Hybrid energy storage power plant

Abstract

The application discloses a hybrid energy storage power station, which comprises an upper reservoir, a lower reservoir, a pump-turbine unit and a gas storage reservoir; the upper reservoir is arranged on a mountain body; the lower reservoir is located below the upper reservoir so that the lower reservoir has a height difference with the upper reservoir; the pump-turbine unit is connected with the upper reservoir through a water diversion pipe; the pump-turbine unit is connected with the lower reservoir through a tail water pipe; the gas storage reservoir is located below the upper reservoir so that the gas storage reservoir has a height difference with the upper reservoir; the gas storage reservoir is provided with a water inlet and outlet and an air inlet and outlet; the water inlet and outlet are connected with the upper reservoir through a water pressure pipe; and the air inlet and outlet are connected with an air compression and expansion machine unit through a main air pipe. The hybrid energy storage power station has the advantages of high economic and social benefits, large energy storage capacity, high energy storage efficiency, avoidance of stress fatigue of the gas storage reservoir and high utilization rate of the gas storage reservoir.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a hybrid energy storage power station. Background Art

[0002] Pumped storage is the most prevalent large-capacity, long-term electricity storage method. It utilizes excess electricity during periods of low electricity demand to pump water from a lower reservoir to a higher upper reservoir. During peak electricity demand, water from the upper reservoir flows back to the lower reservoir, driving turbine generators for power generation. With an energy storage efficiency of approximately 75%, pumped storage offers peak shaving, frequency regulation, phase modulation, and backup capabilities. However, pumped storage suffers from low energy density, large reservoir capacity, and significant terrain variations, making site selection difficult. The number of available sites nationwide is limited, and the total investment required is high, leading to long construction periods.

[0003] Compressed air energy storage is also an electric energy storage system that can achieve large-capacity and long-term electrical energy storage. It has decades of operating experience. It stores excess electricity by compressing normal-pressure air to high pressure through a compressor and storing it. When electricity is needed, the high-pressure air is released and expanded to generate power. The energy storage efficiency can reach 70%, and the energy density is relatively high. However, compressed air energy storage devices require the configuration of an ultra-large gas storage reservoir. The gas storage reservoir is too large, which is very unfavorable for the site selection, land occupation and investment of the compressed air energy storage device. In the absence of auxiliary measures, the gas storage reservoir cannot operate at a constant pressure, which has an adverse effect on the energy storage efficiency and cannot fully utilize the gas storage capacity, resulting in waste. The number of existing compressed air energy storage power stations is very small, and their promotion and application face great economic problems.

[0004] Pumped storage and compressed air energy storage both have their own shortcomings and require continuous improvement and innovation to meet the growing demand for energy storage in the power system. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, an embodiment of the present invention proposes a hybrid energy storage power station comprising an upper reservoir, a lower reservoir, a pump-turbine unit and a gas storage reservoir;

[0006] The upper reservoir is set on the mountain, and the lower reservoir is located below the upper reservoir so that there is a height difference between the lower reservoir and the upper reservoir; the pump-turbine unit is connected to the upper reservoir through a water diversion pipe, and the pump-turbine unit is connected to the lower reservoir through a tailwater pipe; the air storage reservoir is located below the upper reservoir so that there is a height difference between the air storage reservoir and the upper reservoir, and the air storage reservoir has a water inlet and an air inlet, the water inlet and the air inlet are connected to the upper reservoir through a water pressure pipe, and the air inlet and the air compression expansion unit are connected through a main air pipe.

[0007] The hybrid energy storage power station according to the embodiment of the present invention has the advantages of high economic and social benefits, large energy storage capacity, high energy storage efficiency, avoidance of stress fatigue of the gas storage reservoir, and high utilization rate of the gas storage reservoir.

[0008] In some embodiments, the volume of the gas storage does not exceed 50% of the total volume of the upper water reservoir.

[0009] In some embodiments, the height difference between the gas storage reservoir and the upper water reservoir is greater than 300 meters.

[0010] In some embodiments, the water inlet and outlet are arranged at the bottom of the gas storage reservoir, the lower end of the water pressure pipe is connected to the water inlet and outlet, and the upper end of the water pressure pipe extends from the top of the upper reservoir into the interior of the upper reservoir. The gas storage reservoir is a pressure vessel or a pipeline gas storage reservoir arranged on the surface.

[0011] In some embodiments, the water inlet and outlet are arranged at the bottom of the gas storage reservoir, the lower end of the water pressure pipe is connected to the water inlet and outlet, and the upper end of the water pressure pipe extends from the bottom of the upper water reservoir into the interior of the upper water reservoir. The gas storage reservoir is a cave or tunnel gas storage reservoir, and each of the cave and the tunnel gas storage reservoir is arranged underground or in a mountain.

[0012] In some embodiments, the air compression and expansion unit includes a multi-stage compressor and a multi-stage expander; the outlet of the compressor of the first stage is connected to the inlet of the compressor of the second stage; the outlet of the expander of the first stage is connected to the inlet of the expander of the second stage, wherein the main air pipe can be switchably connected to one of the outlet of the compressor of the last stage and the inlet of the expander of the first stage.

[0013] In some embodiments, the air compression expander unit further comprises at least a first heat exchanger and a second heat exchanger;

[0014] Each of the first heat exchangers is located between two adjacent compressors, a first end of the first path of each of the first heat exchangers is connected to the outlet of the preceding compressor, and a second end of the first path of each of the first heat exchangers is connected to the inlet of the succeeding compressor;

[0015] The first end of the first path of the second heat exchanger is connected to the outlet of the last section of the compressor, and the second end of the first path of the second heat exchanger is connected to the main gas pipe;

[0016] A first end of the second path of each of the first heat exchanger and the second heat exchanger is connected to a cold tank, and a second end of the second path of each of the first heat exchanger and the second heat exchanger is connected to a hot tank.

