Compressed air energy storage power station storage and power generation fast switching system and control method

Abstract

The invention discloses a compressed air energy storage power station storage and generation rapid switching system and a control method, relates to the technical field of compressed air energy storage, and realizes dual-mode rapid switching of power generation and energy storage through the synergistic effect of double clutches, a control switch group and a generator. In the switching process, the generator always operates within the rated rotating speed range, kinetic energy is maintained through the rotational inertia of the generator, the process that the generator needs to be shut down and then synchronized in a traditional scheme is effectively avoided, and huge energy loss caused by frequent starting and stopping of the generator in a traditional system is also avoided. According to the invention, rapid switching of dual modes is realized, the response speed of the power station and the supporting capability of auxiliary services such as frequency modulation and peak regulation of a power grid are improved, and the problem of slow mode switching of the compressed air energy storage power station is solved; and moreover, only one generator is used, so that compared with a dual-motor redundancy scheme, the equipment investment cost is reduced, and an efficient, energy-saving and quick-response storage and generation switching function is realized.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a rapid switching system and control method for compressed air energy storage power stations. Background Technology

[0002] Compressed air energy storage has become an important research direction in energy storage technology due to its large capacity and long lifespan. However, some problems still exist in the existing technology: the integrated regulating power station in the existing technology uses a single clutch to connect the air turbine and the reused motor. The mode switching depends on the timing control of the valve group and requires a shutdown and restart process, which results in a long switching time. In addition, the energy storage and release mode switching in the existing technology is achieved by connecting the compressor and expander through the switching valve to achieve rapid start-up. However, it still requires the operation of stopping the compressor unit, opening the switching valve, and starting the expander unit, which has the problem of equipment start-up and shutdown losses. Furthermore, the compression and power generation systems are driven independently, which has the problem of dual-motor redundancy.

[0003] The existing technical solutions mentioned above have problems such as long switching time and high energy consumption during generator start-up and shutdown. In the traditional mode, it takes a lot of energy for the generator to start from a standstill to its rated speed or stop. Therefore, there is an urgent need for a switching system and method that can maintain the rated speed of the generator during the switching process, reduce losses by utilizing its rotational inertia, and improve energy utilization to solve the above problems. Summary of the Invention

[0004] In view of the problems existing in the above or prior art, the present invention is proposed.

[0005] To solve the above technical problems, the present invention provides the following technical solution: a compressed air energy storage power station storage-generator fast switching system, including a power conversion unit, wherein the power conversion unit includes an expander unit for converting the internal energy of high-pressure air into mechanical energy, a compressor unit for converting mechanical energy into the potential energy of compressed air, and a generator for bidirectional energy conversion;

[0006] A transmission connection unit, the transmission connection unit including a first clutch disposed between the expander unit and the generator, and a second clutch disposed between the compressor unit and the generator;

[0007] The control unit is used to control the working state of the power conversion unit and the transmission connection unit, so that the generator always rotates within the rated speed range during the switching between energy storage mode and power generation mode, thereby realizing rapid switching between energy storage mode and power generation mode.

[0008] As a preferred embodiment of the compressed air energy storage power station energy storage and generation rapid switching system of the present invention, the expander unit includes a primary expander and a secondary expander disposed on one side of the primary expander;

[0009] The compressor unit includes a primary compressor and a secondary compressor located on one side of the primary compressor.

[0010] By connecting the primary and secondary expanders in series, and the primary and secondary compressors in series, the expansion and compression processes of air can be handled more efficiently, improving the expansion work capacity and compression efficiency. The multi-stage structure can more fully recover and utilize energy, improving the overall recycling rate and efficiency, thereby enhancing the operating efficiency of the entire power plant in both power generation and energy storage modes.

[0011] In a preferred embodiment of the compressed air energy storage power station rapid switching system for energy storage and generation described in this invention, the control unit includes a control switch group, which includes...

[0012] An intake control valve for regulating expansion intake, a check valve for preventing backflow, and a compression intake control valve for regulating compression intake.

[0013] As a preferred embodiment of the compressed air energy storage power station rapid switching system described in this invention, the control switch group further includes:

[0014] A gas storage chamber used for storing high-pressure air.

[0015] The expansion compressor's intake flow is regulated by the intake control valve to achieve smooth start-up; the compressor's load is adjusted by the compression intake control valve to achieve a smooth power reduction; the check valve prevents air from flowing back from the high-pressure storage chamber to the compressor side, ensuring system safety; through the coordinated action of various valves, airflow stability and equipment safety are ensured during mode switching, providing a foundation for reducing the load to a preset threshold in the later stages. The storage chamber, as a high-pressure air storage unit, can provide a continuous and stable high-pressure air source in power generation mode and can also achieve long-term discharge under grid peak-shaving demands; in energy storage mode, it can serve as the final storage container for compressed air.

