Method and system for measuring and calculating average water level of stilling pool of flood discharge dam section

Abstract

The invention relates to the technical field of safety monitoring and hydraulic calculation of water conservancy and hydropower engineering, in particular to a flood discharge dam section stilling pool average water level measuring and calculating method and system.The method comprises the steps that firstly, multi-source monitoring data of the opening degree of a radial gate, the dam front water level, the plant tail water level and the total flow of a warehouse-out station are collected, and quality control processing is conducted on the data; then, on the basis of the opening degree of the radial gate and the water level in front of the dam, the flood discharge flow and the total flood discharge flow of each gate orifice are calculated through a three-dimensional discharge curve; then, according to the difference value between the total flow of the warehouse-out station and the total flood discharge flow, the power generation tail water flow is calculated in combination with a water level-flow relation curve corresponding to the plant tail water level, and a dynamic flow balance model is established; and finally, generating a stilling pool water level initial value by adopting a non-constant flow empirical formula method, iteratively calculating the conjugate water depth through a hydraulic jump equation, and improving the calculation precision through an iteration method. According to the method, the problems of direct measurement difficulty in a torrential water flow environment and calculation errors in a non-constant flow condition are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of safety monitoring and hydraulic calculation technology for water conservancy and hydropower projects, and in particular to a method, system and computer-readable storage medium for calculating the average water level of the stilling basin in a spillway section. Background Technology

[0002] In concrete dam engineering, the stilling basin is a key facility for energy dissipation and scour prevention, and its internal water level directly affects energy dissipation efficiency and structural safety. Traditional stilling basin water level monitoring faces the following technical challenges: (1) Difficulty in direct measurement: Under the impact of high-speed water flow, the water surface often fluctuates violently, which makes it impossible for the float-type water level gauge to accurately measure the water level value. At the same time, the violent water flow often generates a large number of bubbles in the water body, which changes the density distribution of the water body, causing the signals of non-contact measuring devices such as sound waves and radar to be scattered and attenuated, resulting in a significant increase in measurement error.

[0003] (2) The separation of the guide wall leads to hydraulic asymmetry: In order to avoid mutual influence, the downstream of the dam uses a guide wall to separate the tailrace area of ​​the powerhouse and the flood discharge area. The water flow in the two areas interacts downstream, forming a complex hydraulic connection, so that the water level of the stilling basin is affected by both flood discharge and power generation.

[0004] (3) Variable operating conditions of gates: The surface gates of the spillway dam operate under different opening combinations, which leads to continuous changes in the hydraulic conditions of the stilling basin, and the water level measurement values ​​at fixed points are not representative enough.

[0005] (4) Existing traditional hydraulic calculation methods often assume that the water flow during the gate regulation process is constant, but in the actual gate regulation process, the water flow does not flow out at a constant flow rate, resulting in a large prediction error.

[0006] In summary, the existing methods for calculating the water level of stilling basins are inaccurate, which seriously affects the energy dissipation efficiency of dams. Summary of the Invention

[0007] The present invention aims to at least partially solve one of the technical problems in the related art.

[0008] Therefore, the first objective of this invention is to provide a method for calculating the average water level of the stilling basin in a spillway section, comprising: S1 collects multi-source monitoring data on the opening of the arc gate, the water level in front of the dam, the tailwater level of the powerhouse, and the total flow of the outflow station, and performs quality control processing on the data. S2, based on the opening of the arc-shaped gate and the water level in front of the dam, calculate the flood discharge flow and total flood discharge flow of each gate opening through the three-dimensional discharge curve; S3. Based on the difference between the total outflow of the reservoir and the total flood discharge, and combined with the water level-flow relationship curve corresponding to the tailwater level of the power plant, calculate the power generation tailwater flow and establish a dynamic flow balance model. S4 uses the empirical formula method for unsteady flow to generate the initial value of the stilling basin water level, calculates the conjugate water depth through the hydraulic jump equation iteratively, and improves the calculation accuracy through the iterative method.

[0009] In one embodiment of the present invention, S1 further includes: S11, the moving average method is used to eliminate short-term fluctuations in the multi-source monitoring data, specifically by calculating the average value of the data within the time window and replacing the data at the center point of the window. S12 aligns the timestamps of all monitoring data to a unified time base and unifies the units of water level data, flow rate data, and opening degree data collected by each arc gate.

[0010] In one embodiment of the present invention, step S2 includes: S21, the flood discharge flow of each gate opening is calculated by the three-dimensional discharge curve. The three-dimensional discharge curve is based on the gate opening, the water level in front of the dam and the gate position, and is obtained by hydraulic model test or computational fluid dynamics numerical simulation. S22, Calculate the total flood discharge based on the flood discharge flow of each gate opening, using the following formula: Q g = Σ Q gi ( i =1~n).

[0011] In one embodiment of the present invention, S3 further includes: S31, the water level-discharge relationship curve corresponding to the tailwater level of the powerhouse is obtained through river hydraulic calculation or actual measurement calibration; S32, calculate the power generation tailwater flow rate by combining the water level-flow relationship curve corresponding to the tailwater level of the plant.

