Compact compressed air energy storage system, power system and compressed air energy storage method

Abstract

The present invention provides a compact compressed air energy storage system, an electric power system and a compressed air energy storage method, and relates to the field of energy storage technology. The compact compressed air energy storage system includes an air compression system, a combined gas storage device and an air expansion system; the combined gas storage device includes a first gas storage device and a second gas storage device that are interconnected. The first gas storage device includes a fan tower, and the second gas storage device is arranged underground, fixed underwater or suspended in water; the central axis of the air compression system and the central axis of the air expansion system are coaxially arranged, and the input shaft of the air compression system and the output shaft of the air expansion system are detachably connected to a three-in-one motor. The present invention can solve the problems of the gas storage device of the existing compressed air energy storage system being restricted by geographical conditions, having high construction costs, and having dispersed layout of electromechanical equipment, complex structure, and having many high-cost equipment. It has the effects of not being restricted by geographical conditions, having a compact structure, occupying a small area, and saving infrastructure and equipment costs.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a compact compressed air energy storage system, a power system and a compressed air energy storage method. Background Art

[0002] Large-scale compressed air energy storage technology is a key technology to solve the problems of wind and solar power abandonment, significantly improve the level of new energy consumption, promote the replacement of main energy from fossil energy to renewable energy, and realize distributed energy systems, regional smart microgrids, and friendly source-grid-load-storage.

[0003] Since wind conditions on land or at sea are changeable, including stable wind conditions, gusty wind conditions, and gradually changing wind conditions, and the power generation of wind turbines is affected by wind conditions, wind power is intermittent, volatile, and uncontrollable, and the fluctuation of wind power grid connection will have an impact on the power grid. Therefore, in the prior art, compressed air energy storage devices are used to adjust the instability of the power grid and reduce peak loads. Conventional compressed air energy storage coupled wind power technology includes two application scenarios, onshore and offshore, and both are indirectly connected through large power grids.

[0004] For the gas storage device of the onshore compressed air energy storage system, the method with lower construction cost in the prior art is to use the underground abandoned space for compressed air energy storage, and lay a flexible airtight polymer film on the inner wall of the underground space to store high-pressure air. Specifically, the underground abandoned space includes underground caves, which include salt caves, underground aquifers, hard rock caves, natural salt caves, abandoned natural gas and oil gas storage chambers. On the one hand, these underground abandoned spaces are restricted by geographical conditions, and on the other hand, they require the laying of longer transmission pipelines, which has high construction costs.

[0005] Regarding the gas storage devices of the offshore compressed air energy storage system, in the existing technology, the first solution is to build a sea level gas storage device, which faces problems such as large-scale expropriation of near and far sea areas; the second solution is to build a coastal ground gas storage device, which faces problems such as expropriation of expensive land near the coastline.

[0006] In the prior art, a compressed air energy storage system includes a compression subsystem and an expansion subsystem. Both the compression subsystem and the expansion subsystem need to be connected to mechanical and electrical equipment. However, the mechanical and electrical equipment are dispersed and numerous, resulting in high costs for electromechanical equipment. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of compressed air energy storage in the prior art that is restricted by geographical conditions, has high cost and complex structure of the energy storage system, thereby providing a compact compressed air energy storage system, power system and compressed air energy storage method.

[0008] In order to solve the above problems, the present invention provides a compact compressed air energy storage system, including an air compression system, a combined air storage device and an air expansion system; the output end of the air compression system is connected to the input end of the combined air storage device, and the output end of the combined air storage device is connected to the input end of the air expansion system; wherein the combined air storage device includes a first air storage device and / or a second air storage device. The first air storage device includes a wind turbine tower, and the wind turbine tower is provided with a first air storage cavity; the second air storage device is arranged underground, underwater or suspended in water, and the second air storage device is provided with a second air storage cavity, and the first air storage cavity is connected to the second air storage cavity; the central axis of the air compression system and the central axis of the air expansion system are coaxially arranged, and the input shaft of the air compression system and the output shaft of the air expansion system are detachably connected to the three-in-one motor.

[0009] Optionally, the tower includes a plurality of tower sections that are axially separated and arranged; and the first air storage cavity is arranged in one or more tower sections.

[0010] Optionally, the tower includes an outer cylinder and an inner cylinder which are radially sleeved; an annular gap between the outer cylinder and the inner cylinder constitutes a first air storage cavity.

[0011] Optionally, the second gas storage device includes an artificial chamber, the cavity of the artificial chamber constitutes a second gas storage cavity, the artificial chamber is arranged below the tower, and the first gas storage cavity is connected to the second gas storage cavity through or through a pipeline.

[0012] Optionally, the combined gas storage device includes a storage tank fixed on the seabed, the inner cavity of the storage tank constitutes a second gas storage cavity, the storage tank is arranged below the tower, and the first gas storage cavity is connected to the second gas storage cavity through a through-hole or through a pipeline.

[0013] Optionally, the combined air storage device includes an air bag suspended in water, the inner cavity of the air bag constitutes a second air storage cavity, the first air storage cavity of the tower is provided with an interface, and the air nozzle of the air bag and the interface are connected by a pipeline.

[0014] Optionally, the air compression system includes a multi-stage compressor connected in series, and the central axes of the multi-stage compressors are coaxially arranged; the air expansion system includes a multi-stage gas expander connected in series, and the central axes of the multi-stage gas expander are coaxially arranged; the central axis of the compressor located at the end of the air compression system and the central axis of the gas expander located at the end of the air expansion system are connected through a switching device.