[0017] In some embodiments, each of the first heat exchangers is further located between two adjacent expanders, and the first end of the first path of each of the first heat exchangers is switchably connected to one of the outlet of the compressor of the preceding stage and the inlet of the expander of the following stage, and the second end of the first path of each of the first heat exchangers is switchably connected to one of the inlet of the compressor of the following stage and the outlet of the expander of the preceding stage;

[0018] The first end of the first path of the second heat exchanger is switchably connected to one of the outlet of the last-stage compressor and the inlet of the first-stage expander.

[0019] In some embodiments, the air compression expander unit further includes at least a first cooler and a second cooler;

[0020] Each of the first coolers is located between two adjacent compressors, the outlet of the first path of each of the first coolers is connected to the inlet of the compressor of the subsequent stage, and the second end of the first path of each of the first heat exchangers is switchably connected to one of the inlet of the first path of the first cooler connected to the compressor of the subsequent stage and the outlet of the expander of the previous stage;

[0021] The main air pipe can be switchably connected to the second end of the first path of the second heat exchanger and one of the outlets of the first path of the second cooler, and the second end of the first path of the second heat exchanger can be switchably connected to the inlet of the first path of the second cooler and one of the main air pipe.

[0022] In some embodiments, the first end of the second path of each of the first cooler and the second cooler is connected to the lower water reservoir through an inlet pipe, and the second end of the second path of each of the first cooler and the second cooler is connected to the lower water reservoir through an outlet pipe, and a cooling water pump is connected to the inlet pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is one of the layout diagrams of a hybrid energy storage power station according to an embodiment of the present invention.

[0024] Figure 2 This is the second schematic diagram of the layout of a hybrid energy storage power station according to an embodiment of the present invention.

[0025] Figure 3 Schematic diagram of an air compression expansion unit according to an embodiment of the present invention.

[0026] Reference signs: 100, hybrid energy storage power station; 1, mountain; 2, upper reservoir; 3, water diversion pipe; 4, pump-turbine unit; 5, tail water pipe; 6, lower reservoir; 7, air compression-expansion unit; 711, first stage compressor; 712, second stage compressor; 713, third stage compressor; 714, fourth stage compressor; 721, first stage expander; 722, second stage expander; 723, third stage expander; 724, fourth stage expander; 731, first heat exchanger; 732, first heat exchanger; 733, first heat exchanger; 734, second heat exchanger; 741, first cold tank; 742, first hot tank; 743, second cold tank; 744, second hot tank; 745, third cold tank; 746, third hot tank; 747, fourth cold tank; 748, fourth hot tank; 751, first cooler; 752, first cooler; 753, first cooler; 754, second cooler; 761, first switching valve; 762, second switching valve; 763, third switching valve; 764, fourth switching valve; 765, fifth switching valve; 766, sixth switching valve; 767, seventh switching valve; 768, eighth switching valve; 769, ninth switching valve; 8, water inlet pipe; 9, water outlet pipe; 10, water pressure pipe; 11, air storage; 111, air inlet and outlet; 112, water inlet and outlet; 12, main air pipe; 13, cooling water pump. DETAILED DESCRIPTION

[0027] Embodiments of the present application are described in detail below with reference to examples illustrated in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0028] Reference is made below Figure 1-Figure 3 A hybrid energy storage power station 100 according to an embodiment of the present application is described. The hybrid energy storage power station 100 according to an embodiment of the present application includes an upper reservoir 2, a lower reservoir 6, a pump-turbine unit 4, and an air storage 11.

[0029] The upper reservoir 2 is disposed on a mountain 1, and the lower reservoir 6 is located below the upper reservoir 2 so that the lower reservoir 6 has a height difference from the upper reservoir 2, i.e., the upper reservoir 2 is located above the lower reservoir 6. The pump-turbine unit 4 is connected to the upper reservoir 2 through a water diversion pipe 3, and the pump-turbine unit 4 is connected to the lower reservoir 6 through a tail water pipe 5. The air storage 11 is located below the upper reservoir 2 so that the air storage 11 has a height difference from the upper reservoir 2. The air storage 11 has a water inlet and outlet 112 and an air inlet and outlet 111. The water inlet and outlet 112 is connected to the upper reservoir 2 through a water pressure pipe 10, and the air inlet and outlet 111 is connected to the air compression-expansion unit 7 through a main air pipe 12.

[0030] In the prior art, energy storage power stations are either standalone pumped-storage power stations or standalone compressed air energy storage power stations. However, pumped-storage power stations have low energy density, large reservoir capacity, and significant terrain variations, making site selection difficult. The number of available sites nationwide is limited, and the total investment is high, leading to a long construction period. Compressed air energy storage requires an extremely large gas storage reservoir. This large volume significantly hinders site selection, land occupation, and investment for compressed air energy storage devices. Furthermore, without auxiliary measures, the gas storage reservoir cannot operate at a constant pressure, negatively impacting energy storage efficiency and preventing full utilization of the storage capacity, resulting in waste. Because the expander's inlet pressure cannot be too low, the pressure drops when the gas storage reservoir releases high-pressure air. Once the pressure drops below a certain value, further discharge is stopped. In prior art compressed air energy storage devices, the high-pressure air in the gas storage reservoir is typically filled to 10 MPa, released to 7 MPa, then refilled to 10 MPa, and released to 7 MPa again, repeating this cycle. Only approximately 30% of the gas in the gas storage reservoir is used for the energy storage and release cycle.

