A distributed power adjustable two-stage compressed air energy storage system and method of operating the same

Abstract

The application belongs to the technical field of energy storage, and discloses a distributed power-adjustable two-stage compressed air energy storage system and an operating method thereof. The distributed power-adjustable two-stage compressed air energy storage system comprises a first air compressor, a first heat exchanger, a first air tank, a second heat exchanger, a first turbine, a second air compressor, a third heat exchanger, a second air tank, a fourth heat exchanger and a second turbine. In the energy storage process, the first air compressor is used for keeping a constant pressure ratio; the second air compressor is used for keeping the pressure at the inlet constant, and the pressure at the outlet gradually increases with the pressure in the second air tank; in the energy releasing process, the first turbine is used for keeping a constant expansion ratio; and the second turbine is used for keeping the pressure at the outlet constant, and the pressure at the inlet gradually decreases with the pressure in the second air tank. The application can make the energy storage system stably operate in the design working condition, can realize distributed arrangement, and has high utilization rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage, and particularly relates to a distributed power-adjustable two-stage compressed air energy storage system and an operation method thereof. BACKGROUND

[0002] The application of energy storage technology can solve the volatility and intermittency of new energy power generation to a great extent, effectively solve the problem of peak load shifting, and has been paid more and more attention in recent years. The compressed air energy storage technology is considered as one of the most promising energy storage technologies due to its high energy storage efficiency and clean and pollution-free characteristics.

[0003] In the prior art, the compressed air energy storage still has the following technical defects, specifically including:

[0004] (1) The gas storage device is usually a constant volume container, and the pressure in the container will gradually increase or decrease with the inflow or outflow of air. The above situation will cause the variable operating conditions of the compressor and the turbine, and the power change of the system energy storage and release process is large, so that the operation of the system deviates from the design condition, and long-term use will cause the performance of the components to deteriorate, thereby affecting the service life and performance of the system;

[0005] (2) The system energy storage pressure is usually 10 MPa or even higher, and the underground rock cavity or abandoned mine is used as the gas storage space, which is greatly limited by geographical conditions and is not conducive to the distributed arrangement of the system. In addition, the underground rock cavity or abandoned mine usually has a minimum pressure limit to ensure its safe operation, so the energy storage pressure is usually high, which not only leads to the waste of part of the compression work and is not conducive to the further improvement of the system energy storage efficiency, but also makes the utilization rate of the gas storage space low. SUMMARY

[0006] The application aims to provide a distributed power-adjustable two-stage compressed air energy storage system and an operation method thereof to solve one or more of the above technical problems. The technical scheme provided by the application can make the energy storage system stably operate at the design condition, realize distributed arrangement, and has high utilization rate.

[0007] To achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0008] The distributed power-adjustable two-stage compressed air energy storage system provided by the application comprises a first air compressor, a first heat exchanger, a first gas storage tank, a second heat exchanger, a first turbine, a second air compressor, a third heat exchanger, a second gas storage tank, a fourth heat exchanger and a second turbine.

[0009] The outlet of the first compressor is connected with the first inlet of the first gas tank through the first heat exchange channel of the first heat exchanger, and the first outlet of the first gas tank is connected with the inlet of the first turbine through the second heat exchange channel of the second heat exchanger.

[0010] The second outlet of the first gas tank is connected with the inlet of the second compressor, the outlet of the second compressor is connected with the inlet of the second gas tank through the first heat exchange channel of the third heat exchanger, and the outlet of the second gas tank is connected with the inlet of the second turbine through the second heat exchange channel of the fourth heat exchanger; the outlet of the second turbine is connected with the second inlet of the first gas tank.

[0011] In the energy storage process, the first compressor is used for keeping constant pressure ratio, the second compressor is used for keeping constant inlet pressure, and the outlet pressure gradually rises with the pressure in the second gas tank, and the inlet guide vane angle and rotating speed of the second compressor are dynamically adjusted with the change of the pressure in the process of the change of the outlet pressure; in the energy release process, the first turbine is used for keeping constant expansion ratio, the second turbine is used for keeping constant outlet pressure, and the inlet pressure gradually decreases with the pressure in the second gas tank, and the inlet guide vane angle and rotating speed of the second turbine are dynamically adjusted with the change of the pressure in the process of the change of the inlet pressure.

