Control method for accelerating surge attenuation of pump storage power station surge chamber

Abstract

The present application relates to the technical field of water conservancy and hydropower engineering, and particularly relates to a control method for accelerating surge attenuation of a surge chamber of a pumped storage power station. Two units are first unloaded, and at a first opening time T1, one unit is opened from no-load opening to guide vane pause relative opening τ Z . Most of the surge chamber water level fluctuation is offset by opening a large opening degree for first-stage regulation, and the remaining water level fluctuation is reserved for subsequent guide vane action to offset; subsequently, the guide vane maintains a constant relative opening τ Z , and at a second opening time T2, the guide vane is opened from τ Z to full opening. The remaining surge chamber water level fluctuation is offset by opening a small opening degree for second-stage regulation, and through stepwise differential regulation, rapid attenuation of the water level fluctuation is achieved. A solution method for the first opening time T1 and the second opening time T2, and the guide vane pause relative opening τ Z is given. The present application accelerates the attenuation of the surge of the surge chamber, reduces the grid-connection waiting time after the unit is unloaded, improves the flexibility of the unit operation, and increases the power generation benefit of the hydropower station.

Description

Technical Field

[0001] This invention relates to the field of water conservancy and hydropower engineering technology, specifically to a control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station. Background Technology

[0002] In hydropower systems with long diversion tunnels or long tailrace tunnels, surge tanks are often constructed at the junction of the tunnel and the pressure pipeline. Surge tanks are used to reflect water hammer waves, optimize water hammer pressure in the pressure pipeline, and improve the operating conditions of the generating units. The longer the tunnel, the longer the period of mass fluctuation in the surge tank, and the more likely the mass fluctuations in the surge tank will superimpose. For example, when the load of the hydropower generating units changes, the water level in the surge tank on the pressure pipeline will change accordingly, significantly affecting the stability of the pipeline.

[0003] Currently, to ensure the stability of hydropower station pipeline operation, the surge tank is designed from the outset with the most unfavorable superimposed conditions of surge tank quality fluctuations under combined operating conditions in mind. For example, the hydropower station units may experience "load increase followed by load shedding" (i.e., the unit load increases and then shedding) and "load shedding followed by load increase" (i.e., the unit load shedding occurs and then needs to be increased). The minimum and maximum surge waves of the surge tank are calculated for these two superimposed conditions, respectively, and these are used as the design basis for the top elevation and bottom elevation of the surge tank.

[0004] To address the most favorable superposition of surge tank mass fluctuations under combined operating conditions, a study on the most favorable superposition of surge tank mass fluctuations was conducted. It was found that the rising and falling processes of surge tank water level fluctuations form a series of operable "time windows." By increasing the load during the rising process of surge tank water level and reducing the load during the falling process of surge tank water level fluctuations, the goal of rapidly attenuating surge tank water level fluctuations can be achieved.

[0005] For the superimposed "load shedding followed by load increase" operating condition, the load shedding is uncontrollable, but the load increase can be manually intervened. Therefore, existing technologies propose increasing the unit load during the rise of the surge tank water level and pausing the load increase during the fall of the surge tank water level. This "increase-stop-increase" step-shaped load increase method is used to quickly attenuate the surge tank swell. However, for the "increase-stop-increase" step-shaped load increase method, the start time of the load increase is selected when the surge tank water level rises, and the start time of pausing the load increase is selected when the surge tank water level falls. This makes it difficult to achieve the optimal control method for quickly attenuating the surge tank swell.

[0006] In summary, when a generator unit in a diversion-type hydropower station experiences load shedding, how to design a surge control method to rapidly attenuate surges in a voltage-regulating system and reduce the waiting time for the unit to reconnect to the grid after load shedding has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a surge control method for situations where the generating units of a diversion-type hydropower station experience load shedding. This method aims to rapidly attenuate surges in a voltage-regulating system, reduce the waiting time for the generating units to reconnect to the grid after load shedding, and improve the power generation efficiency of the hydropower station.

