Variable speed pumped storage power station, variable speed pumped storage unit and its water turbine draft tube

Abstract

This application provides a variable-speed pumped-storage power station, a variable-speed pumped-storage unit, and its turbine tailrace. The turbine tailrace includes a tailrace cone with multiple first guide channels formed on its inner wall. These first guide channels are arranged circumferentially along the tailrace cone and near its leading edge, extending axially along the tailrace cone. Alternatively, the turbine tailrace includes a tailrace cone and multiple first guide elements. These first guide elements are arranged circumferentially along the inner wall of the tailrace cone and near its leading edge, extending axially along the tailrace cone. A first guide channel is formed between adjacent first guide elements. By reducing the magnitude and distribution of the axial and tangential velocities within the guide channel, the first guide channels disrupt tangential vortices, generating jets to disrupt the conditions for the formation of helical vortices within the tube, thereby suppressing cavitation and pressure pulsation phenomena.

Description

Technical Field

[0001] This application relates to the field of vortex motion control technology for variable speed pumped storage power stations, and in particular to a variable speed pumped storage power station, a variable speed pumped storage unit and its turbine tailrace pipe. Background Technology

[0002] In the development and construction of new energy sources in my country, hydropower stations are important power generation facilities. Meanwhile, new energy sources such as wind power and photovoltaics are characterized by intermittency and strong fluctuations, and have high requirements for natural conditions, resulting in unstable power generation and frequent power shortages. Variable-speed pumped-storage hydropower stations convert excess electrical energy into the gravitational potential energy of water and store it during off-peak periods; during peak periods, they release water to generate electricity, supplementing power shortages and improving the stability of the power grid.

[0003] On the other hand, as the national energy structure and energy security are gradually improved, variable-speed pumped-storage hydroelectric power stations are playing and will play an increasingly important role, which is of great significance to national energy security and national economic development. In a variable-speed pumped-storage hydroelectric power station, the turbine is the core engineering structure. During periods of low electricity demand, the turbine transports water to the upper reservoir, converting excess electrical energy into potential energy to achieve energy storage; during periods of high electricity demand, the upper reservoir releases water, converting potential energy into electrical energy to supplement the power shortage. During this process, if the turbine deviates from its optimal operating condition, the water flow will generate a tangential velocity component inside the tailrace pipe, thus forming vortices. At the center of the vortex, the pressure drops sharply due to centrifugal force. When the pressure falls below the vaporization pressure, water vaporizes, forming a low-pressure cavity. This cavity stretches and rotates under the influence of the rotating water flow, forming a spiral vortex. This vortex carries air bubbles, rotating and oscillating around the central axis of the tailrace tube. Collisions with the tailrace tube structure cause cavitation and pressure pulsations, leading to unstable fluid flow within the turbine's tailrace tube section and shortening the equipment's lifespan. Therefore, eliminating or mitigating such vortices is crucial for the safe and efficient operation of the entire reservoir system. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of related technologies and provide a variable speed pumped storage power station, a variable speed pumped storage unit and its turbine tailrace pipe.

[0005] In a first aspect, embodiments of this application provide a turbine tailrace pipe for a variable-speed pumped storage unit, comprising: A tailrace cone, comprising a front edge and a rear edge, wherein the front edge has an inlet, and the diameter of the tailrace cone gradually increases from the front edge to the rear edge; the inner wall of the tailrace cone has multiple first guide channels, which are arranged circumferentially along the tailrace cone and close to one end of the front edge of the tailrace cone, and extend axially along the tailrace cone; or The tailwater conical pipe includes a front edge and a rear edge. The front edge is provided with an inlet. The diameter of the tailwater conical pipe gradually increases from the front edge to the rear edge. The multiple first flow guides are arranged circumferentially on the inner wall of the tailwater conical pipe and close to one end of the front edge of the tailwater conical pipe. The first flow guides extend axially along the tailwater conical pipe, and a first flow guide groove is formed between two adjacent first flow guides.

