Novel pumped storage system and energy storage method

Abstract

The invention relates to a novel pumped storage system and an energy storage method. The novel pumped storage system comprises a pressure storage tank, a reservoir, a water turbine and a power generator, a water storage space is formed in the pressure storage tank and completely filled with a plurality of compressible gas capsules, and a valve is arranged at an opening of the pressure storage tank and connected with a water inlet of the water turbine through a first pipeline; the reservoir is connected with a water outlet of the water turbine through a second pipeline. The water turbine is connected with the generator and drives the generator to generate electricity. The energy storage method adopts the novel pumped storage system and comprises an energy storage stage and an energy release stage. The novel pumped storage system and the energy storage method are improved on the basis of a conventional pumped storage system and a conventional compressed air energy storage system, and water in a reservoir can be pressurized and injected into a pressure storage tank when the load of a power grid is in a low ebb; and when the power grid load peak occurs, the water in the pressure storage tank pushes the water turbine to do work and further drives the generator to generate power.

Description

Technical Field

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

[0002] Conventional pumped-storage systems use water as the energy storage medium and achieve the storage and management of electrical energy through the mutual conversion of electrical energy and potential energy. However, such pumped-storage systems have the following problems: (1) Geographic dependence: Due to the need to consider the height difference between the upper and lower reservoirs and the reservoir capacity, they can often only be built at specific geographical locations, with certain limitations in geographical layout; (2) Long construction period: The construction sites are generally remote, and the construction support capabilities are poor. Time is required to configure the support conditions before construction, and the construction workload is also large, making construction difficult, resulting in a general construction period of 6 - 8 years; (3) Environmental impact: The construction process will have a certain impact on the surrounding ecological environment and water resources.

[0003] Conventional compressed air energy storage systems use air as the energy storage medium. During the low-load period of the power grid, electrical energy is used to compress air for energy storage, and during the high-load period of the power grid, the compressed air is released to drive the expander to generate electricity. And such compressed air energy storage systems have the following problems: (1) Unfavorable for investment: Since the energy density of compressed air is relatively low, in order to achieve sufficient energy storage, the volume of the gas storage pipe / tank / warehouse for storing compressed air needs to be large enough, with a high cost, thus affecting investment; (2) High safety risk: Since the specific heat of air is small, the temperature changes significantly during the compression and expansion of air, easily causing temperature fatigue damage to the gas storage pipe / tank / warehouse, with a relatively high safety risk.

[0004] In addition, at present, there has also emerged an energy storage system that couples pumped-storage and compressed air energy storage. This coupled energy storage system uses both water and air as energy storage media and conducts pumped-storage and compressed air energy storage respectively. However, such a coupled energy storage system has the following problems: (1) An obvious interface will be generated between water and air, resulting in uneven heat transfer, accelerating the corrosion of the inner wall of the gas storage tank / warehouse, and generating thermal alternating stress on a large scale, causing safety risks; (2) Eddy currents may be generated during the energy release process, causing air to flow out of the gas storage tank / warehouse along with the water flow, causing cavitation damage to the water turbine blades and shortening the service life of the water turbine. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a novel pumped-storage system and an energy storage method improved on the basis of both conventional pumped-storage systems and conventional compressed air energy storage systems.

[0006] The present invention adopts the following technical solutions:

[0007] The present invention provides a novel pumped - storage energy system, which includes a pressure storage tank, a reservoir, a water turbine, and a generator. A water storage space is formed inside the pressure storage tank, and the water storage space is completely filled with a plurality of compressible gas capsules. A valve is provided at the opening of the pressure storage tank and is connected to the water inlet of the water turbine through a first pipeline. The reservoir is connected to the water outlet of the water turbine through a second pipeline. The water turbine is connected to the generator and drives the generator to generate electricity.

[0008] Preferably, a plurality of grids are arranged at intervals inside the pressure storage tank. The plurality of grids divide the water storage space into a plurality of water storage sub - spaces. The plurality of water storage sub - spaces are interconnected, and each water storage sub - space is completely filled with a plurality of compressible gas capsules.

[0009] Preferably, a filter screen is provided at the opening of the first pipeline near the pressure storage tank.

[0010] Preferably, the water in the reservoir is fresh water or seawater.

[0011] Preferably, the gas in the compressible gas capsule is air.

