Pumping storage energy storage power generation system and method
By setting up a pressure regulation device and using nanofluid media in the pumped storage power generation system, the problem of low start-up efficiency was solved, enabling rapid start-up and efficient power generation, and improving the system's flexibility and economy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 国网电力工程研究院有限公司
- Filing Date
- 2025-12-09
- Publication Date
- 2026-04-24
AI Technical Summary
Existing pumped storage power generation systems have low start-up efficiency, weak rapid start-up capability, and poor operational flexibility, and urgently need to be improved.
By setting up a first sealed medium reservoir and a second sealed medium reservoir in the pumped storage power generation system, and using a pressure regulating device to adjust the gas pressure difference, the pumped storage medium is accelerated to flow. Combined with nanofluid as the pumped storage medium, the flow velocity and power generation efficiency are improved.
It significantly improves the start-up efficiency and operational stability of pumped storage power generation systems, enabling rapid start-up and efficient power generation, simplifying system structure, and reducing equipment costs and floor space.
Smart Images
Figure CN121916111A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of pumped storage power generation technology, and in particular to a pumped storage energy storage power generation system and method. Background Technology
[0002] Pumped storage power generation systems can store clean energy such as wind power, hydropower and solar power. It is the most mature and widely used choice among many energy storage technologies. Its energy storage round-trip efficiency can reach 70% to 85%, and it has good stability and economic benefits in large-scale energy storage.
[0003] However, the current pumped storage power generation system needs to overcome the inertia of the pumped storage medium and establish a stable fluid state to start up. It takes several minutes to more than ten minutes for the unit to go from startup to full load operation. The rapid startup capability is weak and the operation flexibility is poor. There is an urgent need to improve the startup efficiency of the pumped storage power generation system. Summary of the Invention
[0004] In view of this, the present invention provides a pumped storage energy power generation system and method to solve or partially solve the technical problem of low start-up efficiency of pumped storage energy power generation systems.
[0005] The technical solution proposed in this invention is as follows: In a first aspect, the present invention provides a pumped storage energy generation system, comprising: The first sealed medium reservoir is used to hold the pumped medium; The second sealed medium reservoir is used to contain pumped storage medium and is connected to the first sealed medium reservoir through a medium channel. A water turbine is installed on the medium channel. The height of the first sealed medium reservoir is greater than the height of the second sealed medium reservoir. A pressure regulating device is used to adjust the gas pressure of the first sealed medium reservoir and / or the second sealed medium reservoir. When the pumped storage power generation system generates electricity, the turbine uses the kinetic energy of the pumped storage medium flowing from the first sealed medium reservoir to the second sealed medium reservoir to generate electricity. The pressure regulating device adjusts the gas pressure of the first sealed medium reservoir to be greater than the gas pressure of the second sealed medium reservoir.
[0006] According to the pumped storage energy storage power generation system of the present invention, when the pumped storage energy storage power generation system generates electricity, the pumped storage medium flows from the first sealed medium reservoir to the second sealed medium reservoir through the medium channel under the action of gravity. The gas pressure of the first sealed medium reservoir is adjusted to be greater than that of the second sealed medium reservoir by the pressure regulating device. The gas pressure is used to accelerate the flow of the pumped storage medium downward along the medium channel, which can overcome the inertial resistance of the pumped storage medium, rapidly increase the flow velocity of the pumped storage medium, and effectively improve the power generation start-up efficiency.
[0007] In some alternative embodiments, the pressure regulating device includes a first pressure regulating module, which is connected to a first sealing medium reservoir for evacuating and blowing air into the first sealing medium reservoir.
[0008] According to the pumped storage energy storage power generation system of the present invention, the gas pressure of the first sealed medium reservoir can be more precisely adjusted by regulating the gas transport gas of the first pressure regulating module, thereby better controlling the flow of the pumped storage medium and the power generation process, and improving the stability of the system.
[0009] In some alternative embodiments, the pressure regulating device includes a second pressure regulating module connected to a second sealing medium reservoir for evacuating and blowing air into the second sealing medium reservoir.