[0031] The hybrid energy storage power station 100 according to an embodiment of the present invention organically combines pumped storage technology and compressed air energy storage technology. On the one hand, a gas storage reservoir 11 can be installed in the existing pumped storage power station's reservoir area, in the shallow area of ​​the lower reservoir 6, or within the mountain 1. The existing pumped storage power station can provide good site conditions for the installation of gas storage reservoir 11, thereby allowing the existing pumped storage power station's site resources and facilities to be redeveloped and utilized, generating positive economic and social benefits. Compared to the separately installed pumped storage power stations in related technologies, without requiring modification to the main pumped storage power station, only a small amount of water in the upper reservoir 2 is occupied. By applying the compressed air energy storage device, including gas storage reservoir 11, air compression expansion unit 7, and hydraulic pipe 10, to the pumped storage power station, the energy storage capacity of the original pumped storage power station can be expanded to form a larger capacity, high-efficiency energy storage power station, thereby significantly increasing the energy storage capacity of the original pumped storage power station.

[0032] On the other hand, when a new energy storage power station is constructed, the energy storage power station can be directly configured as a hybrid energy storage power station 100 according to an embodiment of the present invention, including an upper reservoir 2, a lower reservoir 6, a pump-turbine unit 4, a gas storage reservoir 11, and an air compression expansion unit 7. This allows the gas storage reservoir 11 to fully utilize the idle area around the upper reservoir 2 and the lower reservoir 6. That is, without increasing the area of ​​land around the lower reservoir 2, the hybrid energy storage power station 100 can provide good site conditions for the layout of the gas storage reservoir 11, thereby enabling the site resources and facility conditions of the hybrid energy storage power station 100 to be fully developed and utilized, thereby forming a larger capacity, high-efficiency energy storage power station and generating good economic and social benefits.

[0033] The basic process of energy storage and release of the hybrid energy storage power station 100 according to the embodiment of the present invention is as follows:

[0034] When using the hybrid energy storage power station 100 of the present invention to store energy during periods of low electricity demand, the pump-turbine unit 4 operates in pump mode and consumes electricity. Specifically, the pump-turbine unit 4 transports water from the lower reservoir 6 to the upper reservoir 2 via the tailwater pipe 5 and the water diversion pipe 3. The air compressor-expander unit 7 operates in compression mode, consuming electricity to compress ambient air to a high pressure, thereby producing high-pressure air. This high-pressure air is transported via the main air pipe 12 to the gas storage reservoir 11. The water in the gas storage reservoir 11, under the pressure of the high-pressure air, is transported via the hydraulic pipe 10 to the upper reservoir 2. In the process of the water in the gas storage reservoir 11 being pressed out of the gas storage reservoir 11, since there is a large height difference between the liquid level of the water in the gas storage reservoir 11 and the liquid level of the water in the upper water reservoir 2, and the change in the liquid level of the water in the gas storage reservoir 11 and the change in the liquid level of the water in the upper water reservoir 2 can be ignored, the water in the gas storage reservoir 11 has a water column pressure on the high-pressure air entering the gas storage reservoir 11. In the process of the high-pressure air overcoming this water column pressure and gradually entering the gas storage reservoir 11, the pressure of the high-pressure air in the gas storage reservoir 11 remains basically constant.

[0035] This not only prevents stress fatigue of the gas storage reservoir 11 due to internal pressure changes, but also enables the compressor to compress air more efficiently to a certain extent (because when designing the compressor, only one target compression pressure needs to be considered to maximize the efficiency of this design point. When the target compression pressure is not constant, a pressure range needs to be considered when designing the compressor, and a compromise design is adopted within this pressure range. At this time, the efficiency of the compressor is not the highest value), thereby effectively improving the energy storage efficiency of the hybrid energy storage power station 100.

[0036] During peak electricity demand, when the hybrid energy storage power station 100 of the present invention is used to release energy, the pump-turbine unit 4 operates in turbine mode and generates electricity. Water from the upper reservoir 2 first enters the pump-turbine unit 4 through the water diversion pipe 3, performs work, and drives the generator to generate electricity. The water then exits the pump-turbine unit 4 through the tailwater pipe 5 and is transported to the lower reservoir 6. The air compressor-expander unit 7 operates in expansion mode. High-pressure air from the gas storage reservoir 11 is transported to the air compressor-expander unit 7 through the main air pipe 12. The high-pressure air expands in the air compressor-expander unit 7, performs work, and drives the generator to generate electricity. While the high-pressure air from the gas storage reservoir 11 is being transported through the main air pipe 12, water from the upper reservoir 2 is transported to the gas storage reservoir 11 through the hydraulic pipe 10 by gravity or siphonage. Since there is a large height difference between the liquid level of water in the gas storage reservoir 11 and the liquid level of water in the upper water reservoir 2, and the change in the liquid level of water in the gas storage reservoir 11 and the change in the liquid level of water in the upper water reservoir 2 can be ignored, the water in the gas storage reservoir 11 always exerts a certain water column pressure on the high-pressure air in the gas storage reservoir 11. During the process of gradual output of high-pressure air from the gas storage reservoir 11, the pressure of the high-pressure air in the gas storage reservoir 11 remains basically constant.

[0037] This not only avoids stress fatigue of the gas storage reservoir 11 due to internal pressure changes, but also keeps the inlet pressure of the expander in the air compression expansion unit 7 constant, which can enable the expander to output more work (because when the high-pressure air in the gas storage reservoir 11 is not at a constant pressure, in order to maintain a certain inlet pressure of the expander, the gas coming out of the gas storage reservoir 11 is often throttled to a lower pressure before entering the expander. This throttling process wastes pressure energy and reduces the work of the expander. When the high-pressure air in the gas storage reservoir 11 is at a constant pressure, there will be no throttling loss), thereby effectively improving the energy storage efficiency of the hybrid energy storage power station 100.