[0012] The further improvement of the present application is that,

[0013] The inlet of the first compressor is connected with the atmosphere.

[0014] The outlet of the first turbine is connected with the atmosphere.

[0015] The further improvement of the present application is that, the present application further comprises a first cold storage tank and a first heat storage tank, wherein,

[0016] The outlet of the first cold storage tank is connected with the inlet of the first heat storage tank through the second heat exchange channel of the first heat exchanger, and the outlet of the first heat storage tank is connected with the inlet of the first cold storage tank through the first heat exchange channel of the second heat exchanger.

[0017] The further improvement of the present application is that, the present application further comprises a second control valve and a third control valve, wherein,

[0018] The second control valve is arranged in the connecting pipeline between the first cold storage tank and the first heat exchanger, and the third control valve is arranged in the connecting pipeline between the first heat storage tank and the second heat exchanger.

[0019] The further improvement of the present application is that, the present application further comprises a second cold storage tank and a second heat storage tank, wherein,

[0020] The outlet of the second cold storage tank is connected with the inlet of the second heat storage tank through the second heat exchange channel of the third heat exchanger, and the outlet of the second heat storage tank is connected with the inlet of the second cold storage tank through the first heat exchange channel of the fourth heat exchanger.

[0021] Further improvement of the present application is that it further comprises a fifth control valve and a sixth control valve, wherein

[0022] The fifth control valve is arranged in the connecting pipeline between the third heat exchanger and the second cold storage tank, and the sixth control valve is arranged in the connecting pipeline between the second heat storage tank and the fourth heat exchanger.

[0023] Further improvement of the present application is that it further comprises an energy storage device, wherein

[0024] The energy storage device is connected with the second turbine, and is used for realizing the function of "peak load shifting" when the load of the second turbine changes.

[0025] Further improvement of the present application is that it further comprises a first control valve, a fourth control valve, a seventh control valve and an eighth control valve, wherein

[0026] The first control valve is arranged in the connecting pipeline between the first gas tank and the second heat exchanger, the fourth control valve is arranged in the connecting pipeline between the first gas tank and the second turbine, the seventh control valve is arranged in the connecting pipeline between the second gas tank and the fourth heat exchanger, and the eighth control valve is arranged at the inlet of the first compressor.

[0027] The present application provides an operation method of a distributed power adjustable two-stage compression air energy storage system, which comprises the following steps:

[0028] The compressed air with a preset storage pressure is pre-stored in the first gas tank and the second gas tank as working medium;

[0029] When the user is in the power valley, the energy storage is carried out, including: the electric power drives the first compressor to compress the air at normal temperature and pressure, the compressed air enters the first heat exchanger to exchange heat and cool down, and the cooled air enters the first gas tank; the compressed air in the first gas tank maintains a preset storage pressure; with the continuous entry of the compressed air, the excess compressed air enters the second compressor for compression, the compressed air enters the third heat exchanger for heat exchange and cooling, and the cooled compressed air is stored in the second gas tank, thus completing the compression and heat storage of the working medium; wherein, in the energy storage process, the first compressor is used to maintain a constant pressure ratio; the second compressor is used to maintain a constant pressure at the inlet, and the outlet pressure gradually rises with the pressure in the second gas tank, and the inlet guide vane angle and the rotating speed of the second compressor are dynamically adjusted with the change of the pressure in the process of outlet pressure change;

