Distributed compressed air energy storage system and stable-pressure operation method thereof

Abstract

The invention discloses a distributed compressed air energy storage system and a stable-pressure operation method thereof. The system comprises an air compression unit, a high-pressure air storage unit, an air expansion unit, a heat storage and cold storage unit, a motor and a generator. In the high-pressure air storage unit, a multi-stage air storage tank is connected with a heater or a cooler in series to heat or cool high-pressure air in the tank, so that the pressure in the tank is constant. During energy storage, high-temperature air in the air storage tank is cooled through the cooler, and a space is provided for injection of compressed air until the rated air storage pressure is reached; and during energy release, the low-temperature air in the air storage tank is continuously heated by the heater, so that the pressure in the tank is stabilized at the rated air storage pressure. The constant pressure in the air storage tank in the air charging and discharging process is achieved all the time, the energy storage efficiency is improved, and the cost of an energy storage system is reduced; and meanwhile, a cold and hot storage tank is adopted in the heat and cold storage unit, so that the investment cost and occupied space of the heat storage device are greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a distributed compressed air energy storage system and a voltage-stabilizing operation method thereof. Background Art

[0002] With the rapid growth of installed capacity for renewable energy sources such as wind power and photovoltaics, their intermittent and fluctuating characteristics pose severe challenges to the stable operation of power grids. Against this backdrop, energy storage technologies that combine long-term energy storage capabilities with rapid response have become key support for building new power systems. Compressed air energy storage technology, with its excellent scalability, long cycle life, and low cost, demonstrates unique advantages in large-scale energy storage.

[0003] Current large-scale compressed air energy storage systems typically utilize treated salt caverns to store high-pressure compressed air. Distributed compressed air energy storage directly utilizes high-pressure gas tanks (usually made of metal) to store compressed air, and is deployed as needed near unstable power sources. Compared to salt caverns, the volume and redundancy of high-pressure gas tanks cannot be too large, otherwise the cost will be too high. This results in pressure fluctuations during energy storage and release that are far greater than those of large-scale compressed air energy storage systems utilizing salt caverns, posing a significant challenge to the strength of the high-pressure gas tanks. Furthermore, this will cause the operating conditions of the air compressor units to constantly change, preventing them from stabilizing at the efficient and stable design conditions, thereby reducing energy storage efficiency and affecting economic efficiency.

[0004] Large-scale compressed air energy storage systems usually rely on specific geographical conditions to maintain a constant gas storage pressure. For example, Zhang Jianjun et al. (CN113294293B) proposed a large-scale offshore power storage and comprehensive utilization system based on compressed air energy storage, which achieves constant pressure gas storage through the static pressure characteristics of water, but such solutions are highly dependent on the geographical environment and are difficult to promote and apply to distributed energy storage scenarios. In addition, large-scale advanced adiabatic compressed air energy storage relies on efficient heat storage to achieve high system efficiency, so the heat storage device has a complex structure. For example, Jiang Li et al. (CN119308823A) proposed a compressed air energy storage system based on double-tank pressurized water heat storage, which includes a high-temperature heat storage tank and a low-temperature heat storage tank, and uses nitrogen to balance the pressure. However, the double-tank heat storage device is large in size and the pressure balancing device is complex, making it difficult to use in distributed energy storage systems. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a distributed compressed air energy storage system and a method for operating it under constant pressure, by connecting a multi-stage gas storage tank in series with a heater or cooler to heat or cool the high-pressure air in the tank, thereby achieving a constant pressure in the tank. During energy storage, the high-temperature air in the gas tank is cooled by the cooler to provide space for the injection of compressed air until it reaches room temperature and the rated gas storage pressure; during energy release, the low-temperature air in the gas tank is continuously heated by the heater to stabilize the pressure in the gas tank at the rated gas storage pressure. Through the above-mentioned method, the pressure in the high-pressure gas storage tank can be kept constant during the air filling and discharging process. Compared with other constant pressure gas storage solutions (such as underwater gas storage), the dependence on geographical conditions and the design difficulty are effectively reduced, and the cost of the energy storage system is reduced. At the same time, by using the method of connecting a multi-stage gas storage tank in series, the system can flexibly switch between energy storage / energy release modes without the help of the external environment (such as underground, seabed cavities, etc.), thereby enhancing the flexibility of the system. The overall system is highly efficient, safe, and has the characteristics of energy saving and emission reduction.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A distributed compressed air energy storage system, comprising: an air compression unit, a high-pressure air storage unit, an air expansion unit, a heat storage unit, a cold storage unit, an electric motor 1, and a generator 6;