[0038] In addition, the pressure of the high-pressure air in the gas storage reservoir 11 is basically kept constant, and the high-pressure air in the gas storage reservoir 11 can be completely released to the air compression expansion unit 7 through the main air pipe 12, so that the volume of the gas storage reservoir 11 can be fully utilized, the utilization rate of the gas storage reservoir 11 can be improved, and waste can be avoided.

[0039] Therefore, the hybrid energy storage power station 100 according to the embodiment of the present invention has the advantages of high economic and social benefits, large energy storage capacity, high energy storage efficiency, avoidance of stress fatigue of the gas storage reservoir 11 and high utilization rate of the gas storage reservoir 11.

[0040] The hybrid energy storage power station 100 according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] refer to Figure 1 and Figure 2 According to an embodiment of the present invention, a hybrid energy storage power station 100 includes an upper reservoir 2, a lower reservoir 6, a pump-turbine unit 4, and a gas storage reservoir 11. The upper reservoir 2 is located on a mountain 1, and the lower reservoir 6 is located below the upper reservoir 2, so that there is a height difference between the lower reservoir 6 and the upper reservoir 2, for example, a height difference of 400-500 meters. The pump-turbine unit 4 is connected to the upper reservoir 2 via a water diversion pipe 3, and the pump-turbine unit 4 is connected to the lower reservoir 6 via a tailwater pipe 5. The gas storage reservoir 11 is located below the upper reservoir 2, so that there is a height difference between the gas storage unit 11 and the upper reservoir 2, for example, a height difference of 400 meters.

[0042] The air storage reservoir 11 has a water inlet and outlet 112 and an air inlet and outlet 111. The water inlet and outlet 112 is located below the air inlet and outlet 111. This ensures that the compressed air and water do not affect each other during the process of compressed air entering the air storage reservoir 11 through the air inlet and outlet 111 and water exiting the air storage reservoir 11 through the water inlet and outlet 112. Similarly, the compressed air and water do not affect each other during the process of compressed air exiting the air storage reservoir 11 through the air inlet and outlet 111 and water entering the air storage reservoir 11 through the water inlet and outlet 112. The water inlet and outlet 112 is connected to the upper water reservoir 2 via the hydraulic pipe 10, and the air inlet and outlet is connected to the air compression and expansion unit 7 via the main air pipe 12.

[0043] refer to Figure 1 and Figure 2 The upper reservoir 2 is located at the top of the mountain 1, and the lower reservoir 6 is located at the bottom of the mountain 1. For example, the lower reservoir 6 can be located at the bottom or halfway up the mountain 1, depending on the situation. This ensures that the upper reservoir 2 is located at a higher position in the mountain 1 relative to the lower reservoir 6, and the lower reservoir 6 is located at a lower position in the mountain 1 relative to the upper reservoir 2. As a result, when water from the upper reservoir 2 flows into the lower reservoir 6, it can generate work through the pump-turbine unit 4.

[0044] Preferably, the volume of the gas storage reservoir 11 does not exceed 50% of the total volume of the upper reservoir 2. This can prevent the gas storage reservoir 11 from occupying too much water in the upper reservoir 2, thereby avoiding affecting the operation of the water pump turbine unit 4.

[0045] Preferably, the height difference between gas storage 11 and upper reservoir 2 is greater than 300 meters. Therefore, when the height difference between upper reservoir 2 and gas storage 11 is large, the difference in liquid levels between the water in upper reservoir 2 and gas storage 11 can generate a water column pressure that matches the pressure of the high-pressure air in gas storage 11. Furthermore, the greater the height difference between upper reservoir 2 and gas storage 11, the higher the gas pressure in gas storage 11. The smaller the volume of air of the same mass, the smaller the gas storage 11, and thus the lower the cost of construction.

[0046] refer to Figure 1 A water inlet and outlet 112 is located at the bottom of the gas storage reservoir 11, and the lower end of the hydraulic pipe 10 is connected to the water inlet and outlet 112. Therefore, during energy storage, all the water in the gas storage reservoir 11 is forced into the hydraulic pipe 10 by compressed air. During energy release, all the high-pressure air in the gas storage reservoir 11 is forced out of the gas storage reservoir 11 by the water pressure, thereby fully utilizing the capacity of the gas storage reservoir 11 and enabling full filling and discharging of the gas storage reservoir 11. This also prevents compressed air from entering the hydraulic pipe 10, thereby ensuring stable and reliable operation of the hybrid energy storage power station 100.

[0047] refer to Figure 1 The upper end of the hydraulic pipe extends from the top of the upper reservoir 2 into the interior of the upper reservoir 2. In this case, the hydraulic pipe 10 is equivalent to a siphon pipe arranged from the top of the upper reservoir 2. The hydraulic pipe 10 can be laid along the outer surface of the mountain 1 to the lower part of the mountain 1. This makes it easy to arrange the hydraulic pipe 10 and the gas storage reservoir 11, low in cost, and simple to maintain. In this case, the gas storage reservoir 11 can be a pressure vessel or a pipeline gas storage arranged on the surface. For example, the gas storage reservoir 11 can be arranged on the open space in the storage area of ​​the lower reservoir 6, or it can be arranged in the shallow area around the lower reservoir 6 by piling.