[0010] According to an embodiment of the present invention, the pumped storage power generation system is connected to a second sealed medium reservoir via a second pressure regulating module, which can pump and blow gas into the reservoir. This allows for independent adjustment of the gas pressure in the second sealed medium reservoir. In conjunction with the first pressure regulating module, the system can more flexibly and precisely control the pressure difference between the first and second sealed medium reservoirs, further optimizing the flow of the pumped storage medium and the power generation effect.
[0011] In some alternative embodiments, the first sealed medium reservoir and / or the second sealed medium reservoir includes a tank and a lid, which are detachably connected.
[0012] The pumped storage energy generation system according to embodiments of the present invention facilitates the installation, maintenance, repair, and internal cleaning of the sealed medium reservoir. When it is necessary to inspect or replace internal components or clean residual pumped storage medium, the cover can be easily disassembled.
[0013] In some alternative implementations, the pumping medium is a nanofluid.
[0014] The pumped storage power generation system according to an embodiment of the present invention uses nanofluid as the pumping medium, which has a significantly increased density compared to water as the pumping medium. It has good inertial characteristics and fluid properties, which helps to improve the power generation efficiency of the pumping medium.
[0015] In some alternative embodiments, the nanofluid is a nanofluid comprising an iron-nickel alloy material.
[0016] In some alternative implementations, the turbine is a reversible turbine.
[0017] According to the pumped storage power generation system of the present invention, the reversible turbine can generate electricity and drive operation using electrical energy during off-peak hours to pump the pumped storage medium in the second sealed medium reservoir to the first sealed medium reservoir, converting electrical energy into the gravitational potential energy of the pumped storage medium. This achieves multiple uses in one machine, simplifies the system structure, and reduces equipment costs and floor space.
[0018] In a second aspect, the present invention provides a pumped-storage energy storage power generation method, applied to a pumped-storage energy storage power generation system as described in any of the first aspects of the present invention, comprising: Obtain the operating mode of the pumped storage power generation system; When the operating mode is power generation mode, the turbine is controlled to generate electricity using the kinetic energy of the pumped storage medium flowing from the first sealed medium reservoir to the second sealed medium reservoir, and the gas pressure in the first sealed medium reservoir is controlled to be greater than the gas pressure in the second sealed medium reservoir.
[0019] According to the pumped storage energy storage power generation method of the present invention, when the pumped storage energy storage power generation system is in power generation mode, the gas pressure of the first sealed medium reservoir is controlled to be greater than the gas pressure of the second sealed medium reservoir, so as to accelerate the flow of the pumped storage medium downward along the medium channel and improve the power generation start-up efficiency.
[0020] In some alternative implementations, after obtaining the operating mode of the pumped storage power generation system, the following steps are included: When the operating mode is energy storage mode, the turbine is controlled to consume electrical energy to transport the pumped storage medium from the second sealed medium reservoir to the first sealed medium reservoir, and the gas pressure in the first sealed medium reservoir is controlled to be lower than the gas pressure in the second sealed medium reservoir.
[0021] According to the pumped storage energy storage power generation method of the present invention, when the pumped storage energy storage power generation system is in the energy storage mode, the pumped storage medium is accelerated to be transported upward along the medium channel to the first sealed medium reservoir, thereby improving the energy storage efficiency of the pumped storage medium.
[0022] In some alternative embodiments, controlling the gas pressure of the first sealed medium reservoir to be greater than the gas pressure of the second sealed medium reservoir includes: The first pressure regulating module is controlled to blow gas into the first sealing medium reservoir to increase the gas pressure of the first sealing medium reservoir, and the second pressure regulating module is controlled to extract gas from the second sealing medium reservoir to decrease the gas pressure of the second sealing medium reservoir. And / or, controlling the gas pressure of the first sealed medium reservoir to be less than the gas pressure of the second sealed medium reservoir includes: The second pressure regulating module is controlled to blow gas into the second sealing medium reservoir, increasing the gas pressure in the second sealing medium reservoir; the first pressure regulating module is controlled to extract gas from the first sealing medium reservoir, decreasing the gas pressure in the first sealing medium reservoir.