[0012] Preferably, a plurality of pressure storage tanks are provided, and each pressure storage tank is respectively connected to the water inlet of the water turbine through a first pipeline.

[0013] Preferably, a plurality of water turbines are provided. The water inlet of each water turbine is connected to the pressure storage tank through a first pipeline, and the water outlet is connected to the reservoir through a second pipeline. The plurality of water turbines are installed in parallel with the same generator and drive the generator to generate electricity.

[0014] The present invention also provides an energy storage method, which adopts the novel pumped - storage energy system of any one of the above, and includes two stages: energy storage and energy release:

[0015] Energy storage stage: Open the valve at the opening of the pressure storage tank and connect the water turbine to the power grid, then reverse - start the water turbine to pressurize and inject the water in the reservoir into the pressure storage tank. As the water in the reservoir is injected, the volume of the compressible gas capsules in the pressure storage tank gradually becomes smaller, and the pressure of the gas in the compressible gas capsules gradually increases. When it is found that the reading of the pressure gauge on the pressure storage tank reaches the set pressure, close the valve and the water turbine;

[0016] Energy release stage: Open the valve at the opening of the pressure storage tank and connect the generator to the power grid. The volume of the compressible gas capsules gradually returns to its original state. The water in the pressure storage tank enters the water turbine under pressure and drives the water turbine to do work, and the generator also generates electricity and sends the electric energy into the power grid. When it is found that the reading of the pressure gauge on the pressure storage tank returns to the initial state of an empty tank, close the valve.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The novel pumped-storage system of the present invention is improved based on the conventional pumped-storage system and the conventional compressed air energy storage system. When the power grid load is at a low valley, the water turbine can be reversely started to be used as a water pump to pressurize and inject the water in the reservoir into the pressure storage tank; when the power grid load is at a peak, the valve at the opening of the pressure storage tank is opened, and the water in the pressure storage tank can be used to push the water turbine to do work under the action of the restoring force of the expanding and restoring volume of the compressible gas capsule, thereby driving the generator to generate electricity.

[0019] Obviously, the novel pumped-storage system of the present invention no longer relies on gravitational potential energy, but realizes energy storage through high-pressure water, thus being able to overcome the defects of the conventional pumped-storage system being restricted by geographical location and the small energy density of the energy storage medium of the conventional compressed air energy storage system, which is not conducive to investment; in addition, due to the presence of the compressible gas capsule, although water and the compressible gas have a large contact area, they do not directly contact, thus being able to avoid the corrosion of the inner wall of the pressure storage tank and the water turbine blades and reducing the safety risk.

[0020] Since the energy storage method of the present invention adopts the above-mentioned novel pumped-storage system, it can store the redundant electricity of the power grid in the system when the power grid load is at a low valley according to the requirements of the power system, and release the electricity stored in the system to the power grid when the power grid load is at a peak, realizing the function of "peak shaving and valley filling". BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the novel pumped-storage system in the embodiment of the present invention.

[0022] Among them, the reference numerals are explained as follows:

[0023] 1. Pressure storage tank

[0024] 101. Water storage space

[0025] 2. Reservoir

[0026] 3. Water turbine

[0027] 4. Generator

[0028] 5. Compressible gas capsule

[0029] 6. Valve

[0030] 7. First pipeline

[0031] 8. Second pipeline

[0032] 9. Grid

[0033] 10. Filter screen DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The following further elaborates on the specific embodiments of the present invention in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention and are not intended to limit the present invention.

[0035] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In addition, in the description of the present invention, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0038] Refer to Figure 1 , this embodiment provides a new type of pumped-storage system, including a pressure storage tank 1, a reservoir 2, a water turbine 3, and a generator 4. A water storage space 101 is formed inside the pressure storage tank 1, and the water storage space 101 is completely filled with a plurality of compressible gas capsules 5. A valve 6 is provided at the opening of the pressure storage tank 1 and is connected to the water inlet of the water turbine 3 through a first pipeline 7. The reservoir 2 is connected to the water outlet of the water turbine 3 through a second pipeline 8. The water turbine 3 is connected to the generator 4 and drives the generator 4 to generate electricity.

