A hydraulic turbine forced air supply system and method of operation

Abstract

The present application relates to a kind of water turbine forced air supplement system and operating method, comprising the following steps: S1, real-time acquisition unit load, water head and unit stability index;S2, load and water head and unit are in vibration area, and the threshold value of water head is compared with the threshold value of load, judge whether current unit is in vibration area, if not, return to step S1, if yes, then enter step S3;S3, unit stability index data and unit stability index threshold value when unit is in stable state are compared, judge whether unit stability index is out of limit, if not, return to step S1, if yes, then enter step S4;S4, according to unit load and water head, calculate the air supplement amount required for current unit to reach stable state, adjust air valve to corresponding opening, real-time air supplement is carried out to unit.The present application can calculate real-time air supplement amount when air supplement, so that air supplement amount can be automatically regulated with load change, and the tail vortex zone is stably improved, and the unit operation stability is improved.

Description

Technical Field

[0001] This invention relates to the field of turbine air supply technology, and in particular to a forced air supply system and operating method for a turbine. Background Technology

[0002] By injecting air into the turbine top cover, the pressure distribution in the flow field can be altered. The gas displaces the liquid flow field, reducing the ratio of its circumferential velocity component to its axial velocity component. This makes the axial velocity distribution in the cross section more uniform, effectively reducing the vortex eccentricity and suppressing pressure pulsation. At the same time, the air injection also changes the pressure gradient distribution in the flow field. As air is introduced into the tailrace pipe, the pressure distribution in the tailrace pipe becomes more uniform, the reverse pressure gradient along the flow direction decreases, and the vortex belt shedding caused by vortex separation transforms into a columnar vortex belt. Simultaneously, the radial cross-sectional pressure gradient distribution also becomes more uniform, thereby suppressing the generation of pressure pulsation.

[0003] Currently, there are two main methods for turbine air replenishment: natural air replenishment and forced air replenishment. Natural air replenishment involves connecting one end of the air replenishment pipe to the atmosphere and the other end to the draft tube. When the turbine deviates from its design operating conditions, vortices form in the draft tube, causing a pressure drop. When the pressure drops below atmospheric pressure, a pressure difference exists between the atmosphere and the draft tube, allowing air to enter the draft tube along the air replenishment pipe. This affects the pressure and pressure gradient within the draft tube, but the amount of air replenishment is difficult to control, failing to achieve the desired effect. Forced air replenishment uses an air compressor to deliver high-pressure gas to the draft tube. When the pressure inside the draft tube is higher than atmospheric pressure, the atmosphere cannot enter the draft tube due to the pressure difference, necessitating this method. While this method solves the problem of high pressure in the draft tube preventing natural air replenishment, the amount of air replenishment cannot be automatically adjusted according to changes in turbine load. This results in insufficient air replenishment under certain loads, ineffective suppression of pressure pulsations in the draft tube, and reduced turbine efficiency due to excessive air replenishment. Therefore, this method still has its drawbacks. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the existing forced air supply method, which cannot be automatically adjusted according to the change of turbine unit load, resulting in insufficient air supply to the turbine unit under a certain load, insignificant effect on suppressing tailrace pressure pulsation, and excessive air supply reducing turbine efficiency. Therefore, the present invention provides a forced air supply system and operation method for a turbine.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for forced air injection operation of a water turbine includes the following steps: S1. Real-time acquisition of unit load, head, and unit stability indicators; S2. Compare the load and head obtained in S1 with the threshold values ​​of head and load when the unit is in the vibration zone to determine whether the unit is currently in the vibration zone. If not, return to step S1; if yes, proceed to step S3. S3. Compare the unit stability index data obtained in S1 with the unit stability index threshold when the unit is in a stable state, and determine whether the unit stability index exceeds the standard. If not, return to step S1; if yes, proceed to step S4. S4. Calculate the amount of air needed for the unit to reach a stable state based on the unit load and head obtained in step S1. Adjust the air valve to the corresponding opening degree and provide real-time air supply to the unit.

