Combined surge shaft and adjusting method for hydraulic transition process

Abstract

The invention discloses a combined surge shaft which is suitable for a water diversion and power generation system of a pumped storage power station and is arranged right above or obliquely above a water conveying pipeline, the water conveying pipeline is connected with the bottom of the surge shaft through an impedance pipe, and a mechanical energy storage pressure regulating device is arranged in the surge shaft. The adjusting method for the hydraulic transition process comprises the steps that when pressure fluctuation occurs in a water conveying pipeline, the water level in a surge shaft changes along with the pressure fluctuation; the hydraulic power drives the rotor to rotate, and the torque is transmitted to the energy storage clockwork spring; when the deformation resistance of the energy storage clockwork spring is balanced with the hydraulic driving force, the water level in the surge shaft reaches a fluctuation extreme value; afterwards, the water level begins to change reversely, the energy storage clockwork spring releases potential energy, the hydraulic driving rotor is driven to rotate reversely, energy is fed back to water flow, and the water level in the surge shaft is accelerated to recover to a stable state. The safety guarantee level of the water diversion power generation system can be fundamentally improved, and the method has important significance in promoting sustainable and healthy development of a pumped storage power station.

Description

Technical Field

[0001] This invention relates to the technical field of water conveyance and power generation facilities in water conservancy and hydropower projects, and in particular to a composite surge tank and a method for regulating the hydraulic transition process suitable for a pumped storage power station's water diversion and power generation system. Background Technology

[0002] In recent years, with the increasing prominence of global climate change, the new energy sector has ushered in unprecedented development opportunities. Among them, pumped storage power stations, due to their advantages such as low cost, large energy storage capacity, and flexible grid dispatch, have entered a peak period of large-scale construction.

[0003] With the continuous expansion of pumped storage power station installed capacity, these stations are developing towards high-head, long-distance water conveyance, which significantly increases the difficulty of controlling the hydraulic transient process. During the operation of a pumped storage power station, when the power system load suddenly changes, the balance between turbine output and generator load is disrupted, resulting in a severe hydraulic transient process in the water intake system. As a key facility ensuring the safety of the project, the surge tank plays an irreplaceable role in this process. By effectively regulating water level fluctuations within the system, it reduces or weakens the adverse effects of the hydraulic transient process, thereby ensuring the safe and stable operation of the entire hydraulic system.

[0004] Existing surge tanks mainly include traditional types such as simple, impedance, and differential surge tanks. Their working principle primarily relies on the inertial rise and fall of the water body and the effect of gravity to absorb energy. From a technical perspective, this inertial-gravity pressure regulation mechanism still has room for optimization. From an engineering practice perspective, to ensure sufficient pressure regulation volume to effectively attenuate fluctuations, traditional surge tanks often require the excavation of massive underground caverns. With the continuous expansion of surge tank size, large caverns and long-span underground space structures bring a series of challenges to engineering construction: the excavation width of the cavern can reach 20-30 meters, and the support methods and excavation costs are extremely high; to meet the requirements of internal and external air pressure balance, ventilation and safety tunnels hundreds or even thousands of meters long need to be set up; long-term surrounding rock stability and seepage control are prominent issues in large underground spaces, and the requirements for geological conditions become more stringent with the increase in scale, bringing high difficulty, high cost, and high risk to engineering construction. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a novel composite surge tank suitable for pumped-storage power station water diversion and power generation systems. It also provides a method for regulating the hydraulic transition process, applicable to long-distance large-scale water conveyance tunnel systems, used to regulate pressure and water level fluctuations during the hydraulic transition process, ensuring the stable operation of the water diversion and power generation system. Specifically, the following technical solutions can be adopted: The composite surge tank of the present invention is suitable for the water diversion and power generation system of a pumped storage power station. The surge tank is located directly above or diagonally above the water transmission pipeline, and the water transmission pipeline is connected to the bottom of the surge tank through an impedance pipe. A mechanical energy storage and pressure regulating device is installed inside the surge tank.

[0006] When pressure fluctuations occur in the water pipeline, the water level in the surge tank changes. This invention utilizes the water level change in the surge tank to drive the operation of a mechanical energy storage and pressure regulating device, enabling the conversion of water kinetic energy and mechanical energy. This allows for storage when water kinetic energy is abundant and supplementation through mechanical energy when water kinetic energy is lacking. This not only prevents the water level in the surge tank from becoming too high but also quickly balances the water pressure. While ensuring the safe and stable operation of the hydraulic system, it reduces the construction difficulty and investment cost of underground caverns such as surge tanks.

