

[0083] 2) Generation Stage 2: Open the second control valve 21, the third control valve 23, and the fifth control valve 25, and close the other valves; the air in the water-air co-containment tank 8 expands to generate electricity, and the water at the bottom of the water-air co-containment tank 7 is discharged to the pumped storage unit 3 to generate electricity; during this stage, the third pressure sensor 53 works continuously, and when the pressure it measures is less than the lower limit pressure P of the high-efficiency zone of the pumped storage unit 3 during power generation... 1t When the third solenoid valve 43 is opened, the high-pressure air in at least one of the air storage tanks 8 expands, replenishing the water-air co-containment tank 7 with air. When the pressure measured at the third pressure sensor 53 reaches the upper limit pressure P of the high-efficiency zone of the pumped storage unit 3 during power generation... 2tAfterwards, the third solenoid valve 43 is closed; throughout the entire gas replenishment process, the pumped storage unit 3 continues to generate electricity; after the gas replenishment operation is repeated, the air pressure in at least one of the gas storage tanks 8 decreases, and when the pressure measured by the fourth pressure sensor 54 drops to the upper limit pressure P2 of the high-efficiency zone of the pumped storage unit 3, the second stage of power generation ends.

[0084] 3) Power generation stage 3: Open the first control valve 21, the third control valve 23 and the fifth control valve 25, and the air in the water-gas common tank 7 and at least one gas storage tank 8 expand together to generate electricity; when the water level in the water-gas common tank 7 measured by the liquid level sensor 55 drops to the initial water level, the power generation stage 3 ends and the power generation process is completed.

[0085] Example 2

[0086] like Figure 2 As shown, the difference between Embodiment 2 and Embodiment 1 is that Embodiment 2 is equipped with two water pumps 4 (upper and lower) and two air storage tanks 8 (upper and lower). The two water pumps 4 are arranged side by side, and the pipeline is controlled by the fourth control valve. The upper limit pressure P3 of the high-efficiency operating zone of the lower water pump 4 is close to and greater than the lower limit pressure of the high-efficiency operating zone of the upper water pump 4. The upper air storage tank 8 is connected to the eighth control valve through a pipeline, and the lower air storage tank 8 is connected to the ninth control valve through a pipeline. The upper and lower air storage tanks 8 are arranged at intervals and are on the same horizontal plane. Appropriately increasing the number of water pumps 4 and air storage tanks 8 can improve the overall energy storage capacity and operating efficiency of the system.

[0087] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0088] It should also be noted that the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. The terms "upper," "lower," "left," "right," etc., indicate the orientation based on the orientation shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device referred to must have a specific orientation, or be constructed or operated in a specific orientation.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-machine near-constant pressure pumped hydro pneumatic hybrid energy storage system, characterized by: The hydraulic mechanical module, the compression expansion mechanical module and the near-isothermal compression module are included, the hydraulic mechanical module is used for energy supply, the near-isothermal compression module is used for energy storage, and the compression expansion mechanical module is used for realizing energy conversion; The hydraulic mechanical module includes a water pool (1), an air bag type accumulator (2), a pumped storage unit (3), a water pump (4), a third control valve (23), a fourth control valve (24) and a fifth control valve (25), the water pool (1) is connected with the air bag type accumulator (2) through the fifth control valve (25), the outlet ends of the pumped storage unit (3) and the water pump (4) are respectively provided with the third control valve (23) and the fourth control valve (24), and the water pool (1) is connected with the near-isothermal compression module through the parallelly arranged pumped storage unit (3) and water pump (4); The near-isothermal compression module includes a water-gas co-container (7), a gas storage tank (8), a first control valve (21), a second control valve (22), a sixth control valve (26), a seventh control valve (27), a first safety valve (31), a second safety valve (32), a third electromagnetic valve (43), a first pressure sensor (51), a second pressure sensor (52), a third pressure sensor (53), a fourth pressure sensor (54), a liquid level sensor (55), a first spare joint (61) and a second spare joint (62), the pumped storage unit (3) and the water pump (4) are connected with the water-gas co-container (7) through the third control valve (23) and the fourth control valve (24) respectively, the bottom end of the water-gas co-container (7) is provided with the sixth control valve (26), the lower side of the water-gas co-container (7) is provided with the liquid level sensor (55), the upper side of the water-gas co-container (7) is provided with the first pressure sensor (51) and the second pressure sensor (52), one opening at the upper end of the water-gas co-container (7) is connected with the first safety valve (31) and the first spare joint (61), the other opening at the upper end of the water-gas co-container (7) is connected with one opening of the gas storage tank (8) through the parallelly arranged first control valve (21) and third electromagnetic valve (43), the third pressure sensor (53) is arranged at the inlet end of the third electromagnetic valve (43) through the second control valve (22), the third pressure sensor (53) is electrically connected with the third electromagnetic valve (43), the other opening of the gas storage tank (8) is connected with the second safety valve (32) and the second spare joint (62), the upper side of the gas storage tank (8) is provided with the fourth pressure sensor (54), the lower end of the gas storage tank (8) is provided with the seventh control valve (27), and the other opening at the upper end of the water-gas co-container (7) is connected with the compression expansion mechanical module. The compression expansion mechanical module comprises an expander (5), a compressor (6), a first electromagnetic valve (41) and a second electromagnetic valve (42), the expander (5) is connected with another opening at the upper end of a water-gas co-container (7) through the first electromagnetic valve (41), the compressor (6) is connected with another opening at the upper end of the water-gas co-container (7) through the second electromagnetic valve (42), a first pressure sensor (51) is electrically connected with the first electromagnetic valve (41), and a second pressure sensor (52) is electrically connected with the second electromagnetic valve (42).