[0015] Optionally, the switching device includes a first clutch detachably connected to the central shaft of the air compression system and a second clutch detachably connected to the central shaft of the air expansion system.

[0016] Optionally, a common heat exchange device is provided between the air compression system and the air expansion system, and the common heat exchange device includes a first heat exchange channel, a second heat exchange channel and a third heat exchange channel; the input end of the first heat exchange channel is connected to the heat output end of the air compression system, and the output end of the first heat exchange channel is connected to the input end of the combined air storage device; the input end of the second heat exchange channel is connected to the output end of the combined air storage device, and the output end of the second heat exchange channel is connected to the heat input end of the air expansion system; and the third heat exchange channel circulates heat exchange medium.

[0017] A second aspect of the present invention provides an electric power system, comprising a power grid, a wind turbine generator set, and a compact compressed air energy storage system described in any of the above technical solutions, wherein the air compression system is electrically connected to the power grid, or the air compression system is electrically connected to the wind turbine generator set, and the air expansion system is electrically connected to the power grid.

[0018] The third aspect of the present invention provides a compressed air energy storage method, which uses the compact compressed air energy storage system described in any one of the above technical solutions to store air energy, including the following steps: during the energy storage process, the three-in-one motor and the input shaft of the air compression system are connected, the air is compressed and cooled, and the compressed air is stored in a combined air storage device; during the energy release process, the three-in-one motor and the output shaft of the air expansion system are connected, the compressed air stored in the combined air storage device is heated and injected into the air expansion system for expansion work output; wherein, "storing the compressed air in the combined air storage device" includes storing the compressed air in the first air storage device and / or the second air storage device.

[0019] Optionally, the heat energy generated by air compression during the energy storage process is used to heat the compressed air during the energy release process; and the cold energy generated by compressed air expansion during the energy release process is used to cool the air during the energy storage process.

[0020] Optionally, during the energy storage process, the air is compressed to a supercritical state, and the compressed air in the supercritical state is stored in a combined air storage device.

[0021] The present invention has the following advantages:

[0022] 1. Utilizing the technical solution of the present invention, utilizing the compressed air combined energy storage system or compressed air energy storage method provided by the present invention, during energy storage, the air is compressed by the air compression system and stored in the combined air storage device, and during energy release, the compressed air in the combined air storage device is released and output to the air expansion system, and electricity is generated by expansion; the central axis of the air compression system and the central axis of the air expansion system are coaxially arranged, and the input shaft of the air compression system and the output shaft of the air expansion system are detachably connected to the three-in-one motor, which can make the structure of the compressed air combined energy storage system more compact and can significantly reduce the cost of mechanical equipment and electrical equipment;

[0023] By setting a combined gas storage device, wherein a first gas storage cavity is set in the tower, the space of the tower itself can be used as a part of the energy storage space, and a second gas storage device is set, the second gas storage device is set with a second gas storage cavity, the first gas storage cavity and the second gas storage cavity are connected, and the second gas storage device and the tower are combined to store gas, which can expand the energy storage space of compressed air. When used on land, the second gas storage device is set underground. Compared with the prior art that uses the underground space of waste gas, the present invention is not limited by geographical conditions. The second gas storage device can be set close to the tower, shortening the gas transmission pipeline and reducing the construction cost of the energy storage device; when used at sea, the second gas storage device is set underwater or suspended in water. Compared with the prior art that constructs underground space along the coast, it is not necessary to occupy expensive land space along the coast, and the length of the gas transmission pipeline is shortened, reducing the construction cost;

[0024] The energy storage capacity of the first gas storage cavity and the second gas storage cavity can be flexibly allocated according to the actual energy storage needs such as the site selection wind farm, geological conditions, deep sea conditions, etc.;

[0025] When used at sea, the second air storage device is installed underwater or suspended in water, and the static pressure of the water is used to maintain the constant pressure operation of the compressed air combined energy storage system at sea, avoiding the air compression system and the air expansion system from deviating from the design conditions and operating inefficiently due to pressure changes, thereby improving the energy conversion efficiency of the system.

[0026] 2. One or more tower sections are arranged axially on the tower, and the first gas storage cavity is arranged in one or more tower sections, or the tower is provided with an outer cylinder body and an inner cylinder body, and the annular gap between the two constitutes the first gas storage cavity. The arrangement mode of the first gas storage cavity can be flexibly selected according to the actual situation of the tower. Since the tower itself is a pipeline steel storage tank structure, the internal space structure of the tower can be optimized and utilized to replace the existing underground gas storage space, thereby reducing the construction cost of the underground or ground gas storage space.

[0027] 3. By setting up a common heat exchange device, the heat energy generated by air compression during the energy storage process can be used to heat the compressed air during the energy release process; the cold energy generated by the expansion of compressed air during the energy release process can be used to cool the air during the energy storage process. The common heat exchange device is shared by the energy storage process and the energy release process. During energy storage, the air is compressed and cooled, and the pressure potential energy and temperature thermal energy are stored in the combined gas storage device and the common heat exchange device respectively; during energy release, the high-pressure air in the combined gas storage device is heated by the common heat exchange device to become high-pressure and high-temperature air, and then injected into the gas expander to expand and do work. Setting up a common heat exchange device can improve the system's thermal energy utilization rate and improve the system's operating efficiency on the one hand, and on the other hand, it is conducive to simplifying the system structure, reducing the occupied space, and reducing the construction and operation and maintenance costs, which has the effect of reducing costs and increasing efficiency.