[0007] Preferably, the mechanical energy storage pressure regulating device includes a hydraulically driven rotor and an energy storage spring. The hydraulically driven rotor includes a rotating shaft and blades disposed thereon. The rotating shaft is connected to a bracket disposed on the well wall. The energy storage spring is a planar spiral structure arranged around the rotating shaft, and one end of the energy storage spring is fixedly connected to the rotating shaft, and the other end is fixedly connected to the well wall.

[0008] The mechanical energy storage and pressure regulating device used in this invention cleverly combines a hydraulically driven rotor and an energy storage spring. By absorbing and releasing the kinetic energy of water through the hydraulically driven rotor-spring energy storage system, it achieves active suppression and attenuation of surge waves. The pressure regulating well structure it adopts can significantly reduce the cavern size of the pressure regulating well, optimize the hydraulic transition process, reduce engineering construction costs and geological risks, and improve the safety and economy of engineering operation.

[0009] Preferably, the well wall comprises a top spherical section, a middle straight section, and a lower conical section connected in sequence; the support includes an upper support disposed at the top of the middle straight section and a lower support disposed at the bottom of the lower conical section, and both the upper support and the lower support are provided with ball bearings located at the center of the well wall cavity; the rotating shaft is connected to the upper support and the lower support through the ball bearing rotating shaft.

[0010] The upper and lower supports used in this invention are rigidly connected to the well wall of the pressure regulating well to bear the radial and axial loads transmitted by the rotating shaft; the rotating shaft is connected to the upper and lower supports through bearings to ensure that it can rotate smoothly and to minimize the loss of mechanical energy during operation.

[0011] Preferably, the blade is a double-helix blade made of high-strength composite material, and the outer edge of the blade is set close to the well wall.

[0012] The double-helix blades used in this invention have excellent dynamic balance performance, stable operation, reduced bearing load, and higher conveying efficiency. Furthermore, since the diameter of the double-helix blades is close to that of the surge tank, most of the water is conveyed along the rotation of the double-helix blades as it rises, greatly improving energy conversion efficiency.

[0013] Preferably, the energy storage spring is disposed at the top of the rotating shaft and located above the upper support.

[0014] The structure in this invention, in which the energy storage spring is located above the upper support, not only facilitates the setting of the rotating shaft structure, but also effectively avoids the energy storage spring from contacting the water surface, reducing the chance of water flow corrosion and extending its service life.

[0015] Preferably, there are at least two energy storage springs, and a corresponding number of anchoring steel columns are evenly arranged on the outer side of the well wall. The outer end of each energy storage spring passes through the well wall and is connected to the anchoring steel column.

[0016] In this invention, the preload of the energy storage spring can be calibrated according to the designed water level fluctuation range. Multiple springs are evenly arranged around the rotating shaft, which can distribute the force on the rotating shaft, improve the stability of the rotating shaft torque output, and make the system powerful, fast in response, large in energy storage capacity, safe and reliable.

[0017] Preferably, taking into account geology, topography and operational requirements, the water pipeline can be installed on the water intake line or tailwater line to ensure the safety of the device and meet economic requirements.

[0018] The method for regulating the hydraulic transition process described in this invention is achieved through the aforementioned composite surge tank. Specifically, when pressure fluctuations occur in the water pipeline, the water level in the surge tank changes accordingly. The change in the water level in the surge tank drives the hydraulically driven rotor to rotate, and transmits torque to the energy storage spring through the shaft, converting the kinetic energy of the water flow into elastic potential energy. When the deformation resistance of the energy storage spring balances the hydraulic driving force, the water level in the surge tank reaches its extreme fluctuation value. Subsequently, the water level begins to change in the opposite direction, the energy storage spring releases its potential energy, drives the hydraulically driven rotor to rotate in the opposite direction, feeds energy back to the water flow, and accelerates the restoration of the water level in the surge tank to a stable state.

[0019] This invention is applicable to at least one of the following situations: 1) It is applicable to large pumped storage power stations with poor hydraulic transition conditions, large flow rates, and high heads; 2) It is applicable to engineering geological conditions with harsh geological conditions that limit the use of large caverns; 3) It is applicable to projects with higher requirements for economic indicators. The aforementioned novel surge tank can effectively reduce the size of the cavern, decrease the excavation diameter and height, and eliminate the need for a ventilation safety tunnel connecting the surge tank to the atmosphere. Without weakening the effectiveness of the surge tank, it effectively reduces the risks of engineering construction, lowers engineering costs, and shortens the construction period, fundamentally improving the safety level of the water diversion and power generation system. This is of great significance for promoting the sustainable and healthy development of pumped storage power stations. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the pressure regulating well described in this invention.

[0021] Figure 2 yes Figure 1 Enlarged view of part A in the image.

[0022] Figure 3 This is a schematic diagram of the working process of the pressure regulating well described in this invention.

[0023] Figure 4 This invention relates to the superposition principle of pressure regulating well water level changes. Figure 1 .