[0016] As a preferred embodiment of the compressed air energy storage power station rapid switching system for energy storage and generation described in this invention, it further includes a heat exchange and energy storage unit.

[0017] The heat exchange and energy storage unit includes a heat storage tank for storing high-temperature heat energy generated during compression, a cold storage tank for storing low-temperature cold energy generated during compression, and a heat exchanger assembly.

[0018] The heat recovery and management of thermal energy are achieved through heat storage tanks and cold storage tanks. During the compression process, the heat generated during compression is stored in the heat storage tank; during the expansion process, the stored heat is used to preheat the air, while the residual cold after expansion is stored in the cold storage tank; this reduces energy waste and improves the system's cycle efficiency.

[0019] As a preferred embodiment of the compressed air energy storage power station rapid switching system for energy storage and generation described in this invention, the heat exchanger assembly includes:

[0020] A first heat exchanger for preheating before expansion, a second heat exchanger for heat dissipation after expansion, a third heat exchanger for heat exchange after compression, and a fourth heat exchanger for heat exchange during compression.

[0021] The first, second, third, and fourth heat exchangers ensure that air is fully cooled during compression and fully preheated before expansion, thus achieving cascaded energy utilization and effectively improving the equivalent efficiency of the compression and expansion processes.

[0022] The beneficial effects of this solution are as follows: Through the coordinated action of the dual clutch, control switch group, and generator, rapid switching between power generation and energy storage modes is achieved; during the switching process, the generator always operates within its rated speed range, utilizing its own rotational inertia to maintain kinetic energy, effectively avoiding the generator shutdown and resynchronization process required in traditional solutions, and also avoiding the huge energy loss caused by frequent generator start-stop in traditional systems; this invention achieves rapid switching between dual modes, improving the power station's response speed and its support capability for grid frequency regulation, peak shaving, and other auxiliary services, solving the problem of slow mode switching in compressed air energy storage power stations; furthermore, this invention uses only one generator, reducing equipment investment costs compared to dual-motor redundancy solutions, and achieving efficient, energy-saving, and rapid-response power storage switching functions.

[0023] Another objective of this invention is to provide a control method for a compressed air energy storage power station's rapid switching system between energy storage and generation, comprising the following steps:

[0024] When switching from energy storage to power generation: the intake control valve is opened to drive the expander unit to start, and the compressor intake control valve is adjusted synchronously to reduce the load on the compressor unit. When the expander unit speed reaches the rated speed and the compressor unit load drops to the preset threshold, the second clutch is disengaged and the first clutch is engaged.

[0025] When switching from power generation to energy storage: the compressor intake control valve is opened to drive the compressor unit to start, and the intake control valve is adjusted synchronously to reduce the load of the expander unit. When the compressor unit speed reaches the rated speed and the expander unit load drops to the preset threshold, the first clutch is disengaged and the second clutch is engaged.

[0026] As a preferred embodiment of the control method for the compressed air energy storage power station's rapid switching system for energy storage and generation, wherein:

[0027] In the initial state of switching from energy storage to power generation, the second clutch is engaged, the compressor unit starts running, and the check valve is fully open.

[0028] In the initial state of switching from power generation to energy storage, the first clutch is engaged, the expander unit starts operating, and the intake control valve is fully open.

[0029] By opening and closing specific valves, efficient countercurrent heat exchange between the intermediate medium and compressed air is ensured in multiple intermediate medium heat exchangers, thereby improving the heat exchange efficiency during the energy storage stage.

[0030] In a preferred embodiment of the control method for the compressed air energy storage power station's rapid switching system for energy storage and generation, the threshold value is smoothly reduced from the rated value to less than or equal to 5%.

[0031] The beneficial effects of this plan are:

[0032] This invention enables the target generator to be started in advance and brought close to its rated speed when switching from energy storage to power generation or vice versa. At the same time, the load of the original working generator is gradually reduced to a preset threshold. Once the conditions are met, the clutch switching is completed. The entire process does not require shutdown, the switching time is ≤5 seconds, the response speed is fast, and it meets the grid's requirements for rapid frequency regulation and peak shaving. More importantly, the dual-condition generator always maintains its rated speed, completely avoiding kinetic energy loss during start-up and shutdown. A single switch can save approximately 169.4 kWh of electricity, and long-term operation can save more than 120,000 kWh of energy per year, with significant energy-saving benefits. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the overall structure of a compressed air energy storage power station's rapid switching system for energy storage and generation.