[0028] 4. By setting up an electromechanical coaxial device, the three-in-one motor, clutch, and impeller mechanical part of the compression / expansion system are compactly integrated. When storing energy, the three-in-one motor is connected to the input shaft of the air compression system as an electric motor, driving the central shaft of the compressor unit to rotate to achieve air compression and energy conversion; when releasing energy, the three-in-one motor is connected to the output shaft of the air expansion system as a generator, and is driven by the central shaft of the expansion unit to achieve air expansion and external output; at the same time, the three-in-one motor can be used as a phase regulator in the power system to increase reactive output when the grid voltage drops, absorb reactive power when the grid voltage rises, maintain the grid voltage, improve system stability, and improve the system power supply quality. On the one hand, the setting of an electromechanical coaxial device can reduce the electromechanical conversion loss caused by multi-axis connection and improve energy conversion efficiency. On the other hand, it is conducive to improving the system integration level and space utilization, saving construction and operation and maintenance costs, and achieving the effect of reducing costs and increasing efficiency.

[0029] 5. The air compression system and air expansion system can compress the air to a supercritical state, which can significantly improve system efficiency and reduce the space occupied by gas storage. They can also compress the air to a non-supercritical state and flexibly select the specific gas storage state of the compact compressed air energy storage system according to the power and duration required to store electrical energy during off-peak hours of wind farms or power grids.

[0030] 6. By utilizing the power system of the present invention to directly couple the compressed air combined energy storage system with an offshore wind farm with relatively high and stable wind speeds, distributed energy storage and regional microgrids can be realized, close to coastal load centers, and reduce transmission and distribution costs.

[0031] 7. In the power system, when used at sea, except for the combined gas storage device arranged at sea, the rest can be arranged at sea, which can shorten the gas transmission pipeline. It can also be distributed on land, using long-distance power transmission instead of long-distance gas transmission, which can make full use of compression heat, reduce energy waste and improve system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 A schematic structural diagram of a compressed air combined energy storage system provided by an embodiment of the present invention is shown;

[0034] Figure 2A structural schematic diagram of a first implementation of a combined air storage device in a compressed air combined energy storage system provided in an embodiment of the present invention is shown;

[0035] Figure 3 A schematic structural diagram of a second implementation of a combined air storage device in a compressed air combined energy storage system provided in an embodiment of the present invention is shown;

[0036] Figure 4 A schematic structural diagram of a third embodiment of the first air storage device in the compressed air combined energy storage system provided by the present invention is shown;

[0037] Figure 5 A schematic structural diagram of a first embodiment of a first air storage device in a compressed air combined energy storage system provided by the present invention is shown;

[0038] Figure 6 A schematic structural diagram of a second embodiment of the first air storage device in the compressed air combined energy storage system provided by the present invention is shown;

[0039] Figure 7 A schematic diagram showing the structure of a common heat exchange device located on the low-pressure side in the compressed air combined energy storage system provided by the present invention;

[0040] Figure 8 A schematic structural diagram showing a common heat exchange device located on the high pressure side in the compressed air combined energy storage system provided by the present invention.

[0041] Description of reference numerals:

[0042] 1. Air compression system; 11. Compressor; 12. Cooler; 2. Combined gas storage device; 21. Tower; 211. Tower section; 212. Outer cylinder; 213. Inner cylinder; 214. First gas storage cavity; 215. Manhole; 216. Connecting pipe; 22. Second gas storage device; 221. Storage tank; 222. Air bag; 223. Second gas storage cavity; 224. Artificial chamber; 3. Air expansion system; 31. Gas expander; 4. Pressure reducing device; 41. Liquid expander; 5. Pressurizing device; 51. Cryogenic pump; 6. Cold storage heat exchanger; 7. Public heat exchange device; 8. Three-in-one motor; 9. Switching device; 91. First clutch; 92. Second clutch; 100. Compact compressed air energy storage system; 300. Wind turbine. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] In order to facilitate the introduction of the technical solution of the present invention, it is described in detail below with reference to the accompanying drawings and specific embodiments, but the embodiments should not be regarded as limiting the present invention.

[0048] Example 1

[0049] A compressed air combined energy storage system, referring to Figure 1-Figure 8, including an air compression system 1, a combined air storage device 2 and an air expansion system 3; the output end of the air compression system 1 is connected to the input end of the combined air storage device 2, and the output end of the combined air storage device 2 is connected to the input end of the air expansion system 3; the combined air storage device 2 includes a first air storage device and / or a second air storage device 22. The first air storage device includes a fan tower 21, and the fan tower 21 is provided with a first air storage cavity 214; the second air storage device 22 is arranged underground, underwater or suspended in water, and the second air storage device 22 is provided with a second air storage cavity 223, and the first air storage cavity 214 and the second air storage cavity 223 are connected; the central axis of the air compression system 1 and the central axis of the air expansion system 3 are coaxially arranged, and the input shaft of the air compression system 1 and the output shaft of the air expansion system 3 are detachably connected to the three-in-one motor 8.

