Valve flow control method and device, storage medium and computer equipment

Abstract

The invention relates to the technical field of thermal power automatic control, and discloses a valve flow control method and device, a storage medium and computer device.The method comprises the steps that historical operation data of a valve are collected, and the historical operation data comprise actual opening degrees adjusted when the valve responds to opening degree instructions covering the full opening degree range; the flow of the fluid at the valve at each time point in the time period corresponding to the opening instruction covering the full opening range is calculated; carrying out per-unit treatment on the flow of the fluid at the valve to obtain a per-unit value of the flow; fitting the relationship between the per-unit value of the flow and the actual opening of the valve through a least square method, and constructing an actual opening model of the flow; and predicting a target opening degree adjusted by a valve required for outputting the expected flow through the actual flow opening degree model. The corresponding relation between the flow and the opening can be smoother by constructing the actual flow opening model, and the control precision of the valve flow is improved.

Description

Technical Field

[0001] The present application relates to the technical field of thermal power automatic control, and in particular to a valve flow control method and device, a storage medium, and a computer device. Background Art

[0002] In the thermal power control process, the regulating valve is the core executive device for achieving precise flow control. Its flow characteristics (i.e. the mapping relationship between valve opening and medium flow) directly affect the stability and accuracy of the control system. Ideally, the valve should have predictable flow characteristics (such as linear, equal percentage, parabolic characteristics). However, in actual operation, due to problems such as valve core and valve seat wear, erosion, corrosion, and mechanical aging, the actual flow characteristics of the valve deviate from the theoretical curve, causing control loop oscillation and reduced regulation accuracy.

[0003] The existing thermal power valve flow characteristic optimization is mainly carried out for the high-pressure regulating valve of the steam turbine. The reason is that the high-pressure regulating valve of the steam turbine is used for precise control of active power, and its valve flow characteristics affect the quality of AGC control and the profitability of auxiliary services such as peak-shaving and frequency regulation of the power grid. The high-pressure regulating valve of the steam turbine is usually configured in 4 or 6 parallel operation modes. The optimization of its valve flow characteristics is mostly carried out by test methods. During the test, the valve opening of a single high-pressure regulating valve of the steam turbine is slowly adjusted from the fully open state to the fully closed state, and then the new flow characteristic curve of the current test valve is calculated by collecting test data. When a single high-pressure regulating valve is fully closed, steam can enter the steam turbine through other high-pressure regulating valves without cutting off the steam flow. The test lasts for a long time, about 8 to 12 hours, resulting in loss of power generation and peak-shaving and frequency regulation auxiliary service profitability. In addition, the main steam pressure needs to be manually controlled during the test, which is easy to cause boiler overpressure and affect safe operation.

[0004] At present, thermal power units frequently participate in deep peak regulation, and most of the time they operate at 20% of the rated power, which results in many valves opening too small, and the valve flow characteristics are significantly different from the normal opening, which easily causes the control loop to oscillate and cannot be put into automatic control. For example, during deep regulation, the denitrification control loop and the superheated steam cooling water control loop are often unable to be put into automatic control. Many valves of thermal power units do not have redundant valves running in parallel, and do not meet the test conditions. If the valve flow characteristic curve is optimized through test methods, the valve needs to change from fully open to fully closed, causing the working fluid flow to change from the maximum to the minimum, or even cut off the flow. At the same time, the test time is long, which is easy to destroy the system balance and form a safety hazard. Summary of the invention

[0005] In view of this, the present application provides a valve flow control method, device, storage medium, and computer device. By collecting historical operation data to construct a flow actual opening model, it avoids the power generation loss and profit reduction caused by long-term experiments, and reduces the safety risks caused by manually controlling the unit load. At the same time, this flow actual opening model makes the correspondence between flow and opening smoother, effectively improves the control accuracy of the controller for valve flow, and reduces problems such as control loop oscillation and regulation accuracy decline caused by the deviation of the actual characteristics of the valve from the theoretical curve, ensuring the stability and safety of the thermal power control system.