[0008] To achieve the above objectives, the present invention adopts the following scheme: a control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station is proposed, comprising: adjusting the first-sag-then-increase condition of a water conveyance power generation system with an upstream surge chamber, characterized in that: utilizing the most favorable moment of the superposition of surge chamber water level fluctuations in two stages, through graded differential adjustment, the potential energy difference between the surge chamber water level and the reservoir water level and the difference in the inertial performance of the tunnel water flow are gradually reduced, thereby achieving rapid attenuation of surge chamber water level fluctuations.

[0009] As a preferred embodiment, a control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station includes the following steps:

[0010] Step 1: Determine the first-stage start-up time for surge in the pressure regulating chamber. T The timing of occurrence of 1, and the relative opening of the guide vane at pause. τ Z The value of and the second-level start time T The time of occurrence of 2;

[0011] Step 2: When a water-transfer power generation system with an upstream surge chamber and a "one tunnel, two generators" configuration experiences a load shedding followed by load increase, both generators will first shed their load at the first-level start-up time. T 1. The relative opening degree of a machine from its no-load opening to its guide vane pausing. τ Z The primary regulation increases the opening to offset most of the pressure chamber water level fluctuations, while retaining the remaining water level fluctuations for subsequent guide vane actions to offset them.

[0012] Step 3: Maintain the relative opening of the guide vanes. τ Z Constant, at the second-level opening time T 2 by τ Z Open to full opening, and then adjust to a smaller opening through secondary regulation to offset the remaining water level fluctuations in the pressure regulating chamber, thereby achieving rapid attenuation of water level fluctuations.

[0013] Based on the principle of superimposed water level fluctuations, the most favorable moment for superimposed water level fluctuations is when the surge tank water level and the tunnel flow rate are tangent under the initial and superimposed operating conditions. When water level fluctuations are superimposed at this moment, the potential energy difference between the surge tank water level and the reservoir water level, as well as the mutual conversion of the tunnel flow inertia, can be offset to the greatest extent, thus attenuating the surge tank water level fluctuations. However, through single-stage regulation, the potential energy difference between the surge tank water level and the reservoir water level, and the difference in tunnel flow inertia, are significant. An optimal control method for rapidly attenuating surge tank waves involves graded differential regulation to gradually reduce the potential energy difference between the surge tank water level and the reservoir water level, and the difference in tunnel flow inertia, thereby achieving rapid attenuation of water level fluctuations.

[0014] As a preferred option, in step one, the first-level activation time T 1. This occurs when the water level in the surge chamber rises during the second wave, at which the flow rate into the surge chamber is at its maximum. This moment can be easily measured by a pressure sensor or a flow sensor, and can be used as the most favorable moment for the first-level regulation of water level fluctuations.

[0015] As a preferred option, the guide vane pauses relative opening. τ Z The value of needs to be determined through numerical simulation of the transient process.

[0016] As a preferred option, the second-level activation time T 2. This occurs when the water level in the surge tank rises during the third wave, at which the flow rate into the surge tank is at its maximum. This moment can be easily measured by a pressure sensor or a flow sensor, and can be used as the most favorable moment for secondary regulation by superimposed water level fluctuations.

[0017] This invention provides a control method for accelerating the attenuation of surge waves in the surge chamber of a pumped-storage power station. Compared with existing technologies, this method has the following outstanding substantive features and significant advancements: It utilizes the most favorable moment of superimposed surge wave fluctuations in the surge chamber in two stages. Through graded differential regulation, it gradually reduces the potential energy difference between the surge chamber water level and the reservoir water level, as well as the difference in inertial properties of the tunnel flow, achieving rapid attenuation of surge chamber water level fluctuations. The physical meaning is clear, overcoming the blindness of existing technologies. The surge chamber water level fluctuations can be quickly stabilized within a certain range, reducing the grid connection waiting time after unit load shedding, improving the flexibility of unit operation, and increasing the power generation efficiency of the hydropower station. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the water level change process in the pressure chamber at different superimposed moments during the second wave of water level rise, using single-stage regulation in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the process of water level change in the pressure chamber by adjusting the relative opening of different guide vanes in two stages in an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the process of pressure chamber water level and guide vane relative opening change when the optimal guide vane pausing relative opening is adjusted in two stages in an embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the assembly structure of the adjusting device in an embodiment of the present invention;

