Gas storage device, pumped storage system using gas storage device and control method

Abstract

The invention provides a gas storage device, a pumped storage system using the gas storage device and a control method. The gas storage device comprises multiple stages of gas storage spaces connected through pressure increasing valves. Water and gas are stored in the first-stage gas storage space located at the bottommost end of the gas storage space; the first-stage gas storage space comprises a water conveying pipeline which is used for conveying water into the gas storage space so as to compress gas in the gas storage space; the system uses compressed gas in a gas storage device as a compensation water head; the control method comprises the steps that during charging, water in a lower reservoir is input into a first-stage gas storage space, gas in the gas storage space is compressed, and when the pressure intensity of the compressed gas reaches a preset value, a pressure increasing valve is closed; during power generation, the compressed gas in the first-stage gas storage space applies pressure to water in the upper reservoir, and when the pressure intensity of the gas in the first-stage gas storage space is smaller than a preset value, the pressure increasing valve is opened. By means of the technical scheme, the compressed gas compensation water head can be used for building a high-efficiency large-scale energy storage power station.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage, and in particular to a gas storage device, a pumped storage system using the gas storage device, and a control method. Background Art

[0002] In recent years, the energy crisis and climate problems around the world have become increasingly serious. New energy combined with energy storage is a powerful way to solve the above two problems. With the large-scale access of new energy to the power grid, the demand for large-scale energy storage in the power system is increasing. Pumped storage and compressed air energy storage can be used as large-scale energy storage technologies to a certain extent, but pumped storage has too high requirements for terrain and extremely limited site selection flexibility. Some hilly areas lack terrain that can be used to build pumped storage; although compressed air energy storage is more flexible in site selection, during the power generation process, the gas storage reservoir has a very large sliding pressure range and the turbine operates under variable conditions, resulting in low efficiency of the electric-electric cycle. Summary of the invention

[0003] The embodiments of the present invention provide a gas storage device, a pumped storage system using the gas storage device, and a control method, so as to construct a large-scale energy storage power station with higher efficiency by using compressed gas such as air to compensate for the water head.

[0004] In order to achieve the above object, on the one hand, a gas storage device is provided, comprising:

[0005] A multi-stage closed flexible gas storage space connected by a booster valve, wherein the outer wall of the flexible gas storage space is a flexible wall;

[0006] Among them, the first-level flexible gas storage space located at the bottom of the multi-level flexible gas storage space stores water and gas, and the flexible gas storage spaces of other levels store gas. The first-level flexible gas storage space includes a first water pipeline, and the first water pipeline is used to input water into the first-level flexible gas storage space to compress the gas in the first-level flexible gas storage space.

[0007] Preferably, in the gas storage device, the flexible gas storage space comprises: an air bag.

[0008] Preferably, in the gas storage device, the water stored in the first-stage flexible gas storage space is used as an upper reservoir for pumped storage.

[0009] Preferably, in the gas storage device, the gas in each level of the multi-level flexible gas storage space has equal pressure.

[0010] Preferably, in the gas storage device, the gas includes: air or carbon dioxide.

[0011] Preferably, the gas storage device further comprises:

[0012] A pressure detector is arranged in the first-level flexible gas storage space, and is used to detect the pressure of the gas in the first-level flexible gas storage space; wherein, when the pressure of the gas in the first-level flexible gas storage space is less than a predetermined pressure value, the boosting valve is opened so that the gas in one or more of the other flexible gas storage spaces except the first-level flexible gas storage space is pressurized and mixed with the gas in the first-level flexible gas storage space; when the pressure of the gas in the first-level flexible gas storage space reaches the predetermined pressure value, the boosting valve is closed.

[0013] On the other hand, a pumped storage system is provided, comprising: an upper reservoir and a lower reservoir, characterized in that compressed gas stored in a gas storage device as described in any of the above texts is used as a compensation head for pumped storage, the position of the first-level flexible gas storage space is higher than the lower reservoir, the water stored in the first-level flexible gas storage space is used as an upper reservoir for pumped storage, and the first-level flexible gas storage space is connected to the lower reservoir via the first water transmission pipeline.

[0014] Preferably, the pumped storage system further comprises:

[0015] The water pump and the water turbine arranged between the lower reservoir and the first water delivery pipeline are used to deliver water to the upper reservoir.

[0016] On the other hand, a control method of a pumped storage system is provided, for controlling the pumped storage system as described above, comprising:

[0017] During charging, water in the lower reservoir is input into the first-stage flexible gas storage space in the gas storage device through the first water pipeline, and the gas in each stage of the flexible gas storage space is compressed by the input water. When the pressure of the compressed gas reaches a predetermined first pressure value, the booster valves between the various stages of the flexible gas storage space are closed, and charging is terminated.