[0008] Air compression unit: compresses the air in multiple stages and generates compression heat;

[0009] Air expansion unit: performs multi-stage expansion on the high-temperature gas to generate mechanical energy that drives the generator 6 to generate electricity;

[0010] High-pressure gas storage unit: includes multiple stages of gas storage tanks connected in series. The multi-stage gas storage tanks, the first circulating fan 101, and the cooler 11 form a cooling circuit, and the multi-stage gas storage tanks, the second circulating fan 102, and the heater 12 form a heating circuit. The high-temperature side outlet of the air compression unit is connected to the inlet of the first-stage gas storage tank; the outlet of the last-stage gas storage tank is connected to the low-temperature side inlet of the air expansion unit.

[0011] Heat storage and cold storage unit: includes a first cold and hot storage tank 71, which includes a low-temperature heat storage chamber 711 and a high-temperature heat storage chamber 713. The outlet of the low-temperature heat storage chamber 711 is connected to the low-temperature side inlet of the air compression unit through a first heat storage medium pump 91, and the low-temperature side outlet of the air compression unit is connected to the inlet of the high-temperature heat storage chamber 713; the outlet of the high-temperature heat storage chamber 713 is connected to the high-temperature side inlet of the air expansion unit through a second heat storage medium pump 92, and the high-temperature side outlet of the air expansion unit is connected to the inlet of the low-temperature heat storage chamber 711.

[0012] The air compression unit includes a multi-stage coaxially connected air compressor in series and a multi-stage low-temperature side heat storage heat exchanger connected in parallel. The multi-stage air compressor corresponds to the multi-stage heat storage heat exchanger, and each stage of the heat storage heat exchanger is arranged on the pipeline after the air outlet of the corresponding air compressor;

[0013] The air expansion unit includes a multi-stage coaxially connected air expander in series and a multi-stage high-temperature side heat release heat exchanger connected in parallel. The multi-stage air expander corresponds to the multi-stage heat release heat exchanger, and each stage of the heat release heat exchanger is arranged on the pipeline before the air inlet of the corresponding air expander;

[0014] The multi-stage air compressor is coaxially connected in series with the motor 1, and the motor 1 is used to drive the multi-stage air compressor to perform multi-stage compression on the air; the multi-stage air expander is coaxially connected in series with the generator 6, and performs multi-stage expansion work on the high-temperature gas, and the generated mechanical energy drives the generator 6 to generate electricity.

[0015] The high-temperature side outlet of the heat storage heat exchanger after the air outlet of the last-stage air compressor is connected to the inlet of the first-stage air storage tank; the outlet of the last-stage air storage tank is connected to the low-temperature side inlet of the heat release heat exchanger before the air inlet of the first-stage air expander;

[0016] The outlet of the low-temperature heat storage chamber 711 is split after passing through the first heat storage medium pump 91, and is respectively connected to the low-temperature side inlet of the heat storage heat exchanger after the air outlet of each stage of the air compressor, and the low-temperature side outlet of the heat storage heat exchanger after the air outlet of each stage of the air compressor is connected to the inlet of the high-temperature heat storage chamber 713; the outlet of the high-temperature heat storage chamber 713 is split after passing through the second heat storage medium pump 92, and is respectively connected to the high-temperature side inlet of the heat release heat exchanger before the air inlet of each stage of the air expander, and the high-temperature side outlet of the heat release heat exchanger before the air inlet of each stage of the air expander is connected to the inlet of the low-temperature heat storage chamber 711.

[0017] The system also includes a valve regulation unit, which includes a first regulating valve 41 arranged on the high-temperature side outlet pipeline of the heat storage heat exchanger after the air outlet of the last-stage air compressor, a second regulating valve 42 arranged on the low-temperature side inlet pipeline of the heat release heat exchanger before the air inlet of the first-stage air expander, a third regulating valve 43 arranged on the outlet pipeline of the cooler 11, a fourth regulating valve 44 arranged on the outlet pipeline of the heater 12, a fifth regulating valve 45 arranged on the outlet pipeline of the low-temperature heat storage chamber 711, and a sixth regulating valve 46 arranged on the outlet pipeline of the high-temperature heat storage chamber 713.

[0018] The air in the cooling circuit flows in from the lower part of each stage of the gas storage tank and flows out from the upper part; the air in the heating circuit flows in from the upper part of each stage of the gas storage tank and flows out from the lower part.

[0019] A movable heat insulating layer 712 is provided between the low-temperature heat storage chamber 711 and the high-temperature heat storage chamber 713 .