[0012] In one embodiment of the present invention, S32 further includes: Calculate the total outflow from the reservoir based on the tailrace flow of the power plant and the total flood discharge flow: Q o = Q p + Q g ; in, Q p The flow rate of the tailwater for power generation, Q g Total flood discharge; Calculate the flow deviation based on the actual effects of measurement errors and unsteady flow: Δ Q = Q o - ( Q p + Q g ); When |Δ Q When the data exceeds the threshold, a data credibility assessment and source data verification are required.

[0013] In one embodiment of the present invention, S4 further includes, S41, the initial water level of the stilling basin is calculated using the empirical formula method for unsteady flow. The formula is: Z s,t = Z s,0 + a ×( Z s,t-1 - Z s,0 ) + b × Q g,t ; in, Z s,t Let t be the initial water level of the stilling basin. Z s,0 The reference water level of the stilling basin is [the reference water level of the stilling basin]. Z s,0 It is determined based on the stilling basin water level during the period when the gate is fully closed. a To reflect the attenuation coefficient of the water level receding rate, b To reflect the response coefficient of flood discharge flow to water level, Q g,t Let be the flood discharge rate at time t, and be the attenuation coefficient. a and response coefficient b It is obtained by fitting the flow rate data during the uniform opening and closing period of the gate using the least squares method, where 0 < a <1; S42, Construct the hydraulic jump equation for the stilling basin, the formula is:

[0014] in, h 1 represents the water depth before the jump. Q g The total flood discharge flow rate, B The total width of the stilling basin, v 1 represents the average flow velocity at the pre-jump cross section. ,in, The velocity coefficient is... g It is the acceleration due to gravity; The formula for calculating the conjugate water depth based on the stilling basin water level is: ; in, α This is the momentum correction factor. α The value range is [1.0, 1.1]. Fr 1 is the pre-jump Froude number. ,and Fr 1≥2.5; The formula for calculating the average water level of the stilling basin based on the conjugate water depth is as follows: Z s = Z b + h 2× σ in, Z b The elevation of the stilling basin bottom, σ This is the flooding coefficient.

[0015] In one embodiment of the present invention, S42 further includes, when the Froude number Fr When 1 < 2.5, the formula for calculating the conjugate water depth is:

[0016] in, β The influence coefficient of the wide tail pier.

[0017] In one embodiment of the present invention, S42 further includes, when the gate opening is asymmetrical, the average water level of the stilling basin needs to be corrected, and the corrected average water level of the stilling basin is: When the gate opening is large in the middle and small at both ends... Z s ' = Z s × (1 - k w ); in, Z s 'This represents the corrected average water level of the stilling basin, with a water level correction factor.' k w The value range is [0.03~0.05]; When one end of the gate is large and the other end is small Z s ' = Z s × (1 - kw ); in, Z s 'This represents the corrected average water level of the stilling basin, with a water level correction factor.' k w The value range is [0.05~0.08].

[0018] To achieve the above objectives, a second aspect of the present invention provides a device for calculating the average water level of the stilling basin in a spillway section, comprising: The multi-source monitoring data acquisition and quality control module is used to collect multi-source monitoring data such as the opening of the arc gate, the water level in front of the dam, the tailwater level of the powerhouse, and the total flow of the outflow station, and to perform quality control processing on the data. The three-dimensional discharge curve calculation and total discharge flow accumulation module is used to calculate the discharge flow of each gate opening and accumulate the total discharge flow based on the arc gate opening and the water level in front of the dam. The dynamic flow balance model establishment module is used to calculate the power generation tailwater flow based on the difference between the total outflow of the reservoir and the total flood discharge flow, combined with the water level-flow relationship curve corresponding to the tailwater level of the power plant, and to establish a dynamic flow balance model. The stilling basin water level calculation and correction module is used to generate the initial value of the stilling basin water level using the empirical formula method of unsteady flow, calculate the conjugate water depth through the hydraulic jump equation iteratively, and determine the final average water level by combining the stilling basin bottom elevation and the submergence coefficient. At the same time, a transverse velocity correction coefficient is introduced for secondary correction based on the gate opening distribution pattern.

[0019] To achieve the above objectives, a third aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method described in the first aspect.

[0020] The method, system, and storage medium of this invention can achieve high-precision continuous measurement of the average water level of the stilling basin in the spillway section, effectively overcoming the difficulties of direct measurement in turbulent water flow environments and the calculation error problem under unsteady flow conditions.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of a method for calculating the average water level of a stilling basin in a spillway section according to an embodiment of the present invention; Figure 2This is a schematic diagram of an average water level calculation system for a stilling basin in a spillway section according to an embodiment of the present invention. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0025] The following describes, with reference to the accompanying drawings, a method and system for calculating the average water level of the stilling basin in a spillway section according to an embodiment of the present invention.

[0026] Example 1 Figure 1 This is a flowchart of a method for calculating the average water level of the stilling basin in a spillway section according to an embodiment of the present invention.

[0027] like Figure 1 As shown, the method for calculating the average water level of the stilling basin in the spillway section includes the following steps: S1 collects multi-source monitoring data on the opening degree of the arc gate, the water level in front of the dam, the tailwater level of the powerhouse, and the total flow rate of the outflow station, and performs quality control processing on the data.