[0018] During power generation, the compressed gas in the first-level flexible gas storage space applies pressure to the water in the upper reservoir. When the pressure of the gas in the first-level flexible gas storage space is less than the predetermined second pressure value, the booster valves between the flexible gas storage spaces of each level are opened, so that the gas in one or more flexible gas storage spaces other than the first-level flexible gas storage space is pressurized and mixed with the gas in the first-level flexible gas storage space.

[0019] Preferably, in the control method, the first pressure value is greater than or equal to the second pressure value.

[0020] Preferably, in the control method, the first pressure value is equal to the gas pressure value in the airbag with the highest pressure in the multi-stage flexible air storage space.

[0021] Preferably, the control method further comprises: before the first charging, pre-inflating the multi-stage flexible gas storage space according to the energy storage scale of the pumped storage system.

[0022] The above technical solution has the following technical effects:

[0023] The technical solution of the embodiment of the present invention uses multi-stage air bags connected by boosting valves to store compressed gas such as compressed air used to compensate for water head. When releasing energy, the compressed gas such as compressed air in the multi-stage air bags is mixed to apply pressure to the upper reservoir, thereby achieving a higher power density, so that the sliding pressure of the gas storage device will not be too large during power generation, thereby providing an effective way to use compressed gas such as air to compensate for water head. In hilly areas with small altitude differences, a compressed gas such as compressed air energy storage power station with a higher equivalent water head coupled with pumped storage can be built. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of a pumped storage system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0026] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0027] Embodiment 1:

[0028] Figure 1 It is a schematic diagram of the structure of a pumped storage system according to an embodiment of the present invention. The pumped storage system according to this embodiment uses compressed gas stored in a gas storage device including multiple flexible gas storage spaces as a compensation head for pumped storage. In the gas storage device, multiple stages of closed flexible gas storage spaces are connected by a booster valve, and the outer wall of the flexible gas storage space is a flexible wall. The pressure of the gas in each stage of the airbag is equal or approximately equal. In a specific implementation, the approximate equality of the pressure of the gas in each stage of the gas storage space means that the pressure difference between the gas in each stage of the gas storage space is less than a predetermined threshold value to indicate. The threshold value is a predetermined smaller value.

[0029] In a specific implementation, the flexible gas storage space is an air bag. Preferably, the valve is a booster valve. When the booster valve in the upper gas storage space is opened, the gas in its own space is pressurized and pressed downward into the connected lower gas storage space. In a specific implementation, the gas includes: air or carbon dioxide or other selected gas.

[0030] like Figure 1 In this example, the gas storage device includes three levels of gas storage space: a first-level gas storage space, a second-level gas storage space, and a third-level gas storage space; the first-level gas storage space is located at the bottom and is the lowest level of gas storage space. The first-level gas storage space stores water and gas, and the water stored is usually a large volume of water, which is used as an upper reservoir, that is, it contains the upper reservoir in the first-level gas storage space, and the position of the first-level gas storage space is higher than the lower reservoir. The flexible gas storage space of other levels stores gas. The volume of the flexible gas storage space is usually very large, for example, it can be a large-capacity air bag. The first-level gas storage space includes a first water pipeline, which is used to input water from the lower reservoir to the first-level gas storage space, and the input water is used to compress the gas in the first gas storage space. In a specific implementation, when charging, water is transported to the above-mentioned upper reservoir by a water pump and a turbine arranged between the lower reservoir and the first water pipeline. In other implementations, the number of levels of the gas storage space can be two or more than three.

[0031] In a specific implementation, the gas storage device further includes: a pressure detector, which is arranged in the first-stage flexible gas storage space, and is used to detect the pressure of the gas in the first-stage flexible gas storage space; wherein, when the pressure of the gas in the first-stage flexible gas storage space is less than a predetermined pressure value, the boost valve is opened, and the gas in each stage of the gas storage space is mixed; when the pressure of the gas in the first-stage flexible gas storage space reaches a predetermined pressure value, the opened boost valve is closed. In a specific implementation, the boost valves between all stages of the gas storage space can be opened, or the boost valves between several gas storage spaces can be selectively opened.

[0032] In a specific implementation, a pressure detector is provided in the portion of the gas storage space that is in direct contact with the upper reservoir. Preferably, when the pressure of the gas in the first-stage flexible gas storage space is less than a predetermined pressure value, the booster valve is opened, and the gas in the next-stage gas storage space, such as air, is compressed into the first-stage gas storage space after a certain pressure increase, so that the pressure of the gas, such as air, above the water surface of the upper reservoir can be reduced as little as possible, that is, the original pressure can be maintained as much as possible.