[0006] Preferably, the unit load, head, and unit stability indicators are only acquired in real time after the unit has been running stably for a certain period of time.

[0007] Preferably, the unit stability indicators include tailwater pressure pulsation, top cover XY direction vibration, guide vane arm vibration, and inlet door vibration.

[0008] Preferably, in step S4, the air supply volume of the turbine under various operating conditions is determined through numerical simulation and actual machine test results. Then, the load, head and corresponding air supply volume under various operating conditions are formed into multiple sets of data. Through training and learning by the neural network intelligent algorithm, an algorithm model about the head H, load N and air supply volume Q can be obtained. Based on the current unit load and head, the system uses the algorithm model about the head H, load N and air supply volume Q obtained from the training and learning of the neural network intelligent algorithm to calculate the air supply volume required by the current unit.

[0009] A forced air supply system for a water turbine includes a unit status monitoring subsystem, a unit data acquisition and processing subsystem, a controller, an air supply component, and an air supply pipe, wherein the air supply component is electrically connected to the controller. One end of the aforementioned air supply pipe is connected to the air outlet of the aforementioned air supply component, and the other end is connected to the inner cavity of the turbine and installed on the turbine top cover; An air valve is connected to the aforementioned air supply pipe. The aforementioned air valve is electrically connected to the aforementioned controller. The aforementioned controller is electrically connected to the aforementioned unit data acquisition and processing subsystem. The aforementioned unit data acquisition and processing subsystem is electrically connected to the aforementioned unit status monitoring subsystem.

[0010] Preferably, it also includes a main pipeline, the air inlet of which is connected to the air outlet of the air supply component, and there are multiple air supply pipes, the air inlet of any one of the air supply pipes is connected to the main pipeline, and the multiple air supply pipes are evenly distributed circumferentially on the turbine top cover.

[0011] Preferably, any one of the aforementioned air supply pipes is also connected to a check valve, which is located downstream of the aforementioned air valve.

[0012] Preferably, any one of the above-mentioned gas supply pipes is also connected to a gas flow meter, and the gas flow meter is electrically connected to the controller.

[0013] Preferably, the above-mentioned air replenishment component includes an air compressor and an air tank, the air outlet of the air compressor is connected to the air inlet of the air tank, and the air outlet of the air tank is connected to the air replenishment pipe.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The system acquires real-time data on the unit's load, head, and stability indicators. Only when all three indicators are within the vibration zone is the system accurately determined that the unit is in the vibration zone and air replenishment is required. This prevents accidental air replenishment, which could interfere with the unit's operational stability. Furthermore, the required air replenishment amount under real-time load is calculated based on the acquired load and head data, allowing for automatic adjustment and replenishment as the unit's load changes. This prevents insufficient air replenishment under certain load conditions, thereby stabilizing the tailrace vortex zone and improving the unit's operational stability and efficiency. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a diagram illustrating the system operation method in an embodiment of the present invention; Figure 2 This is an overall schematic diagram of an embodiment of the present invention; Figure 3 This is a structural diagram of the device within an embodiment of the present invention; Figure 4 This is a comparison diagram of the X-axis vibration of the top cover before and after forced air replenishment in an embodiment of the present invention; Figure 5 This is a comparison diagram of the top cover vibration in the Y direction before and after forced air replenishment in an embodiment of the present invention; Figure 6 This is a comparison diagram of the vibration of the guide vane arm before and after forced air injection in an embodiment of the present invention; Figure 7 This is a comparison diagram of the vibration of the forced air supply inlet door in an embodiment of the present invention; Figure 8 This is a diagram showing the relationship between different water heads and unit output corresponding to the amount of supplemental air in the system in the embodiments of the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Air supply assembly; 11. Air compressor; 12. Air storage tank; 2. Main pipeline; 3. Air supply pipe; 4. Air valve; 5. Check valve; 6. Gas flow meter; 7. Turbine top cover. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not 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 the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Example This invention provides a method for forced air injection operation of a water turbine, such as... Figure 1 As shown, it includes the following steps. S1. Real-time acquisition of unit load, head, and unit stability indicators; S2. Compare the load and head obtained in S1 with the threshold values ​​of head and load when the unit is in the vibration zone to determine whether the unit is currently in the vibration zone. If not, return to step S1; if yes, proceed to step S3. S3. Compare the unit stability index data obtained in S1 with the unit stability index threshold when the unit is in a stable state, and determine whether the unit stability index exceeds the standard. If not, return to step S1; if yes, proceed to step S4. S4. Calculate the amount of air needed for the unit to reach a stable state based on the unit load and head obtained in step S1. Adjust the air valve to the corresponding opening degree and provide real-time air supply to the unit.