[0035] Among them, the red line represents the high-temperature heat medium circulation of the heat storage tank and heat exchanger group; the blue line represents the air flow direction (energy storage stage → gas storage chamber, power generation stage → atmosphere); and the green line represents the low-temperature refrigerant circulation of the cold storage tank and heat exchanger group.

[0036] 11. Generator; 12. First-stage expander; 13. Second-stage expander; 14. First-stage compressor; 15. Second-stage compressor; 21. First clutch; 22. Second clutch; 31. Intake control valve; 32. Check valve; 33. Compressor intake control valve; 34. Gas storage chamber; 41. Heat storage tank; 42. Cold storage tank; 43. First heat exchanger; 44. Second heat exchanger; 45. Third heat exchanger; 46. Fourth heat exchanger. Detailed Implementation

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0039] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0040] Example 1

[0041] Reference Figure 1 This is the first embodiment of the present invention, which provides a compressed air energy storage power station energy storage and generation fast switching system, comprising,

[0042] The power conversion unit includes an expander unit for converting the internal energy of high-pressure air into mechanical energy, a compressor unit for converting mechanical energy into the potential energy of compressed air, and a dual-mode generator 11 for bidirectional energy conversion; the dual-mode generator 11 has a moment of inertia of 12380 kg·m. 2 It always maintains the rated speed; the dual-condition generator 11 is a doubly fed asynchronous motor with a rated power of 50-350MW, a power generation mode efficiency of ≥96%, and an electric mode efficiency of ≥95%, and can realize the switching between power generation and electric modes.

[0043] The transmission connection unit includes a first clutch 21 disposed between the expander unit and the dual-mode generator 11, used to selectively connect or disconnect the expander unit and the dual-mode generator 11; and a second clutch 22 disposed between the compressor unit and the dual-mode generator 11, used to selectively connect or disconnect the compressor unit and the dual-mode generator 11. The first clutch 21 and the second clutch 22 can be magnetic powder clutches or hydraulic clutches, and have pre-charge or pre-synchronization control functions to achieve smooth torque transition.

[0044] The control unit is used to control the working state of the power conversion unit and the transmission connection unit. Specifically, it coordinates and controls the working state of the first clutch 21, the second clutch 22, the control switch group, and the dual-mode generator 11, so that the dual-mode generator 11 always rotates within the rated speed range during the switching between energy storage mode and power generation mode, realizing rapid switching between energy storage mode and power generation mode, and its kinetic energy is maintained by the rotational inertia of the system, without having to go through a complete shutdown or start-up process.

[0045] Furthermore, the expander unit includes a primary expander 12 and a secondary expander 13 disposed on one side of the primary expander 12; the primary expander 12 and the secondary expander 13 are connected in series;

[0046] The compressor unit includes a primary compressor 14 and a secondary compressor 15 disposed on one side of the primary compressor 14; the primary compressor 14 and the secondary compressor 15 are connected in series;

[0047] It should be noted that in this embodiment, a primary expander 12 and a secondary expander 13, a primary compressor 14 and a secondary compressor 15 are used. However, in actual applications, the number of series stages of the primary expander 12 and the secondary expander 13, the primary compressor 14 and the secondary compressor 15 can be extended to three stages or more, and multi-stage circulation can be adapted by adding heat exchangers and clutches.

[0048] This invention achieves rapid switching between energy storage and power generation modes through independent dual-clutch control, adjustment of the control switch group, and coordination of the dual-condition generator 11. During the switching process, the system maintains the generator 11 at its rated speed, utilizing rotational inertia to avoid start-stop energy consumption. Combined with closed-loop management of thermal and cold storage, system efficiency is significantly improved. Through smooth load transition and flexible clutch switching, the system solves the problems of response lag and energy waste in traditional solutions, making it suitable for large-scale grid peak shaving and new energy consumption scenarios.

[0049] Example 2

[0050] Reference Figure 1 This is the second embodiment of the present invention, which differs from the first embodiment in that...

[0051] The control unit includes a control switch group, which includes...

[0052] An intake control valve 31 for regulating expansion intake, a check valve 32 for preventing backflow, and a compression intake control valve 33 for regulating compression intake.

[0053] Furthermore, the control switch assembly also includes a gas storage chamber 34 for storing high-pressure air.

[0054] It should be noted that in this embodiment, the intake control valve 31 and the compressor intake control valve 33 are electrically adjustable valves with linear flow regulation function and a response rate of not less than ±10% / s of the rated power. The check valve 32 is a hydraulically controlled check valve or a pneumatic check valve with a pressure rating of ≥16MPa to prevent high-pressure air in the air storage chamber 34 from flowing back to the compressor side.