[0024] Figure 5 This invention relates to the superposition principle of pressure regulating well water level changes. Figure 2 . Detailed Implementation

[0025] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific working processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0026] like Figure 1-5 As shown, the composite surge tank of the present invention is suitable for the water diversion and power generation system of a pumped storage power station. The surge tank 1 is located directly above or diagonally above the water transmission pipeline 2, and the water transmission pipeline 2 is connected to the bottom of the surge tank 1 through an impedance pipe 3. A mechanical energy storage and pressure regulating device is installed inside the surge tank 1.

[0027] In this embodiment, the mechanical energy storage pressure regulating device mainly consists of a hydraulically driven rotor and an energy storage spring 4. The hydraulically driven rotor includes a rotating shaft 51 and blades 52 mounted thereon. The rotating shaft 51 is connected to a support mounted on the well wall. The energy storage spring 4 is a planar volute structure arranged around the rotating shaft, with one end of the energy storage spring 4 fixedly connected to the rotating shaft 51 and the other end fixedly connected to the well wall.

[0028] Specifically, the well wall is a concrete structure comprising a top spherical section, a middle straight section, and a lower conical section connected in sequence. Supports are installed below the top spherical section, including an upper support 53 at the top of the middle straight section and a lower support 54 at the bottom of the lower conical section. The upper support 53 and lower support 54 have similar structures, each including a steel ring 551 embedded in the well wall concrete structure and a central steel ring 552 concentrically arranged therewith, connected by multiple evenly distributed radial ribs 553. Each central steel ring 552 is equipped with ball bearings, and the rotating shaft 51 is connected to the upper support 53 and lower support 54 via these two ball bearing shafts, thereby ensuring smooth rotation of the rotating shaft 51 and minimizing mechanical energy loss during operation.

[0029] The aforementioned blade 52 is a double-helix blade made of high-strength composite material (usually high-strength glass fiber reinforced resin). Its outer surface is sequentially coated with a base epoxy layer, a middle gel coat layer, and a topcoat layer, thereby preventing water flow corrosion and extending its service life. The diameter of the aforementioned double-helix blade 52 is close to the diameter of the surge tank 1. As the water flow rises, most of it is transported along the blade's rotation, greatly improving energy conversion efficiency.

[0030] The aforementioned energy storage spring 4 is mounted on top of the rotating shaft 51 and located above the upper support 53. In this embodiment, two energy storage springs 4 are installed on the rotating shaft 51, and the outer end of each energy storage spring 4 passes through the well wall and is connected to the anchor steel column 31 pre-embedded in the well wall. The preload of the aforementioned energy storage spring 4 can be calibrated according to the design water level fluctuation range. During operation, the rotating shaft 51 is subjected to uniform force, the torque output is stable, the system has a large energy storage capacity, fast response speed, and is safe and reliable.

[0031] In actual engineering construction, geological conditions, topography, and operational requirements should be comprehensively considered, taking into account both safety and cost. The aforementioned surge tank 1 and water pipeline 2 should be placed on the water diversion line or tailrace line to ensure the safety of the device while also meeting economic requirements.

[0032] Based on the aforementioned composite surge tank 1, the method for regulating the hydraulic transition process described in this invention includes: when pressure fluctuations occur in the water pipeline 2, the water level in the surge tank 1 changes accordingly; the change in water level in the surge tank 1 drives the hydraulically driven rotor to rotate, and transmits torque to the energy storage spring 4 through the rotating shaft 51, converting the kinetic energy of the water flow into elastic potential energy for storage; when the deformation resistance of the energy storage spring 4 is balanced with the hydraulic driving force, the water level in the surge tank 1 reaches the extreme value of the fluctuation; thereafter, the water level begins to change in the opposite direction, the energy storage spring 4 releases potential energy, drives the hydraulically driven rotor to rotate in the opposite direction, feeds energy back to the water flow, and accelerates the water level in the surge tank 1 back to a stable state.

[0033] Specifically, the process includes the following: Process I: When a turbine suddenly sheds its load or starts up, pressure waves will propagate along the water conveyance pipe 2 and impedance pipe 3 to the surge tank 1. For example, if the turbine suddenly sheds its load and stops during power generation, the water flow will continue due to inertia. If the surge tank 1 is located in the water intake line, the downstream water flow will be obstructed due to the turbine stopping, while the upstream water flow will continue to flow in. This will cause the water body to be greatly compressed, causing the water level in the surge tank 1 to rise. If the surge tank 1 is located in the tailrace line, the downstream water flow will not stop due to inertia, causing the water body to be under great negative pressure, causing the water level in the surge tank 1 to rise and fall.