[0022] In the above method, the system acquires real-time data on the unit's load, head, and stability indicators. Only when the load, head, and stability indicators are all within the vibration zone is the system accurately determined that the unit is in the vibration zone and air replenishment is required. This avoids accidental air replenishment, which could interfere with the stability of the unit's operation. Moreover, the amount of air replenishment required by the unit under real-time load is calculated based on the acquired load and head, allowing the unit's air replenishment to be automatically adjusted and replenished as the unit's load changes. This prevents insufficient air replenishment of the turbine unit under a certain load, thereby steadily improving the tailrace vortex zone and enhancing the unit's operational stability and efficiency.

[0023] Furthermore, after the unit has been running stably for 3-5 minutes, the unit load, head, and stability indicators are acquired in real time. Then, step S2 is performed to determine whether the unit is in the vibration zone, so as to avoid performing gas supply operation when the unit is in the start-up or shutdown phase. Specifically, the load deviation during stable operation is considered to be within ±10%.

[0024] Furthermore, the unit stability indicators include tailwater pressure pulsation, top cover XY direction vibration, guide vane arm vibration, and inlet door vibration.

[0025] Furthermore, in step S4, the air supply volume of the turbine under various operating conditions is determined through numerical simulation and actual machine test results. Then, the load, head, and corresponding air supply volume under various operating conditions are formed into multiple sets of data. Through training and learning in the neural network intelligent algorithm, an algorithm model is obtained regarding the head H, load N, and air supply volume Q. Based on the current unit load and head, the system uses the algorithm model regarding the head H, load N, and air supply volume Q obtained through training in the neural network intelligent algorithm to calculate the air supply volume required by the current unit. The neural network intelligent algorithm extends the relationship between head H, load N, and air supply volume Q obtained from numerical simulation calculation or actual machine test, solving the problem of limited and discontinuous operating points in numerical simulation calculation or actual machine test, thereby obtaining the air supply volume Q corresponding to each head H and each load N.

[0026] The above-mentioned air-injection operation method corresponds to a turbine forced air-injection system, such as... Figure 2-3As shown, the system includes a unit data acquisition and processing subsystem, a controller, a gas supply component 1, and a gas supply pipe 3. The gas supply component 1 is electrically connected to the controller. One end of the gas supply pipe 3 is connected to the outlet of the gas supply component 1 via a flange, and the other end is connected to the inner cavity of the turbine and installed on the turbine top cover 7 via a flange. An air valve 4 is connected to the gas supply pipe 3 via a flange. The air valve 4 is electrically connected to the controller, the controller is electrically connected to the unit data acquisition and processing subsystem, and the unit data acquisition and processing subsystem is electrically connected to the unit status monitoring subsystem. Specifically, both the unit data acquisition and processing subsystem and the unit status monitoring subsystem are existing systems within the power plant.