[0028] Specifically, in the technical solution of this invention, collecting multi-source monitoring data on the opening degree of the arc gate, the water level in front of the dam, the tailrace water level of the powerhouse, and the total outflow from the reservoir, and performing quality control processing on the data, is the fundamental step for achieving high-precision calculation of the average water level of the stilling basin. This step, by integrating multiple key hydraulic parameters, provides reliable data support for subsequent flow decomposition and water level inversion.

[0029] At the technical implementation level, this step first involves acquiring real-time data through the dam's online monitoring system. Specifically, this includes: the opening degree of the arc-shaped gate (e1~e...). 10 ), water level in front of the dam (Z) a ), tailwater level of the plant (Z) pThe data includes the total outflow from the reservoir (Q0) and other data sources, such as hydraulic structure monitoring sensors, hydrological telemetry systems, and flow meters. In some implementations, it is recommended to control the data acquisition frequency to ≤10 minutes to ensure the continuity of the time series and the ability to capture dynamic responses. Simultaneously, all data must undergo timestamp alignment to ensure consistency across data sources in the time dimension.

[0030] At the parameter level, water level data is uniformly expressed in meters (m), flow rate data in cubic meters per second (m³ / s), and aperture size data are also expressed in meters (m). To improve data quality, this step introduces a moving average method to remove outliers, eliminating short-term fluctuations caused by instantaneous disturbances or equipment drift. In addition, unit conversion and missing value imputation are performed on the data to ensure the completeness and consistency of the input data.

[0031] At the application level, this step is widely applicable to water conservancy projects equipped with overflow orifices, stilling basins, and downstream monitoring facilities. Its data acquisition and quality control capabilities are particularly critical under varying gate operating conditions and unsteady flow conditions. For example, during flood discharge scheduling, the opening of the arc-shaped gate changes frequently; without data cleaning and synchronization, the accuracy of subsequent hydraulic model calculations will be directly affected.

[0032] In terms of technical effectiveness, this step significantly improves the reliability and representativeness of the data through multi-source data fusion and quality control processing, providing a high-confidence input foundation for subsequent flood discharge flow calculation, power generation tailrace flow decomposition, and stilling basin water level inversion. Simultaneously, this step also possesses system self-checking capabilities; when the flow balance deviation exceeds 5% of the average flow over a given period, a data reliability assessment mechanism is triggered, thereby enhancing the robustness and adaptability of the entire system.

[0033] Furthermore, S1 includes: S11, the moving average method is used to eliminate short-term fluctuations in the multi-source monitoring data, specifically by calculating the average value of the data within the time window and replacing the data at the center point of the window.

[0034] Specifically, in this invention, the use of the moving average method to eliminate short-term fluctuations in multi-source monitoring data is a key step in the data preprocessing stage, aiming to improve the stability and accuracy of subsequent hydraulic model calculations. This step is technically based on the moving average (MA) method in time series analysis. Its core principle is to calculate the arithmetic mean of the data within a fixed-length window sliding across the time series, and then use this average as a correction value for the window's center point, thereby smoothing out instantaneous noise and high-frequency fluctuations in the data.

[0035] In the specific implementation, the window length of the moving average This is typically set based on the sampling frequency of the monitoring data and the target fluctuation period. Considering the recommendations of this invention... The sampling frequency is set to minutes, and the window length can be set to... Each sampling point, i.e. The time is 1 second to effectively filter out short-term disturbances caused by instantaneous water level changes or sensor noise.

[0036] In practical applications, the moving average method is widely used in hydrological, meteorological, and industrial monitoring systems to remove transient anomalies and high-frequency noise from data. In this invention, this step is mainly applied to the preprocessing of key parameters such as the opening degree of the arc gate, the water level in front of the dam, and the tailrace water level of the powerhouse, ensuring that the data input to the hydraulic model has good continuity and representativeness. For example, in the flood discharge calculation module, the water level in front of the dam after moving average... With gate opening Together, they serve as input parameters for the three-dimensional discharge curve, thereby improving the accuracy of flow calculation.

[0037] The technical value of this step lies in reducing instantaneous fluctuations in the data, enhancing the signal-to-noise ratio of the monitoring data, and providing a stable foundation for subsequent flow decomposition, hydraulic jump calculation, and iterative correction. Furthermore, the introduction of the moving average method helps improve the system's adaptability to unsteady flow conditions, reduces model calculation deviations caused by instantaneous measurement errors, and thus improves the accuracy and reliability of the stilling basin's average water level measurement.

[0038] S12 aligns the timestamps of all monitoring data to a unified time base and unifies the units of water level data, flow rate data, and opening degree data collected by each arc gate.

[0039] Specifically, in the "data acquisition and processing" step of this invention, aligning the timestamps of all monitoring data to a unified time base and setting the acquisition frequency to within 10 minutes is a crucial prerequisite for subsequent hydraulic model calculations and stilling basin average water level inversion. This step is technically implemented based on a time synchronization mechanism for multi-source heterogeneous data, ensuring that the data from each monitoring point are comparable and consistent in the time dimension, thereby providing a reliable data foundation for flow decomposition and water level calculation.