[0048] refer to Figure 2The upper end of the water pressure pipe 10 can also extend into the upper reservoir 2 from below the upper reservoir 2. For example, the water pressure pipe 10 can be a built-in tunnel arranged in the mountain 1, the upper end of the water pressure pipe 10 communicates with the upper reservoir 2, and the lower end of the water pressure pipe 10 communicates with the gas storage 11. The water pressure pipe 10 can be arranged from the bottom of the upper reservoir 2, and a pipeline is dug in the mountain 1 to a low position of the mountain 1. The water in the gas storage 11 flows to the gas storage 11 from the water pressure pipe 10 by gravity. Arranging the water pressure pipe 10 in the mountain 1 can not only save surface space, but also make the water pressure pipe 10 less affected by the external environment, and increase the service life of the water pressure pipe 10.

[0049] When the water pressure pipe 10 is a built-in tunnel arranged in the mountain 1, the gas storage 11 can be a cave or a tunnel gas storage. The cave can be a natural cave or a man-made cave. The gas storage 11 can be arranged underground or in the mountain 1. Arranging the gas storage 11 in the mountain 1 can not only save surface space, but also make the gas storage 11 less affected by the external environment, and increase the service life of the gas storage 11. Preferably, the gas storage 11 is arranged in the mountain 1, which is convenient for communicating with the water pressure pipe 10 arranged in the mountain 1.

[0050] It should be noted that when the upper end of the water pressure pipe 10 extends into the upper reservoir 2 from the top of the upper reservoir 2, or when the upper end of the water pressure pipe 10 extends into the upper reservoir 2 from below the upper reservoir 2, the upper end of the water pressure pipe 10 needs to be below the liquid level of the upper reservoir 2, so that the water in the upper reservoir 2 can smoothly enter the gas storage 11.

[0051] Reference Figure 3 The air compression and expansion unit 7 includes multiple stages of compressors and multiple stages of expanders. The outlet of a previous stage of compressor is connected to the inlet of a next stage of compressor. The outlet of a previous stage of expander is connected to the inlet of a next stage of expander. The main gas pipe 12 is switchably connected to one of the outlet of the last stage of compressor and the inlet of the first stage of expander. For example, the number of stages of the multiple stages of compressors in the embodiment is four, which are the first stage of compressor 711, the second stage of compressor 712, the third stage of compressor 713, and the fourth stage of compressor 714. The number of stages of the multiple stages of expanders is four, which are the first stage of expander 721, the second stage of expander 722, the third stage of expander 723, and the fourth stage of expander 724.

[0052] The hybrid energy storage power station 100 according to the embodiment of the present application can realize step-by-step compression of air by arranging multiple stages of compressors connected in sequence, so as to obtain high-pressure air with a certain pressure meeting the requirements and realize energy storage. The high-pressure air can be utilized step by step by arranging multiple stages of expanders connected in sequence, so as to fully utilize the pressure energy of the high-pressure air, and further improve the energy storage efficiency of the hybrid energy storage power station 100.

[0053] Reference Figure 3 The air compression-expansion unit 7 further comprises at least one first heat exchanger and one second heat exchanger. For example, there are three first heat exchangers in the embodiment, which are respectively the first heat exchanger 731, the first heat exchanger 732 and the first heat exchanger 733. Each first heat exchanger is located between two adjacent compressor segments. The first end of the first path of each first heat exchanger is connected to the outlet of the previous compressor segment. The second end of the first path of each first heat exchanger is connected to the inlet of the next compressor segment. The first end of the first path of the second heat exchanger is connected to the outlet of the last compressor segment. The second end of the first path of the second heat exchanger is connected to the main air pipe 12. The first end of the second path of each of the first heat exchanger and the second heat exchanger is connected to the cold tank, and the second end of the second path of each of the first heat exchanger and the second heat exchanger is connected to the hot tank. The cold tank is used to store the cold thermal storage medium. The hot tank is used to store the hot thermal storage medium. During thermal storage, the thermal storage medium is transported from the cold tank to the hot tank, and during energy release, the thermal storage medium is transported from the hot tank to the cold tank.

[0054] Thus, during energy storage, the first heat exchanger and the second heat exchanger can transfer the heat of the air at the outlet of the compressor to the thermal storage medium, and then the thermal storage medium that has absorbed the heat is stored in the hot tank, thereby improving the energy storage efficiency of the hybrid energy storage power station 100. At the same time, since the first heat exchanger and the second heat exchanger transfer the heat of the air at the outlet of the compressor to the thermal storage medium, the temperature of the gas at the inlet of the next compressor segment can be reduced, which is beneficial to the normal operation of the compressor.

[0055] Preferably, the number of compressor segments and the number of expansion machine segments are the same, and the compressor and the expansion machine in the air compression-expansion unit 7 can be symmetrically arranged, so that the pressure ratio in the compressor and the expansion ratio in the expansion machine can be substantially consistent, and the working conditions of the first heat exchanger and the second heat exchanger that can be reversibly used during the operation of the compressor and during the operation of the expansion machine are similar, thereby ensuring the stable and reliable operation of the first heat exchanger and the second heat exchanger.

[0056] Reference Figure 3 Each first heat exchanger is also located between two adjacent expansion machine segments. The first end of the first path of each first heat exchanger is switchably connected to one of the outlet of the previous compressor segment and the inlet of the next expansion machine segment. The second end of the first path of each first heat exchanger is switchably connected to one of the inlet of the next compressor segment and the outlet of the previous expansion machine segment. The first end of the first path of the second heat exchanger is switchably connected to one of the outlet of the last compressor segment and the inlet of the first expansion machine segment 721.

[0057] As a result, the multi-stage expander and the multi-stage compressor can share the first and second heat exchangers, streamlining the equipment layout of the hybrid energy storage power station 100 and reducing costs. Simultaneously, as the high-pressure air drives the expander to perform work, the first and second heat exchangers transfer heat from the heat storage medium stored in the hot tank to the high-pressure air at the expander inlet. The cold heat storage medium is then stored in the cold tank, increasing the gas temperature at the inlet of each expander stage. This is equivalent to increasing the thermal energy of the gas at the inlet of each expander stage, thereby increasing the mechanical work output by each expander stage and improving the energy storage efficiency of the hybrid energy storage power station 100.