[0027] Specifically, the unit data acquisition and processing subsystem obtains data from the unit status monitoring subsystem. Then, the unit data acquisition and processing subsystem compares the obtained data with the unit stability data set within it to determine whether the unit is in the vibration zone. If the unit is in the vibration zone, the unit data acquisition and processing subsystem calculates the amount of air replenishment required by the unit at this time and sends a signal to the controller. The controller controls the air valve 4 to open, and the air replenishment component 1 replenishes air through the air replenishment pipe 3, thereby improving the operating stability of the tailrace vortex and the unit in the original vibration zone and ensuring stable operation of the unit.

[0028] Furthermore, it also includes a main pipe 2, the air inlet of the main pipe 2 is connected to the air outlet of the air supply component 1, and there are multiple air supply pipes 3. The air inlet of any one air supply pipe 3 is connected to the main pipe 2. The multiple air supply pipes 3 are evenly distributed circumferentially on the turbine top cover 7, so that the gas entering the bladeless area of ​​the runner remains uniform in the circumferential direction, and the generation of pressure pulsation is stably suppressed.

[0029] Furthermore, each of the air supply pipes 3 is connected to a check valve 5, which is located downstream of the air valve 4 to prevent water and gas from flowing back into the unit and to ensure the normal operation of the air supply pipe 3.

[0030] Furthermore, any one of the gas supply pipes 3 is also connected to a gas flow meter 6, which is electrically connected to the controller. This allows the amount of gas supplied to the unit to be known in real time, thereby displaying the relationship between the amount of gas supplied to the gas supply pipe 3 and the unit's stability indicators in real time, which is convenient for staff to analyze.

[0031] Furthermore, the air supply component 1 includes an air compressor 11 and an air tank 12. The air outlet of the air compressor 11 is connected to the air inlet of the air tank 12, and the air outlet of the air tank 12 is connected to the air inlet of the main pipeline 2 through a flange. By setting the air tank 12, a constant initial pressure is achieved in the air tank 12, and air is stably supplied through the air supply pipe 3.

[0032] The specific operating method of the above-mentioned air replenishment system is as follows: First, the unit data acquisition and processing subsystem obtains real-time unit load, head, and stability indicators from the unit status monitoring subsystem. Then, it compares the collected data with the head threshold and load threshold set within the unit data acquisition and processing subsystem when the unit is in the vibration zone, and then determines whether the unit is currently in the vibration zone. If the unit is not in the vibration zone, the unit data acquisition and processing subsystem does not send a signal to the controller, the unit operates normally, and the unit data acquisition and processing subsystem continues to collect real-time data for comparison, repeating this process. If the unit is in the vibration zone, the unit data acquisition and processing subsystem simultaneously collects and compares the real-time data. The data processing subsystem compares the stability index data obtained from the unit status monitoring subsystem with the standard stability index data set within it, and then determines whether the unit stability index is in a stable state. If it is in a stable state, no signal is sent to the control system, and the system continues to judge based on the re-acquired head, load, and unit stability index, repeating the process. If the unit stability index exceeds the standard, the unit data acquisition and processing subsystem calculates the air replenishment amount and then sends a signal to the controller. The controller controls the air compressor 11 to run, and the air valve 4 opens to the corresponding degree. Then, the gas in the air storage tank 12 is replenished to the turbine through the main pipeline 2 and multiple air replenishment pipes 3.

[0033] Example of effect like Figure 4-7 As shown, the above figures are, in order, comparisons of the X and Y direction vibrations of the top cover, the guide vane arm, and the inlet door before and after forced air injection. From the vibration trend of the top cover / guide vane arm, forced air injection has a significant effect on reducing the vertical vibration amplitude of the top cover and the guide vane arm. The maximum percentage decrease in the effective value of the vertical vibration acceleration amplitude of the top cover reaches 50%. The decrease is significant in the +Y direction of the top cover, i.e., at the inlet of the volute. The forced air injection system has a significant weakening effect on the vibration value in the low-load area.

[0034] like Figure 8 The diagram shows the relationship between different water heads and unit output corresponding to the amount of supplementary air. When the unit output is small, the amount of supplementary air corresponding to different water heads is small and the difference is not significant. As the unit output increases, the amount of supplementary air under each water head also increases. Under the same unit output, the smaller the water head, the greater the amount of supplementary air.