[0006] Optionally, the thickness of the first guide channel is uniformly distributed along the circumferential direction of the tailwater cone; and the length of the first guide channel is the same along the axial direction of the tailwater cone.

[0007] Optionally, the thickness of the first guide channel is uniformly distributed along the circumferential direction of the tailwater cone; and the length of the first guide channel is distributed in an alternating pattern of long and short sections along the axial direction of the tailwater cone.

[0008] Optionally, along the circumferential direction of the tailrace cone, the thickness of the first guide channel gradually increases from the front edge to the rear edge; along the axial direction of the tailrace cone, the length of the first guide channel is the same.

[0009] Optionally, along the circumferential direction of the tailrace cone, the thickness of the first guide channel gradually decreases from the front edge to the rear edge; along the axial direction of the tailrace cone, the length of the first guide channel is the same.

[0010] Optionally, the inner wall of the tailrace cone is provided with a plurality of second guide channels, which are arranged circumferentially along the tailrace cone and close to one end of the rear edge of the tailrace cone. The second guide channels extend axially along the tailrace cone, and the number of the second guide channels does not exceed the number of the first guide channels; or The tailrace cone also includes a plurality of second guide elements, which are arranged circumferentially on the inner wall of the tailrace cone and near the rear edge of the tailrace cone. The second guide grooves extend axially along the tailrace cone, and a second guide groove is formed between two adjacent second guide elements. The number of second guide grooves does not exceed the number of first guide grooves.

[0011] Optionally, the number of the second guide channels is less than the number of the first guide channels; or The number of the second guide channels is the same as the number of the first guide channels, and the positions of the second guide channels and the first guide channels are correspondingly set.

[0012] Optionally, the thickness of the second guide channel is uniform along the circumferential direction of the tailrace cone; the length of the second guide channel is the same along the axial direction of the tailrace cone; and / or The second guide channel and / or the second guide component are made of magnetic material and are detachably disposed on the inner wall of the tailwater cone.

[0013] Secondly, embodiments of this application provide a variable-speed pumped storage unit, including the turbine tailrace as described in the first aspect.

[0014] Thirdly, embodiments of this application provide a variable-speed pumped-storage power station, including the variable-speed pumped-storage unit as described in the second aspect.

[0015] The turbine tailrace pipe of the variable-speed pumped storage power station provided in this application, by setting multiple first guide channels on the inner wall of the tailrace cone, reduces the magnitude and distribution of the axial and tangential velocities in the guide channels, thereby disrupting the tangential vortex and generating jets to destroy the conditions for the formation of spiral vortex bands in the pipe, thus achieving the purpose of suppressing cavitation and pressure pulsation phenomena.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] Figures 1 to 4 This is a schematic diagram of the flow channel fluid model of the turbine tailrace pipe of the variable speed pumped storage power station provided in the embodiments of this application.

[0019] Figure 5 and Figure 6 This is a schematic diagram of the dimensions of the turbine tailrace pipe of a variable speed pumped storage power station provided in one embodiment.

[0020] Figures 7 to 16 This is a schematic diagram of the flow channel fluid model of the turbine tailrace pipe of a variable speed pumped storage power station provided in other embodiments of this application. Detailed Implementation

[0021] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0022] To better understand the technical solution of this application, the variable-speed pumped storage power station, variable-speed pumped storage unit, and turbine tailrace pipe of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other.

[0023] This application relates to the field of vortex motion control in variable-speed pumped storage power stations, and particularly to the field of vortex motion control inside the draft tube of a turbine in a variable-speed pumped storage power station. An embodiment of this application also provides a variable-speed pumped storage power station, including a variable-speed pumped storage unit. The variable-speed pumped storage unit may include the turbine draft tube. See also... Figures 1 to 4 As shown, an embodiment of this application provides a turbine tailrace pipe for a variable-speed pumped storage unit, which can be applied to variable-speed pumped storage power stations.