[0050] By utilizing the technical solution of the present invention and the compressed air combined energy storage system or the compressed air combined gas storage method provided by the present invention, when storing energy, the air is compressed by the air compression system 1 and stored in the combined gas storage device 2, and when releasing energy, the compressed air in the combined gas storage device 2 is released and output to the air expansion system 3, and electricity is generated by expansion work; the central axis of the air compression system 1 and the central axis of the air expansion system 3 are coaxially arranged, and the input shaft of the air compression system 1 and the output shaft of the air expansion system 3 are detachably connected to the three-in-one motor 8, which can make the structure of the compressed air combined energy storage system more compact and can greatly reduce the cost of mechanical equipment and electrical equipment;

[0051] By setting a combined gas storage device 2, wherein the tower 21 is provided with a first gas storage cavity 214, the space of the tower 21 itself can be used as a part of the energy storage space, and a second gas storage device 22 is provided, and the second gas storage device 22 is provided with a second gas storage cavity 223, and the first gas storage cavity 214 and the second gas storage cavity 223 are connected, so that the second gas storage device 22 and the tower 21 can store gas together, and the energy storage space of compressed air can be expanded. When used on land, the second gas storage device 22 is arranged underground. Compared with the prior art that uses the underground space of waste gas, the present invention is not limited by geographical conditions, and the second gas storage device 22 can be arranged close to the tower 21, shortening the gas transmission pipeline and reducing the construction cost of the energy storage device; when used at sea, the second gas storage device 22 is arranged underwater or suspended in water. Compared with the prior art that constructs underground space along the coast, it is not necessary to occupy expensive land space along the coast, and the length of the gas transmission pipeline is shortened, reducing the construction cost;

[0052] The energy storage capacity of the first gas storage cavity 214 and the second gas storage cavity 223 can be flexibly allocated according to the actual energy storage requirements such as the site selection wind farm, geological conditions, deep sea conditions, etc.;

[0053] When used at sea, the second air storage device 22 is disposed underwater or suspended in water, and the static pressure of the water is used to maintain the constant pressure operation of the compressed air combined energy storage system at sea, thereby preventing the air compression system 1 and the air expansion system 3 from deviating from the design conditions and operating inefficiently due to pressure changes, thereby improving the energy conversion efficiency of the system.

[0054] Specifically, the output end of the air compression system 1 refers to the port through which the air compression system 1 outputs gas, which can also be said to be the air outlet. The input end of the combined air storage device 2 refers to the port through which the combined air storage device 2 inputs compressed air, which can also be said to be the air inlet. The output end of the combined air storage device 2 refers to the port through which compressed air is output, which can also be said to be the air outlet. The input end of the air expansion system 3 refers to the port through which compressed air is input into the air expansion system 3, which can also be said to be the air inlet.

[0055] Optionally, the three-in-one motor 8 is an integration of a generator, an electric motor and a phase regulator. When the three-in-one motor 8 is connected to the input shaft of the air compression system 1, it can be used as a motor to drive the central axis of the air compression system 1 to rotate to achieve air compression; when the three-in-one motor 8 is connected to the output shaft of the air expansion system 3, it can be used as a generator to expand the air to generate electricity; when the three-in-one motor 8 is used as a phase regulator, the phase regulator is a synchronous phase regulator, which is a synchronous motor. When applied to the power system, it can automatically increase the reactive output when the grid voltage drops according to the needs of the system, and absorb reactive power when the grid voltage rises, so as to maintain the voltage, improve the stability of the power system, and improve the power supply quality of the system.

[0056] Optional, see Figure 1 The air compression system 1 includes a multi-stage compressor 11 connected in series, and the central axes of the multi-stage compressor 11 are coaxially arranged; the air expansion system 3 includes a multi-stage gas expander 31 connected in series, and the central axes of the multi-stage gas expander 31 are coaxially arranged; the central axis of the compressor 11 located at the end of the air compression system 1 and the central axis of the gas expander 31 located at the end of the air expansion system 3 are connected via a switching device 9.

[0057] Optionally, the switching device 9 includes a first clutch 91 detachably connected to the central axis of the air compression system 1 and a second clutch 92 detachably connected to the central axis of the air expansion system 3. During the energy storage process, one output end of the three-in-one motor 8 is connected to the central axis of the air compression system 1 through the first clutch 91, and at this time, the second clutch 92 is in a disconnected state; during the energy release process, the other output end of the three-in-one motor 8 is connected to the central axis of the air expansion system 3 through the second clutch 92, and at this time, the first clutch 91 is in a disconnected state.

[0058] Optional, Figure 5A structural schematic diagram of a first embodiment of a tower 21 is provided, wherein the tower 21 includes a plurality of tower sections 211 that are axially split and arranged; a first gas storage cavity 214 is arranged in one or more tower sections 211. Specifically, along the axial direction of the tower 21, a flange is arranged at the connecting end of the tower section 211, and two adjacent tower sections 211 are connected by bolts. From bottom to top, the inner diameter of the tower section 211 gradually decreases, and therefore, the capacity of the first gas storage cavity 214 in the plurality of tower sections 211 also decreases from bottom to top. Optionally, a gas storage barrel is arranged in the tower section 211, and the inner cavity of the gas storage barrel constitutes the first gas storage cavity 214.

[0059] Optionally, a manhole 215 is provided on the tower section 211 to facilitate entering the tower 21 for maintenance.

[0060] Optional, Figure 6 A schematic structural diagram of a second embodiment of a tower 21 is provided, wherein the tower 21 comprises an outer cylinder 212 and an inner cylinder 213 which are sleeved in a radial direction; an annular gap between the outer cylinder 212 and the inner cylinder 213 constitutes a first gas storage cavity 214. Optionally, the length of the inner cylinder 213 is equal to the length of the outer cylinder 212, and the annular gap between the inner cylinder 213 and the outer cylinder 212 constitutes the first gas storage cavity 214.