[0055] Example 3

[0056] Reference Figure 1 This is the third embodiment of the present invention, which differs from the first two embodiments in that...

[0057] It also includes a heat exchange and energy storage unit, which includes a heat storage tank 41 for storing high-temperature heat energy generated during compression, which can be used to preheat high-pressure air before expansion and power generation; a cold storage tank 42 for storing low-temperature cold energy during compression, which can be used to cool intermediate-stage airflow during compression; the heat storage tank 41 and the cold storage tank 42 form a heat closed loop; and a heat exchanger assembly.

[0058] Furthermore, the heat exchanger assembly includes a first heat exchanger 43 for preheating before expansion, a second heat exchanger 44 for heat dissipation after expansion, a third heat exchanger 45 for heat exchange after compression, and a fourth heat exchanger 46 for heat exchange during compression at medium temperature.

[0059] It should be noted that the heat storage process involves recovering the high-temperature heat from the compressor unit outlet (reducing from 180℃ to 80℃) through the third heat exchanger 45 and the fourth heat exchanger 46. The heat-absorbing medium is stored in the heat storage tank 41, and then preheated (from 30℃ to 180℃) to the expansion unit inlet gas through the first heat exchanger 43 and the second heat exchanger 44. The heat-releasing medium is stored in the cold storage tank 42, with a heat recovery rate of ≥90%. The medium can be water or oil.

[0060] Example 4,

[0061] Reference Figure 1 This is the fourth embodiment of the present invention, which provides a control method for a compressed air energy storage power station's rapid switching system between energy storage and generation, comprising the following steps:

[0062] When switching from energy storage to power generation: the intake control valve 31 is opened to drive the expander unit to start, and the compressor intake control valve 33 is adjusted synchronously to reduce the load of the compressor unit. When the speed of the expander unit reaches the rated speed and the load of the compressor unit drops to the preset threshold, the second clutch 22 is disengaged and the first clutch 21 is engaged.

[0063] When switching from power generation to energy storage: the compressor unit is driven to start when the compressor intake control valve 33 is opened, and the intake control valve 31 is adjusted synchronously to reduce the load of the expander unit. When the compressor unit speed reaches the rated speed and the expander unit load drops to the preset threshold, the first clutch 21 is disengaged and the second clutch 22 is engaged.

[0064] Furthermore, it also includes the following steps:

[0065] In the initial state of switching from energy storage to power generation, the second clutch 22 is engaged, the compressor unit starts running, and the check valve 32 is fully open;

[0066] In the initial state of switching from power generation to energy storage, the first clutch 21 is engaged, the expander unit starts operating, and the intake control valve 31 is fully open.

[0067] Furthermore, the threshold is to smoothly decrease from the nominal value to less than or equal to 5%.

[0068] The specific operation method for switching from energy storage to power generation is as follows:

[0069] (1) Initial state: The second clutch 22 is engaged, the first clutch 21 is disengaged, the compressor unit is running and charging the gas storage chamber 34, the expander unit is stationary, the check valve 32 is fully open, and the intake control valve 31 is closed.

[0070] (2) After receiving the power grid command, the intake control valve 31 is opened, and high-pressure air is introduced into the expander unit by adjusting the opening degree to drive the expander unit to start running. At the same time, the compressor intake control valve 33 is closed to gradually reduce the load of the compressor unit.

[0071] (3) When the speed of the first-stage expander 12 and the second-stage expander 13 increases to the rated speed (3000 rpm), and the load of the first-stage compressor 14 and the second-stage compressor 15 decreases to ≤5% of the rated power, the second clutch 22 is disengaged and the first clutch 21 is engaged;

[0072] (4) Operate generator 11 to connect to the grid. After the grid connection is completed, the switching ends. The whole process takes ≤5 seconds.

[0073] The specific operation method for switching from power generation to energy storage is as follows:

[0074] (1) Initial state: the first clutch 21 is engaged, the second clutch 22 is disengaged, the expander unit runs to drive the generator 11 to generate electricity, the compressor unit is stationary, the intake control valve 31 is fully open, the check valve 32 is closed;

[0075] (2) After receiving the power grid command, the compressor intake control valve 31 is opened to introduce the atmosphere into the compressor unit. The rated speed of the generator 11 is used to drive the compressor unit to start running. At the same time, the intake control valve 31 is closed to gradually reduce the load of the expander unit.