[0039] The new type of pumped-storage system in this embodiment is improved on the basis of the conventional pumped-storage system and the conventional compressed air energy storage system. When the grid load is at a low valley, the water turbine 3 can be reversely started to be used as a water pump to pressurize and inject the water in the reservoir 2 into the pressure storage tank 1; when the grid load is at a peak, the valve 6 at the opening of the pressure storage tank 1 is opened, and the water in the pressure storage tank 1 can be pushed under high pressure to drive the water turbine 3 to do work under the action of the restoring force of the volume expansion of the compressible gas capsules 5, and then drive the generator 4 to generate electricity.

[0040] Obviously, the new pumped-storage system of this embodiment no longer relies on gravitational potential energy, but realizes energy storage through high-pressure water, thus being able to overcome the defects of the conventional pumped-storage system being restricted by geographical location and the small energy density of the energy storage medium of the conventional compressed air energy storage system, which is not conducive to investment; in addition, due to the presence of the compressible gas capsule 5, although water and the compressible gas have a large contact area, they will not come into direct contact, thus being able to avoid the corrosion of the inner wall of the pressure storage tank 1 and the blades of the water turbine 3 and reducing the safety risk.

[0041] Preferably, referring to Figure 1 , a plurality of grids 9 are arranged at intervals in the pressure storage tank 1, and the plurality of grids 9 divide the water storage space 101 into a plurality of water storage sub-spaces. The plurality of water storage sub-spaces communicate with each other, and each water storage sub-space is completely filled with a plurality of compressible gas capsules 5.

[0042] The setting of the grid 9 can equalize the distribution of the compressible gas capsules 5 in the pressure storage tank 1 to ensure that the water in the pressure storage tank 1 can be completely emptied; at the same time, due to the large specific heat capacity of water, the heat generated by the volume change of the compressible gas capsule 5 will be absorbed by the water in the pressure storage tank 1, so that the temperature change in the pressure storage tank 1 is not large, which can avoid temperature fatigue damage of the pressure storage tank 1, reduce the safety risk, and the equalized distribution of the compressible gas capsules 5 can avoid large local temperature changes in the pressure storage tank 1, further reducing the possibility of temperature fatigue damage of the pressure storage tank 1 and reducing the investment of the entire system.

[0043] Preferably, referring to Figure 1 , a filter screen 10 is arranged at the opening of the first pipeline 7 close to the pressure storage tank 1 to prevent the compressible gas capsules 5 in the pressure storage tank 1 from being discharged with the water flow.

[0044] Preferably, the water in the reservoir 2 is fresh water or seawater. Other incompressible fluid media can also be put into the reservoir 2, but since fresh water and seawater are relatively easy to obtain, fresh water or seawater is particularly adopted.

[0045] Preferably, the gas in the compressible gas capsule 5 is air. Similarly, other compressible fluids can also be used in the compressible gas capsule 5.

[0046] Preferably, referring to Figure 1 , in order to increase the peak shaving scale of the entire system, a plurality of pressure storage tanks 1 can be provided, and each pressure storage tank 1 is respectively connected to the water inlet of the water turbine 3 through the first pipeline 7; in addition, a plurality of water turbines 3 can also be provided, the water inlet of each water turbine 3 is connected to the pressure storage tank 1 through the first pipeline 7, and the water outlet is connected to the reservoir 2 through the second pipeline 8. The plurality of water turbines 3 are installed in parallel with the same generator 4 and drive the generator 4 to generate electricity.

[0047] It should be noted that the construction period of a conventional pumped-storage system is 6 to 8 years, while the construction period of the novel pumped-storage system of this embodiment can be reduced to 2 to 4 years; at the same time, when the gravitational potential energy generated by the conventional pumped-storage system is equal to the pressure energy generated by the novel pumped-storage system of this embodiment, the amount of water required by the novel pumped-storage system of this embodiment is less than 1 / 10 of the amount of water required by the conventional pumped-storage system.