[0061] The designers can flexibly select the above two implementation modes of the first gas storage cavity 214 according to the actual situation of the tower 21 and the energy storage demand, so as to make full use of the internal space of the tower 21 .

[0062] When used at sea, refer to Figure 2 The second gas storage device 22 includes a storage tank 221 fixed on the seabed. The inner cavity of the storage tank 221 constitutes a second gas storage cavity 223. The storage tank 221 is arranged below the tower 21. The bottom of the tower 21 is connected to the storage tank 221, that is, the storage tank 221 can be used as the foundation of the bottom of the tower 21. The bottom of the tower 21 is connected to the storage tank 221, then, the inner cavity of the tower 21 and the inner cavity of the storage tank 221 are directly connected.

[0063] Optional, see Figure 3 The second air storage device 22 includes an air bag 222 suspended in water, the inner cavity of the air bag 222 constitutes a second air storage cavity 223, the tower 21 is provided with an interface, and the air nozzle of the air bag 222 and the interface of the tower 21 are connected by a pipeline to connect the first air storage cavity 214 and the second air storage cavity 223.

[0064] The use of the airbag 222 can realize a compact compressed air energy storage system 100 floating at sea, which can break through the near-shore restrictions and avoid multi-functional interference. It is suitable for large-scale floating offshore wind turbines 300 and meets the development needs of the continuously increasing single-unit capacity of offshore wind turbines 300.

[0065] When used at sea, the air compression system 1 and the air expansion system 3 of the compact compressed air energy storage system are coaxially arranged. Due to differences in offshore and onshore wind farm resources, the current maximum single-unit capacity of the offshore wind turbine 300 has reached 18MW, while the maximum single-unit capacity of the onshore wind turbine 300 is about 8MW. The requirements for the requisitioned land area under the same wind farm capacity are different, and the offshore wind turbine 300 has more advantages. In addition, the cost of requisitioning sea areas is higher and the demand is more urgent. The compact coaxial arrangement can better reflect its value, and it has the application prospect of integrating the distributed small-capacity compressed air energy storage system into the offshore wind turbine cabin. When used on land, refer to Figure 4 The second gas storage device 22 includes an artificial chamber 224, the cavity of the artificial chamber 224 constitutes a second gas storage cavity 223, the artificial chamber 224 is arranged below the tower 21, and the first gas storage cavity 214 is connected to the second gas storage cavity 223 through or through a pipeline.

[0066] Optionally, the first gas storage cavity 214 and the second gas storage cavity 223 are connected via a connecting pipe 216 .

[0067] Optionally, a pressure reducing device 4 is provided between the air compression system 1 and the combined air storage device 2; the output end of the air compression system 1 is connected to the input end of the pressure reducing device 4, and the output end of the pressure reducing device 4 is connected to the input end of the combined air storage device 2; a pressurizing device 5 is provided between the combined air storage device 2 and the air expansion system 3, the input end of the pressurizing device 5 is connected to the output end of the combined air storage device 2, and the output end of the pressurizing device 5 is connected to the input end of the air expansion system 3.

[0068] The storage states of compressed air include gaseous and non-gaseous states, and the non-gaseous states include liquid and supercritical states.

[0069] As a first embodiment of the compact compressed air energy storage system 100, refer to Figure 1 The air compression system 1 includes a plurality of compressors 11 connected in series, and a cooler 12 is connected after each compressor 11; specifically, the cooler 12 includes an intercooler arranged between two compressors 11 and an aftercooler arranged downstream of the terminal compressor 11. The air expansion system 3 includes a plurality of gas expanders 31 connected in series, and a reheater is connected before each gas expander 31; a cold storage heat exchanger 6 is connected between the air compression system 1 and the combined gas storage device 2, and between the air expansion system 3 and the combined gas storage device 2; the output end of the air compression system 1 is connected to the first input end of the cold storage heat exchanger 6, and the first output end of the cold storage heat exchanger 6 is connected to the input end of the combined gas storage device 2; the output end of the combined gas storage device 2 is connected to the second input end of the cold storage heat exchanger 6, and the second output end of the cold storage heat exchanger 6 is connected to the air expansion system 3.

[0070] Working principle: When storing energy, the multi-stage compressor 11 and the interstage cooler 12 can perform multi-stage compression and cooling on the air, compress the air, and store it in the combined gas storage device 2, and the storage state of the compressed air is gaseous; when releasing energy, the compressed air is injected into the gas expander 31, and after multi-stage heating and expansion, it is output as work to the outside.

[0071] As a second embodiment of the compact compressed air energy storage system 100, a cold storage heat exchanger 6 is provided between the air compression system 1 and the combined gas storage device 2, and the air compression system 1 includes a pressure reduction device 4 provided between the cold storage heat exchanger 6 and the combined gas storage device 2. The cold storage heat exchanger 6 has a first inlet, a first outlet, a second inlet, and a second outlet. The output end of the compressor 11 is connected to the first inlet of the cold storage heat exchanger 6, the first outlet of the cold storage heat exchanger 6 is connected to the input end of the pressure reduction device 4, and the output end of the pressure reduction device 4 is connected to the input end of the combined gas storage device 2. During energy storage, the high-pressure gas is compressed and cooled by the multi-stage compressor 11 and the interstage cooler 12, heat is exchanged by the cold storage heat exchanger 6, and cooled again. After being reduced in pressure by the pressure reduction device 4, it is stored in the combined gas storage device 2 at normal pressure, and the storage state of the compressed air is non-gaseous. Optionally, the pressure reduction device 4 includes a liquid expander 41 or a throttle valve.