[0030] When the user is in the power peak, the energy is released, including: the compressed air in the second gas tank enters the fourth heat exchanger to heat and warm up, the compressed air after heating enters the second turbine to expand and do work, which is used to drive the generator to generate electricity, and then the compressed air expanded to the preset pressure of the first gas tank enters the first gas tank, the compressed air in the first gas tank enters the second heat exchanger from the first outlet to heat and warm up, the compressed air after heating enters the first turbine to expand and do work, which drives the generator to generate electricity, and finally the air expanded to normal temperature and pressure is discharged to the atmosphere, thus completing the expansion and heat release of the working medium; wherein, in the energy release process, the first turbine is used to maintain a constant expansion ratio; the second turbine is used to maintain a constant outlet pressure, and the inlet pressure gradually decreases with the pressure in the second gas tank, and the inlet guide vane angle and the rotating speed of the second turbine are dynamically adjusted with the change of the pressure in the process of changing the inlet pressure.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] The air compressor and turbine inlet guide vane and rotating speed used in the distributed power adjustable two-stage compression air energy storage system provided by the present application can make the flow basically stable when the pressure ratio changes, so that the energy storage system can stably operate at the design working condition, and the stability of the output power of the entire system can be guaranteed, thereby improving the stability and adjustability of the entire system. In addition, the air energy storage system designed by the present application has the characteristics of light weight and portability compared with the traditional air energy storage system, so that it is more convenient to install and is beneficial to distributed arrangement. Specifically, to solve the problem of large power variation in the energy storage and release process of the existing compressed air energy storage system, the present application uses the staged operation of the first air compressor, the first turbine, the second air compressor and the second turbine, the first air compressor and the first turbine operate at a constant rotating speed and a constant pressure, and bear the basic load, and the second air compressor and the second turbine operate at a variable rotating speed and a variable load, which can effectively improve the energy storage and release efficiency of the system; the rotating speed and the inlet guide vane of the second air compressor and the second turbine can be adjusted according to the actual operation, the flow can be basically stabilized by adjusting the guide vane angle when the pressure ratio changes, and the rotating speed is adjusted to make the second air compressor and the second turbine reach the best speed ratio, thereby improving the stability of the system.

[0033] In addition, a small energy storage device is arranged at the second turbine, which realizes the function of "peak clipping and valley filling" when the load of the second turbine changes, and by cooperating with the small energy storage device, the stability of the output power of the entire system can be further guaranteed, and the stability and adjustability of the entire system can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings required by the embodiments or prior art description; obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0035] Figure 1 is a structural schematic diagram of a distributed power adjustable two-stage compressed air energy storage system provided by the embodiment of the present application;

[0036] Figure 1 In the figure, 1 is a first compressor, 2 is a first heat exchanger, 3 is a first gas storage tank, 4 is a first cold storage tank, 5 is a first heat storage tank, 6 is a second heat exchanger, 7 is a first turbine, 8 is a second compressor, 9 is a third heat exchanger, 10 is a second gas storage tank, 11 is a second cold storage tank, 12 is a second heat storage tank, 13 is a fourth heat exchanger, 14 is a second turbine, and 15 is an energy storage device.

[0037] 16 is a first control valve, 17 is a second control valve, 18 is a third control valve, 19 is a fourth control valve, 20 is a fifth control valve, 21 is a sixth control valve, 22 is a seventh control valve, and 23 is an eighth control valve. DETAILED DESCRIPTION

[0038] In order to make the person skilled in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort should be within the scope of protection of the present application.

[0039] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0040] The present application will be described in further detail below with reference to the drawings:

[0041] Please refer to Figure 1 The embodiment of the present application discloses a distributed power adjustable two-stage compression air energy storage system, and the main system comprises a first air compressor 1, a first heat exchanger 2, a first air tank 3, a second heat exchanger 6, a first turbine 7, a second air compressor 8, a third heat exchanger 9, a second air tank 10, a fourth heat exchanger 13 and a second turbine 14.

[0042] In the embodiment of the present application, the first cold storage tank 4 and the first heat storage tank 5 can also be included.

[0043] In the embodiment of the present application, the second cold storage tank 11 and the second heat storage tank 12 can also be included.

[0044] In the embodiment of the present application, the energy storage device 15 can also be included.

[0045] In the embodiment of the present application, the first control valve 16, the second control valve 17, the third control valve 18, the fourth control valve 19, the fifth control valve 20, the sixth control valve 21, the seventh control valve 22 and the eighth control valve 23 can also be included.