[0023] According to the pumped storage energy storage power generation method of the present invention, by controlling the first pressure regulating module and the second pressure regulating module to blow in or extract gas from the corresponding sealed medium reservoirs, the pressure difference between the two sealed medium reservoirs can be precisely adjusted, thereby better controlling the flow direction and speed of the pumped storage medium, and ensuring that the system can operate efficiently and stably in both power generation and energy storage modes. Attached Figure Description
[0024] 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 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.
[0025] Figure 1 This is a schematic diagram of the pumped storage power generation system in an embodiment of the present invention; Figure 2 This is a schematic flowchart of a pumped storage energy generation method according to an embodiment of the present invention; Figure 3 This is a schematic flowchart of another pumped storage energy generation method in an embodiment of the present invention.
[0026] Figure label: 1. First sealing medium reservoir; 2. Second sealing medium reservoir; 3. Pumped storage medium; 4. Medium channel; 5. Water turbine; 6. First pressure regulating module; 7. Second pressure regulating module. Detailed Implementation
[0027] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0028] In the description of this invention, it should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible embodiments.
[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0030] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0031] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.
[0032] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0033] like Figure 1 As shown, an embodiment of the present invention provides a pumped storage energy generation system, comprising: The first sealed medium reservoir 1 is used to contain the pumped medium 3; The second sealed medium reservoir 2 is used to contain the pumped medium 3 and is connected to the first sealed medium reservoir 1 through the medium channel 4. A water turbine 5 is installed on the medium channel 4. The height of the first sealed medium reservoir 1 is greater than the height of the second sealed medium reservoir 2. The pressure regulating device is used to adjust the gas pressure of the first sealed medium reservoir 1 and / or the second sealed medium reservoir 2. When the pumped storage power generation system generates electricity, the turbine 5 uses the kinetic energy of the pumped storage medium 3 flowing from the first sealed medium reservoir 1 to the second sealed medium reservoir 2 to generate electricity. The pressure regulating device adjusts the gas pressure of the first sealed medium reservoir 1 to be greater than the gas pressure of the second sealed medium reservoir 2.
[0034] Specifically, both the first sealed medium reservoir 1 and the second sealed medium reservoir 2 are closed containers that contain the pumped medium 3, and have a certain degree of sealing to prevent leakage of the pumped medium 3. There is a certain height difference between the first sealed medium reservoir 1 and the second sealed medium reservoir 2, which realizes the conversion of the gravitational potential energy of the pumped medium 3 into the kinetic energy of the pumped medium 3, and then into electrical energy through the turbine 5.
[0035] In a preferred embodiment, both the first sealed medium reservoir 1 and the second sealed medium reservoir 2 include a tank and a cover, or either the first sealed medium reservoir 1 or the second sealed medium reservoir 2 includes a tank and a cover, and the tank and the cover are detachably connected.
[0036] Specifically, the cover is located on top of the tank, and the cover and tank are connected by a snap-fit seal. A sealing ring may be provided between the cover and the tank to enhance the airtightness. The cover is closed during use, providing a sealed environment for the internal storage medium 3 and preventing the loss of the storage medium 3. During routine maintenance of the first sealed medium reservoir 1 or the second sealed medium reservoir 2, the cover can be opened for convenient maintenance.
[0037] The pumped medium 3 flows through the medium channel 4 between the first sealed medium reservoir 1 and the second sealed medium reservoir 2, and the kinetic energy generated during the flow is converted into electrical energy by equipment such as a water turbine 5. The pumped medium 3 can be water or other fluids.
[0038] In a preferred embodiment, the pumped storage medium 3 is a nanofluid. Specifically, the nanofluid is a nanofluid comprising an iron-nickel alloy material. The iron-nickel alloy material has a high fluid density, and when used as the pumped storage medium 3, its density is significantly increased compared to water as the pumped storage medium 3. It has good inertial characteristics and fluid properties, which helps to improve the power generation efficiency of the pumped storage medium 3.