[0072] Optionally, the air expansion system 3 includes a pressurizing device 5, the input end of the pressurizing device 5 is connected to the output end of the combined gas storage device 2, the output end of the pressurizing device 5 is connected to the second inlet of the cold storage heat exchanger 6, and the second outlet of the cold storage heat exchanger 6 is connected to the input end of the gas expander 31. When releasing energy, the compressed air in the combined gas storage device 2 is pressurized by the pressurizing device 5, then heated to room temperature by the cold storage heat exchanger 6, and then heated and expanded by the multi-stage gas expander 31 and the pre-stage reheater, and finally output. Optionally, the pressurizing device 5 includes a cryogenic pump 51.

[0073] With regard to the heat exchange devices of compressed air energy storage systems on land and at sea, the prior art requires that multiple heat exchange devices, hot and cold storage tanks, and pumping devices be arranged on each side of the air compression system 1 and the air expansion system 3, respectively. In addition, the heat exchange pipelines are complicated, resulting in inevitable large pressure loss and heat dissipation along the way.

[0074] In order to solve the above problems, optionally, a common heat exchange device 7 is provided between the air compression system 1 and the air expansion system 3. The common heat exchange device 7 is connected to the air compression system 1 and is used to cool the gas during the air compression process. The common heat exchange device 7 is connected to the air expansion system 3 and is used to heat the gas during the air expansion process.

[0075] Specifically, the compressed air combined energy storage system includes a common heat exchange device 7, which includes a first heat exchange channel, a second heat exchange channel and a third heat exchange channel. The input end of the first heat exchange channel is connected to the heat output end of the air compression system 1, and the output end of the first heat exchange channel is connected to the input end of the combined air storage device 2; the input end of the second heat exchange channel is connected to the output end of the combined air storage device 2, and the output end of the second heat exchange channel is connected to the heat input end of the air expansion system 3, and the third heat exchange channel circulates heat exchange medium.

[0076] Specifically, during the air compression process, the compression heat generated enters the first heat exchange channel and exchanges heat with the heat exchange medium in the third heat exchange channel. The air in the first heat exchange channel is cooled, and the heat is stored in the heat exchange medium in the third heat exchange channel. During the air expansion process, the heat exchange medium in the third heat exchange channel exchanges heat with the air in the second heat exchange channel to heat the air for air expansion work. At the same time, the heat exchange medium in the third heat exchange channel is cooled and can be used to cool the air in the next round of air compression, thereby realizing that the air compression system 1 and the air expansion system 3 share the common heat exchange device 7. By setting up the common heat exchange device 7, the heat energy generated by air compression during the energy storage process can be used to heat the compressed air during the energy release process, and the cold energy generated by air expansion during the energy release process can be used to cool the compressed air during the energy storage process. The common heat exchange device 7 is shared by the energy storage process and the energy release process. During energy storage, the air is compressed and cooled, and the pressure potential energy and temperature thermal energy are stored in the combined gas storage device 2 and the common heat exchange device 7 respectively; during energy release, the high-pressure air in the combined gas storage device 2 is heated by the common heat exchange device 7 to become high-pressure and high-temperature air, and then injected into the gas expander 31 to expand and do work. On the one hand, setting up the common heat exchange device 7 can simplify the pipeline layout, reduce the pressure loss and heat dissipation along the way, improve the system thermal energy utilization rate, and improve the system operation efficiency. On the other hand, it is conducive to improving the system integration level and space utilization rate, saving construction costs, and achieving the effect of reducing costs and increasing efficiency.

[0077] In this embodiment, since the air compression system 1 and the air expansion system 3 share the common heat exchange device 7, the common heat exchange device 7 serves as a reheater.

[0078] The air compression system 1 and the air expansion system 3 share a common heat exchange device 7. During the energy storage process, the first heat exchange channel of the common heat exchange device 7 operates to cool the air; during the energy release process, the second heat exchange channel of the common heat exchange device 7 operates to heat the air. The first heat exchange channel and the second heat exchange channel do not operate at the same time. Using one common heat exchange device 7 can realize two functions in the energy storage and energy release processes.

[0079] Optionally, the air compression system 1 has a first pressure side and a second pressure side, and the pressure of the second pressure side is greater than the pressure of the first pressure side; the air compression system 1 includes at least two compressors 11 connected in series, and the multiple compressors 11 are respectively arranged on the first pressure side and the second pressure side; the air expansion system 3 includes at least two gas expanders 31 connected in series, and the multiple gas expanders 31 are respectively arranged on the first pressure side and the second pressure side. Specifically, the first pressure side is the low pressure side, and the second pressure side is the high pressure side.

[0080] As a first embodiment of the common heat exchange device 7, on the low-pressure side, adjacent compressors 11 are connected to the first heat exchange channel of the common heat exchange device 7, and adjacent gas expanders 31 are connected to the second heat exchange channel of the common heat exchange device 7. Figure 7 As shown, in this embodiment, the temperature parameters of the common heat exchange device 7 on the low-pressure side are similar. Since the pressure difference is small, the number and tonnage of heat exchange equipment can be reduced after sharing the common heat exchange device 7.

[0081] As a second embodiment of the common heat exchange device 7, on the high-pressure side, adjacent compressors 11 are connected to the first heat exchange channel of the common heat exchange device 7, and adjacent gas expanders 31 are connected to the second heat exchange channel of the common heat exchange device 7. Figure 8 As shown, in this embodiment, the temperature parameters of the common heat exchange device 7 on the high-pressure side are similar. Due to the large pressure difference, the pressure change needs to be considered when the first heat exchange channel and the second heat exchange channel are switched. After sharing the common heat exchange device 7, the number and tonnage of heat exchange equipment can be significantly reduced.