[0040] In some implementations, timestamp alignment uses a unified time zone reference (such as UTC or the standard time zone of the project location) and records timestamps with second- or millisecond-level precision. All monitoring equipment (including arc gate opening sensors, dam-front water level gauges, powerhouse tailrace water level gauges, and outflow station flow meters) must be connected to a unified clock synchronization system, such as NTP (Network Time Protocol) or a GPS time synchronization module, to ensure that the time deviation of each data source is controlled within ±1 second. Optionally, the system can be configured with a timestamp verification mechanism to mark or remove data that exceeds the synchronization error threshold, avoiding distortion in flow calculations due to time asynchrony.

[0041] Furthermore, the sampling frequency is set to within 10 minutes (i.e., sampling interval). This frequency is designed to meet the dynamic response requirements for water level and flow changes under unsteady flow conditions. The frequency needs to balance data real-time performance with system storage pressure, typically selected between 1 and 5 minutes, with adjustments made based on project scale and monitoring system performance. For example, in large-scale water conservancy projects, a 5-minute sampling interval is recommended to improve the ability to capture instantaneous hydraulic changes.

[0042] In application scenarios, this step is suitable for spillway dam sections with multiple monitoring points. Especially under complex hydraulic conditions such as guide wall separation and asymmetrical gate opening, time synchronization and high-frequency acquisition can effectively capture the dynamic changes of zone water level and flow, providing high-precision input for subsequent flow balance verification and hydraulic jump equation calculation.

[0043] In summary, timestamp alignment and acquisition frequency control are the core components of the data processing flow of this invention. Their technical implementation directly affects the accuracy and stability of the hydraulic model, providing solid data support for the subsequent inversion of the average water level of the stilling basin.

[0044] S2, based on the opening of the arc-shaped gate and the water level in front of the dam, calculate the flood discharge flow and total flood discharge flow of each gate opening through the three-dimensional discharge curve.

[0045] Specifically, in some implementations, calculating the flood discharge flow at each gate opening based on the arc-shaped gate opening and the water level in front of the dam, and then summing them to obtain the total flood discharge flow, is one of the key steps in this invention for calculating the average water level of the stilling basin. The core technical principle of this step is to establish a nonlinear mapping relationship between the gate opening, the water level in front of the dam, and the single-gate flood discharge flow using a pre-calibrated three-dimensional flood discharge curve obtained through hydraulic model tests or computational fluid dynamics (CFD) numerical simulation. The three-dimensional flood discharge curve considers the combined effects of gate location, three-dimensional water flow distribution, and boundary conditions, and has higher hydraulic simulation accuracy compared to traditional two-dimensional empirical formulas.

[0046] In the specific implementation, the real-time opening degree of each surface-mounted arc gate is first obtained. (Unit: m) and water level in front of the dam (Unit: m), where Indicates the first The numbering range of the gate is as follows: Subsequently, the three-dimensional discharge curve function was calculated. Calculate the flood discharge flow of each gate. (unit: The construction of this function needs to be based on hydraulic model tests or CFD simulations to ensure its applicability and accuracy under different opening and water level combinations.

[0047] Furthermore, the flood discharge rates from all the gate openings are summed to obtain the total flood discharge rate. Its mathematical expression is: ; This step is typically implemented in spillway sections with multiple surface gates in practical applications, and is suitable for operating conditions where gate openings change frequently and water flow conditions are complex. This method enables dynamic, real-time calculation of the spillway discharge, providing fundamental data support for subsequent flow decomposition and stilling basin water level inversion.

[0048] In terms of technical effectiveness, this step, by introducing a three-dimensional discharge curve, effectively overcomes the problems of neglecting the gate position effect and the three-dimensional structure of water flow in traditional methods, thus improving the accuracy and reliability of flow calculation. Simultaneously, by relying on data input from existing monitoring systems, it reduces reliance on additional measuring equipment, enhancing the system's economy and practicality.

[0049] Furthermore, S2 includes: S21. The flood discharge flow of each gate opening is calculated by the three-dimensional discharge curve. The three-dimensional discharge curve is based on the gate opening, the water level in front of the dam and the gate position, and is obtained by hydraulic model test or computational fluid dynamics numerical simulation.

[0050] S22, Calculate the total flood discharge based on the flood discharge flow of each gate opening.

[0051] Specifically, in some implementations, the three-dimensional discharge curve is pre-calibrated through hydraulic model tests or computational fluid dynamics (CFD) numerical simulations. Its core lies in establishing the nonlinear hydraulic relationship between the gate opening, the upstream water level, and the gate position, thus providing a basis for the accurate calculation of subsequent flood discharge. This curve reflects the flood discharge of a single gate under different operating conditions. The changing pattern, among which The water level in front of the dam (m). For the first The opening degree (m) of the gate. Number the gate ( ), For the first The flood discharge flow of the sluice gate ( ).