[0020] A second cold / hot storage tank 72 is provided between the low-temperature side of the cooler 11 and the high-temperature side of the heater 12 , and its structure is the same as that of the first cold / hot storage tank 71 .

[0021] The heat exchange medium of the first cold and hot storage tank 71 and the second cold and hot storage tank 72 are both pressurized water or thermal oil.

[0022] A method for stabilizing pressure of a distributed compressed air energy storage system, comprising:

[0023] In the energy storage operation mode, the motor 1 drives the multi-stage air compressor to compress the air, and the compressed high-temperature air enters the first-stage air storage tank through the cooling circuit; at this time, the first circulation fan 101 draws the high-temperature gas from the last-stage air storage tank into the cooler 11 to cool it down. The gas cooled by the cooler 11 flows back to the first-stage air storage tank through the third regulating valve 43; in addition, the low-temperature heat storage medium in the first low-temperature heat storage chamber 711 is divided after passing through the fifth regulating valve 45 and flows through the multi-stage heat storage heat exchanger respectively, exchanging heat with the air in the compression process to increase its temperature. The high-temperature heat storage medium after heat exchange flows back to the first high-temperature heat storage chamber 713 to store the heat generated during the air compression process;

[0024] In the energy release operation mode, the second circulation fan 102 draws a part of the low-temperature gas from the last-stage gas tank into the heater 12, heats it, and flows back to the first-stage gas tank through the fourth regulating valve 44; the other part of the low-temperature gas passes through the second regulating valve 42 and flows through the multi-stage air expander in sequence to drive its operation; at this time, the generator 6 coaxially connected to the multi-stage air expander is driven to operate, and the generated electricity is connected to the power grid for users to use; in addition, the high-temperature heat storage medium in the first high-temperature heat storage chamber 713 is diverted after passing through the sixth regulating valve 46, and flows through the multi-stage heat release heat exchanger respectively, exchanges heat with the air in the expansion process to increase the temperature, and the low-temperature heat storage medium after heat exchange flows back to the first low-temperature heat storage chamber 711.

[0025] Compared with the prior art, the beneficial effects of the present invention include the following aspects:

[0026] (1) The present invention connects a multi-stage series-connected gas storage tank in series with a heater or a cooler to heat or cool the air in the tank, thereby achieving a constant pressure in the tank. When storing energy, the high-temperature air in the tank is cooled by the cooler to provide space for the injection of compressed air until the rated gas storage pressure is reached; when releasing energy, the low-temperature air in the gas storage tank is continuously heated by the heater to stabilize the pressure in the tank at the rated gas storage pressure. Through the above method, the pressure in the gas storage tank can be kept constant during the air filling and discharging process, avoiding the gas storage tank from constantly switching between high pressure and low pressure. The strength requirements of the gas storage tank are relatively low, effectively reducing the complexity and design difficulty of the system and reducing the cost of the energy storage system.

[0027] (2) The present invention designs the gas storage device as a multi-stage gas storage tank connected in series, which can flexibly complete the switching of the system between energy storage / energy release modes without the help of the external environment (such as underground, seabed cavities, etc.), thereby enhancing the flexibility of the system. The overall system has high efficiency and good safety, low dependence on geographical conditions, and has the advantages of energy saving and emission reduction.

[0028] (3) Compared to conventional heat storage systems that use a high-temperature heat storage tank and a low-temperature heat storage tank, the heat storage device used in this invention is designed as a hot and cold storage tank. The hot and cold storage tanks are divided into a low-temperature cold storage chamber and a high-temperature heat storage chamber, with a removable insulating material separating the two chambers. This approach significantly reduces the investment cost and floor space of the heat storage device, thereby improving the system's levelized cost of electricity and volumetric energy density.

[0029] (4) The present invention adds a second cold and hot storage tank between the cooler and the heater, which can directly use the cold and hot energy stored in the circuit, avoiding external energy consumption and reducing operating costs.

[0030] In summary, the distributed compressed air energy storage system proposed in the present invention not only achieves constant pressure in the high-pressure gas storage tank during the air charging and discharging process, thereby improving energy storage efficiency and reducing the cost of the energy storage system; it also uses hot and cold storage tanks in the heat storage and cold storage units, greatly reducing the investment cost and space occupied by the heat storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural diagram of a distributed compressed air energy storage system according to the first embodiment of the present invention.

[0032] Figure 2 2 is a schematic structural diagram of a distributed compressed air energy storage system according to the second embodiment of the present invention.