[0046] In the embodiment of the present application, the inlet of the first air compressor 1 is connected with the atmosphere through the eighth control valve 23, the outlet of the first air compressor 1 is connected with the first channel inlet of the first heat exchanger 2, the first channel outlet of the first heat exchanger 2 is connected with the first inlet of the first air tank 3, the second outlet of the first air tank 3 is connected with the inlet of the second air compressor 8, the outlet of the second air compressor 8 is connected with the first channel inlet of the third heat exchanger 9, and the first channel outlet of the third heat exchanger 9 is connected with the inlet of the second air tank 10; the above connection relationship is used to complete the compression storage of the working medium.

[0047] In the embodiment of the present application, the outlet of the first cold storage tank 4 is connected with the second channel inlet of the first heat exchanger 2 through the second control valve 17, and the second channel outlet of the first heat exchanger 2 is connected with the inlet of the first heat storage tank 5; the above connection relationship is used to complete the storage of the heat of the first high-pressure waterway part.

[0048] In the embodiment of the present application, the outlet of the second cold storage tank 11 is connected with the second channel inlet of the third heat exchanger 9 through the fifth control valve 20, and the second channel outlet of the third heat exchanger 9 is connected with the inlet of the second heat storage tank 12; the above connection relationship is used to complete the storage of the heat of the second high-pressure waterway part.

[0049] In the embodiment of the present application, the outlet of the second gas storage tank 10 is connected with the second passage inlet of the fourth heat exchanger 13 through the seventh control valve 22, the second passage outlet of the fourth heat exchanger 13 is connected with the inlet of the second turbine 14, the outlet of the second turbine 14 is connected with the second inlet of the first gas storage tank 3 through the fourth control valve 19, the first outlet of the first gas storage tank 3 is connected with the second passage inlet of the second heat exchanger 6 through the first control valve 16, the second passage outlet of the second heat exchanger 6 is connected with the inlet of the first turbine 7, and the outlet of the first turbine 7 is connected with the atmosphere.

[0050] In the embodiment of the present application, the outlet of the second heat storage tank 12 is connected with the first passage inlet of the fourth heat exchanger 13 through the sixth control valve 21, and the first passage outlet of the fourth heat exchanger 13 is connected with the inlet of the second cold storage tank 11; illustratively, the above connection relationship is used to complete the release of energy of the normal-pressure water route part.

[0051] In the embodiment of the present application, the outlet of the first heat storage tank 5 is connected with the first passage inlet of the second heat exchanger 6 through the third control valve 18, and the first passage outlet of the second heat exchanger 6 is connected with the inlet of the first cold storage tank 4; illustratively, the above connection relationship is used to complete the release of energy of the high-pressure water route part.

[0052] Specifically, in view of the deficiencies of the existing compressed air energy storage technology, the embodiment of the present application specifically proposes a distributed power-adjustable two-stage compressed air energy storage system, which sets two-stage compressors with different operating modes to reduce the influence of high-pressure tank pressure change on the power of the energy storage process. In the energy storage process, the first compressor 1 maintains a constant pressure ratio and bears the basic energy storage load. The compressed air first enters the first gas storage tank for buffering, so that the compressed air can maintain the designed intermediate pressure to enter the second compressor 8. The second compressor 8 maintains a constant inlet pressure, and the outlet pressure gradually rises with the pressure in the second gas storage tank 10. In the process of outlet pressure change, the inlet guide vane angle and the rotating speed of the second compressor 8 are dynamically adjusted with the change of the pressure, so as to realize the basic stability of the flow and make the compressor achieve the best speed ratio. Correspondingly, in the energy release process, the first turbine 7 maintains a constant expansion ratio and bears the basic energy release load, and the second turbine 14 maintains a constant outlet pressure and the inlet pressure gradually decreases with the pressure in the second gas storage tank 10. In the process of inlet pressure change, the inlet guide vane angle and the rotating speed of the second turbine 14 are dynamically adjusted with the change of the pressure, so as to realize the basic stability of the flow and make the turbine achieve the best speed ratio.