[0006] According to one aspect of the present application, a valve flow control method is provided, and the method includes: Collect historical operation data of the valve, where the historical operation data includes the actual opening adjusted by the valve when responding to each opening command covering the full opening range, and the flow rate at each time point within the time period corresponding to the opening command covering the full opening range of the fluid at the valve, and the opening range is 0% to 100%; Perform per-unit processing on the flow rate of the fluid at the valve, so that the per-unit processed flow rate is scaled to the same range as the opening range of the opening command, and obtain the per-unit value of the flow rate; Fit the relationship between the per-unit value of the flow rate and the actual opening of the valve by the least squares method to construct a flow actual opening model; Determine the expected flow rate of the fluid flowing out of the expected valve, and predict the target opening adjusted by the valve required to output the expected flow rate through the flow actual opening model, so that when the fluid passes through the valve adjusted to the target opening, the output is the expected flow rate.

[0007] According to another aspect of the present application, a valve flow control device is provided, and the device includes: A historical data acquisition module for collecting historical operation data of the valve, where the historical operation data includes the actual opening adjusted by the valve when responding to each opening command covering the full opening range, and the flow rate at each time point within the time period corresponding to the opening command covering the full opening range of the fluid at the valve, and the opening range is 0% to 100%; A flow per-unit processing module for performing per-unit processing on the flow rate of the fluid at the valve, so that the per-unit processed flow rate is scaled to the same range as the opening range of the opening command, and obtain the per-unit value of the flow rate; A flow opening model construction module for fitting the relationship between the per-unit value of the flow rate and the actual opening of the valve by the least squares method to construct a flow actual opening model; A valve flow control module is used to determine the desired flow rate of fluid flowing out at a desired valve, and predict, through a flow actual opening model, a target opening degree of the valve adjustment required to output the desired flow rate, so that when the fluid passes through the valve adjusted to the target opening degree, the output is the desired flow rate.

[0008] According to another aspect of the present application, a storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the above-mentioned valve flow control method is implemented.

[0009] According to still another aspect of the present application, a computer device is provided, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, and when the processor executes the program, the above-mentioned valve flow control method is implemented.

[0010] By means of the above technical solutions, a valve flow control method, device, storage medium, and computer device provided by the present application can make the correspondence between the flow rate and the opening degree smoother by constructing a model, and improve the control accuracy of the valve flow rate.

[0011] The above description is only an overview of the technical solutions of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features, and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation to the present application. In the drawings: Figure 1 A flowchart showing a valve flow control method provided by an embodiment of the present application is shown; Figure 2 A flowchart showing a valve flow per-unit processing method provided by an embodiment of the present application is shown; Figure 3 A structural diagram showing a valve flow control device provided by an embodiment of the present application is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] The present application will be described in detail below with reference to the drawings and in combination with embodiments. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0014] In this embodiment, a valve flow control method is provided, as Figure 1 shown, the method includes: Step 101: Collect the historical operation data of the valve. The historical operation data includes the actual opening degrees adjusted by the valve when responding to each opening degree command covering the full opening range, and the flow rates at each time point within the time period corresponding to the opening degree commands covering the full opening range of the fluid at the valve. The opening range is from 0% to 100%.

[0015] In the above embodiments of the present application, it can be applied to the regulating valve with flow detection in a thermal power unit. The "flow-actual opening model" is constructed using historical data, so as to optimize the flow characteristic curve of the valve online, which can reduce the maintenance cost and improve the automatic control quality. Specifically, the full-range historical data of the valve opening command u(k), opening feedback fb(k) (actual opening), and flow signal q(k) (flow) of the DCS (Distributed Control System) can be collected. At the same time, it is required that the opening command covers the range from 0% to 100% for constructing the subsequent "flow-actual opening model".

[0016] Furthermore, for example, the opening range of the denitration ammonia injection regulating valve in a thermal power unit is usually from 0% to 100%. When collecting the historical operation data, it is necessary to ensure that the opening command can cover this entire range to obtain the relevant data at different valve openings.

[0017] At different power generation load stages, the distributed control system (DCS) of the thermal power unit will send different opening commands to the denitration ammonia injection regulating valve to control its flow rate. Through the historical data recording function of the DCS, the opening command data sent to the denitration ammonia injection regulating valve at different time points can be collected. These opening command data reflect the opening values expected for the denitration ammonia injection regulating valve to reach.

[0018] The actuator of the denitration ammonia injection regulating valve adjusts the actual opening of the valve according to the received opening command. An opening feedback device, such as a displacement sensor, is installed on the denitration ammonia injection regulating valve, which can measure the actual opening of the valve in real time and feedback the actual opening signal back to the DCS. Through the DCS, the actual opening data of the denitration ammonia injection regulating valve corresponding to the opening command can be collected.