[0033] Among them: 1-electric motor; 21-first air compressor; 22-second air compressor; 31-first heat storage heat exchanger; 32-second heat storage heat exchanger; 33-first heat release heat exchanger; 34-second heat release heat exchanger; 41-first regulating valve; 42-second regulating valve; 43-third regulating valve; 44-fourth regulating valve; 45-fifth regulating valve; 46-sixth regulating valve; 51-first air expander; 52-second air expander; 6-generator; 71-first cold and hot storage tank; 711-first low-temperature cold storage chamber; 712-first thermal insulation Layer; 713-first high-temperature heat storage chamber; 72-second cold and hot storage tank; 721-first low-temperature cold storage chamber; 722-first thermal insulation layer; 723-first high-temperature heat storage chamber; 81-first gas storage tank; 82-second gas storage tank; 83-third gas storage tank; 84-fourth gas storage tank; 91-first heat storage medium pump; 92-second heat storage medium pump; 93-third heat storage medium pump; 94-fourth heat storage medium pump; 101-first circulation fan; 102-second circulation fan; 11-cooler; 12-heater; 13-second cold and hot storage tank.

[0034] Specific implementation mode

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention are further described in detail below in conjunction with the embodiments and drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] The present invention provides a distributed compressed air energy storage system, which includes an air compression unit, a high-pressure air storage unit, an air expansion unit, a heat storage unit, a valve adjustment unit, an electric motor 1, and a generator 6; wherein:

[0037] Air compression unit: includes a multi-stage coaxially connected air compressor in series, with a heat storage heat exchanger installed after each stage of the air compressor, and the low-temperature sides of adjacent heat storage heat exchangers are connected in parallel; the multi-stage air compressor is coaxially connected in series with the motor 1, and the motor 1 is used to drive the multi-stage air compressor to perform multi-stage compression on the air, generating compression heat, which is exchanged in parallel with the heat storage medium in the heat storage heat exchanger;

[0038] The air expansion unit comprises a multi-stage coaxially connected air expander, with a heat release heat exchanger provided before the inlet of each stage of the air expander, and the high-temperature sides of adjacent heat release heat exchangers connected in parallel. The multi-stage air expander is coaxially connected in series with the generator 6, performing multi-stage expansion work on the high-temperature gas, and the generated mechanical energy drives the generator 6 to generate electricity;

[0039] High-pressure gas storage unit: includes a multi-stage gas storage tank, a cooler 11, and a heater 12 connected in series through pipelines. The multi-stage gas storage tank, the first circulating fan 101, and the cooler 11 form a cooling circuit, and the multi-stage gas storage tank, the second circulating fan 102, and the heater 12 form a heating circuit. In the cooling circuit, the high-temperature air compressed by the air compression unit is transported to the gas storage tank, cooled by the cooler 11, and stored in the gas storage tank. In the heating circuit, a portion of the low-temperature air in the gas storage tank is heated by the heater 12 and stored in the gas storage tank, while the remaining portion enters the air expansion unit.

[0040] The heat storage and cold storage unit includes a first cold and hot storage tank 71 having a first low-temperature heat storage chamber 711 and a first high-temperature heat storage chamber 713. In the energy storage mode, the heat generated by the air compression unit is stored in the first cold and hot storage tank 71. In the energy release mode, the high-temperature heat storage medium stored in the first cold and hot storage tank 71 is transferred to the air expansion unit to improve the operating efficiency of the expander.

[0041] The valve regulating unit includes a first regulating valve 41 , a second regulating valve 42 , a third regulating valve 43 , a fourth regulating valve 44 , a fifth regulating valve 45 and a sixth regulating valve 46 ; the normal operation of the system is achieved through the corresponding regulating valves.

[0042] The technical solution of the present invention is further described below through specific embodiments.

[0043] Example 1

[0044] like Figure 1 As shown, a distributed compressed air energy storage system includes: an air compression unit, a high-pressure air storage unit, an air expansion unit, a heat storage unit, a valve adjustment unit, a motor 1, a generator 6 and related auxiliary equipment;

[0045] Air compression unit: includes two-stage coaxially connected air compressors, namely a first air compressor 21 and a second air compressor 22; the first air compressor 21 and the second air compressor 22 are coaxially connected in series with the electric motor 1; the outlet of the first air compressor 21 is connected to the high-temperature side inlet of the first heat storage heat exchanger 31, the high-temperature side outlet of the first heat storage heat exchanger 31 is connected to the inlet of the second air compressor 22, and the outlet of the second air compressor 22 is connected to the high-temperature side inlet of the second heat storage heat exchanger 32; the two air compressors are driven by the electric motor 1 to perform two-stage compression.