[0058] refer to Figure 3 , the air compression expansion unit 7 also includes at least one first cooler and a second cooler. For example, there are three first coolers in the present embodiment, namely the first cooler 751, the first cooler 752 and the first cooler 753. Each first cooler is located between two adjacent compressors. The outlet of the first circuit of each first cooler is connected to the inlet of the latter compressor. The second end of the first circuit of each first heat exchanger can be switchably connected to the inlet of the first circuit of the first cooler connected to the latter compressor and one of the outlets of the previous expansion machine. The main air pipe 12 can be switchably connected to the second end of the first circuit of the second heat exchanger and one of the outlets of the first circuit of the second cooler. The second end of the first circuit of the second heat exchanger can be switchably connected to the inlet of the first circuit of the second cooler and one of the main air pipes 12.

[0059] According to an embodiment of the present invention, the air compression and expansion unit 7, by providing a first cooler between two adjacent compressor stages, not only dissipates excess heat from the gas flowing out of the first heat exchanger, but also precisely controls the inlet temperature of the gas entering the next compressor stage to remain within a specified range, thereby ensuring reliable operation of the compressor. Similarly, providing a second cooler at the outlet of the final compressor not only dissipates excess heat from the air flowing out of the second heat exchanger, but also effectively controls the temperature of the gas entering the gas storage reservoir 11, thereby ensuring that the temperature within the gas storage reservoir 11 remains within a normal range.

[0060] refer to Figure 3 The first end of the second circuit of each of the first and second coolers is connected to the lower reservoir 6 via an inlet pipe 8. The second end of the second circuit of each of the first and second coolers is connected to the lower reservoir 6 via an outlet pipe 9. A cooling water pump 13 is connected to the inlet pipe 8. The cooling water pump 13 is used to supply water from the lower reservoir 6 to the first and second coolers. This facilitates the supply of cooling water to the first and second coolers via the lower reservoir 6, thereby ensuring the removal of excess heat during the compressed air energy storage process.

[0061] refer to Figure 3Specifically, the air compression expansion unit 7 includes a first heat exchanger 731, a first heat exchanger 732, a first heat exchanger 733, and a second heat exchanger 734. The first end of the first circuit of the first heat exchanger 731 is switchably connected to the outlet of the first-stage compressor 711 and the inlet of the fourth-stage expander 724 via a first switching valve 761. The second end of the first circuit of the first heat exchanger 731 is switchably connected to the inlet of the first cooler 751 and the outlet of the third-stage expander 723 via a second switching valve 762, and the outlet of the first cooler 751 is connected to the inlet of the second-stage compressor 711. The first end of the second circuit of the first heat exchanger 731 is connected to the first hot tank 742. The second end of the second circuit of the first heat exchanger 731 is connected to the first cold tank 741.

[0062] The first end of the first circuit of the first heat exchanger 732 is switchably connected to the outlet of the second-stage compressor 712 and the inlet of the third-stage expander 723 via the third switching valve 763. The second end of the first circuit of the first heat exchanger 732 is switchably connected to the inlet of the first cooler 752 and the outlet of the second-stage expander 722 via the fourth switching valve 764. The outlet of the first cooler 752 is connected to the inlet of the third-stage compressor 713. The first end of the second circuit of the first heat exchanger 732 is connected to the second hot tank 744. The second end of the second circuit of the first heat exchanger 732 is connected to the second cold tank 743.

[0063] The first end of the first circuit of the first heat exchanger 733 is switchably connected to the outlet of the third-stage compressor 713 and the inlet of the second-stage expander 722 via the fifth switching valve 765. The second end of the first circuit of the first heat exchanger 733 is switchably connected to the inlet of the first cooler 753 and the outlet of the first-stage expander 721 via the sixth switching valve 766, and the outlet of the first cooler 753 is connected to the inlet of the fourth-stage compressor 714. The first end of the second circuit of the first heat exchanger 733 is connected to the third hot tank 746. The second end of the second circuit of the first heat exchanger 733 is connected to the third cold tank 745.

[0064] The first end of the first circuit of the second heat exchanger 734 is switchably connected to the outlet of the fourth-stage compressor 714 and the inlet of the first-stage expander 721 via the seventh switching valve 767. The second end of the first circuit of the second heat exchanger 734 is switchably connected to the inlet of the second cooler 754 and the main gas pipe 12 via the eighth switching valve 768. The main gas pipe 12 is switchably connected to the outlet of the second cooler 754 and the eighth switching valve 768 via the ninth switching valve 769. The first end of the second circuit of the second heat exchanger 734 is connected to the fourth hot tank 748. The second end of the second circuit of the second heat exchanger 734 is connected to the fourth cold tank 747.

[0065] refer to Figure 1-Figure 3 The detailed process of energy storage and release of the hybrid energy storage power station 100 is as follows:

[0066] When using the hybrid energy storage power station 100 of the present invention to store energy during periods of low electricity demand, the pump-turbine unit 4 operates in pump mode and consumes electricity. Water from the lower reservoir 6 is transported to the upper reservoir 2 via the tailwater pipe 5 and the water diversion pipe 3. The air compression-expansion unit 7 operates in compression mode, delivering high-pressure air to the gas storage reservoir 11. Under the pressure of the high-pressure air, the water in the gas storage reservoir 11 is transported to the upper reservoir 2 via the hydraulic pipe.