[0024] In one embodiment, the turbine tailrace pipe may include a tailrace cone 10, which includes a leading edge and a trailing edge, which are along the y-axis, i.e., the length direction of the tailrace cone 10. The leading edge has an inlet 11, and the diameter of the tailrace cone 10 gradually increases from the leading edge to the trailing edge. The inner wall of the tailrace cone 10 has multiple first guide grooves 20, which are arranged circumferentially (i.e., in a circular direction perpendicular to the y-axis) and close to one end of the leading edge of the tailrace cone 10. The first guide grooves 20 extend axially (i.e., along the y-axis) of the tailrace cone 10. The first guide grooves 20 are groove structures, and may be J-shaped grooves.

[0025] In another embodiment, the turbine tailrace may include a tailrace cone 10 and a plurality of first guide members. The tailrace cone 10 includes a leading edge and a trailing edge, which are along the y-axis, i.e., the length direction of the tailrace cone 10. The leading edge has an inlet 11, and the diameter of the tailrace cone 10 gradually increases from the leading edge to the trailing edge along the y-axis. A plurality of first guide members are arranged circumferentially (i.e., in a circumferential direction perpendicular to the y-axis) on the outer wall of the tailrace cone 10, near one end of the leading edge. The first guide members extend axially (i.e., along the y-axis) of the tailrace cone 10, and a first guide groove 20 is formed between adjacent first guide members. The first guide groove 20 is a groove structure, which may be a J-shaped groove. Thus, the turbine tailrace of the variable-speed pumped storage unit provided in this application structurally modifies the tailrace tube's shape to address the fluid vortices formed inside. By setting multiple first guide channels 20 on the inner wall of the tailrace cone 10, the magnitude and distribution of axial and tangential velocities within the guide channels (i.e., the tailrace cone) are reduced, causing the first guide channels 20 to disrupt tangential vortices and generate jets that disrupt the conditions for the formation of spiral vortices within the tube, thereby suppressing cavitation and pressure pulsation. During the operation of the pumped storage unit, based on passive control logic, the flow field is regulated using the water's own energy without external power, suppressing the generation of tangential vortices within the tailrace tube with minimal efficiency loss. This further suppresses cavitation and pressure fluctuations caused by vortices on the turbine, ensuring stable and efficient operation of the variable-speed pumped storage unit, extending the turbine's service life, and demonstrating broad engineering application prospects and significant economic value.

[0026] It should be noted that the number of the first guide element and the first guide channel 20 can be set according to actual needs, and this application does not impose any restrictions on this. Under ideal conditions, the more first guide elements and the more first guide channels 20 there are, the greater the obstruction to water flow and the greater the efficiency loss, but the better the suppression effect.

[0027] like Figure 1 As shown, in some optional embodiments, the thickness of the first guide channel 20 is uniformly distributed along the circumferential direction of the tailrace cone 10. The length of the first guide channel 20 is the same along the axial direction of the tailrace cone 10. Figure 1 The example shown can be considered as a basic design type A for the tailrace pipe, where the first guide channel 20 has a consistent thickness and length from the trailing edge to the front edge. Its operating mechanism is based on passive control logic. By installing the first guide channel 20 (hereinafter referred to as the J-channel) on the inner wall of the tailrace pipe cone (i.e., the area where vortex generation and development are most intense), the flow field is regulated using the water's own energy, disrupting the tangential flow velocity to suppress vortex generation, thereby inhibiting vortex generation, pressure pulsation, and cavitation development. When water flows through the J-channel, the geometry of the groove alters the fluid's trajectory.