[0046] Air expansion unit: includes two stages of coaxially connected air expanders in series, namely a first air expander 51 and a second air expander 52; the inlet of the first air expander 51 is connected to the low-temperature side outlet of the first heat-releasing heat exchanger 33, the outlet of the first air expander 51 is connected to the low-temperature side inlet of the second heat-releasing heat exchanger 34, and the low-temperature side outlet of the second heat-releasing heat exchanger 34 is connected to the inlet of the second air expander 52; the first air expander 51 and the second air expander 52 are coaxially connected in series with the generator 6, using high-temperature gas to perform multi-stage expansion work, and the mechanical energy generated drives the generator 6 to generate electricity, and the electricity generated by the generator 6 is connected to the power grid for users.

[0047] High-pressure gas storage unit: includes four gas tanks, namely the first gas tank 81, the second gas tank 82, the third gas tank 83, and the fourth gas tank 84; different gas tanks are connected in series through pipelines according to the direction of gas flow, and the internal pressures of the four gas tanks remain consistent and are stable at the rated gas storage pressure; the four series-connected gas tanks and the first circulation fan 101, the cooler 11, and the third regulating valve 43 form a cooling circuit, the outlet of the fourth gas tank 84 is connected to the high-temperature side inlet of the cooler 11 through the first circulation fan 101, and the third regulating valve 43 is provided on the high-temperature side outlet pipeline of the cooler 11, and the high-temperature side outlet of the cooler 11 is connected to the inlet of the first gas tank 81 through the third regulating valve 43, and the gas in the cooling circuit flows in from the lower part of each gas tank and flows out from the upper part. Four gas storage tanks connected in series and the second circulation fan 102, the heater 12, and the fourth regulating valve 44 form a heating circuit. The outlet of the fourth gas storage tank 84 is connected to the low-temperature side inlet of the heater 12 through the second circulation fan 102. The fourth regulating valve 44 is provided on the low-temperature side outlet pipeline of the heater 12. The low-temperature side outlet of the heater 12 is connected to the inlet of the first gas storage tank 81 through the fourth regulating valve 44. The gas in the heating circuit flows in from the upper part of each gas storage tank and flows out from the lower part.

[0048] The high-temperature side outlet of the second heat storage heat exchanger 32 is connected to the inlet of the first air storage tank 81, and a first regulating valve 41 is provided on the high-temperature side outlet pipeline of the second heat storage heat exchanger 32 to transport the high-temperature air compressed by the air compression unit to the first air storage tank 81; the outlet of the fourth air storage tank 84 is connected to the low-temperature side inlet of the first heat releasing heat exchanger 33, and a second regulating valve 42 is provided on the low-temperature side inlet pipeline of the first heat releasing heat exchanger 33 to transport a part of the low-temperature air in the fourth air storage tank 84 to the air expansion unit for expansion and work.

[0049] The present invention uses external cold and heat sources to exchange heat with the air in the gas tanks, thereby maintaining the pressure in the four gas tanks at a constant pressure state. The specific implementation method is as follows:

[0050] During the energy storage process, the first circulation fan 101 draws high-temperature air from the fourth gas storage tank 84 into the cooler 11, cools it down, increases its density and reduces its volume to provide space for injecting more compressed air, and couples and adjusts the cooling temperature of the cooler 11 (less than 50°C) and the amount of circulating air drawn to maintain the gas inside the four gas storage tanks stable at the rated gas storage pressure.

[0051] During the energy release process, the second circulation fan 102 draws low-temperature air from the fourth gas tank 84 into the heater 12, heats it to reduce its density and increase its volume. After being heated, the low-temperature gas fills the space in the tank left after part of the gas is extracted. The heating temperature of the heater 12 (less than 300°C) and the amount of circulating air extracted are coupled and adjusted to maintain the rated gas storage pressure of the gas inside the four gas tanks.

[0052] The heat storage and cold storage unit includes a first cold and hot storage tank 71, which includes a first low-temperature heat storage chamber 711 and a first high-temperature heat storage chamber 713. A movable first thermal insulation layer 712 is provided between the first low-temperature heat storage chamber 711 and the first high-temperature heat storage chamber 713. The first thermal insulation layer 712 is composed of an insulating material. The movable first thermal insulation layer 712 can be a piston plate, the edge of which is slidably sealed with the inner wall of the heat storage chamber and can move back and forth.