[0033] Specifically, when the interstage valve is opened, the air in the adjacent two-stage air storage space will mix. Because the air in the closed space comes into contact with a large volume of water, it is considered to be an isothermal process. Therefore, the following formula can be used to express the pressure change of the compressed air before and after mixing:

[0034] pV=pi V i +(p i+1 +p0)V i+1

[0035] Among them, p, p i , p o+1 are the compressed air pressure after mixing, the compressed air pressure in the first-stage air storage space before mixing, and the compressed air pressure in the first-stage air storage space before and after mixing, respectively; V, V i , V i+1 are the volume of compressed air after mixing, the volume of compressed air in the first-stage air storage space before mixing, and the volume of compressed air in the first-stage air storage space before and after mixing; p0 is the air pressure that the boost valve can add to the air in the second-stage air storage space. This example uses air as an example for explanation. In other implementations, other gases can be used, which will not be repeated here.

[0036] like Figure 1 In the pumped storage system of this embodiment, the above-mentioned air storage device, i.e., the air storage reservoir, is used as a compensating head device for pumped storage, and a water pump and a water turbine are arranged between the lower reservoir and the first water transmission pipeline, i.e., the water diversion pipeline, to construct a pumped storage structure capable of storing and releasing energy, and compressed air provides a compensating head above the upper reservoir.

[0037] Generally, the water head in a pumped storage power station is the water level difference between the upper and lower reservoirs. However, in terrain without a high water level difference, the water storage density is small, the upper and lower reservoirs required to build a storage power station are large, the construction cost is high, and the construction period is long. Therefore, using compressed air to compensate for the water head is a possible effective way. After compensation, the calculation method of the equivalent water head is described by the following formula:

[0038]

[0039] Among them, h eq , h0 is the equivalent head and the actual geographical location, i.e., the head provided by the height difference between the upper and lower reservoirs; p is the pressure of the compressed gas in direct contact with the upper reservoir, such as compressed air; ρ is the density of water, generally 1 g cm -3 ; g is the acceleration due to gravity, usually 9.8N·kg -1 .

[0040] Embodiment 2:

[0041] The present invention provides a control method for a pumped storage system, which is used to control the operation of the pumped storage system as described above, and the control method comprises:

[0042] During charging, water from the lower reservoir is input into the first-stage flexible gas storage space in the gas storage device through the first water pipeline, and the gas in each stage of the flexible gas storage space is compressed by the input water. When the pressure of the compressed gas reaches a predetermined pressure value, the booster valves between the various stages of the flexible gas storage space are closed; at this time, the various stages of the flexible gas storage space are independent of each other, and the gas between them is not mixed;

[0043] During power generation, the compressed air in the first-stage flexible gas storage space applies pressure to the water in the upper reservoir. When the pressure of the air in the first-stage flexible gas storage space is less than a predetermined pressure value, the booster valves between the various levels of flexible gas storage space are opened, so that the gas in one or more flexible gas storage spaces other than the first-stage flexible gas storage space is pressurized and mixed with the gas in the first-stage flexible gas storage space. When the booster valve is opened, the gas in the higher-level gas storage space is pressurized and then pressed into the previous-level gas storage space, so that the gas pressure in contact with the upper reservoir hardly changes when releasing energy.

[0044] Specifically:

[0045] Using compressed air for compensation can reduce the required volume of the upper and lower reservoirs to a certain extent, but the pressure of the compressed air will drop rapidly as the water leaves quickly during power generation. This will cause the turbine to quickly move away from the rated working point, so the embodiment of the present invention proposes a flexible compensation method using a multi-stage airbag. During charging, the water pump pumps water into the gas storage reservoir, and the air in the gas storage reservoir is compressed; after being compressed to a certain degree, the valve between the stages is closed. During power generation, the high-pressure air in the first-stage gas storage space applies pressure to the upper reservoir to compensate for the water head to achieve a higher power density; after releasing energy to a certain degree, the valve between the stages is opened, and the compressed air in the higher-level gas storage space is mixed with the air in the previous stages of the gas storage space, so that the air pressure changes only within a small range. In a specific implementation, whether to close the valve, i.e., the valve of the booster valve, is determined by detecting whether the air pressure in the first-stage gas storage space reaches a predetermined pressure value; if the predetermined pressure value is reached, the valve is closed. In a specific implementation, the above-mentioned control of the valve is implemented through the corresponding control system of the power station.

[0046] Preferably, before the first charging, the multi-stage flexible gas storage space is pre-inflated according to the energy storage scale of the pumped storage system.