[0022] Figure 5 This is a three-dimensional structural schematic diagram of the adjustment device in an embodiment of the present invention;

[0023] Figure 6 yes Figure 5 The main view;

[0024] Figure 7 yes Figure 6 A bottom view;

[0025] Figure 8 This is an isometric sectional view of the adjustment device in an embodiment of the present invention.

[0026] Reference numerals in the attached diagram: 1. Upstream reservoir; 2. Upstream water diversion pipeline; 3. Upstream surge tank; 4. Power generation chamber; 5. Turbine; 6. Guide vane ring; 7. Regulating assembly; 8. Downstream water diversion pipeline; 9. Connecting seat; 10. Waterproof cover; 11. Diversion cover; 71. Turntable; 72. Baffle unit; 73. Transmission structure; 74. Motor; 721. Rotating shaft; 722. Water baffle; 731. Connecting plate; 732. Arc-shaped gear plate; 733. Transmission gear. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] Example 1

[0029] like Figure 1-3 As shown in the embodiment of the present invention, a control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station is proposed. This method utilizes the most favorable moment of superposition of surge chamber water level fluctuations in two stages. Through graded differential regulation, it gradually reduces the potential energy difference between the surge chamber water level and the reservoir water level, as well as the difference in inertial properties of the tunnel water flow, achieving rapid attenuation of surge chamber water level fluctuations. The physical meaning is clear, overcoming the blindness of existing technologies. The surge chamber water level fluctuations can be quickly stabilized within a certain range, reducing the grid connection waiting time after unit load shedding, improving the flexibility of unit operation, and increasing the power generation efficiency of the hydropower station.

[0030] This invention proposes a control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station, comprising:

[0031] Step 1: Determine the first-stage start-up time for surge in the pressure regulating chamber. TThe timing of occurrence of 1, and the relative opening of the guide vane at pause. τ Z The value of and the second-level start time T The time of occurrence of 2;

[0032] Step 2: When a water-transfer power generation system with an upstream surge chamber and a "one tunnel, two generators" configuration experiences a load shedding followed by load increase, both generators will first shed their load at the first-level start-up time. T 1. The relative opening degree of a machine from its no-load opening to its guide vane pausing. τ Z The primary regulation increases the opening to offset most of the pressure chamber water level fluctuations, while retaining the remaining water level fluctuations for subsequent guide vane actions to offset them.

[0033] Step 3: Maintain the relative opening of the guide vanes. τ Z Constant, at the second-level opening time T 2 by τ Z Open to full opening, and then adjust to a smaller opening through secondary regulation to offset the remaining water level fluctuations in the pressure regulating chamber, thereby achieving rapid attenuation of water level fluctuations.

[0034] Based on the principle of superimposed water level fluctuations, the most favorable moment for superimposed water level fluctuations is when the surge tank water level and the tunnel flow rate are tangent under the initial and superimposed operating conditions. When water level fluctuations are superimposed at this moment, the potential energy difference between the surge tank water level and the reservoir water level, as well as the mutual conversion of the tunnel flow inertia, can be offset to the greatest extent, thus attenuating the surge tank water level fluctuations. However, through single-stage regulation, the potential energy difference between the surge tank water level and the reservoir water level, and the difference in tunnel flow inertia, are significant. An optimal control method for rapidly attenuating surge tank waves involves graded differential regulation to gradually reduce the potential energy difference between the surge tank water level and the reservoir water level, and the difference in tunnel flow inertia, thereby achieving rapid attenuation of water level fluctuations.