[0082] As a third embodiment of sharing the common heat exchange device 7, on the low-pressure side and the high-pressure side, the first heat exchange channel of the common heat exchange device 7 is connected between adjacent compressors 11, and the second heat exchange channel of the common heat exchange device 7 is connected between adjacent gas expanders 31, such as Figure 1 shown.

[0083] The air compression system 1 and the air expansion system 3 share the common heat exchange device 7, thereby reducing the investment and construction cost of the heat exchange system.

[0084] Working principle:

[0085] When storing energy, the multi-stage compressor 11 and the cooler 12 can perform multi-stage compression and cooling on the air, and store the high-pressure air in a supercritical state or liquid state after heat exchange and pressure reduction; when releasing energy, the supercritical state or liquid air is pressurized and heat exchanged, and then multi-stage heated and expanded to output work to the outside. The air compression system 1 and the air expansion system 3 can compress the air to a supercritical state, which can significantly improve the efficiency of the system. The air can also be compressed to a liquid state, and the specific gas storage state of the energy storage system can be flexibly selected according to the power and duration required to store electric energy in the wind farm or the off-peak electricity of the power grid. For example, when the energy storage is lower than the demand due to other factors such as peak power consumption or low wind force, the air in the supercritical state occupies less space than the air in the non-supercritical state. Therefore, the air can be compressed to a supercritical state to increase the volume of the existing combined gas storage device 2 to meet the actual energy storage demand.

[0086] Example 2

[0087] For onshore and offshore compressed air energy storage coupled with wind power systems, the current application is to regulate the unstable power supply on the grid side. The grid connection of compressed air energy storage systems and source-side power sources such as wind power requires the laying of long transmission and distribution lines, which is costly.

[0088] An electric power system, referring to Figure 1 , including a power grid, a wind turbine 300 and the compact compressed air energy storage system 100 in Example 1, the air compression system 1 is electrically connected to the power grid, or the air compression system 1 is electrically connected to the wind turbine 300, and the air expansion system 3 is electrically connected to the power grid. The compact compressed air energy storage system 100 is coupled with the power grid and the wind turbine 300, and the driving power in the compact compressed air energy storage system 100 can be provided by the power grid or by the wind turbine 300.

[0089] By utilizing the power system of the present invention, the compact compressed air energy storage system 100 is directly coupled to the source-side wind farm power supply nearby, so that distributed energy storage and regional microgrids can be realized. When coupled with the offshore wind turbine generator set 300, it is close to the coastal load center, thereby reducing the cost of power transmission and distribution.

[0090] In the power system, when coupled with the offshore wind turbine generator set 300, except for the combined gas storage device 2 arranged at sea, the rest can be arranged at sea, which can shorten the gas transmission pipeline. It can also be distributed on land, using long-distance power transmission instead of long-distance gas transmission, which can make full use of compression heat, reduce energy waste, and improve system efficiency.

[0091] Working principle:

[0092] Since the air storage state can be selected according to the power and duration of the stored electrical energy, the following takes the storage in the supercritical state as an example for explanation.

[0093] During energy storage, the wind turbine 300 or the excess electric energy of the grid at low load is used to drive the multi-stage compressor 11 to compress the low-pressure air to a supercritical state, and after being cooled to room temperature by the multi-stage cooler, the low-pressure air is cooled and liquefied by isobaric cooling using the cold energy stored in the cold storage heat exchanger 6, and after being reduced in pressure by the pressure reducing device 4, it is stored in the combined gas storage device 2 at normal pressure, and at the same time, the air compression heat is recovered and stored in the common heat exchange device 7;

[0094] When releasing energy, the air in the supercritical state in the combined gas storage device 2 is pressurized by the pressurizing device 5, heated to room temperature by the cold storage heat exchanger 6, passes through the multi-stage reheater, and absorbs the compression heat in the common heat exchange device 7, and finally expands and works by the multi-stage gas expander 31 and outputs it to the outside. At the same time, the air expansion cold is recovered and stored in the common heat exchange device 7.

[0095] When the power system provided in this embodiment is applied at sea, the combined air storage device can use the static pressure of water to maintain the system's constant pressure operation, avoid the air compression system 1 and the air expansion system 3 from deviating from the design conditions and operating inefficiently due to pressure changes, and improve the system's energy conversion efficiency.

[0096] For the power system obtained by coupling onshore and offshore compressed air energy storage systems with wind power, the compressed air energy storage system with a coaxial compact layout is easy to integrate in the nacelle of a large-capacity offshore wind turbine, with larger space conditions and better application prospects.

[0097] Example 3

[0098] A compressed air energy storage method, using the compact compressed air energy storage system 100 described in Example 1 to store air energy, includes the following steps: during the energy storage process, the three-in-one motor 8 is connected to the input shaft of the air compression system 1, the air is compressed and cooled, and the compressed air is stored in the combined air storage device 2; during the energy release process, the three-in-one motor 8 is connected to the output shaft of the air expansion system 3, the compressed air stored in the combined air storage device 2 is heated and injected into the air expansion system 3, and expansion work is output; wherein, "storing the compressed air in the combined air storage device 2" includes storing the compressed air in the first air storage device and / or the second air storage device 22.