[0028] by Figure 1 Taking the basic design type A as an example, its uniformly thick first guide channel 20 causes the water flow to form a symmetrical backflow near the leading edge due to viscosity. This backflow originates from the velocity difference on both sides of the leading edge; the water flow velocity is faster near the mainstream area and slower near the wall of the first guide channel 20, thus forming vortices within the first guide channel 20. As the water flows towards the trailing edge, the vortices gradually converge into small jets, which are ejected from the trailing edge of the first guide channel 20, laterally impacting the mainstream and weakening the tangential velocity component, thereby suppressing the rotational intensity of the vortex.

[0029] like Figure 2 As shown, in some optional embodiments, the thickness of the first guide channel 20 is uniformly distributed along the circumferential direction of the tailrace cone 10. Along the axial direction of the tailrace cone 10, the lengths of the first guide channels 20 are distributed in an alternating pattern of long and short. Optionally, the ends of each first guide channel 20 near the rear edge are flush, and the ends of each first guide channel 20 near the front edge are distributed in an alternating pattern of long and short. Figure 2 The example shown can be considered as the basic design type B of the tailrace pipe.

[0030] like Figure 3 As shown, in some optional embodiments, the thickness of the first guide channel 20 gradually increases from the front edge to the rear edge (i.e., the rear edge is thickened) along the circumferential direction of the tailrace cone 10. The length of the first guide channel 20 is the same along the axial direction of the tailrace cone 10. Figure 3 The example shown can be considered as a basic design type C for the tailrace pipe.

[0031] like Figure 4 As shown, in some optional embodiments, the thickness of the first guide channel 20 gradually decreases from the leading edge to the trailing edge (i.e., the leading edge is thickened) along the circumferential direction of the tailwater conical pipe 10. The length of the first guide channel 20 is the same along the axial direction of the tailwater conical pipe 10. Figure 4 The example shown can be considered as the basic design type D of the tailrace pipe.

[0032] Essentially, the first guide channel 20, taking the J-shaped channel as an example, converts the kinetic energy of water flow into the rotational energy of the vortex within the channel, and then re-injects it into the mainstream in the form of a jet. In this process, the tangential vortex kinetic energy is consumed, weakening the energy basis for the formation of the vortex band. The difference between the different groove designs of the first guide channel 20 lies in the direction, size, and pulsation characteristics of the jet and its different application conditions.

[0033] The operating principle of this application is as described above. This passive control method, which requires no external energy, achieves active intervention in water flow through structural optimization, thus realizing the purpose of suppressing tangential vortices in the tailrace pipe, and consequently suppressing vortex bands, pressure pulsations, and cavitation phenomena. The tailrace pipe vortex motion control and modification structure of this application is simple in structure, stable and efficient in operation, and has broad application prospects.

[0034] See Figure 5 and Figure 6 As shown, Figure 5 This is a side view of the tailrace pipe along the x-axis of the basic design type A. Figure 6This is a side view of the tailrace pipe of basic design type A along the y-axis. Where R1 is the end radius of the J-shaped channel; R2 is the front radius of the J-shaped channel; L1 is the axial length of the J-shaped channel; L2 is the distance from the front of the J-shaped channel to the tailrace pipe inlet; θ is the circumferential angle of a single J-shaped channel. Taking a first guide channel 20 with 12 channels as an example... Figures 1 to 4 In the embodiments, the circumferential angle of each J-shaped groove is 15°, and the specific modified size structure is shown in Table 1.

[0035] Table 1 – Dimensional Design of J-type Grooves (Types A, B, C, and D) Note: Type B features an alternating distribution of J-shaped grooves of both long and short lengths. In summary, the working process of the J-channel design can be simply described as follows: Vortices within the tailrace pipe often possess high axisymmetry, a fundamental condition for the formation of stable and powerful vortex bands. The J-channel introduces physical obstacles and irregular geometry along the vortex's path (circumferential direction). When the vortex flows through the J-channel, the channel's edges interfere with and cut the water flow, hindering its continuous rotational motion and disrupting its stable helical flow field structure. Simultaneously, during operation, the J-channel guides the water flow to generate jets towards the low-pressure area of ​​the central axis. These jets increase the pressure in the core region of the vortex band, making it difficult to reduce below the vaporization pressure, thus inhibiting the formation and development of cavities. Furthermore, the jets create new reverse flow regions inside the tailrace pipe, further cutting and dispersing the vortex band structure, transforming it from a helical shape to a columnar shape, significantly reducing the size and intensity of the vortex band.