[0053] In addition, the system provided by the embodiment of the present application is further provided with a set of small energy storage devices 15 connected with the second turbine 14, which realizes the function of "peak clipping and valley filling" when the load of the second turbine 14 changes, thereby guaranteeing the stability of the output power. Specifically, when the output power of the turbine is higher than the set value, the extra energy is stored in the small energy storage device, and when the output power is lower than the set value, the energy stored in the small energy storage device is released, so that the output power of the turbine reaches the set value, thereby realizing the stability and adjustability of the energy release power of the system.

[0054] In summary, the present application provides a distributed power adjustable two-stage compression air energy storage system, which can realize the basic stability of the flow in the energy storage and release process of the energy storage system, thereby guaranteeing the stable operation of the entire system under the design working condition; at the same time, the output power of the entire system can be adjusted by changing the setting of the intermediate pressure and the working range of the small energy storage device, which can effectively realize the storage and release of energy and reduce the user's electricity cost; further specific explanation, the advantages include: (1) the present application uses the staged operation of the first compressor, the first turbine, the second compressor and the second turbine, the first compressor and the first turbine operate at a constant speed and a constant pressure, and bear the basic load, the second compressor and the second turbine operate at a variable speed and a variable load, which effectively improves the energy storage and release efficiency of the system; the speed and the inlet guide vane of the second compressor and the second turbine can be adjusted according to the actual operation condition, when the pressure ratio changes, the basic stability of the flow can be realized by adjusting the guide vane angle, and the speed of the second compressor and the second turbine is adjusted to achieve the best speed ratio, thereby improving the stability of the system. (2) the present application is provided with a small energy storage device at the second turbine, which realizes the function of "peak clipping and valley filling" when the load of the second turbine changes, thereby guaranteeing the stability of the output power. Specifically, when the output power of the turbine is higher than the set value, the extra energy is stored in the small energy storage device, and when the output power is lower than the set value, the energy stored in the small energy storage device is released, so that the output power of the turbine reaches the set value, thereby realizing the stability and adjustability of the energy release power of the system. (3) the overall pressure level of the compressed air energy storage system of the present application is relatively low, by adopting the multi-stage compression and expansion mode, the pressure ratio and the expansion ratio of each stage are relatively small, therefore the volume of the system is small, and the distributed arrangement can be realized; (4) the utilization rate of the gas storage tank in the compressed air energy storage system of the present application is high, and the gas storage tank has no minimum pressure limit, only needs to meet the requirement of the ratio of the storage pressure between the intermediate pressure and the second gas storage tank, and can realize the application of a large range of pressure.

[0055] The operation method of the distributed power adjustable two-stage compression air energy storage system of the embodiment of the present application specifically includes the following steps:

[0056] In the initial state, all eight control valves are closed, and the first gas tank 3 and the second gas tank 10 store compressed air at a set medium storage pressure (for example, the target pressure in the second gas tank 10 is set to about 2 MPa, and the pressure in the first gas tank 3 is set to about 60% of the target pressure of the second gas tank 10) as the working medium;

[0057] When the user is in the off-peak period, the second control valve 17, the fifth control valve 20, and the eighth control valve 23 are closed, and the first control valve 16, the third control valve 18, the fourth control valve 19, the sixth control valve 21, and the seventh control valve 22 are opened; the energy release part starts to work; the compressed air in the second gas tank 10 enters the fourth heat exchanger 13 and exchanges heat with the normal pressure water from the second heat storage tank 12 to increase the temperature, and the compressed air after the temperature increase enters the second turbine 14 to expand and do work, driving the generator to generate electricity. Then, the compressed air expanded to the set pressure of the first gas tank enters the first gas tank 3, the compressed air in the first gas tank 3 enters the second heat exchanger 6 from the first outlet and exchanges heat with the high-pressure water from the first heat storage tank 5 to increase the temperature, and the compressed air after the temperature increase enters the first turbine 7 to expand and do work, driving the generator to generate electricity, and finally, the air expanded to normal temperature and pressure is discharged to the atmosphere; thus, the expansion and heat release of the working medium are completed.