[0053] In the energy storage operation mode, the outlet of the first low-temperature heat storage chamber 711 is connected to the low-temperature side inlets of the first heat storage heat exchanger 31 and the second heat storage heat exchanger 32 respectively through the first heat storage medium pump 91. A fifth regulating valve 45 is provided on the outlet pipe of the first low-temperature heat storage chamber 711, and the low-temperature side outlets of the first heat storage heat exchanger 31 and the second heat storage heat exchanger 32 are both connected to the inlet of the first high-temperature heat storage chamber 713; the low-temperature heat storage medium in the first low-temperature heat storage chamber 711 is separated after passing through the first heat storage medium pump 91, and is respectively exchanged with the compression heat in the first heat storage heat exchanger 31 and the second heat storage heat exchanger 32. After being heated to high-temperature heat storage medium, it is merged and stored in the first high-temperature heat storage chamber 713.

[0054] In the energy release working mode, the outlet of the first high-temperature heat storage chamber 713 is connected to the high-temperature side inlets of the first heat-releasing heat exchanger 33 and the second heat-releasing heat exchanger 34 respectively through the second heat storage medium pump 92. A sixth regulating valve 46 is provided on the outlet pipe of the first high-temperature heat storage chamber 713. The high-temperature side inlets of the first heat-releasing heat exchanger 33 and the second heat-releasing heat exchanger 34 are both connected to the inlet of the first low-temperature heat storage chamber 711. The high-temperature heat storage medium in the first high-temperature heat storage chamber 713 is diverted after passing through the second heat storage medium pump 92, and high-temperature heat storage is provided to the first heat-releasing heat exchanger 33 and the second heat-releasing heat exchanger 34 respectively to heat the high-pressure air. The heat of the high-temperature heat storage medium is absorbed to form a low-temperature heat storage medium, which is then merged and stored in the first low-temperature heat storage chamber 711.

[0055] The heat exchange medium used in the first cold and hot storage tank 71 is pressurized water or thermal oil.

[0056] A voltage stabilization operation method for a distributed compressed air energy storage system, including an energy storage operation mode and an energy release operation mode;

[0057] In energy storage mode, the first regulating valve 41, the fifth regulating valve 45, and the third regulating valve 43 are open; the second regulating valve 42, the sixth regulating valve 46, and the fourth regulating valve 44 are closed; the air compression unit and related equipment in the cooling circuit are in operation, and the air expansion unit and related equipment in the heating circuit are closed. Motor 1 drives the first air compressor 21 and the second air compressor 22 to perform two-stage air compression. The compressed high-temperature air enters the first air tank 81 through the cooling circuit. At this time, the first circulating fan 101 draws high-temperature air from the fourth air tank 84 into the cooler 11, cooling it to increase its density and reduce its volume. The cooled gas in the cooler 11 flows back to the first air tank 81 through the third regulating valve 43. The four gas tanks are connected by pipelines, with gas flowing in from the bottom and out from the top of each tank. After cooling, the high-temperature gas creates space for the injection of more compressed air. The cooling temperature (less than 50°C) of the cooler 11 and the amount of circulating air extracted are coupled to maintain the gas inside the four tanks at the rated storage pressure. Furthermore, the low-temperature heat storage medium in the first low-temperature heat storage chamber 711 is split after passing through the fifth regulating valve 45, flowing through the first and second heat storage heat exchangers 31 and 32, respectively, to exchange heat with the air during the compression process and increase its temperature. After heat exchange, the high-temperature heat storage medium flows back to the first high-temperature heat storage chamber 713, storing the heat generated during the air compression process.

[0058] In energy-release mode, the second regulating valve 42, the sixth regulating valve 46, and the fourth regulating valve 44 are open; the first regulating valve 41, the fifth regulating valve 45, and the third regulating valve 43 are closed; the air expansion unit and related equipment in the heating circuit are in operation mode; and the air compression unit and related equipment in the cooling circuit are closed. The second circulating fan 102 draws a portion of the low-temperature gas from the fourth gas tank 84 into the heater 12, heating it to reduce its density and increase its volume. The gas then flows back to the first gas tank 81 through the fourth regulating valve 44. Another portion of the low-temperature gas passes through the second regulating valve 42 and flows sequentially through the first and second air expanders 51, 52, driving their operation. At this point, the generator 6, coaxially connected to the air expander, is driven to operate, and the generated electricity is fed into the grid for user use. The four gas storage tanks are connected by pipelines, with gas flowing in from the top of each high-pressure tank and out from the bottom. The low-temperature gas, after being heated and heated, fills the space left inside the tank after the gas is partially extracted. The heating temperature of the heater 12 (greater than 300°C) and the amount of circulating air extracted are coupled to regulate the gas inside the four tanks to maintain a stable gas storage pressure. Furthermore, the high-temperature heat storage medium in the first high-temperature heat storage chamber 713 is split after passing through the sixth regulating valve 46, flowing through the first and second heat release heat exchangers 33 and 34, respectively, to exchange heat with the air during the expansion process and increase its temperature, thereby improving the operating efficiency of the expander. After heat exchange, the low-temperature heat storage medium flows back to the first low-temperature heat storage chamber 711.