[0036] The expected operating conditions of the J-slot design for different foundation models are analyzed as follows: Basic Design Type A: The J-type groove has a uniform and constant thickness, which can generate a stable and continuous jet. It can evenly cover the vortex band suppression at the outlet of the impeller and the center of the tailrace pipe, and has the best pressure pulsation suppression. However, due to the characteristics of its large-size groove, it significantly increases the wall friction resistance, resulting in the largest efficiency loss compared to other modifications. Due to the comprehensiveness of its suppression effect, it is suitable for grid peak-shaving units.

[0037] Basic Design Type B: The thickness of the J-shaped groove remains uniform, but it adopts an alternating arrangement of long and short grooves, which optimizes the defects of the large-size groove in the basic design and reduces friction loss. Compared with other modifications, it has the smallest efficiency loss. However, the asymmetric jet causes the flow field to be unstable, resulting in unstable suppression of pressure pulsation. It sacrifices the suppression strength of vortex bands and cavitation, and is suitable for efficiency-sensitive projects.

[0038] Basic Design Type C: The thickness of the trailing edge of the J-shaped channel is increased, which enhances the jet intensity in the central area of ​​the tailrace. The high-speed jet directly cuts the core part of the vortex belt, causing the spiral vortex belt to degenerate into a columnar shape, which greatly reduces the oscillation amplitude and intensity of the vortex belt. Its suppression effect on the vortex belt is also the highest among several design schemes. However, this design abandons the coverage of the runner outlet, which weakens the cavitation suppression effect of the impeller and increases the risk of impeller cavitation. Due to its strong targeting effect on vortex belt suppression, it is suitable for high-head variable operating condition units and can greatly reduce structural vibration under non-operating conditions.

[0039] Basic Design Type D: The leading edge thickness of the J-shaped groove is increased, which enhances the supplementary effect of the jet to the low-pressure area of ​​the impeller outlet, increases the pressure at the impeller blade outlet, and suppresses cavitation on the blade surface. However, due to the increase in leading edge thickness, the axial flow velocity in the groove is reduced and the jet intensity is weakened. The suppression effect on vortex bands and pressure pulsation is weakened compared to the basic design. Because it is more targeted at suppressing impeller cavitation, it is suitable for high-risk impeller cavitation scenarios and can focus on protecting the impeller.

[0040] See Figures 7 to 14 As shown, in some optional implementations, based on the four basic designs ABCD mentioned above, a J-shaped groove design can also be added to the latter half of the tailwater pipe, which can be regarded as adding an E (N') type design.

[0041] In one embodiment, the inner wall of the tailrace cone 10 is provided with a plurality of second guide channels 30. The plurality of second guide channels 30 are arranged circumferentially along the tailrace cone 10 and close to one end of the rear edge of the tailrace cone 10. The second guide channels 30 extend axially along the tailrace cone 10, and the number of the second guide channels 30 does not exceed the number of the first guide channels 20. The second guide channels 30 are groove structures, and can be J-shaped grooves.

[0042] In another embodiment, the tailrace cone 10 further includes a plurality of second guide members, arranged circumferentially along the inner wall of the tailrace cone 10 and near one end of the tailrace cone 10's rear edge. The second guide members extend axially along the tailrace cone 10, and a second guide groove 30 is formed between adjacent second guide members. The number of second guide grooves 30 does not exceed the number of first guide grooves 20. The second guide groove 30 is a groove structure, which may be a J-shaped groove.