[0035] In step one, the first level is activated. T 1. This occurs when the water level in the surge chamber rises during the second wave, at which the flow rate into the surge chamber is at its maximum. This moment can be easily measured by a pressure sensor or a flow sensor, and can be used as the most favorable moment for the first-level regulation of water level fluctuations.

[0036] Guide vane pause relative opening τ Z The value of needs to be determined through numerical simulation of the transient process.

[0037] Level 2 activation time T 2. This occurs when the water level in the surge tank rises during the third wave, at which the flow rate into the surge tank is at its maximum. This moment can be easily measured by a pressure sensor or a flow sensor, and can be used as the most favorable moment for secondary regulation by superimposed water level fluctuations.

[0038] The control method of this invention is applied to the Jinzhai pumped storage power station in Anhui Province. The upstream surge tank corresponds to two generating units, and the opening rate of both stages of the guide vanes is 1 / 30s⁻¹. For example... Figure 1 As shown, initially, both generating units shed load. During the second wave of water level rise in the surge tank, one unit adopted single-stage regulation, starting from no-load and gradually increasing to full opening. When the start-up occurred at the most favorable moment for the superposition of water level fluctuations, the water level rise was the lowest, and subsequent water level fluctuations were minimal. This verifies that the superposition of water level fluctuations occurring at the most favorable moment can maximize the offsetting of the potential energy difference between the surge tank water level and the reservoir water level, as well as the mutual conversion of the tunnel flow inertia, thus attenuating the water level fluctuations in the surge tank. However, the potential energy difference between the surge tank water level and the reservoir water level, and the difference in tunnel flow inertia, are significant, and subsequent water level fluctuations cannot be ignored.

[0039] like Figure 2 As shown, the relative opening τ of the guide vane at pause was calculated through trial and error. Z This method allows for the convenient identification of the optimal relative opening of the guide vanes during two-stage regulation to effectively and smoothly manage water level fluctuations in the surge tank. In this example, the optimal relative opening of the guide vanes during two-stage regulation is 0.8. Through the first stage of regulation, the water level rises slightly, but subsequent fluctuations remain. Through the second stage of regulation, these fluctuations are further reduced, resulting in a generally smooth water level fluctuation. This verifies that the graded differential regulation method can progressively reduce the potential energy difference between the surge tank and reservoir water levels, as well as the difference in the inertial properties of the tunnel flow, thereby achieving rapid attenuation of water level fluctuations.

[0040] like Figure 3 This paper presents an optimal control method for rapidly attenuating surges in a surge chamber. Initially, both generating units shed load, and their guide vanes are closed to their no-load opening. The surge chamber water level initially rises and then falls. During the second surge in water level, at the moment when the inflow into the surge chamber is at its maximum or the slope of the surge chamber water level rise is at its maximum, a primary regulation is implemented. One generating unit opens from its no-load opening to the optimal guide vane pause relative opening of 0.85, and then maintains the optimal guide vane pause relative opening at 0.85. The surge chamber water level rises relatively low, while retaining the remaining water level fluctuations to be offset by subsequent guide vane actions. During the third surge in water level, at the moment when the inflow into the surge chamber is at its maximum or the slope of the surge chamber water level rise is at its maximum, a secondary regulation is implemented. One generating unit opens from the optimal guide vane pause relative opening of 0.85 to its full opening. The surge chamber water level shows virtually no rise, and subsequent water level fluctuations are generally smooth.

[0041] Example 2

[0042] The control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station, as proposed in this embodiment of the invention, involves a regulating device. For example... Figure 4 As shown, the regulating device includes a water turbine 5 and a regulating component 7.

[0043] The turbine 5 is located inside the power generation chamber 4 of the pumped storage power station. The side wall of the power generation chamber 4 is connected to the upstream water intake pipe 2. A guide vane ring 6 is fitted on the outside of the turbine 5. The guide vane ring 6 and the turbine 5 form an intake chamber. The upstream water intake pipe 2 is used to introduce water from the upstream reservoir 1 into the power generation chamber 4.