[0059] Example 2

[0060] Reference Figure 2 The structure of this embodiment is essentially the same as that of the first embodiment, differing in that while the first embodiment uses an external cold and heat source, the second embodiment utilizes stored cold and hot media. Specifically, a second cold and hot storage tank 72 is added between the cooler 11 and the heater 12, using pressurized water or thermal oil as the heat exchange medium. This second cold and hot storage tank 72 comprises a second low-temperature heat storage chamber 721 and a second high-temperature heat storage chamber 723, with a removable second thermal insulation layer 722 disposed between the second low-temperature heat storage chamber 721 and the second high-temperature heat storage chamber 723. Its operating principle is similar to that of the heat storage medium and the first cold and hot storage tank 71. In energy storage mode, the low-temperature heat storage medium in the second low-temperature heat storage chamber 723 is transported to the low-temperature side of the cooler 11 via a fourth heat storage medium pump 94 to cool the compressed air. After the heat storage medium heats up, it flows out of the low-temperature outlet of the cooler 11 and enters the second high-temperature heat storage chamber 721 for storage. In the energy release operation mode, the high-temperature heat storage medium in the second high-temperature heat storage chamber 721 is transported to the high-temperature side of the heater 12 through the third heat storage medium pump 93 for heating the compressed air; after the temperature of the heat storage medium is reduced, it flows out from the high-temperature side outlet of the heater 12 and enters the low-temperature heat storage chamber 723 for storage.

[0061] It should be noted that, in this specification, relational terms such as first and second are merely used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities. The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A distributed compressed air energy storage system, characterized in that: include: An air compression unit, a high-pressure air storage unit, an air expansion unit, a heat storage unit, a cold storage unit, an electric motor (1), and a generator (6); Air compression unit: compresses the air in multiple stages and generates compression heat; Air expansion unit: performs multi-stage expansion on the high-temperature gas to generate mechanical energy to drive the generator (6) to generate electricity; The high-pressure gas storage unit comprises a multi-stage gas storage tank connected in series, wherein the multi-stage gas storage tank, a first circulation fan (101), and a cooler (11) form a cooling circuit, and the multi-stage gas storage tank, a second circulation fan 102, and a heater (12) form a heating circuit; the high-temperature side outlet of the air compression unit is connected to the inlet of the first-stage gas storage tank; and the outlet of the last-stage gas storage tank is connected to the low-temperature side inlet of the air expansion unit; The heat storage and cold storage unit comprises a first cold and hot storage tank (71), the first cold and hot storage tank (71) comprising a low-temperature heat storage chamber (711) and a high-temperature heat storage chamber (713), the outlet of the low-temperature heat storage chamber (711) being connected to the low-temperature side inlet of the air compression unit through a first heat storage medium pump (91), and the low-temperature side outlet of the air compression unit being connected to the inlet of the high-temperature heat storage chamber (713); the outlet of the high-temperature heat storage chamber (713) being connected to the high-temperature side inlet of the air expansion unit through a second heat storage medium pump (92), and the high-temperature side outlet of the air expansion unit being connected to the inlet of the low-temperature heat storage chamber (711).

2. A distributed compressed air energy storage system according to claim 1, characterized in that: The air compression unit includes a multi-stage coaxially connected air compressor in series and a multi-stage low-temperature side heat storage heat exchanger connected in parallel. The multi-stage air compressor corresponds to the multi-stage heat storage heat exchanger, and each stage of the heat storage heat exchanger is arranged on the pipeline after the air outlet of the corresponding air compressor; The air expansion unit includes a multi-stage coaxially connected air expander in series and a multi-stage high-temperature side heat release heat exchanger connected in parallel. The multi-stage air expander and the multi-stage heat release heat exchanger correspond to each other, and each stage of the heat release heat exchanger is arranged on the pipeline before the air inlet of the corresponding air expander.

3. A distributed compressed air energy storage system according to claim 2, characterized in that: The multi-stage air compressor is coaxially connected in series with the electric motor (1), and the electric motor (1) drives the multi-stage air compressor to perform multi-stage compression on the air; the multi-stage air expander is coaxially connected in series with the generator (6), and performs multi-stage expansion on the high-temperature gas to perform work, and the generated mechanical energy drives the generator (6) to generate electricity.