[0039] Medium channel 4 connects the first sealed medium reservoir 1 and the second sealed medium reservoir 2, and serves as the flow path for pumped-storage medium 3. Specifically, medium channel 4 is a liquid conveying tunnel or fluid pipeline. A water turbine 5 is installed on the channel to generate electricity using the kinetic energy of the pumped-storage medium 3.
[0040] In one example, the first sealing medium reservoir 1 is located to the upper left of the second sealing medium reservoir 2, the medium channel 4 includes an inclined section and a horizontal section, and the turbine 5 is located on the horizontal section.
[0041] The turbine 5 is a device that converts the kinetic energy of a fluid into mechanical energy. In the pumped storage power generation system, the turbine 5 is installed on the medium channel 4. When the pumped storage medium 3 flows from the first sealed medium reservoir 1 to the second sealed medium reservoir 2, the turbine 5 uses the kinetic energy of the pumped storage medium 3 to rotate, thereby driving the generator to generate electricity and converting mechanical energy into electrical energy.
[0042] In a preferred embodiment, the turbine 5 is a reversible turbine 5. While generating electricity, the reversible turbine 5 can also be driven by electricity during off-peak hours to pump the pumped storage medium 3 from the second sealed medium reservoir 2 to the first sealed medium reservoir 1, converting electrical energy into the gravitational potential energy of the pumped storage medium 3. This achieves multiple uses in one machine, simplifies the system structure, and reduces equipment costs and floor space.
[0043] The pressure regulating device is a component used to adjust the gas pressure of the first sealed medium reservoir 1 and / or the second sealed medium reservoir 2. By adjusting the gas pressure inside the first sealed medium reservoir 1 and / or the second sealed medium reservoir 2 through the pressure regulating device, the pressure difference between the first sealed medium reservoir 1 and the second sealed medium reservoir 2 is changed, thereby improving the start-up efficiency of the pumped storage power generation system.
[0044] In a preferred embodiment, the pressure regulating device includes a first pressure regulating module 6 and a second pressure regulating module 7. The first pressure regulating module 6 is connected to the first sealing medium reservoir 1 and is used to evacuate and blow air into the first sealing medium reservoir 1. The second pressure regulating module 7 is connected to the second sealing medium reservoir 2 and is used to evacuate and blow air into the second sealing medium reservoir 2.
[0045] Specifically, the first pressure regulating module 6 can use a pump body such as a vacuum pump or a centrifugal pump, which can inject high-pressure compressed gas into the sealing medium reservoir to increase the gas pressure inside the sealing medium reservoir, and also has the ability to reverse to extract gas from the corresponding sealing medium reservoir to reduce the gas pressure inside the sealing medium reservoir.
[0046] In other embodiments, only the first pressure adjustment module 6 or the second pressure adjustment module 7 may be provided, and the effect of having a certain pressure difference between the first sealing medium reservoir 1 and the second sealing medium reservoir 2 can be achieved by adjusting the first sealing medium reservoir 1 or the second sealing medium reservoir 2 separately.
[0047] In the pumped storage power generation system of this invention, when the pumped storage power generation system generates electricity, the pumped storage medium 3 flows from the first sealed medium reservoir 1 to the second sealed medium reservoir 2 through the medium channel 4 under the action of gravity. The gas pressure of the first sealed medium reservoir 1 is adjusted to be greater than that of the second sealed medium reservoir 2 by the pressure regulating device. The gas pressure is used to accelerate the flow of the pumped storage medium 3 downward along the medium channel 4, which can overcome the inertial resistance of the pumped storage medium 3, rapidly increase the flow velocity of the pumped storage medium 3, and effectively improve the power generation start-up efficiency.
[0048] This invention improves the conventional pumped storage medium 3 by establishing a first sealed medium reservoir 1, a second sealed medium reservoir 2, and matching first pressure regulating module 6 and second pressure regulating module 7. This allows the pumped storage medium 3 to flow downwards by gravity, achieving a more efficient start-up efficiency of the pumped storage power generation system under its own weight and gas pressure. Without significantly changing the original power station construction cost, it can significantly improve the operating efficiency and economic benefits of the pumped storage power station.