[0076] (3) When the speed of the first-stage compressor 14 and the second-stage compressor 15 increases to the rated speed (3000 rpm), and the load of the first-stage expander 12 and the second-stage expander 13 is ≤5% of the rated power, the first clutch 21 is disengaged and the second clutch 22 is engaged.

[0077] (4) Operate generator 11 to switch to electric mode, drive compressor unit to compress air into air storage chamber 34, switch ends, the whole process ≤5s.

[0078] In this invention, the energy consumption calculation for the start-up and shutdown of generator 11 is specifically as follows:

[0079] Rated parameters: Rotational speed n = 3000 rpm = 50 r / s, angular velocity ω = 2πn = 31416 rad / s, moment of inertia J = 12380 kg·m 2 ;

[0080] Kinetic energy formula:

[0081] Calculation process:

[0082]

[0083] The above calculations show that in the traditional mode, generator 11 consumes approximately 169.4 kWh per start-up and shutdown. This invention saves this energy by maintaining the rated speed and switching once. Based on two switching times per day, the annual energy saving is approximately 123,346 kWh, solving the problem of high start-up and shutdown losses in the existing technology.

[0084] Importantly, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A rapid switching system for compressed air energy storage power station, characterized in that: include, The power conversion unit includes an expander unit for converting the internal energy of high-pressure air into mechanical energy, a compressor unit for converting mechanical energy into the potential energy of compressed air, and a generator (11) for bidirectional energy conversion. The transmission connection unit includes a first clutch (21) disposed between the expander unit and the generator (11), and a second clutch (22) disposed between the compressor unit and the generator (11); The control unit is used to control the working state of the power conversion unit and the transmission connection unit, so that the generator (11) always rotates within the rated speed range during the switching between energy storage mode and power generation mode, thereby realizing the rapid switching between energy storage mode and power generation mode.

2. The compressed air energy storage power station energy storage and generation rapid switching system as described in claim 1, characterized in that: The expander unit includes a primary expander (12) and a secondary expander (13) disposed on one side of the primary expander (12); The compressor unit includes a primary compressor (14) and a secondary compressor (15) disposed on one side of the primary compressor (14).

3. The compressed air energy storage power station energy storage and generation rapid switching system as described in claim 1, characterized in that: The control unit includes a control switch group, the control switch group including, An intake control valve (31) for regulating expansion intake, a check valve (32) for preventing backflow, and a compression intake control valve (33) for regulating compression intake.

4. The compressed air energy storage power station energy storage and generation fast switching system as described in claim 3, characterized in that: The control switch group also includes, Storage chamber (34) for storing high-pressure air.

5. The compressed air energy storage power station energy storage and generation fast switching system as described in claim 1, characterized in that: It also includes heat exchange and energy storage units. The heat exchange and energy storage unit includes a heat storage tank (41) for storing high-temperature heat energy generated during compression, a cold storage tank (42) for storing low-temperature cold energy during compression, and a heat exchanger assembly.

6. The compressed air energy storage power station energy storage and generation fast switching system as described in claim 5, characterized in that: The heat exchanger assembly includes A first heat exchanger (43) for preheating before expansion, a second heat exchanger (44) for heat dissipation after expansion, a third heat exchanger (45) for heat exchange after compression, and a fourth heat exchanger (46) for heat exchange during compression.

7. A control method for a rapid switching system between energy storage and power generation in a compressed air energy storage power station, characterized in that: Includes the following steps: When switching from energy storage to power generation: the intake control valve (31) is opened to drive the expander unit to start, and the compressor intake control valve (33) is adjusted synchronously to reduce the load of the compressor unit. When the speed of the expander unit reaches the rated speed and the load of the compressor unit drops to the preset threshold, the second clutch (22) is disengaged and the first clutch (21) is engaged. When switching from power generation to energy storage: the compressor intake control valve (33) is opened to drive the compressor unit to start, and the intake control valve (31) is adjusted synchronously to reduce the load of the expander unit. When the compressor unit speed reaches the rated speed and the expander unit load drops to the preset threshold, the first clutch (21) is disengaged and the second clutch (22) is engaged.

8. The control method for a rapid switching system between energy storage and generation in a compressed air energy storage power station as described in claim 7, characterized in that, It also includes the following steps: In the initial state of switching from energy storage to power generation, the second clutch (22) is engaged, the compressor unit starts running, and the check valve (32) is fully open; In the initial state of switching from power generation to energy storage, the first clutch (21) is engaged, the expander unit is running, and the intake control valve (31) is fully open.

9. The control method for a compressed air energy storage power station's rapid switching system for energy storage and generation as described in claim 7, characterized in that: The threshold is a smooth decrease from the rated value to less than or equal to 5%.

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