[0044] like Figure 5 As shown, the adjustment assembly 7 includes a turntable 71, baffle units 72, a transmission structure 73, and a motor 74 that drives the turntable 71 to rotate. The turntable 71 is located below the guide vane ring 6. The motor 74 is connected to the turntable 71 via the transmission structure 73. The baffle units 72 are located in the water inlet chamber. Multiple baffle units 72 are arranged in a circle along the axis of the turntable 71.

[0045] like Figure 7 Combination Figure 8 As shown, the baffle unit 72 includes a rotating shaft 721 and a baffle plate 722. One end of the rotating shaft 721 is connected to the casing of the turbine 5. The other end of the rotating shaft 721 is connected to the turntable 71. The baffle plate 722 is fixed to the side wall of the rotating shaft 721. A water inlet channel is formed between the baffle plate 722 and the guide vane ring 6.

[0046] Among them, the guide vane ring 6 on the outside of the turbine 5 and the baffle unit 72 in the regulating assembly 7 form a water inlet channel at the water inlet of the turbine 5. The motor 74 drives the turntable 71 to rotate through the transmission structure 73, which in turn drives the baffle 722 connected to the rotating shaft 721 to rotate together, thereby realizing the adjustment of the relative opening within the water inlet channel.

[0047] like Figure 4 As shown, a waterproof cover 10 is provided at the end of the shaft 721 that is connected to the housing. The waterproof cover 10 is connected to the housing. With this configuration, the waterproof cover 10 is used to form a protection at the end of the shaft 721, preventing water from entering the turbine 5 from the end of the shaft 721, which helps to reduce the corrosion of the shaft 721 by the water flow, thereby improving the service life of the regulating component 7.

[0048] A diversion shroud 11 is installed at the bottom of the turbine 5. This design allows the diversion shroud 11 to guide the tailflow of the turbine 5 into the downstream water intake pipe 8, which helps to relieve the pressure inside the water intake pipe.

[0049] like Figure 6 As shown, the transmission structure 73 includes a connecting plate 731, an arc-shaped gear plate 732, and a transmission gear 733. One end of the connecting plate 731 is fixed to the side wall of the turntable 71. The other end of the connecting plate 731 is connected to the arc-shaped gear plate 732 by fasteners. The transmission gear 733 is mounted on the output shaft of the motor 74. The transmission gear 733 meshes with the arc-shaped gear plate 732.

[0050] With this configuration, the output shaft of the motor 74 is connected to the side wall of the turntable 71 via the gear transmission structure 73 and the connecting plate 731, which helps to improve the transmission accuracy and thus improves the positional accuracy of the baffle plate 722 in the regulating assembly 7 as it rotates with the rotating shaft 721. During the load reduction process of the unit, this further promotes the attenuation of the surge amplitude in the upstream pressure regulating chamber 3.

[0051] like Figure 7 As shown, a connecting seat 9 is provided at the bottom of the turntable 71. The connecting seat 9 is fixed to the bottom of the turntable 71. The end of the rotating shaft 721 is embedded in the connecting seat 9. With this configuration, the connecting seat 9 is used to reduce the assembly difficulty of the rotating shaft 721 and the turntable 71, which helps to improve the stability of the rotating shaft 721 as it rotates with the turntable 71, and thus helps to ensure the consistency of rotation among the various baffle units 72.

[0052] For example, the end of the shaft 721 is connected to the casing of the turbine 5 via a bearing. This arrangement helps to further reduce the assembly difficulty between the shaft 721 and the turbine 5.

[0053] The guide vane ring 6 has fixed guide vanes inside, which are arranged in a circle along the axis of the guide vane ring 6. Each of the fixed guide vanes corresponds to a baffle plate, which helps to create a uniform opening in the water inlet channel. For example, the number of fixed guide vanes is preferably 10-16, and the number of baffle plates is the same as the number of fixed guide vanes.