[0019] A suitable flow measurement device, such as a differential pressure flowmeter, can be installed on the outlet pipeline of the denitration ammonia injection regulating valve to measure the flow rate of the fluid passing through the valve. The selection of the flow measurement device can be determined according to factors such as the properties of the fluid (such as steam, water, etc.), the diameter of the pipeline, and the measurement accuracy requirements.

[0020] The flow measurement device can measure the fluid flow rate through the denitration ammonia injection regulating valve in real time and transmit the flow signal to the DCS. Through the data acquisition system of the DCS, the flow rate data of the fluid at the valve can be collected at certain time intervals (such as every second). When collecting the flow rate data, it is also necessary to ensure that the flow rate data at multiple time points can be collected to accurately reflect the change of the flow rate over time.

[0021] Finally, the collected opening command data, actual opening data, and flow rate data are correlated and stored in chronological order, and a complete set of valve historical operation data can be obtained, which includes the actual opening of the denitration ammonia injection regulating valve under different opening commands and the corresponding fluid flow rate information. These data can provide a basis for constructing the flow rate-opening model subsequently.

[0022] Optionally, when collecting the historical operation data of the valve, the flow rates within each preset opening interval within the opening range are collected in batches. The collected flow rate is obtained by taking the average of the flow rate values collected by multiple sampling points corresponding to the valve. The number of sampling points is greater than the preset number.

[0023] In the above embodiments of the present application, when collecting relevant data such as valve opening and flow rate, the sampling point density can be set to ≥20 points / 3% opening interval. That is, in order to ensure that the subsequent constructed flow rate-actual opening model has high accuracy and reliability, within each 3% opening interval, the number of collected sampling points should be no less than 20. For example, when the valve opening is in the range from 0% to 3%, at least 20 different opening degrees and their corresponding flow rate and other data points should be collected; the same is true for the interval from 3% to 6% opening, and so on. A higher sampling point density can capture the law of the flow rate changing with the opening more carefully.

[0024] Particularly, the opening command can also be selected to cover the range from 5% to 80%. That is, the opening command range involved in data collection and subsequent model construction can cover the range from 5% to 80%. Because in the actual operation of the valve, there may be some special situations when the opening is close to 0% and 100%. For example, there may be sealing problems when the valve is close to fully closed (0% opening), and the fluid flow state may not change when the valve is close to fully open (100% opening). The opening range from 5% to 80% is usually the range where the valve operates normally and can better reflect the relationship between the flow rate and the opening. Collecting data and constructing a model within this range can make the model (flow rate-actual opening model) more practical and representative, and can more accurately describe the flow rate-opening characteristics of the valve under normal working conditions.

[0025] Step 102, perform normalization processing on the flow rate of the fluid at the valve so that the normalized flow rate is scaled to the same range as the opening range of the opening command, and obtain the normalized flow rate value.

[0026] Next, normalize the flow rate to 0% to 100%. The calculation process is, for example, first calculate the range R = q max -q min , offset , and finally the normalized flow rate value .

[0027] Optionally, as Figure 2 shown, Step 102 performs normalization processing on the flow rate of the fluid at the valve so that the normalized flow rate is scaled to the same range as the opening range of the opening command, and obtain the normalized flow rate value. Specifically, it includes: Step 1021, for the flow rate at each time point within the time period corresponding to the opening command covering the full opening range of the valve, obtain the maximum flow rate and the minimum flow rate, and determine the range of the flow rate of the fluid at the valve based on the difference between the maximum flow rate and the minimum flow rate. Among them, the determined range is: R = q max -q min , R is the range, q max is the maximum flow rate, and q min is the minimum flow rate.

[0028] Step 1022, for any time point within the time period corresponding to the opening command covering the full opening range, calculate the difference between the flow rate at this time point and the minimum flow rate to obtain the flow rate offset at this time point. Among them, the calculation formula for the flow rate offset is: , is the flow rate offset, is the flow rate at the time point.

[0029] Step 1023, calculate the normalized flow rate value of the flow rate at this time point based on the ratio of the flow rate offset to the range. Among them, the calculation formula for the normalized flow rate value is: , is the normalized flow rate value.

[0030] In the above embodiments of the present application, performing normalization processing on the flow rate of the fluid at the valve to obtain the normalized flow rate value involves the calculation of the range and the offset. The specific steps are, for example: 1. Determine the range (R): The formula is R=q max -q min That is, the range R is the maximum flow rate q of the fluid at the valve. max With the minimum flow q min The difference between the two indicates the range of the fluid flow rate at the valve. For example, in practical applications, if the maximum fluid flow rate at the valve is 100m 3 / h, minimum is 0m 3 / h, then the range .