[0049] Simultaneously, the compressed air energy provided by the first pressure regulation module 6 is also converted into the kinetic energy of the pumped storage medium 3, realizing the dual energy storage capability of air compression-gravity energy storage. The compressed gas inside the first sealed medium reservoir 1 and the second sealed medium reservoir 2 also serves as an energy storage method. When the pumped storage power generation system is storing energy, the pumped storage medium 3 can be transported from the second sealed medium reservoir 2 to the first sealed medium reservoir 1 by controlling the turbine 5 to consume electrical energy. The pressure regulation device adjusts the gas pressure in the first sealed medium reservoir 1 to be lower than the gas pressure in the second sealed medium reservoir 2, causing the pumped storage medium 3 to accelerate upward flow along the medium channel 4, thereby improving the energy storage efficiency.
[0050] This invention also provides a pumped-storage energy storage power generation method, applicable to pumped-storage energy storage power generation systems as described in any of the above embodiments of this invention, such as... Figure 2 As shown, the method includes: Step S201: Obtain the operating mode of the pumped storage power generation system; Step S202: When the operating mode is power generation mode, the turbine 5 is controlled to generate electricity using the kinetic energy of the pumped storage medium 3 flowing from the first sealed medium reservoir 1 to the second sealed medium reservoir 2, and the gas pressure of the first sealed medium reservoir 1 is controlled to be greater than the gas pressure of the second sealed medium reservoir 2.
[0051] Specifically, the operation modes of pumped storage power generation systems include power generation mode and energy storage mode.
[0052] Generally, pumped storage power generation systems are connected to new energy power plants such as wind power plants and photovoltaic power plants. During peak electricity consumption periods, the pumped storage power generation system undertakes the power generation function. The first sealed medium reservoir 1 is opened, and the pumped storage medium 3 flows downward from the medium channel 4 to the second sealed medium reservoir 2, generating electricity through the turbine 5. During this process, the first pressure regulating module 6 blows gas into the first sealed medium reservoir 1, increasing the gas pressure in the first sealed medium reservoir 1, while the second pressure regulating module 7 extracts gas from the second sealed medium reservoir 2, decreasing the gas pressure in the second sealed medium reservoir 2. This results in the gas pressure in the first sealed medium reservoir 1 being greater than the gas pressure in the second sealed medium reservoir 2, causing the pumped storage medium 3 to flow downward along the medium channel 4 at an accelerated speed, improving the power generation start-up efficiency.
[0053] At the same time, the air compression energy provided by the first pressure regulating module 6 is also converted into the kinetic energy of the pumped storage medium 3, realizing the dual energy storage capacity of air compression and gravity energy storage. The compressed gas inside the first sealed medium reservoir 1 and the second sealed medium reservoir 2 will also serve as an energy storage means to improve energy storage efficiency.
[0054] In some embodiments, such as Figure 3 As shown, after obtaining the operating mode of the pumped storage power generation system, the following steps are included: Step S203: When the operating mode is energy storage mode, the turbine 5 is controlled to consume electrical energy to transport the pumped storage medium 3 from the second sealed medium reservoir 2 to the first sealed medium reservoir 1, and the gas pressure of the first sealed medium reservoir 1 is controlled to be less than the gas pressure of the second sealed medium reservoir 2.
[0055] Specifically, during off-peak electricity demand periods, the pumped-storage power generation system assumes the energy storage function. This involves starting the turbine 5 to consume excess electricity from the new energy power station, drawing the pumped-storage medium 3 from the second sealed medium reservoir 2 through the medium channel 4 to the first sealed medium storage. During this process, the second pressure regulating module 7 blows gas into the second sealed medium reservoir 2, increasing its gas pressure. The first pressure regulating module 6 extracts gas from the first sealed medium reservoir 1, decreasing its gas pressure. This results in the gas pressure in the first sealed medium reservoir 1 being lower than that in the second sealed medium reservoir 2, causing the pumped-storage medium 3 to flow upwards along the medium channel 4 at an accelerated rate, thus improving energy storage efficiency.