[0047] In a specific implementation, the pumped storage system of an embodiment of the present invention includes four working modes: pre-charging, charging, discharging and static. During pre-charging, a compressor is used to inflate the multi-stage airbags, and the quality of the inflated gas depends on the scale of the power station. It is worth noting that pre-charging is only required after each power station shutdown for maintenance, and does not require pre-charging in each cycle. That is, preferably, no air replenishment is required during the charge and discharge cycle. During charging, the water pump pumps water into the gas storage reservoir, and the gas in the gas storage space is compressed; when the air pressure of the compressed gas reaches the air pressure p2 in the airbag with the highest air pressure in the multi-stage airbag, the valve is closed and the charging ends. Among them, the air pressure p2 in the airbag with the highest air pressure is usually greater than the predetermined pressure value p1. During power generation, in the first stage, i.e., the initial stage, the air pressure of the multi-stage airbags is p2. At this time, the equivalent water head of the air storage device is greater than the equivalent water head required by the predetermined design. After a certain period of power generation, the second stage is reached. At this time, the air pressure in the first-stage air storage space, such as the first-stage airbag, reaches a predetermined pressure value p1, and the entire system begins to generate power stably; the high-pressure air in the first-stage air storage space applies pressure to the upper reservoir to compensate for the water head to achieve a higher power density; after releasing energy to a certain extent, the valve between the stages is opened, and the compressed air in the higher-level air storage space is mixed with the air in the previous stages of the air storage space, so that the air pressure in the first-stage air storage space changes only within a small range. Specifically, as power generation proceeds, the air pressure in the first-stage air storage space may be lower than p1. At this time, using the control method of the embodiment of the present invention, the valves of the multi-stage air storage space are opened, and the gas with a higher air pressure flows from the higher-level air storage space to the first-stage air storage space, so that the pressure applied to the upper reservoir in the first-stage air storage space is basically maintained at p1. In a static state, the energy storage of the pumped storage system does not change.

[0048] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A gas storage device, characterized in that: include: A multi-stage closed flexible gas storage space connected by a booster valve, wherein the outer wall of the flexible gas storage space is a flexible wall; Among them, the first-level flexible gas storage space located at the bottom of the multi-level flexible gas storage space stores water and gas, and the flexible gas storage spaces of other levels store gas. The first-level flexible gas storage space includes a first water pipeline, and the first water pipeline is used to input water into the first-level flexible gas storage space to compress the gas in the first-level flexible gas storage space.

2. The gas storage device according to claim 1, characterized in that: The flexible air storage space includes an air bag.

3. The gas storage device according to claim 1, characterized in that: The water stored in the first-level flexible gas storage space is used as an upper reservoir for pumped storage.

4. The gas storage device according to claim 1, characterized in that: The gases in the multi-stage flexible gas storage spaces have equal pressure.

5. The gas storage device according to claim 1, characterized in that: The gas includes: air or carbon dioxide.

6. The gas storage device according to claim 1, characterized in that: Also includes: A pressure detector is arranged in the first-level flexible gas storage space, and is used to detect the pressure of the gas in the first-level flexible gas storage space; wherein, when the pressure of the gas in the first-level flexible gas storage space is less than a predetermined pressure value, the boosting valve is opened so that the gas in one or more of the other flexible gas storage spaces except the first-level flexible gas storage space is pressurized and mixed with the gas in the first-level flexible gas storage space; when the pressure of the gas in the first-level flexible gas storage space reaches the predetermined pressure value, the boosting valve is closed.

7. A pumped storage system comprising: The upper reservoir and the lower reservoir are characterized in that the compressed gas stored in the gas storage device as described in any one of claims 1 to 6 is used as the compensation head for pumped storage, the position of the first-level flexible gas storage space is higher than the lower reservoir, the water stored in the first-level flexible gas storage space is used as the upper reservoir for pumped storage, and the first-level flexible gas storage space is connected to the lower reservoir through the first water supply pipeline.

8. The pumped storage system according to claim 7, characterized in that: Also includes: The water pump and the water turbine arranged between the lower reservoir and the first water delivery pipeline are used to deliver water to the upper reservoir.

9. A control method for a pumped storage system, used for controlling the pumped storage system according to claim 7 or 8, characterized in that: include: During charging, water in the lower reservoir is input into the first-stage flexible gas storage space in the gas storage device through the first water pipeline, and the gas in each stage of the flexible gas storage space is compressed by the input water. When the pressure of the compressed gas reaches a predetermined first pressure value, the booster valves between the various stages of the flexible gas storage space are closed, and charging is terminated. During power generation, the compressed gas in the first-level flexible gas storage space applies pressure to the water in the upper reservoir. When the pressure of the gas in the first-level flexible gas storage space is less than the predetermined second pressure value, the booster valves between the flexible gas storage spaces of each level are opened, so that the gas in one or more flexible gas storage spaces other than the first-level flexible gas storage space is pressurized and mixed with the gas in the first-level flexible gas storage space.

10. The control method according to claim 9, characterized in that: The first pressure value is greater than or equal to the second pressure value.

Images