[0058] When the user is in the off-peak period, the second control valve 17, the fifth control valve 20, and the eighth control valve 23 are closed, and the first control valve 16, the third control valve 18, the fourth control valve 19, the sixth control valve 21, and the seventh control valve 22 are opened; the energy release part starts to work; the compressed air in the second gas tank 10 enters the fourth heat exchanger 13 and exchanges heat with the normal pressure water from the second heat storage tank 12 to increase the temperature, and the compressed air after the temperature increase enters the second turbine 14 to expand and do work, driving the generator to generate electricity. Then, the compressed air expanded to the set pressure of the first gas tank enters the first gas tank 3, the compressed air in the first gas tank 3 enters the second heat exchanger 6 from the first outlet and exchanges heat with the high-pressure water from the first heat storage tank 5 to increase the temperature, and the compressed air after the temperature increase enters the first turbine 7 to expand and do work, driving the generator to generate electricity, and finally, the air expanded to normal temperature and pressure is discharged to the atmosphere; thus, the expansion and heat release of the working medium are completed.

[0059] In the embodiment of the present application, a storage device 15 is arranged in connection with the second turbine 14, and a set output power of the second turbine 14 is arranged, when the output power of the second turbine 14 is higher than the set value, the part of power exceeding the set value is stored in the storage device 15, with the proceeding of the energy releasing process, the output power of the second turbine 14 is reduced with the pressure reduction in the second gas tank 10, when the output power of the second turbine 14 is lower than the set value, at this time, the storage device 15 starts to release energy, and the stored power is output to the second turbine 14, so that the output power of the second turbine 14 reaches the set value, and the stability of the power output is realized.

[0060] In the embodiment of the present application, preferably, the first compressor 1 and the first turbine 7 are of fixed speed and fixed pressure operation, and respectively undertake the basic load of energy storage and energy release. The second compressor 8 and the second turbine 14 are of variable speed and variable load operation according to the pressure change in the second gas tank 10. When the pressure in the second gas tank 10 changes, the change of the inlet and outlet pressure ratio of the second compressor 8 and the second turbine 14 is caused, at this time, the basic stability of the flow is realized through adjusting the guide vane angle, and the second compressor and the second turbine reach the optimal speed ratio through adjusting the speed, so that the stability of the system operation is ensured.

[0061] The control method provided by the embodiment of the present application can realize:

[0062] In the valley of electricity use, the energy storage is used by the valley power, and the energy release is completed in the electricity peak, and the stability of the system power output is guaranteed by using the staged working mode of the first compressor, the first turbine and the second compressor, the second turbine. The specific working mode is as follows, in the energy storage process, the first compressor 1 keeps constant pressure ratio, bears the basic energy storage load, the compressed air first enters the first air tank 3 for buffering, so that the compressed air can maintain the designed intermediate pressure to enter the second compressor 8, the second compressor 8 keeps the inlet pressure constant, and the outlet pressure will gradually rise with the pressure in the second air tank 10, in the process of the change of the outlet pressure, the inlet guide vane angle and the rotating speed of the second compressor 8 are dynamically adjusted with the change of the pressure, so that the flow is basically stable and the compressor reaches the best speed ratio. Correspondingly, in the energy release process, the first turbine 7 keeps constant expansion ratio, bears the basic energy release load, the second turbine 14 keeps the outlet pressure constant, the inlet pressure gradually decreases with the pressure in the second air tank 10, in the process of the change of the inlet pressure, the inlet guide vane angle and the rotating speed of the second turbine 14 are dynamically adjusted with the change of the pressure, so that the flow is basically stable and the turbine reaches the best speed ratio, in addition, the system also adds a small energy storage device 15 connected with the second turbine 14, which realizes the function of “peak clipping and valley filling” when the load of the second turbine 14 changes, so as to guarantee the stability of the output power. The specific performance is that when the output power of the turbine is higher than the set value, the extra energy is stored in the small energy storage device, when the output power is lower than the set value, the energy stored in the small energy storage device will be released, so that the output power of the turbine reaches the set value. When the set value changes, the adjustable release power of the system can be realized. The technical scheme of the embodiment of the application uses high-pressure water to store the exhaust heat energy of the compressor, the pressure of the high-pressure water is set according to the pressure of the first air tank, so as to guarantee that the heat storage medium does not produce vaporization phenomenon in the system running process, and the waste of heat is avoided.