[0031] 2. Calculate the offset ( ): The formula is Specifically, the offset Δq is the difference between the current flow value q(k) and the minimum flow value q min The difference reflects the degree of deviation of the current flow rate from the minimum flow rate.

[0032] For example, the current flow rate q(k)=50m 3 / h, minimum flow rate q min =0m 3 / h, the offset is: .

[0033] 3. Calculate the flow rate per unit value (f): The formula is That is, the offset Δq is divided by the range R to obtain a ratio between 0 and 1, and then multiplied by 100 to convert it into a percentage form to obtain the flow per unit value f. Through this processing, the range of the flow per unit value f can be the same as the opening range of the opening instruction (0% to 100%). Taking the previously calculated data as an example, Δq=50m 3 / h, R=100m 3 / h, then the per unit flow value f=50 / 100×100=50.0%.

[0034] Step 103, fitting the relationship between the per unit flow value and the actual opening of the valve by the least square method, and constructing an actual flow opening model.

[0035] Next, the least squares method can find a curve that best fits the data distribution between the per-unit value of flow rate and the actual opening of the valve, thereby establishing an accurate mathematical relationship between the two. During the operation of a thermal power unit, when a given per-unit value of flow rate (desired flow rate) is specified, the actual opening of the corresponding valve can be accurately calculated using this model, enabling the valve to adjust the flow rate more precisely and reducing the flow control error. The operating conditions of thermal power units are complex and variable, and the flow characteristics of the valve may be affected by various factors and change. The model obtained by fitting with the least squares method can better adapt to these changes and provide a relatively accurate flow-opening relationship under different operating conditions, thereby improving the stability and accuracy of flow control.

[0036] The model obtained by fitting (flow actual opening model) makes the corresponding relationship between the flow rate and the opening of the valve smoother, avoiding frequent valve actions and drastic changes in flow rate caused by data fluctuations or noise interference. This helps reduce the oscillation of the control loop and makes the control system of the thermal power unit more stable and reliable.

[0037] Traditional calibration of the valve flow characteristics requires a large number of tests to obtain data and calculate the characteristic curve. The process is cumbersome and time-consuming. However, using the least squares method to fit historical operation data to construct a model can, to a certain extent, replace some tests, reduce the occupancy of the unit operation time, and lower the test cost.

[0038] In particular, when the flow characteristics of the valve change to a certain extent, only new operation data need to be collected and the least squares method is used for fitting again, and the flow actual opening model can be quickly updated without conducting large-scale tests, improving the work efficiency.

[0039] In addition, the flow actual opening model obtained by fitting with the least squares method is a clear mathematical expression, which is convenient to integrate it into the distributed control system (DCS) of the thermal power unit. The control system can perform precise calculations and controls based on this model to achieve automatic flow regulation. At the same time, based on this model, the control strategy of the valve can also be optimized, such as adjusting control parameters, optimizing the opening adjustment logic, etc., to improve the operation efficiency and performance of the entire thermal power unit.

[0040] Optionally, step 103 constructs a flow actual opening model by fitting the relationship between the per-unit value of flow rate and the actual opening of the valve using the least squares method, specifically including: Step 1031, fit the per-unit value of flow rate and the actual opening of the valve according to the least squares fitting formula to obtain a flow actual opening model, where the flow actual opening model is: ; is the actual opening of the valve, is the per-unit value of the flow rate, , , , , , which are respectively the first to sixth polynomial coefficients of the actual opening model of the flow rate.

[0041] In the above embodiments of the present application, an actual opening model of the flow rate is established to output a fifth-degree polynomial. Specifically, for example, the actual opening model of the flow rate is set as a fifth-degree polynomial in the form of: ; Next, an error function can be set. For example, it is assumed that n pairs of data are collected: (f k1 , u k1 ), (f k2 , u k2 ), ……, (f kn , u kn ).

[0042] For each set of data, there is an error between the predicted value and the actual value of the model. The error function can be expressed as: .

[0043] Next, solve for the coefficients. The goal of the least squares method is to find a set of coefficients , , , , , such that the error function E is minimized. This can be achieved by taking the partial derivatives of the error function E with respect to , , , , , respectively, and setting the partial derivatives to 0 to obtain a system of linear equations. Then, by solving the system of linear equations, the specific values of each coefficient can be obtained.