[0043] The thickness of the second guide channel 30 is uniformly distributed along the circumferential direction of the tailwater conical pipe 10. The length of the second guide channel 30 is the same along the axial direction of the tailwater conical pipe 10.

[0044] It should be noted that the number of the second flow guide and the second flow guide channel 30 can be set according to actual needs, and this application does not impose any restrictions on this. Under ideal conditions, the more second flow guides and the more second flow guides and the more second flow guide channels 30 there are, the greater the obstruction to water flow and the greater the efficiency loss, but the better the suppression effect.

[0045] exist Figures 1 to 4 In the illustrated embodiment, without the second guide channel 30 installed at the rear edge of the tailrace pipe, the cross-sectional area of ​​the flow channel in the latter half of the tailrace pipe increases, the flow velocity decreases, and the static water pressure increases. This may lead to water flow blockage and the formation and expansion of dead water zones, causing the vortex band to be further strengthened, thus significantly reducing the effectiveness of the four basic design features (A, B, C, and D) mentioned above. By installing the second guide channel 30 at the rear edge of the tailrace pipe, the water flow in the latter half is guided, preventing the further strengthening of the vortex band.

[0046] However, it should be noted that an excessive number of second guide channels 30 or improper placement of their positions can lead to increased energy loss. Based on this consideration, the number of second guide channels 30 should not exceed the number of first guide channels 20. When the two numbers are the same, the placement of the second guide channels 30 can correspond to the position of the first guide channels 20 in the four basic designs of ABCD mentioned above, that is, the two positions are opposite to form a smooth flow channel.

[0047] In some alternative embodiments, the number of the second guide channels 30 may be less than the number of the first guide channels 20, such as... Figure 7 and Figure 12 As shown in the embodiment. Alternatively, the number of the second guide channels 30 can be the same as the number of the first guide channels 20, and the positions of the second guide channels 30 and the first guide channels 20 are correspondingly arranged, such as... Figure 13 and Figure 14 As shown in the embodiments.

[0048] Among them, Figure 7 and Figure 8 In the embodiment shown, there are 12 first guide channels 20 and 3 second guide channels 30, which can be regarded as the E(3) type design of the tailwater pipe.

[0049] exist Figure 9 and Figure 10 In the embodiment shown, there are 12 first guide channels 20 and 4 second guide channels 30, which can be regarded as the E(4) type design of the tailwater pipe.

[0050] exist Figure 11 and Figure 12 In the embodiment shown, there are 12 first guide channels 20 and 6 second guide channels 30, which can be regarded as the E(6) type design of the tailwater pipe.

[0051] exist Figure 13and Figure 14 In the embodiment shown, there are 12 first guide channels 20 and 12 second guide channels 30, and the two are positioned opposite each other, which can be regarded as the E (12) type design of the tailwater pipe.

[0052] The specific dimensions and structure of the modified version are shown in Table 2.

[0053] Table 2 – Design of Dimensions for Four Types of E (N') and J-Type Grooves It should be noted that by combining designs A, B, C, and D with whether or not to add design E (N'), and which type of design E (N') to add, 20 possible combination implementation schemes can be obtained. Some schematic diagrams of these combination implementation schemes are shown below. Figures 7 to 14 As shown in Table 3, the design is expected to cover a wide range of operating conditions through combined implementation schemes. The expected operating conditions of the 20 combined implementation schemes are analyzed in Table 3.

[0054] Table 3 – Analysis of Expected Operating Conditions of the Combined Scheme See Figure 15 and Figure 16 As shown, in some optional embodiments, the second guide channel 30 and the second guide member can be made of magnetic material and detachably disposed on the inner wall of the tailwater conical pipe 10. Thus, the structure connecting the tailwater pipe with the magnetic material facilitates installation and disassembly; a schematic diagram of its detachable portion is shown below. Figure 15 and Figure 16 .