[0063] Specifically, the maximum pressure in the second air tank in the application can reach about 4MPa, the pressure in the first air tank is determined according to the pressure of the second air tank, and in actual operation, only the pressure ratio between the medium-pressure air tank and the high-pressure air tank needs to be maintained at about 2:5, so that the storage pressure can be regulated in a large range. For example, when the compressed air pressure in the first air tank 3 is maintained at about 0.8MPa, the maximum pressure stored in the second air tank 10 can reach about 2MPa, at this time, the tank utilization rate of the system in the application can reach about 60%; and the minimum storage pressure of the cave used in the traditional compressed air energy storage system is usually 4.2MPa, and the maximum storage pressure is 7.2MPa, and the cave utilization rate is only 41.64%.

[0064] Specifically, the exhaust heat energy of the second compressor is stored by using normal pressure water, and the exhaust heat energy of the first compressor is stored by using high pressure water. The pressure of the high pressure water is determined by the storage pressure set by the first gas tank. For example, when the first gas tank of the system of the present application is set at a pressure of 0.8 MPa, and the pressure of the high pressure water is set at 8.86 MPa, no vaporization phenomenon occurs during the operation of the system, thereby improving the utilization rate of the heat of the entire system.

[0065] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that: the specific embodiments of the present application can still be modified or replaced by the equivalent, without departing from the spirit and scope of the present application, any modification or equivalent replacement, which should be covered within the protection scope of the claims of the present application.

Claims

1. A distributed power adjustable two-stage compressed air energy storage system, characterized in that, It comprises: The first compressor (1), the first heat exchanger (2), the first gas tank (3), the second heat exchanger (6), the first turbine (7), the second compressor (8), the third heat exchanger (9), the second gas tank (10), the fourth heat exchanger (13) and the second turbine (14); The outlet of the first compressor (1) is connected with the first inlet of the first gas tank (3) through the first heat exchange channel of the first heat exchanger (2), and the first outlet of the first gas tank (3) is connected with the inlet of the first turbine (7) through the second heat exchange channel of the second heat exchanger (6); The second outlet of the first gas tank (3) is connected with the inlet of the second compressor (8), the outlet of the second compressor (8) is connected with the inlet of the second gas tank (10) through the first heat exchange channel of the third heat exchanger (9), the outlet of the second gas tank (10) is connected with the inlet of the second turbine (14) through the second heat exchange channel of the fourth heat exchanger (13), and the outlet of the second turbine (14) is connected with the second inlet of the first gas tank (3); It further comprises an energy storage device (15), wherein the energy storage device (15) is connected with the second turbine (14) and is used for realizing the function of peak shaving when the load of the second turbine (14) changes; In the energy storage process, the first compressor (1) is used for keeping constant pressure ratio, the second compressor (8) is used for keeping constant inlet pressure, the outlet pressure gradually rises with the pressure in the second gas tank (10), and the inlet guide vane angle and the rotating speed of the second compressor (8) are dynamically adjusted with the change of the pressure in the process of the change of the outlet pressure; in the energy release process, the first turbine (7) is used for keeping constant expansion ratio, the second turbine (14) is used for keeping constant outlet pressure, the inlet pressure gradually decreases with the pressure in the second gas tank (10), and the inlet guide vane angle and the rotating speed of the second turbine (14) are dynamically adjusted with the change of the pressure in the process of the change of the inlet pressure; In the process of dynamic adjustment when the outlet pressure changes or the inlet pressure changes, the flow stability is realized by adjusting the guide vane angle, and the optimal speed ratio is achieved by adjusting the rotating speed.

2. The distributed power-adjustable two-stage compression air energy storage system according to claim 1, wherein The inlet of the first compressor (1) is connected with the atmosphere; The outlet of the first turbine (7) is connected with the atmosphere.

3. A distributed power adjustable two-stage compressed air energy storage system according to claim 1, wherein, It further comprises: The first cold storage tank (4) and the first heat storage tank (5), wherein The outlet of the first cold storage tank (4) is connected with the inlet of the first heat storage tank (5) through the second heat exchange channel of the first heat exchanger (2), and the outlet of the first heat storage tank (5) is connected with the inlet of the first cold storage tank (4) through the first heat exchange channel of the second heat exchanger (6).