[0099] Optionally, the heat energy generated by air compression during the energy storage process is used to heat the compressed air during the energy release process; and the cold energy generated by compressed air expansion during the energy release process is used to cool the air during the energy storage process.

[0100] Optionally, during the energy storage process, the air is compressed to a supercritical state, and the compressed air in the supercritical state is stored in the combined air storage device 2 .

[0101] The compressed air energy storage method provided in this embodiment has all the beneficial effects in Embodiment 1, which will not be described again here.

[0102] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A compact compressed air energy storage system, characterized in that: The invention comprises an air compression system (1), a combined air storage device (2) and an air expansion system (3); the output end of the air compression system (1) is connected to the input end of the combined air storage device (2), and the output end of the combined air storage device (2) is connected to the input end of the air expansion system (3); wherein the combined air storage device (2) comprises: A first air storage device, the first air storage device comprising a wind turbine tower (21), the wind turbine tower (21) being provided with a first air storage cavity (214); a second gas storage device (22), the second gas storage device (22) being arranged underground, on the seabed or suspended in water, the second gas storage device (22) being provided with a second gas storage cavity (223), the first gas storage cavity (214) being in communication with the second gas storage cavity (223); The central axis of the air compression system (1) and the central axis of the air expansion system (3) are coaxially arranged, and the input shaft of the air compression system (1) and the output shaft of the air expansion system (3) are detachably connected to the three-in-one motor (8); The second gas storage device (22) comprises an artificial chamber (224), the cavity of the artificial chamber (224) constituting the second gas storage cavity (223), the artificial chamber (224) being arranged below the wind turbine tower (21), and the first gas storage cavity (214) and the second gas storage cavity (223) being connected through or through a pipeline; Alternatively, the combined gas storage device (2) comprises a storage tank (221) fixedly arranged on the seabed, the inner cavity of the storage tank (221) forming the second gas storage cavity (223), the storage tank (221) being arranged below the wind turbine tower (21), and the first gas storage cavity (214) and the second gas storage cavity (223) being connected through or through a pipeline; Alternatively, the combined air storage device (2) comprises an air bag (222) suspended in water, the inner cavity of the air bag (222) constituting the second air storage cavity (223), the first air storage cavity (214) of the wind turbine tower (21) being provided with an interface, and the air nozzle of the air bag (222) and the interface being connected via a pipeline; The air compression system (1) comprises a multi-stage compressor (11) connected in series, wherein the central axes of the multi-stage compressors (11) are coaxially arranged; the air expansion system (3) comprises a multi-stage gas expansion machine (31) connected in series, wherein the central axes of the multi-stage gas expansion machine (31) are coaxially arranged; the central axis of the compressor (11) located at the input end of the air compression system (1) and the central axis of the gas expansion machine (31) located at the output end of the air expansion system (3) are connected to the three-in-one motor (8) via a switching device (9); The switching device (9) comprises a first clutch (91) detachably connected to the central shaft of the air compression system (1) and a second clutch (92) detachably connected to the central shaft of the air expansion system (3); A common heat exchange device (7) is provided between the air compression system (1) and the air expansion system (3), the common heat exchange device (7) comprising a first heat exchange channel, a second heat exchange channel and a third heat exchange channel, the input end of the first heat exchange channel being connected to the heat output end of the air compression system (1), the output end of the first heat exchange channel being connected to the input end of the combined gas storage device (2); the input end of the second heat exchange channel being connected to the output end of the combined gas storage device (2), the output end of the second heat exchange channel being connected to the heat input end of the air expansion system (3); and a heat exchange medium flowing through the third heat exchange channel; The three-in-one motor (8) integrates a generator, a motor and a phase regulator.

2. The compact compressed air energy storage system according to claim 1, characterized in that: The wind turbine tower (21) comprises a plurality of tower sections (211) which are separately arranged along the axial direction; the first air storage cavity (214) is arranged in one or more of the tower sections (211); Alternatively, the wind turbine tower (21) comprises an outer cylinder (212) and an inner cylinder (213) which are sleeved in a radial direction; and an annular gap between the outer cylinder (212) and the inner cylinder (213) constitutes the first air storage cavity (214).

3. A power system, characterized in that: The invention comprises a power grid, a wind turbine generator set (300), and the compact compressed air energy storage system according to claim 1 or 2, wherein the air compression system (1) is electrically connected to the power grid, or the air compression system (1) is electrically connected to the wind turbine generator set (300), and the air expansion system (3) is electrically connected to the power grid.

4. A compressed air energy storage method, characterized in that: Using the compact compressed air energy storage system according to claim 1 or 2 to store air energy comprises the following steps: Energy storage process: connecting the three-in-one motor (8) to the input shaft of the air compression system (1), compressing and cooling the air, and storing the compressed air in the combined air storage device (2); Energy release process: connecting the three-in-one motor (8) and the output shaft of the air expansion system (3), heating the compressed air stored in the combined air storage device (2) and injecting it into the air expansion system (3) to perform expansion and work output; Wherein, storing the compressed air in the combined air storage device (2) includes storing the compressed air in the first air storage device and / or the second air storage device (22).

5. The compressed air energy storage method according to claim 4, characterized in that: The heat energy generated by air compression during the energy storage process is used to heat the compressed air during the energy release process; the cold energy generated by the expansion of compressed air during the energy release process is used to cool the air during the energy storage process.

6. The compressed air energy storage method according to claim 4 or 5, characterized in that: During the energy storage process, air is compressed to a supercritical state, and the compressed air in the supercritical state is stored in the combined air storage device (2).

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