[0044] In particular, a part of the collected data that was not involved in the fitting can also be used to verify the accuracy of the model. Input the per-unit value of the flow rate into the constructed model, calculate the predicted value of the actual opening of the corresponding valve, and compare it with the actual valve opening value to calculate the error. If the error is within an acceptable range, it indicates that the model is accurate and reliable.

[0045] To this end, in the control system of a thermal power unit, when a desired per-unit value of flow rate is given, it is input into the actual opening model of the flow rate, and the model will output the corresponding opening of the valve, thus achieving precise control of the flow rate. Through the above steps, an actual opening model of the flow rate applicable to the denitration ammonia injection regulating valve can be constructed. This model can accurately describe the relationship between the per-unit value of the flow rate and the actual opening of the valve, improving the accuracy and stability of the valve flow rate control in the thermal power unit.

[0046] Optionally, the actual opening model of the flow rate is a cubic polynomial, a quintic polynomial, or a septic polynomial. When the actual opening model of the flow rate is a cubic polynomial, it includes 4 polynomial coefficients; when the actual opening model of the flow rate is a quintic polynomial, it includes 6 polynomial coefficients; when the actual opening model of the flow rate is a septic polynomial, it includes 8 polynomial coefficients.

[0047] In the above embodiments of the present application, a polynomial with a lower degree (such as cubic) is relatively simple, has fewer parameters, and less computational complexity, which can effectively avoid the overfitting problem caused by an overly complex model. Overfitting makes the model perform well on the training data but have a large error on the new test data. While polynomials with higher degrees (such as quintic and septic) can better fit the complex non-linear relationships in the data, reducing the possibility of underfitting. Underfitting means that the model is too simple to capture the true patterns in the data. By choosing cubic, quintic, and septic polynomials, a good balance can be achieved between the model complexity and the fitting accuracy. The operating conditions of a thermal power unit are complex and changeable, and the flow characteristics of the valve will also change accordingly. The cubic polynomial is suitable for working conditions where the relationship between the flow opening is relatively simple; when the working conditions become more complex, the quintic polynomial can provide a better fitting effect; and for some special or complex working conditions, the septic polynomial can more accurately describe the non-linear relationship between the flow rate and the opening.

[0048] In addition, the higher the degree of the polynomial, the more resources (such as computing time, memory, etc.) are required for the calculation. The cubic polynomial calculation is relatively simple and can quickly complete the calculation and give the valve opening command in a control system with limited resources or in scenarios with high real-time requirements. Although the quintic and septic polynomials are more complex than the cubic polynomial, compared with polynomials of even higher degrees, they can ensure a certain fitting accuracy without consuming excessive computing resources and can complete the model calculation and valve opening adjustment within a reasonable time. During the real-time control process of a thermal power unit, it is necessary to quickly calculate the corresponding valve opening according to the flow rate demand. The calculation speeds of the cubic, quintic, and septic polynomials are relatively fast, which can meet the requirements of real-time control, ensuring that the control system can promptly respond to the flow rate change and maintain the stable operation of the unit.

[0049] Step 104: Determine the desired flow rate of the fluid flowing out at the desired valve. Predict the target opening degree of the valve adjustment required to output the desired flow rate through the flow rate-actual opening degree model, so that when the fluid passes through the valve adjusted to the target opening degree, the output is the desired flow rate.

[0050] Next, the flow rate-actual opening degree model establishes an accurate mathematical relationship between the flow rate and the valve opening degree. When a desired flow rate is given, the model can accurately calculate the corresponding target opening degree of the valve according to this relationship. This enables the valve to be precisely adjusted to the required opening degree, thereby outputting an actual flow rate that highly matches the desired flow rate, greatly reducing the error of flow rate control.

[0051] During the operation of a thermal power unit, the flow rate demand may change dynamically with the change of working conditions. This model can quickly respond to these changes, predict a new target opening degree in a timely manner according to the new desired flow rate, enable the valve to be adjusted in real time, always maintain precise control of the flow rate, and meet the flow rate requirements of the unit under different working conditions.

[0052] By predicting the target opening degree through the model, the valve can be adjusted to a relatively accurate opening degree position at one time, avoiding flow rate fluctuations caused by repeated probing and adjustment. The stable flow rate output helps to maintain the stable operation of related systems of the thermal power unit (such as steam turbines, boilers, etc.), reduces system oscillations and parameter fluctuations caused by unstable flow rates, and improves the operation stability of the entire unit.