4. A distributed power adjustable two-stage compressed air energy storage system according to claim 3, wherein, It further comprises: The second control valve (17) and the third control valve (18), wherein The second control valve (17) is arranged in the communication pipeline between the first cold storage tank (4) and the first heat exchanger (2); and the third control valve (18) is arranged in the communication pipeline between the first heat storage tank (5) and the second heat exchanger (6).

5. A distributed power adjustable two-stage compressed air energy storage system in accordance with claim 1, wherein, Further comprising: The second cold storage tank (11) and the second heat storage tank (12); wherein The outlet of the second cold storage tank (11) is communicated with the inlet of the second heat storage tank (12) through the second heat exchange channel of the third heat exchanger (9), and the outlet of the second heat storage tank (12) is communicated with the inlet of the second cold storage tank (11) through the first heat exchange channel of the fourth heat exchanger (13).

6. A distributed power adjustable two-stage compressed air energy storage system according to claim 5, wherein, Further comprising: The fifth control valve (20) and the sixth control valve (21); wherein The fifth control valve (20) is arranged in the communication pipeline between the third heat exchanger (9) and the second cold storage tank (11); and the sixth control valve (21) is arranged in the communication pipeline between the second heat storage tank (12) and the fourth heat exchanger (13).

7. A distributed power adjustable two-stage compressed air energy storage system according to claim 1, characterized in that, Further comprising: The first control valve (16), the fourth control valve (19), the seventh control valve (22) and the eighth control valve (23); wherein The first control valve (16) is arranged in the communication pipeline between the first gas storage tank (3) and the second heat exchanger (6); the fourth control valve (19) is arranged in the communication pipeline between the first gas storage tank (3) and the second turbine (14); the seventh control valve (22) is arranged in the communication pipeline between the second gas storage tank (10) and the fourth heat exchanger (13); and the eighth control valve (23) is arranged at the inlet of the first compressor (1).

8. A method of operating the distributed power adjustable two-stage compressed air energy storage system of claim 1, characterized in that, Comprising the following steps: Pre-storing compressed air with a preset storage pressure in the first gas storage tank (3) and the second gas storage tank (10) as working medium; When the user is in the off-peak period, energy storage is performed, including: the electric power drives the first compressor (1) to compress the air at normal temperature and pressure, the compressed air enters the first heat exchanger (2) to exchange heat and cool, the cooled air enters the first gas storage tank (3); the compressed air in the first gas storage tank (3) maintains a preset storage pressure; with the continuous entry of the compressed air, the excess compressed air enters the second compressor (8) for compression, the compressed air enters the third heat exchanger (9) for heat exchange and cooling, and the cooled compressed air is stored in the second gas storage tank (10), thus completing the compression and heat storage of the working medium; wherein, in the energy storage process, the first compressor (1) is used to maintain a constant pressure ratio; the second compressor (8) is used to maintain a constant pressure at the inlet, and the outlet pressure gradually rises with the pressure in the second gas storage tank (10), and the inlet guide vane angle and the rotating speed of the second compressor (8) are dynamically adjusted with the change of the pressure in the process of the outlet pressure change. When the user is in the power peak, the energy is released, including: compressed air in the second gas tank (10) into the fourth heat exchanger (13) heat up, the compressed air after heating into the second turbine (14) expansion work, for driving generator power generation, and then expand to the first gas tank (3) preset pressure compressed air into the first gas tank (3), the compressed air in the first gas tank (3) from the first outlet into the second heat exchanger (6) heat up, the compressed air after heating into the first turbine (7) expansion work, driving generator power generation, and finally expand to the normal temperature and pressure air is discharged to the atmosphere, thus completing the expansion of working medium and heat release; wherein, in the process of energy release, the first turbine (7) is used to keep constant expansion ratio; the second turbine (14) is used to keep the outlet pressure constant, the inlet pressure gradually decreases with the pressure in the second gas tank (10), the inlet guide vane angle and the speed of the second turbine (14) are dynamically adjusted with the change of pressure in the process of inlet pressure change.

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