2. A multi-machine near-constant pressure water-pumping and gas hybrid energy storage system according to claim 1, characterized in that: The eighth control valve (28) and the ninth control valve (29) are further included, the number of the water pump (4), the fourth control valve (24) and the gas storage tank (8) is two, the two water pumps (4) are connected in parallel, and the eighth control valve (28) and the ninth control valve (29) are arranged at one opening of the two gas storage tanks (8) respectively.

3. The multi-machine near-constant pressure water-pumping and gas hybrid energy storage system according to claim 1 or 2, characterized in that: A stainless steel column is arranged at the middle part of the water-gas co-container (7) and the gas storage tank (8), a plurality of plastic discs filled with water are arranged on the stainless steel column in the axial direction.

4. An operation method for a multi-unit near-constant pressure pumped water and compressed air hybrid energy storage system, characterized in that: The multi-machine type near constant pressure water pumping and gas mixing energy storage system adopts any one of claims 1-3, comprising the following steps: Step one: pressure preparation process; In step one: Step 1.1: the second electromagnetic valve (42) and the first control valve (21) are opened, and other valves are closed; Step 1.2: the water-gas co-container (7) and the gas storage tank (8) are simultaneously pre-installed with pressure air through the compressor (6); Step 1.3: The second pressure sensor (52) measures the air pressure in the water-air coexistence tank (7) and transmits to the second electromagnetic valve (42), when the pressure in the water-air coexistence tank (7) and the gas storage tank (8) reaches the pumped storage unit (3) P 1p , the second electromagnetic valve (42) and the first control valve (21) are closed, and the pressure presetting process is completed. Step two: energy storage process; In step two, the energy storage working condition involves the continuous water pumping operation of two units, and is divided into an energy storage first stage and an energy storage second stage; Step 2.1: energy storage first stage The first control valve (21), the third control valve (23) and the fifth control valve (25) are opened, and other valves are closed; the pumped storage unit (3) absorbs electric energy from the power grid to run pumping, and the water in the water pool (1) is pumped into the water-gas common tank (7); at this time, the water-gas common tank (7) and the gas storage tank (8) are communicated through the first control valve (21), and the air in the water-gas common tank (7) and the gas storage tank (8) is compressed together; when the air pressure measured by the first pressure sensor (51) reaches the pressure of the pumped storage unit (5) P 2p , the first energy storage stage ends; Step 2.2: energy storage second stage The first control valve (21), the fourth control valve (24) and the fifth control valve (25) are opened, and other valves are closed; the water pump (4) pumps water from the water pool (1) into the water-air coexistence tank (7), compresses the air in the water-air coexistence tank (7) and the gas storage tank (8), and the air pressure in the water-air coexistence tank (7) and the gas storage tank (8) rises synchronously, when the pressure reaches 3 P 3, the energy storage two-stage ends. Step three: power generation process; In step three: Step 3.1: power generation first stage The electromagnetic valve (41) is opened, and other valves are closed; the high-pressure air at the top of the water-gas coexistence tank (8) expands, pushing the expander (5) to rotate and work to generate electricity. In this process, the first pressure sensor (51) always works, and when the measured pressure in the water-gas coexistence tank (7) decreases to the pressure of the pumped storage unit (3) P 2t , the electromagnetic valve (41) is closed, and the power generation stage ends. Step 3.2: power generation second stage The second control valve (22), the third control valve (23) and the fifth control valve (25) are opened, and other valves are closed; the air in the water-air coexistence tank (8) expands to generate electricity, and the water at the bottom of the water-air coexistence tank (7) is discharged to the pumped storage unit (3) to generate electricity and work; during this stage, the third pressure sensor (53) is always working, and when the pressure measured by the third pressure sensor (53) is less than the pumped storage unit (3) P 1t , the third electromagnetic valve (43) is opened, the high-pressure air in the air tank (8) expands, and the water-air coexistence tank (7) is supplemented with air; when the pressure measured by the third pressure sensor (53) reaches the pumped storage unit (3) P 2t , the third electromagnetic valve (43) is closed; during the entire air supplementing process, the pumped storage unit (3) is always in power generation operation; after air supplementing, the air pressure in the air tank (8) decreases, and when the pressure measured by the pressure sensor (54) decreases to the upper limit pressure of the high-efficiency region of the pumped storage unit (3) in power generation working condition P 2t , the second stage of power generation ends; Step 3.3: power generation third stage The first control valve (21), the third control valve (23) and the fifth control valve (25) are opened, and the air in the water-gas co-container (7) and the gas storage tank (8) is expanded to generate power; when the water level in the water-gas co-container (7) measured by the liquid level sensor (55) decreases to the initial water level, the power generation third stage ends, and the power generation process is completed.

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