[0055] In summary, this application relates to a practical engineering application, providing a J-groove design for the tailrace of a variable-speed pumped-storage power station to stably and efficiently suppress cavitation and pressure fluctuations in the turbine caused by vortices within the tailrace. Based on preliminary numerical calculations, different combinations of A, B, C, D, and E (N') types can be installed in the turbine tailrace under different application conditions. By combining the expected cavitation suppression effect and efficiency loss, the design achieves vortex motion control in the tailrace under different requirements. Specifically, it relates to a vortex motion control and modification structure device inside the turbine tailrace of a variable-speed pumped-storage power station.

[0056] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A turbine tailrace pipe for a variable-speed pumped-storage unit, characterized in that, include: A tailrace cone, comprising a front edge and a rear edge, wherein the front edge has an inlet, and the diameter of the tailrace cone gradually increases from the front edge to the rear edge; the inner wall of the tailrace cone has multiple first guide channels, which are arranged circumferentially along the tailrace cone and close to one end of the front edge of the tailrace cone, and extend axially along the tailrace cone; or The tailwater conical pipe includes a front edge and a rear edge. The front edge is provided with an inlet. The diameter of the tailwater conical pipe gradually increases from the front edge to the rear edge. The multiple first flow guides are arranged circumferentially on the inner wall of the tailwater conical pipe and close to one end of the front edge of the tailwater conical pipe. The first flow guides extend axially along the tailwater conical pipe, and a first flow guide groove is formed between two adjacent first flow guides.

2. The turbine tailrace pipe according to claim 1, characterized in that, Along the circumferential direction of the tailrace cone, the thickness of the first guide channel is uniformly distributed; along the axial direction of the tailrace cone, the length of the first guide channel is the same.

3. The turbine tailrace pipe according to claim 1, characterized in that, Along the circumferential direction of the tailrace cone, the thickness of the first guide channel is uniformly distributed; along the axial direction of the tailrace cone, the length of the first guide channel is distributed in an alternating pattern of long and short.

4. The turbine tailrace pipe according to claim 1, characterized in that, Along the circumferential direction of the tailrace cone, the thickness of the first guide channel gradually increases from the front edge to the rear edge; along the axial direction of the tailrace cone, the length of the first guide channel is the same.

5. The turbine tailrace pipe according to claim 1, characterized in that, Along the circumferential direction of the tailrace cone, the thickness of the first guide channel gradually decreases from the front edge to the rear edge; along the axial direction of the tailrace cone, the length of the first guide channel is the same.

6. The turbine tailrace pipe according to claim 1, characterized in that, The inner wall of the tailrace cone is provided with a plurality of second guide channels, which are arranged circumferentially along the tailrace cone and close to one end of the rear edge of the tailrace cone. The second guide channels extend axially along the tailrace cone, and the number of the second guide channels does not exceed the number of the first guide channels; or The tailrace cone also includes a plurality of second guide members, which are arranged circumferentially on the inner wall of the tailrace cone and near the rear edge of the tailrace cone. The second guide members extend axially along the tailrace cone, and a second guide groove is formed between two adjacent second guide members. The number of second guide grooves does not exceed the number of first guide grooves.

7. The turbine tailrace pipe according to claim 6, characterized in that, The number of the second guide channels is less than the number of the first guide channels; or The number of the second guide channels is the same as the number of the first guide channels, and the positions of the second guide channels and the first guide channels are correspondingly set.

8. The turbine tailrace pipe according to claim 6, characterized in that, Along the circumferential direction of the tailrace cone, the thickness of the second guide channel is uniform; along the axial direction of the tailrace cone, the length of the second guide channel is the same; and / or The second guide channel and / or the second guide component are made of magnetic material and are detachably disposed on the inner wall of the tailwater cone.

9. A variable-speed pumped-storage unit, characterized in that, Includes the turbine tailrace pipe as described in any one of claims 1-8.

10. A variable-speed pumped-storage power station, characterized in that, Including the variable speed pumped storage unit as described in claim 9.

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