[0034] Process II: The water level in surge tank 1 rises or falls with the arrival of pressure waves. During this rise or fall, the double helix blades 52 rotate, and the hydraulically driven rotor transmits torque to the energy storage spring 4. Since the diameter of the double helix blades 52 is close to the diameter of the surge tank, the water pressure can only rise along the rotation of the double helix blades 52, which greatly increases the energy conversion efficiency.

[0035] Process III: As the water level continues to rise or fall, the elastic potential energy of the energy storage spring 4 gradually increases, and the elastic resistance also becomes greater and greater until it reaches its limit. When the elastic resistance of the energy storage spring 4 reaches its maximum, the speed of the water rising or falling is 0 m / s, and the absolute value of the acceleration is at its maximum, which is numerically equal to the vector sum of the elastic resistance and gravity. At the same time, the water level will reach its highest or lowest point, and then the water level will begin to move in the opposite direction to start the next cycle.

[0036] Process IV: During the rise or fall of the water level, the original resistance is now converted into power, which drives the double helix blade 52 to move in the opposite direction. At the same time, the potential energy in the energy storage spring 4 begins to be released, which accelerates the movement of the water flow. When the water level reaches the lowest point, the energy storage spring 4 reaches the elastic potential energy limit again, and so on, performing damping motion. Figure 4 and Figure 5 The diagram shows the trend of water level change in the surge tank. It can be seen that the water level in surge tank 1 gradually decreases in amplitude due to the storage and release of elastic potential energy by the energy storage spring 4.

[0037] The surge tank described in this invention absorbs and releases the kinetic energy of water flow through a hydraulically driven rotor-spring energy storage system, effectively regulating water level fluctuations within the system and reducing or weakening the adverse effects of hydraulic transition. At the same time, it can effectively reduce the size of the tunnel, decrease the tunnel height and diameter, and eliminate the ventilation safety tunnel connecting it to the atmosphere. This allows for effective risk reduction without compromising the effectiveness of the surge tank, and can significantly improve the safety margin of the project, especially when dealing with adverse geological conditions.

[0038] It should be noted that in the description of this invention, terms such as "front," "rear," "left," "right," "vertical," "horizontal," "inner," and "outer" indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

Claims

1. A composite surge tank, suitable for a pumped-storage power station's water diversion and power generation system, characterized in that: The pressure regulating well is located directly above or diagonally above the water transmission pipeline, and the water transmission pipeline is connected to the bottom of the pressure regulating well through an impedance pipe. A mechanical energy storage pressure regulating device is installed inside the pressure regulating well.

2. The composite pressure regulating well according to claim 1, characterized in that: The mechanical energy storage and pressure regulating device includes a hydraulically driven rotor and an energy storage spring. The hydraulically driven rotor includes a rotating shaft and blades disposed thereon. The rotating shaft is connected to a bracket disposed on the well wall. The energy storage spring is a planar volute structure disposed around the rotating shaft, and one end of the energy storage spring is fixedly connected to the rotating shaft, and the other end is fixedly connected to the well wall.

3. The composite pressure regulating well according to claim 2, characterized in that: The well wall comprises a top spherical section, a middle straight section, and a lower conical section connected in sequence; the support includes an upper support disposed at the top of the middle straight section and a lower support disposed at the bottom of the lower conical section, and both the upper support and the lower support are provided with ball bearings located at the center of the well wall cavity; the rotating shaft is connected to the upper support and the lower support through the ball bearing rotating shaft.

4. The composite pressure regulating well according to claim 2, characterized in that: The blade is a double-helix blade made of high-strength composite material, and the outer edge of the blade is set close to the well wall.

5. The composite pressure regulating well according to claim 3, characterized in that: The energy storage spring is located at the top of the rotating shaft and above the upper support.

6. The composite pressure regulating well according to claim 1, characterized in that: The energy storage springs are at least two in number, and a corresponding number of anchoring steel columns are evenly arranged on the outer side of the well wall. The outer end of each energy storage spring passes through the well wall and is connected to the anchoring steel column.

7. The composite pressure regulating well according to claim 1, characterized in that: The water supply pipeline is installed on the water intake line or the tailwater line.

8. A method for regulating the hydraulic transition process, implemented using a composite surge tank as described in any one of claims 1-6, characterized in that: When pressure fluctuations occur in the water pipeline, the water level in the surge tank changes accordingly. The change in water level in the surge tank drives the hydraulically driven rotor to rotate, and transmits torque to the energy storage spring through the shaft, converting the kinetic energy of the water into elastic potential energy. When the deformation resistance of the energy storage spring balances the hydraulic driving force, the water level in the surge tank reaches its extreme fluctuation value. After that, the water level begins to change in the opposite direction, the energy storage spring releases its potential energy, drives the hydraulically driven rotor to rotate in the opposite direction, feeds energy back to the water flow, and accelerates the return of the water level in the surge tank to a stable state.

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