[0052] From a technical implementation perspective, the calibration of the three-dimensional discharge curve needs to consider the influence of the lateral position of the gate opening on the water flow structure, especially in the flood discharge and tailrace areas separated by the guide wall, where the water flow distribution exhibits obvious three-dimensional characteristics. In hydraulic model tests, a scaled-down model is typically used to simulate the actual gate operation conditions. Multiple flow meters, pressure sensors, and level gauges are deployed to obtain flow and level response data under different opening combinations. In CFD numerical simulations, a three-dimensional geometric model including the gate, guide wall, stilling basin, and downstream channel needs to be established. The RANS (Reynolds-averaged Navier-Stokes) equations are used for turbulence modeling, combined with the VOF (volume fraction) method to track the free water surface, to obtain high-precision flow field and flow distribution.

[0053] In practical applications, this step is mainly used to quickly calculate the discharge flow of each gate under different flood discharge conditions, providing key input for the decomposition of outflow. Especially under conditions of asymmetrical gate opening or non-steady flow, the three-dimensional discharge curve can effectively reflect the coupling effect between lateral velocity distribution and water level changes, thereby improving the accuracy of overall water level measurement.

[0054] The technical effect of this step is that by introducing a three-dimensional discharge curve, it overcomes the problem of insufficient adaptability of the traditional steady flow formula to actual complex water flow structures, improves the accuracy and stability of flood discharge calculation, provides reliable basic data for subsequent iterative calculation of stilling basin water level, and enhances the system's adaptability and computational robustness under multiple operating conditions.

[0055] S3. Based on the difference between the total outflow from the reservoir and the total flood discharge, and combined with the water level-flow relationship curve corresponding to the tailwater level of the power plant, calculate the tailwater flow rate for power generation and establish a dynamic flow balance model.

[0056] Specifically, in some implementations, calculating the power generation tailwater flow rate based on the difference between the total outflow rate of the reservoir and the total flood discharge rate, combined with the water level-flow relationship curve corresponding to the tailwater level of the power plant, is one of the key steps in establishing a dynamic flow balance model.

[0057] This step is widely used in practical applications for hydropower station operation and scheduling, flood forecasting, and dam safety monitoring systems. Through a dynamic flow balance model, the hydraulic coupling relationship between power generation and flood discharge can be reflected in real time, providing fundamental support for the inversion calculation of stilling basin water level. Its technical value lies in two aspects: firstly, improving the accuracy and real-time performance of tailrace flow estimation; and secondly, providing reliable initial conditions for subsequent iterative calculations of stilling basin water level, thereby enhancing the robustness and adaptability of the entire water level measurement system.

[0058] Furthermore, S3 includes: S31, the water level-discharge relationship curve corresponding to the tailwater level of the powerhouse is obtained through river hydraulic calculation or actual measurement calibration; S32, calculate the power generation tailwater flow rate by combining the water level-flow relationship curve corresponding to the tailwater level of the plant.

[0059] Specifically, when the flow deviation When the absolute value of the flow rate is greater than 5% of the average flow rate over the period, the data reliability assessment process is initiated. This step is an important part of the flow balance verification mechanism in this invention, and aims to ensure that the input data on which the subsequent water level calculation depends has sufficient accuracy and reliability.

[0060] At the technical implementation level, traffic deviation The calculation formula is: ; in, This represents the total outbound flow of the warehouse. The flow rate of the tailwater for power generation, This refers to the flood discharge flow rate.

[0061] The process includes three key verification steps: (1) Accuracy check of arc gate opening sensor: Check the range, resolution and calibration record of the sensor to ensure that its accuracy meets the requirements of gate opening measurement equipment in GB / T 18459-2015 "Technical Specification for Testing of Hydraulic Metal Structures" and the error should be controlled within ±1%.

[0062] (2) Verification of calibration status of water level monitoring equipment in front of the dam: Confirm whether the water level gauge is operating within the valid calibration period, whether it is affected by siltation, air bubble interference or equipment drift, and ensure that its measurement accuracy meets the accuracy requirements for water level monitoring equipment in DL / T 5015-2004 "Design Specification for Hydrological Automatic Monitoring and Reporting System", which is usually ±2 cm.

[0063] (3) Check the operation log of the flow meter at the outbound station: Check the operation status, maintenance records and data acquisition frequency of the flow meter to ensure that it can still provide stable and continuous flow data under non-constant flow conditions, and comply with the use standards for electromagnetic flow meters or ultrasonic flow meters in SL 303-2004 Hydrological Measurement Specification.

[0064] In practical applications, this step is often used to identify systematic deviations that may occur after sudden changes in dam operating conditions or after long-term equipment operation. For example, if there is an abnormal deviation in the flow balance relationship during periods of rapid gate opening and closing or drastic water level fluctuations, the system will automatically trigger a data verification mechanism to prevent water level calculation errors caused by sensor inaccuracies or abnormal data acquisition.

[0065] The technical value of this step lies in: by setting a clear deviation threshold (i.e., the average flow rate over 5% of the time period), dynamic verification of multi-source monitoring data is achieved, ensuring high reliability of the input data for subsequent hydraulic jump equations and unsteady flow models, thereby improving the accuracy and stability of the stilling basin's average water level calculation. Furthermore, this mechanism also possesses fault diagnosis capabilities, helping to promptly identify and eliminate anomalies in the monitoring system, ensuring the robustness and engineering practicality of the entire hydraulic calculation system.