[0067] In the air compression and expansion unit 7, air first enters the first-stage compressor 711 for compression. At this point, the first end of the first circuit of the first heat exchanger 731 is connected to the outlet of the first-stage compressor 711 via the first switching valve 761, and the second end of the first circuit of the first heat exchanger 731 is connected to the inlet of the first cooler 751 via the second switching valve 762. The compressed air flowing out of the outlet of the first-stage compressor 711 releases its heat of compression through the first heat exchanger 731. The heat storage medium is then transferred from the first cold tank 741 to the first hot tank 742, where it absorbs the heat of compression transferred from the first heat exchanger 731. The compressed air flowing out of the second end of the first circuit of the first heat exchanger 731 is then cooled by the first cooler 751.

[0068] Next, the compressed air flowing out of the outlet of the first cooler 751 enters the second-stage compressor 712 for compression. At this point, the first end of the first circuit of the first heat exchanger 732 is connected to the outlet of the second-stage compressor 712 via the third switching valve 763, and the second end of the first circuit of the first heat exchanger 732 is connected to the inlet of the first cooler 752 via the fourth switching valve 764. The compressed air flowing out of the outlet of the second-stage compressor 712 releases its heat of compression through the first heat exchanger 732. The heat storage medium is then transferred from the second cold tank 743 to the second hot tank 744, where it absorbs the heat of compression transferred from the first heat exchanger 732. The compressed air flowing out of the second end of the first circuit of the first heat exchanger 732 is then cooled by the first cooler 752.

[0069] Next, the compressed air flowing out of the outlet of the first cooler 752 enters the third-stage compressor 713 for compression. At this point, the first end of the first circuit of the first heat exchanger 733 is connected to the outlet of the third-stage compressor 713 via the fifth switching valve 765, and the second end of the first circuit of the first heat exchanger 733 is connected to the inlet of the first cooler 753 via the sixth switching valve 766. The compressed gas flowing out of the outlet of the third-stage compressor 713 releases its heat of compression through the first heat exchanger 733. The heat storage medium is then transferred from the third cold tank 745 to the third hot tank 746, where it absorbs the heat of compression transferred from the first heat exchanger 733. The compressed air flowing out of the second end of the first circuit of the first heat exchanger 733 is further cooled by the first cooler 753.

[0070] Next, the compressed air flowing out of the outlet of the first cooler 753 enters the fourth-stage compressor 714 for compression. At this point, the first end of the first path of the second heat exchanger 734 is connected to the outlet of the fourth-stage compressor 714 via the seventh switching valve 767. The second end of the first path of the second heat exchanger 734 is connected to the inlet of the second cooler 754 via the eighth switching valve 768. The main air pipe 12 is connected to the outlet of the second cooler 754 via the ninth switching valve 769. The compressed gas flowing out of the outlet of the fourth-stage compressor 714 releases heat of compression through the second heat exchanger 734. The heat storage medium is transported from the fourth cold tank 747 to the fourth hot tank 748, where it absorbs the heat of compression transferred from the second heat exchanger 734. The compressed air flowing out of the second end of the first path of the second heat exchanger 734 is further cooled by the second cooler 754. The compressed air flowing out of the outlet of the second cooler 754 enters the gas storage reservoir 11 via the main air pipe 12.

[0071] During peak electricity demand, when the hybrid energy storage power station 100 of the present invention is used to release energy, the pump-turbine unit 4 operates in turbine mode and generates electricity. Water from the upper reservoir 2 is transported to the lower reservoir 6 via the water diversion pipe 3 and the tailwater pipe 5. The air compression and expansion unit 7 operates in expansion mode, and water from the upper reservoir 2 is transported to the gas storage reservoir 11 via the hydraulic pipe. The high-pressure air in the gas storage reservoir 11 is then transported to the air compression and expansion unit 7.

[0072] In the air compression and expansion unit 7, the main air pipe 12 is connected to the eighth switching valve 768 via the ninth switching valve 769. High-pressure air enters the second heat exchanger 734 from the main air pipe 12, absorbing heat. At this point, the first end of the first circuit of the second heat exchanger 734 is connected to the inlet of the first-stage expander 721 via the seventh switching valve 767. The high-pressure air flowing out of the first end of the first circuit of the second heat exchanger 734 expands in the first-stage expander 721, generating work. The heat storage medium is then transported from the fourth hot tank 748 to the fourth cold tank 747, releasing heat.

[0073] Next, since the first end of the first circuit of the first heat exchanger 733 is now connected to the inlet of the second-stage expander 722 via the fifth switching valve 765, and the second end of the first circuit of the first heat exchanger 733 is connected to the outlet of the first-stage expander 721 via the sixth switching valve 766, the high-pressure air flowing out of the outlet of the first-stage expander 721 enters the first heat exchanger 733 to absorb heat. The high-pressure air flowing out of the first end of the first circuit of the first heat exchanger 733 expands and performs work in the second-stage expander 722, and the heat storage medium is transported from the third hot tank 746 to the third cold tank 745 to release heat.

[0074] Next, since the first end of the first path of the first heat exchanger 732 is now connected to the inlet of the third-stage expander 723 via the third switching valve 763, and the second end of the first path of the first heat exchanger 732 is connected to the outlet of the second-stage expander 722 via the fourth switching valve 764, the high-pressure air flowing out of the outlet of the second-stage expander 722 enters the first heat exchanger 732, absorbs heat, expands in the third-stage expander 723, and performs work, the heat storage medium is transported from the second hot tank 744 to the second cold tank 743, releasing heat.