[0054] This invention is not limited to the specific technical solutions described in the above embodiments. Besides the above embodiments, this invention may have other implementation methods. For those skilled in the art, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station, characterized in that, include: The method for regulating the first-drop-then-increase operation of a water conveyance power generation system with an upstream surge chamber is characterized by: utilizing the most favorable moment of the superposition of surge chamber water level fluctuations in two stages, and gradually reducing the potential energy difference between the surge chamber water level and the reservoir water level and the difference in the inertial performance of the tunnel water flow through graded differential regulation, thereby achieving rapid attenuation of surge chamber water level fluctuations. in: Step 1: For surge waves in the pressure regulating chamber, determine the occurrence time of the first-stage opening time T1 and the relative opening degree τ of the guide vanes at pause. Z The value of and the occurrence time of the secondary start time T2; Step 2: When a water conveyance power generation system with an upstream surge chamber and a "one tunnel, two generators" configuration experiences a load shedding followed by load increase, both generators first shed the load. At the first-stage opening moment T1, one generator opens from its no-load opening to the guide vane pausing at a relative opening τ. Z The primary regulation increases the opening to offset most of the pressure chamber water level fluctuations, while retaining the remaining water level fluctuations for subsequent guide vane actions to offset them. Step 3: Maintain the relative opening τ of the guide vanes. Z Constant, at the second-order start time T2, it is determined by τ Z Open to full opening, then adjust to a smaller opening through secondary regulation to offset the remaining water level fluctuations in the pressure regulating chamber, thus achieving rapid attenuation of water level fluctuations; In step one, the first-stage opening time T1 occurs when the flow rate into the pressure chamber is at its maximum during the second wave of the rise in the water level of the pressure chamber. This time can be easily measured by a pressure sensor or a flow sensor, and is used as the most favorable time for the first-stage regulation of the superimposed water level fluctuations. The secondary start-up time T2 occurs when the water level in the pressure chamber rises during the third wave, at the moment when the flow rate into the pressure chamber is at its maximum. This moment can be easily measured by a pressure sensor or a flow sensor, and is used as the most favorable moment for secondary regulation with superimposed water level fluctuations.

2. The control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station according to claim 1, characterized in that, The guide vane pauses at a relative opening τ Z The value of needs to be determined through numerical simulation of the transient process.

3. The control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station according to claim 1, characterized in that, Rapid attenuation of water level fluctuations in the pressure regulating chamber is achieved through an adjustment device, which includes a water turbine and an adjustment assembly. The turbine is located in the power generation chamber of the pumped storage power station. The side wall of the power generation chamber is connected to the upstream water intake pipe. A guide vane ring is fitted on the outside of the turbine, and the guide vane ring and the turbine form a water intake chamber. The adjustment assembly includes a turntable, a baffle unit, a transmission structure, and a motor that drives the turntable to rotate. The turntable is located below the guide vane ring. The motor is connected to the turntable through the transmission structure. The baffle unit is located in the water inlet chamber, and multiple baffle units are arranged in a circle along the axis of the turntable.

4. The control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station according to claim 3, characterized in that, The baffle unit includes a rotating shaft and a baffle plate. One end of the rotating shaft is connected to the casing of the water turbine, and the other end of the rotating shaft is connected to the turntable. The baffle plate is fixed on the side wall of the rotating shaft, and a water inlet channel is formed between the baffle plate and the guide vane ring.

5. The control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station according to claim 4, characterized in that, A waterproof cover is provided at one end of the rotating shaft that is connected to the housing, and the waterproof cover is connected to the housing.

6. The control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station according to claim 3, characterized in that, The guide vane ring has fixed guide vanes inside, which are arranged in a circle along the axis of the guide vane ring.

7. The control method for accelerating the attenuation of surge waves in the surge chamber of a pumped storage power station according to claim 3, characterized in that, The bottom of the water turbine is equipped with a diversion cover.

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