[0066] S4. The initial water level of the stilling basin is generated using an empirical formula method for unsteady flow. The conjugate water depth is calculated iteratively using the hydraulic jump equation, and the calculation accuracy is improved by iterative methods. Specifically, in some implementations, the initial value of the stilling basin water level is generated by the empirical formula method of unsteady flow, and the conjugate water depth is calculated iteratively by the hydraulic jump equation. The final average water level is determined by combining the stilling basin bottom elevation and the submergence coefficient. At the same time, a transverse velocity correction coefficient is introduced according to the gate opening distribution pattern for secondary correction. This is one of the core technical steps of the stilling basin water level calculation module in this invention, which has significant hydraulic modeling accuracy and engineering practicality.

[0067] At the technical implementation level, this step is first based on the empirical formula method for unsteady flow, using the attenuation coefficient calibrated through historical data. and response coefficient Combined with the current flood discharge flow rate Compared to the water level at the previous moment Calculate the initial estimate of the stilling basin water level. Its expression is:

[0068] in, The reference water level of the stilling basin is usually determined by the stable water level under the condition that the gates are fully closed. The attenuation coefficient has a range of values. This reflects the trend of water level receding over time; The response coefficient reflects the dynamic response intensity of the flood discharge to the water level. This formula considers the temporal continuity of the water level and the instantaneous influence of the discharge, and is suitable for preliminary estimation under unsteady flow conditions.

[0069] Furthermore, based on this initial water level Calculate the water depth before the jump. Substitute the solutions into the hydraulic jump equation to solve for the conjugate water depth. The hydraulic jump equation is: ; in, For the Froude number before the leap, This is the momentum correction factor, with a range of values. .

[0070] The formula for calculating the pre-jump water depth is as follows:

[0071] in, h 1 represents the water depth before the jump. Q g The total flood discharge flow rate, B The total width of the stilling basin, v 1 represents the average flow velocity at the pre-jump cross section. ,in, The velocity coefficient is... g This is the acceleration due to gravity.

[0072] The formula for calculating the average water level of the stilling basin based on the conjugate water depth is as follows: Z s = Z b + h 2× σ in, Z b The elevation of the stilling basin bottom, σ This is the flooding coefficient.

[0073] Through iterative calculations, the results are continuously corrected. Z s Until it is consistent with the water depth calculated based on the conjugate water depth The difference is less than the set tolerance, thus obtaining the convergent average water level.

[0074] At the parameter level, this step involves several key parameters, including but not limited to: flow rate coefficient. (Values ​​range from 0.90 to 0.95), momentum correction factor (1.0-1.1) Submergence coefficient (1.05-1.10), Transverse velocity influence coefficient (0.75-1.00) and water level correction factor (0-0.08). These parameters need to be calibrated through hydraulic model tests or CFD numerical simulations based on specific engineering conditions to ensure the applicability and accuracy of the model.

[0075] At the application level, this step is widely applicable to water conservancy projects equipped with overflow orifices, stilling basins, and downstream monitoring facilities, especially under complex hydraulic conditions such as asymmetrical gate opening, low Freund number conditions, or significant three-dimensional flow structures. Through zonal calculations and lateral velocity correction, the representativeness and spatial adaptability of water level measurements can be effectively improved.

[0076] In terms of technical effectiveness, this step, through the coupled iteration of the empirical formula for unsteady flow and the hydraulic jump equation, significantly improves the calculation accuracy of the average water level in the stilling basin, with the error controlled within a certain range. Within this range. Simultaneously, dynamic corrections are made using multi-source monitoring data, enhancing the system's adaptability to actual operating conditions and providing a reliable basis for the structural safety assessment and operational control of the stilling basin.

[0077] The method for calculating the average water level of the stilling basin in the spillway section of the present invention can achieve high-precision and continuous calculation of the average water level of the stilling basin in the spillway section, effectively overcome the measurement difficulties caused by water flow turbulence and gate operating conditions, and improve the comprehensiveness and system reliability of hydraulic state assessment.

[0078] Furthermore, S4 includes: S41, the initial water level of the stilling basin is calculated using the empirical formula method for unsteady flow. The formula is: Z s,t = Z s,0 + a ×( Z s,t -1 - Z s,0 ) + b × Q g,t ; in, Z s,t Let t be the initial water level of the stilling basin. Z s,0 The reference water level of the stilling basin is [the reference water level of the stilling basin]. Z s,0 It is determined based on the stilling basin water level during the period when the gate is fully closed. a To reflect the attenuation coefficient of the water level receding rate, b To reflect the response coefficient of flood discharge flow to water level, Qg,t Let be the flood discharge rate at time t, and be the attenuation coefficient. a and response coefficient b It is obtained by fitting the flow rate data during the uniform opening and closing period of the gate using the least squares method, where 0 < a <1; S42, Construct the hydraulic jump equation for the stilling basin, the formula is: ; in, h 1 represents the water depth before the jump. Q g The total flood discharge flow rate, B The total width of the stilling basin, v 1 represents the average flow velocity at the pre-jump cross section. ,in, The velocity coefficient is... g It is the acceleration due to gravity; The formula for calculating the conjugate water depth based on the stilling basin water level is: ; in, α This is the momentum correction factor. α The value range is [1.0, 1.1]. Fr 1 is the pre-jump Froude number. ,and Fr 1≥2.5; The formula for calculating the average water level of the stilling basin based on the conjugate water depth is as follows: Z s = Z b + h 2× σ ; in, Z b The elevation of the stilling basin bottom, σ This is the flooding coefficient.