[0035] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for forced air supply operation of a water turbine, characterized in that, The steps include the following: S1. Real-time acquisition of unit load, head, and unit stability indicators; S2. Compare the load and head obtained in S1 with the threshold values ​​of head and load when the unit is in the vibration zone to determine whether the unit is currently in the vibration zone. If not, return to step S1; if yes, proceed to step S3. S3. Compare the unit stability index data obtained in S1 with the unit stability index threshold when the unit is in a stable state, and determine whether the unit stability index exceeds the standard. If not, return to step S1; if yes, proceed to step S4. S4. Calculate the amount of air needed for the unit to reach a stable state based on the unit load and head obtained in step S1. Adjust the air valve to the corresponding opening degree and provide real-time air supply to the unit. In step S4, the air supply is calculated as follows: the air supply for various operating conditions of the turbine is determined through numerical simulation and actual machine test results. Then, the load, head and corresponding air supply under various operating conditions are formed into multiple sets of data and trained and learned through a neural network intelligent algorithm to obtain an algorithm model for the head H, load N and air supply Q. Based on the current unit load and head, the system uses the algorithm model for the head H, load N and air supply Q obtained from the training and learning of the neural network intelligent algorithm to calculate the air supply required by the current unit.

2. The forced gas replenishment operation method according to claim 1, characterized in that, Only after the unit has been running stably for a certain period of time will the unit load, head and unit stability indicators be acquired in real time.

3. The forced gas replenishment operation method according to claim 1, characterized in that, The unit stability indicators include tailwater pressure pulsation, top cover XY direction vibration, guide vane arm vibration, and inlet door vibration.

4. A forced air supply system for a water turbine, used to implement the forced air supply operation method according to any one of claims 1-3, characterized in that, This includes a unit status monitoring subsystem, a unit data acquisition and processing subsystem, a controller, a gas supply assembly, and a gas supply pipe; One end of the air supply pipe is connected to the air outlet of the air supply component, and the other end is connected to the inner cavity of the water turbine and installed on the top cover of the water turbine. An air valve is connected to the air supply pipe, and the air valve is electrically connected to the controller; The unit data acquisition and processing subsystem is electrically connected to the unit status monitoring subsystem. The unit data acquisition and processing subsystem obtains real-time unit load, head, and stability indicators from the unit status monitoring subsystem. The unit data acquisition and processing subsystem is used to first compare the acquired unit load and head with the load threshold and head threshold when the unit is in the vibration zone to determine whether the unit is currently in the vibration zone. When the unit is in the vibration zone, the acquired unit stability index data is then compared with the unit stability index threshold when the unit is in a stable state to determine whether the unit stability index exceeds the standard. The unit data acquisition and processing subsystem is electrically connected to the controller so that when the unit stability index data exceeds the standard, it sends a signal to the controller. The controller adjusts the air valve to the corresponding opening degree according to the air replenishment volume calculated by the unit data acquisition and processing subsystem based on the unit load and water head.

5. The air replenishment system according to claim 4, characterized in that, It also includes a main pipeline, the air inlet of which is connected to the air outlet of the air supply component. There are multiple air supply pipes, and the air inlet of any one of the air supply pipes is connected to the main pipeline. The multiple air supply pipes are evenly distributed circumferentially on the turbine top cover.

6. The gas replenishment system according to claim 5, characterized in that, Each of the air supply pipes is also connected to a check valve, which is located downstream of the air valve.

7. The air replenishment system according to claim 5, characterized in that, Each of the gas supply pipes is also connected to a gas flow meter, which is electrically connected to the controller.

8. The air replenishment system according to claim 4, characterized in that, The air replenishment assembly includes an air compressor and an air tank. The air outlet of the air compressor is connected to the air inlet of the air tank, and the air outlet of the air tank is connected to the air replenishment pipe.

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