[0048] This embodiment also provides an energy storage method, which combines Figure 1 , and uses the above-mentioned novel pumped-storage system, and includes two stages: energy storage and energy release:

[0049] Energy storage stage: Open the valve 6 at the opening of the pressure storage tank 1 and connect the water turbine 3 to the power grid, then reverse-start the water turbine 3 to pressurize and inject the water in the reservoir 2 into the pressure storage tank 1. As the water in the reservoir 2 is injected, the volume of the compressible gas capsule 5 in the pressure storage tank 1 gradually becomes smaller, and the pressure of the gas in the compressible gas capsule 5 gradually increases until it is found that the reading on the pressure gauge on the pressure storage tank 1 reaches the set pressure, then close the valve 6 and the water turbine 3;

[0050] Energy release stage: Open the valve 6 at the opening of the pressure storage tank 1 and connect the generator 4 to the power grid. The volume of the compressible gas capsule 5 gradually returns to its original state. The water in the pressure storage tank 1 enters the water turbine 3 under pressure and drives the water turbine 3 to do work. The generator 4 also generates electricity and sends the electric energy into the power grid until it is found that the reading on the pressure gauge on the pressure storage tank 1 returns to the initial state of an empty tank, then close the valve 6.

[0051] Due to the adoption of the above-mentioned novel pumped-storage system, the energy storage method of this embodiment can store the excess power in the power grid during the low load period of the power grid according to the requirements of the power system, and release the stored power in the power grid during the high load period of the power grid, realizing the function of "peak shaving and valley filling".

[0052] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can still be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. A new type of pumped storage system, characterized in that, It includes a pressure storage tank (1), a reservoir (2), a water turbine (3) and a generator (4). A water storage space (101) is formed inside the pressure storage tank (1), and the water storage space (101) is completely filled with a plurality of compressible gas capsules (5). A valve (6) is provided at the opening of the pressure storage tank (1) and is connected to the water inlet of the water turbine (3) through a first pipeline (7). The reservoir (2) is connected to the water outlet of the water turbine (3) through a second pipeline (8). The water turbine (3) is connected to the generator (4) and drives the generator (4) to generate electricity.

2. The novel pumped storage system according to claim 1, wherein, A plurality of grids (9) are arranged at intervals inside the pressure storage tank (1). The plurality of grids (9) divide the water storage space (101) into a plurality of water storage sub-spaces. The plurality of water storage sub-spaces communicate with each other, and each water storage sub-space is completely filled with a plurality of the compressible gas capsules (5).

3. The novel pumped-storage system according to claim 1, wherein A filter screen (10) is provided on the first pipeline (7) near the opening of the pressure storage tank (1).

4. The novel pumped-storage system according to claim 1, characterized in that, The water in the reservoir (2) is fresh water or seawater.

5. The novel pumped-storage system according to claim 1, wherein The gas in the compressible gas capsule (5) is air.

6. The novel pumped-storage system according to claim 1, characterized in that A plurality of pressure storage tanks (1) are provided, and each pressure storage tank (1) is respectively connected to the water inlet of the water turbine (3) through a first pipeline (7).

7. The novel pumped storage system according to claim 1, characterized in that A plurality of water turbines (3) are provided. The water inlet of each water turbine (3) is connected to the pressure storage tank (1) through a first pipeline (7), and the water outlet is connected to the reservoir (2) through a second pipeline (8). The plurality of water turbines (3) are installed in parallel with the same generator (4) and drive the generator (4) to generate electricity.

8. A method for energy storage, characterized in that, The novel pumped-storage system according to any one of claims 1-7 is adopted, and it includes two stages: energy storage and energy release. Energy storage stage: Open the valve (6) at the opening of the pressure storage tank (1) and connect the water turbine (3) to the power grid, and then reverse-start the water turbine (3) to pressurize and inject the water in the reservoir (2) into the pressure storage tank (1). As the water in the reservoir (2) is injected, the volume of the compressible gas capsule (5) in the pressure storage tank (1) gradually becomes smaller, and the pressure of the gas in the compressible gas capsule (5) gradually increases. When it is found that the reading of the pressure gauge on the pressure storage tank (1) reaches the set pressure, close the valve (6) and the water turbine (3). Energy release stage: Open the valve (6) at the opening of the pressure storage tank (1) and connect the generator (4) to the power grid. The volume of the compressible gas capsule (5) gradually returns to its original state. The water in the pressure storage tank (1) enters the water turbine (3) under pressure and drives the water turbine (3) to do work. The generator (4) also generates electricity and sends the electric energy into the power grid. When it is found that the reading of the pressure gauge on the pressure storage tank (1) returns to the initial state of an empty tank, close the valve (6).

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