[0079] When Froude number Fr When 1 < 2.5, the formula for calculating the conjugate water depth is: ; in, β The influence coefficient of the wide tail pier.

[0080] When the gates open asymmetrically, the average water level in the stilling basin needs to be corrected. The corrected average water level in the stilling basin is: When the gate opening is large in the middle and small at both ends... Z s ' = Z s× (1 - k w ); in, Z s 'This represents the corrected average water level of the stilling basin, with a water level correction factor.' k w The value range is [0.03~0.05]; When one end of the gate is large and the other end is small Z s ' = Z s × (1 - k w ); in, Z s 'This represents the corrected average water level of the stilling basin, with a water level correction factor.' k w The value range is [0.05~0.08].

[0081] In practical applications, this step is suitable for flood discharge conditions where gate openings change frequently and water flow is not constant, and it is particularly important in dam operation and scheduling. Through iterative correction, initial estimation errors can be effectively eliminated, improving the reliability of water level calculations and providing crucial data support for stilling basin structural safety assessments and operational control. Its technical value lies in combining the advantages of empirical formulas and hydraulic models, achieving dynamic adaptation and high-precision inversion for complex hydraulic conditions.

[0082] The method for calculating the average water level of the stilling basin in the spillway section of the present invention can achieve high-precision and continuous calculation of the average water level of the stilling basin in the spillway section, effectively overcome the measurement difficulties caused by water flow turbulence and gate operating conditions, and improve the comprehensiveness and system reliability of hydraulic state assessment.

[0083] Table 1 shows a comparison of the effectiveness of the method proposed in this invention with existing water level measurement methods.

[0084] Table 1 Comparison of the method of the present invention with the prior art

[0085] As can be seen from the table above, compared with the traditional direct measurement method and hydraulic calculation method, the method proposed in this invention has higher measurement accuracy and better continuity in water level calculation, and is more comprehensive and has stronger anti-interference ability in the measurement process.

[0086] Example 2 Figure 2 This is a structural diagram of an average water level calculation system for a stilling basin in a spillway section according to an embodiment of the present invention.

[0087] like Figure 2 As shown, the system for calculating the average water level in the stilling basin of the spillway section includes: The multi-source monitoring data acquisition and quality control module is used to collect multi-source monitoring data such as the opening of the arc gate, the water level in front of the dam, the tailwater level of the powerhouse, and the total flow of the outflow station, and to perform quality control processing on the data. The three-dimensional discharge curve calculation and total discharge flow accumulation module is used to calculate the discharge flow of each gate opening and accumulate the total discharge flow based on the arc gate opening and the water level in front of the dam. The dynamic flow balance model establishment module is used to calculate the power generation tailwater flow based on the difference between the total outflow of the reservoir and the total flood discharge flow, combined with the water level-flow relationship curve corresponding to the tailwater level of the power plant, and to establish a dynamic flow balance model. The stilling basin water level calculation and correction module is used to generate the initial value of the stilling basin water level using the empirical formula method of unsteady flow, calculate the conjugate water depth through the hydraulic jump equation iteratively, and determine the final average water level by combining the stilling basin bottom elevation and the submergence coefficient. At the same time, a transverse velocity correction coefficient is introduced for secondary correction based on the gate opening distribution pattern.

[0088] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-mentioned method for calculating the average water level of the stilling basin in the spillway section.

[0089] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0090] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A method for calculating the average water level of a stilling basin of a flood discharge dam section, characterized in that, include: S1 collects multi-source monitoring data on the opening of the arc gate, the water level in front of the dam, the tailwater level of the powerhouse, and the total flow of the outflow station, and performs quality control processing on the data. S2, based on the opening of the arc-shaped gate and the water level in front of the dam, calculate the flood discharge flow and total flood discharge flow of each gate opening through the three-dimensional discharge curve; S3. Based on the difference between the total outflow of the reservoir and the total flood discharge, and combined with the water level-flow relationship curve corresponding to the tailwater level of the power plant, calculate the power generation tailwater flow and establish a dynamic flow balance model. S4 uses the empirical formula method for unsteady flow to generate the initial value of the stilling basin water level, calculates the conjugate water depth through the hydraulic jump equation iteratively, and improves the calculation accuracy through the iterative method.

2. The method of claim 1, wherein, S1 further includes: S11, the moving average method is used to eliminate short-term fluctuations in the multi-source monitoring data, specifically by calculating the average value of the data within the time window and replacing the data at the center point of the window. S12 aligns the timestamps of all monitoring data to a unified time base and unifies the units of water level data, flow rate data, and opening degree data collected by each arc gate.