[0075] Next, since the first end of the first path of the first heat exchanger 731 is now connected to the inlet of the fourth-stage expander 724 via the first switching valve 761, and the second end of the first path of the first heat exchanger 731 is connected to the outlet of the third-stage expander 723 via the second switching valve 762, the high-pressure air flowing out of the outlet of the third-stage expander 723 enters the first heat exchanger 731, absorbs heat, expands in the fourth-stage expander 724, and performs work, the heat storage medium is transported from the first hot tank 742 to the first cold tank 741, releasing heat.

[0076] According to the above embodiment, assuming a pumped storage power station with a storage capacity of 1200MW / 9600MWh and an average height difference of 400m between the upper reservoir 2 and the lower reservoir 6, the scheme of the present invention is combined with a 400MW / 3200MWh constant pressure compressed air energy storage device, and the compressed air energy storage efficiency is about 70%. The pressure of the gas storage reservoir 11 is 4MPa, and the volume of the gas storage reservoir 11 is 800000m 3 , it needs to occupy 800,000m3 of water in the upper reservoir 3 , accounting for nearly 10% of the total water volume of upper reservoir 22. The total energy storage capacity of the hybrid energy storage power station 100 is 1500MW / 12000MWh. Thus, the solution of the present invention enables the compressed air energy storage process to operate at constant pressure and high efficiency without affecting the normal operation of the original pumped-storage power station, fully utilizing the volume of gas storage reservoir 11 and increasing the power station's energy storage capacity by 25%.

[0077] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying 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 should not be understood as limiting the present invention.

[0078] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0079] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0080] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0081] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0082] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A hybrid energy storage power station, characterized in that: include: an upper reservoir, wherein the upper reservoir is arranged on a mountain; a lower reservoir, the lower reservoir being located below the upper reservoir so that there is a height difference between the lower reservoir and the upper reservoir; A pump-turbine unit, wherein the pump-turbine unit is connected to the upper reservoir via a diversion pipe and connected to the lower reservoir via a tailwater pipe; and an air storage reservoir, the air storage reservoir being located below the upper water reservoir so that there is a height difference between the air storage reservoir and the upper water reservoir, the air storage reservoir having a water inlet and an air inlet, the water inlet and the air inlet being connected to the upper water reservoir via a hydraulic pipe, and the air inlet and the air inlet being connected to an air compression expansion unit via a main air pipe; The water inlet and outlet are provided at the bottom of the gas storage reservoir, the lower end of the water pressure pipe is connected to the water inlet and outlet, and the upper end of the water pressure pipe extends from the top or bottom of the upper water reservoir into the interior of the upper water reservoir, so that the volume of the gas storage reservoir is fully utilized and the gas storage reservoir can be fully filled and discharged; The height difference between the gas storage reservoir and the upper reservoir is greater than 300 meters; The air compression expander unit comprises: A multi-stage compressor, wherein the outlet of the compressor of the first stage is connected to the inlet of the compressor of the second stage; and a multi-stage expander, wherein the outlet of the expander of the first stage is connected to the inlet of the expander of the second stage, wherein the main gas pipe is switchably connected to one of the outlet of the compressor of the last stage and the inlet of the expander of the first stage; at least one first heat exchanger, each first heat exchanger being located between two adjacent compressors, a first end of a first path of each first heat exchanger being connected to the outlet of the preceding compressor, and a second end of the first path of each first heat exchanger being connected to the inlet of the succeeding compressor; and a second heat exchanger; At least one first cooler, each of the first coolers is located between two adjacent sections of the compressor, and a second cooler, the main air pipe can switchably connect the second end of the first path of the second heat exchanger and one of the outlets of the first path of the second cooler, the first end of the second path of each of the first cooler and the second cooler is connected to the lower water reservoir through an inlet pipe, the second end of the second path of each of the first cooler and the second cooler is connected to the lower water reservoir through an outlet pipe, and a cooling water pump is connected to the inlet pipe.

2. The hybrid energy storage power station according to claim 1, characterized in that: The volume of the gas storage reservoir does not exceed 50% of the total volume of the upper reservoir.

3. The hybrid energy storage power station according to claim 1, characterized in that: The gas storage is a pressure vessel or a pipeline gas storage arranged on the surface.

4. The hybrid energy storage power station according to claim 1, characterized in that: The gas storage is a cave or tunnel gas storage, and each of the cave and the tunnel gas storage is arranged underground or in a mountain.

5. The hybrid energy storage power station according to claim 1, characterized in that: The air compression expander unit also includes: The first end of the first path of the second heat exchanger is connected to the outlet of the last section of the compressor, and the second end of the first path of the second heat exchanger is connected to the main gas pipe; A first end of the second path of each of the first heat exchanger and the second heat exchanger is connected to a cold tank, and a second end of the second path of each of the first heat exchanger and the second heat exchanger is connected to a hot tank.

6. The hybrid energy storage power station according to claim 5, characterized in that: Each of the first heat exchangers is further located between two adjacent expanders, and the first end of the first path of each of the first heat exchangers is switchably connected to one of the outlet of the compressor of the preceding stage and the inlet of the expander of the following stage, and the second end of the first path of each of the first heat exchangers is switchably connected to one of the inlet of the compressor of the following stage and the outlet of the expander of the preceding stage; The first end of the first path of the second heat exchanger is switchably connected to one of the outlet of the last-stage compressor and the inlet of the first-stage expander.

7. The hybrid energy storage power station according to claim 6, characterized in that: The air compression expander unit also includes: The outlet of the first path of each first cooler is connected to the inlet of the subsequent compressor, and the second end of the first path of each first heat exchanger is switchably connected to one of the inlet of the first path of the first cooler connected to the subsequent compressor and the outlet of the previous expander; and The second end of the first path of the second heat exchanger is switchably connected to one of the inlet of the first path of the second cooler and the main air pipe.

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