[0056] While exemplary embodiments and their advantages have been described in detail, those skilled in the art can make various changes, substitutions and modifications to these embodiments without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined herein.
Claims
1. A pumped-storage energy storage power generation system, characterized in that, include: The first sealed medium reservoir is used to hold the pumped medium; The second sealed medium reservoir is used to contain pumped storage medium and is connected to the first sealed medium reservoir through a medium channel. A water turbine is installed on the medium channel. The height of the first sealed medium reservoir is greater than the height of the second sealed medium reservoir. A pressure regulating device is used to adjust the gas pressure of the first sealed medium reservoir and / or the second sealed medium reservoir. When the pumped storage power generation system generates electricity, the turbine uses the kinetic energy of the pumped storage medium flowing from the first sealed medium reservoir to the second sealed medium reservoir to generate electricity. The pressure regulating device adjusts the gas pressure of the first sealed medium reservoir to be greater than the gas pressure of the second sealed medium reservoir.
2. The pumped-storage energy storage power generation system according to claim 1, characterized in that, The pressure regulating device includes a first pressure regulating module, which is connected to the first sealing medium reservoir and is used to evacuate and purge the first sealing medium reservoir.
3. The pumped-storage energy storage power generation system according to claim 1 or 2, characterized in that, The pressure regulating device includes a second pressure regulating module, which is connected to the second sealing medium reservoir and is used to evacuate and purge the second sealing medium reservoir.
4. The pumped-storage energy storage power generation system according to claim 1, characterized in that, The first sealed medium reservoir and / or the second sealed medium reservoir include a tank and a cover, which are detachably connected.
5. The pumped-storage energy storage power generation system according to claim 1, characterized in that, The pumping medium uses nanofluids.
6. The pumped-storage energy storage power generation system according to claim 5, characterized in that, The nanofluid is a nanofluid containing iron-nickel alloy materials.
7. The pumped-storage energy storage power generation system according to claim 1, characterized in that, The turbine in question is a reversible turbine.
8. A pumped-storage energy storage power generation method, applied to the pumped-storage energy storage power generation system as described in any one of claims 1 to 6, characterized in that, include: Obtain the operating mode of the pumped storage power generation system; When the operating mode is power generation mode, the turbine is controlled to generate electricity using the kinetic energy of the pumped storage medium flowing from the first sealed medium reservoir to the second sealed medium reservoir, and the gas pressure in the first sealed medium reservoir is controlled to be greater than the gas pressure in the second sealed medium reservoir.
9. The pumped-storage energy storage power generation method according to claim 8, characterized in that, After obtaining the operating mode of the pumped storage power generation system, the following is included: When the operating mode is energy storage mode, the turbine is controlled to consume electrical energy to transport the pumped storage medium from the second sealed medium reservoir to the first sealed medium reservoir, and the gas pressure in the first sealed medium reservoir is controlled to be lower than the gas pressure in the second sealed medium reservoir.
10. The pumped-storage energy storage power generation method according to claim 9, characterized in that, Controlling the gas pressure in the first sealed medium reservoir to be greater than the gas pressure in the second sealed medium reservoir includes: The first pressure regulating module is controlled to blow gas into the first sealing medium reservoir to increase the gas pressure of the first sealing medium reservoir, and the second pressure regulating module is controlled to extract gas from the second sealing medium reservoir to decrease the gas pressure of the second sealing medium reservoir. And / or, controlling the gas pressure of the first sealing medium reservoir to be less than the gas pressure of the second sealing medium reservoir includes: The second pressure regulating module is controlled to blow gas into the second sealing medium reservoir, increasing the gas pressure in the second sealing medium reservoir; the first pressure regulating module is controlled to extract gas from the first sealing medium reservoir, decreasing the gas pressure in the first sealing medium reservoir.