3. The method of claim 1, wherein, S2 includes: S21, the flood discharge flow of each gate opening is calculated by the three-dimensional discharge curve. The three-dimensional discharge curve is based on the gate opening, the water level in front of the dam and the gate position, and is obtained by hydraulic model test or computational fluid dynamics numerical simulation. S22, Calculate the total flood discharge based on the flood discharge flow of each gate opening, using the following formula: Q g =∑ Q gi ( i =1~n).

4. The method as described in claim 1, characterized in that, S3 further includes: S31, the water level-discharge relationship curve corresponding to the tailwater level of the powerhouse is obtained through river hydraulic calculation or actual measurement calibration; S32, calculate the power generation tailwater flow rate by combining the water level-flow relationship curve corresponding to the tailwater level of the plant.

5. The method as described in claim 4, characterized in that, S32 further includes: Calculate the total outflow from the reservoir based on the tailrace flow of the power plant and the total flood discharge flow: Q o = Q p + Q g ； in, Q p The flow rate of the tailwater for power generation, Q g Total flood discharge; Calculate the flow deviation based on the actual effects of measurement errors and unsteady flow: D Q = Q o - ( Q p + Q g ); When |Δ Q When the data exceeds the threshold, a data credibility assessment and source data verification are required.

6. The method as described in claim 1, characterized in that, S4 also includes, S41, the initial water level of the stilling basin is calculated using the empirical formula method for unsteady flow. The formula is: Z s,t = Z s,0 + a ×( Z s,t-1 - Z s,0 ) + b × Q g,t ； in, Z s,t Let t be the initial water level of the stilling basin. Z s,0 The reference water level of the stilling basin is [the reference water level of the stilling basin]. Z s,0 It is determined based on the water level in the stilling basin during the period when the gate is fully closed. a To reflect the attenuation coefficient of the water level receding rate, b To reflect the response coefficient of flood discharge flow to water level, Q g,t Let be the flood discharge rate at time t, and be the attenuation coefficient. a and response coefficient b It is obtained by fitting the flow rate data during the uniform opening and closing period of the gate using the least squares method, where 0 < a <1; S42, Construct the hydraulic jump equation for the stilling basin, the formula is: in, h 1 represents the water depth before the jump. Q g The total flood discharge flow rate, B The total width of the stilling basin, v 1 represents the average flow velocity at the pre-jump cross section. ,in, The velocity coefficient is... g It is the acceleration due to gravity; The formula for calculating the conjugate water depth based on the stilling basin water level is: ； in, α This is the momentum correction factor. α The value range is [1.0, 1.1]. Fr 1 is the pre-jump Froude number. ,and Fr 1≥2.5; The formula for calculating the average water level of the stilling basin based on the conjugate water depth is as follows: Z s = Z b + h 2× σ in, Z b The elevation of the stilling basin bottom, σ This is the flooding coefficient.

7. The method as described in claim 6, characterized in that, S42 further includes, when the Froude number Fr When 1 < 2.5, the formula for calculating the conjugate water depth is: in, β The influence coefficient of the wide tail pier.

8. The method as described in claim 6, characterized in that, S42 further includes, when the gate opening is asymmetrical, the average water level of the stilling basin needs to be corrected, and the corrected average water level of the stilling basin is: When the gate opening is large in the middle and small at both ends... Z s ' = Z s × (1 - k w )； in, Z s 'This represents the corrected average water level of the stilling basin, with a water level correction factor.' k w The value range is [0.03~0.05]; When one end of the gate is large and the other end is small Z s ' = Z s × (1 - k w )； in, Z s 'This represents the corrected average water level of the stilling basin, with a water level correction factor.' k w The value range is [0.05~0.08].

9. A system for calculating the average water level of the stilling basin in a spillway dam section, characterized in that, include: The multi-source monitoring data acquisition and quality control module is used to collect multi-source monitoring data such as the opening of the arc gate, the water level in front of the dam, the tailwater level of the powerhouse, and the total flow of the outflow station, and to perform quality control processing on the data. The three-dimensional discharge curve calculation and total discharge flow accumulation module is used to calculate the discharge flow of each gate opening and accumulate the total discharge flow based on the arc gate opening and the water level in front of the dam. The dynamic flow balance model establishment module is used to calculate the power generation tailwater flow based on the difference between the total outflow of the reservoir and the total flood discharge flow, combined with the water level-flow relationship curve corresponding to the tailwater level of the power plant, and to establish a dynamic flow balance model. The stilling basin water level calculation and correction module is used to generate the initial value of the stilling basin water level using the empirical formula method of unsteady flow, calculate the conjugate water depth through the hydraulic jump equation iteratively, and determine the final average water level by combining the stilling basin bottom elevation and the submergence coefficient. At the same time, a transverse velocity correction coefficient is introduced for secondary correction based on the gate opening distribution pattern.

10. A computer-readable storage medium storing a computer program that, when executed by a processor, implements the method as claimed in any one of claims 1-8.

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