4. A distributed compressed air energy storage system according to claim 2, characterized in that: The high-temperature side outlet of the heat storage heat exchanger after the air outlet of the last-stage air compressor is connected to the inlet of the first-stage air storage tank; the outlet of the last-stage air storage tank is connected to the low-temperature side inlet of the heat release heat exchanger before the air inlet of the first-stage air expander; The outlet of the low-temperature heat storage chamber (711) is divided after passing through the first heat storage medium pump (91) and is respectively connected to the low-temperature side inlet of the heat storage heat exchanger after the air outlet of each stage of the air compressor, and the low-temperature side outlet of the heat storage heat exchanger after the air outlet of each stage of the air compressor is connected to the inlet of the high-temperature heat storage chamber (713); the outlet of the high-temperature heat storage chamber (713) is divided after passing through the second heat storage medium pump (92) and is respectively connected to the high-temperature side inlet of the heat release heat exchanger before the air inlet of each stage of the air expander, and the high-temperature side outlet of the heat release heat exchanger before the air inlet of each stage of the air expander is connected to the inlet of the low-temperature heat storage chamber (711).

5. A distributed compressed air energy storage system according to claim 2, characterized in that: The system further comprises a valve regulating unit, which comprises a first regulating valve (41) arranged on the high-temperature side outlet pipeline of the heat storage heat exchanger after the air outlet of the last-stage air compressor, a second regulating valve (42) arranged on the low-temperature side inlet pipeline of the heat release heat exchanger before the air inlet of the first-stage air expander, a third regulating valve (43) arranged on the outlet pipeline of the cooler (11), a fourth regulating valve (44) arranged on the outlet pipeline of the heater (12), a fifth regulating valve (45) arranged on the outlet pipeline of the low-temperature heat storage chamber (711), and a sixth regulating valve (46) arranged on the outlet pipeline of the high-temperature heat storage chamber (713).

6. A distributed compressed air energy storage system according to claim 1, characterized in that: The air in the cooling circuit flows in from the lower part of each stage of the gas storage tank and flows out from the upper part; the air in the heating circuit flows in from the upper part of each stage of the gas storage tank and flows out from the lower part.

7. The distributed compressed air energy storage system according to claim 1, characterized in that: A movable heat-insulating isolation layer (712) is provided between the low-temperature heat storage chamber (711) and the high-temperature heat storage chamber (713).

8. The distributed compressed air energy storage system according to claim 1, characterized in that: A second cold and hot storage tank (72) is provided between the low-temperature side of the cooler (11) and the high-temperature side of the heater (12), and its structure is the same as that of the first cold and hot storage tank (71).

9. A distributed compressed air energy storage system according to claim 8, characterized in that: The heat exchange medium of the first cold and hot storage tank (71) and the second cold and hot storage tank (72) is pressurized water or heat transfer oil.

10. A method for voltage stabilization operation of a distributed compressed air energy storage system according to claims 1-9, characterized in that: include: In the energy storage operation mode, the motor (1) drives the multi-stage air compressor to compress the air, and the compressed high-temperature air enters the first-stage air storage tank through the cooling circuit; at this time, the first circulation fan (101) extracts the high-temperature gas from the last-stage air storage tank into the cooler (11) to cool it down, and the gas cooled by the cooler (11) flows back to the first-stage air storage tank through the third regulating valve (43); in addition, the low-temperature heat storage medium in the first low-temperature heat storage chamber (711) is divided after passing through the fifth regulating valve (45) and flows through the multi-stage heat storage heat exchanger respectively to exchange heat with the air in the compression process to increase the temperature, and the high-temperature heat storage medium after heat exchange flows back to the first high-temperature heat storage chamber (713) to store the heat generated during the air compression process; In the energy release operation mode, the second circulation fan (102) draws a portion of the low-temperature gas from the last-stage gas storage tank into the heater (12), heats it, and flows back to the first-stage gas storage tank through the fourth regulating valve (44); the other portion of the low-temperature gas passes through the second regulating valve (42) and flows through the multi-stage air expander in sequence to drive the operation thereof; At this time, the generator (6) coaxially connected to the multi-stage air expander is driven to operate, and the generated electricity is connected to the power grid for use by users; in addition, the high-temperature heat storage medium in the first high-temperature heat storage chamber (713) is divided after passing through the sixth regulating valve (46), and flows through the multi-stage heat release heat exchanger respectively to exchange heat with the air in the expansion process to increase the temperature, and the low-temperature heat storage medium after heat exchange flows back to the first low-temperature heat storage chamber (711).

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