[0053] The use of the model makes the flow rate control process smoother and more orderly. The valve is adjusted according to the predicted target opening degree, avoiding over-regulation and frequent actions, reducing mechanical wear and energy consumption, and at the same time reducing the impact on the control system, further enhancing the stability and reliability of the system.

[0054] Based on the automatic prediction and adjustment function of the model, the frequency and difficulty of manual intervention in flow rate control by operators are reduced. Operators do not need to perform complex flow rate adjustment operations frequently. They only need to set the desired flow rate, and the system can automatically complete the adjustment of the valve, improving work efficiency and at the same time reducing the risk of human operation errors.

[0055] The flow rate-actual opening degree model can also be conveniently integrated into the distributed control system (DCS) of the thermal power unit. The DCS can automatically control the action of the valve according to the target opening degree predicted by the model, realizing the automation and intelligence of flow rate control. This integration method makes the control of the entire unit more coordinated and efficient, and improves the automation level.

[0056] Optionally, the valve corresponds to a distributed control system controller and an opening adjustment mechanism. A flow actual opening model is built in the distributed control system controller. For step 104, "so that when the fluid passes through the valve adjusted to the target opening, the output is the desired flow rate", it specifically includes: Step 1041, so that the distributed control system controller generates a target opening command according to the calculated target opening and sends it to the opening adjustment mechanism of the valve. The opening adjustment mechanism drives the valve to be adjusted to the target opening according to the received target opening command, so that the fluid output at the valve is the desired flow rate. Among them, when the opening of the valve is adjusted, the flow rate of the fluid passing through the valve changes.

[0057] In the above embodiments of the present application, the DCS controller, that is, the distributed control system, is a new generation of instrument control system based on a microprocessor, adopting the design principle of decentralized control functions, centralized display and operation, and taking into account division and comprehensive coordination. As the core component of the DCS system, the DCS controller is responsible for collecting and processing various data in the production process, and executing corresponding control algorithms to output control signals to achieve precise control of the production process.

[0058] Specifically, after the DCS controller receives the calculated target opening value (for example, 65%), it generates a target opening command according to the preset command format. The target opening command includes information such as valve number, target opening value, and command timestamp. For example, a command with the content "valve number: 001, target opening: 65%, time: 2024-07-15, 10:00:00" is generated.

[0059] Then, signal conversion is performed. The DCS controller converts the generated target opening command into an electrical signal suitable for transmission (such as a 4-20mA current signal or a digital signal). If it is a 4-20mA current signal, then the target opening of 0% corresponds to 4mA, the target opening of 100% corresponds to 20mA, and the current signal corresponding to the target opening of 65% is approximately 4+(20 - 4)×65% = 14.4mA.

[0060] Then, the command is transmitted to the opening adjustment mechanism, which specifically includes: The DCS controller transmits the converted electrical signal to the opening adjustment mechanism of the denitration ammonia injection regulating valve through a cable or a communication network. During the transmission process, certain anti-interference measures can be taken to ensure the accuracy and stability of the signal.

[0061] After the opening adjustment mechanism receives the electrical signal sent by the DCS, it converts it into a digital signal or recognizable opening command information. For example, the 4-20mA current signal is converted into a digital quantity through an analog-to-digital converter for processing by the controller inside the adjustment mechanism.

[0062] Next, the opening adjustment mechanism drives the valve to adjust to the target opening. The controller inside the opening adjustment mechanism compares the received target opening command with the actual current opening of the valve (obtained in real time through the opening feedback device) and calculates the opening difference that needs to be adjusted. For example, if the actual current opening of the valve is 60% and the target opening is 65%, the opening difference is 5%.

[0063] Driving the actuator According to the calculated opening difference, the opening adjustment mechanism controls the actuator (such as an electric actuator or a pneumatic actuator) to act. If it is an electric actuator, the controller can control the rotation direction and speed of the motor to increase or decrease the valve opening; if it is a pneumatic actuator, the controller can adjust the pressure and flow rate of the air source to drive the valve to act.

[0064] During the valve adjustment process, the opening feedback device monitors the actual opening of the valve in real time and sends the feedback signal to the opening adjustment mechanism. The adjustment mechanism continuously adjusts the action of the actuator according to the feedback signal until the actual opening of the valve reaches the target opening (65%).

[0065] When the valve is adjusted to the target opening (65%), the ammonia flow rate through the valve will change. Since the actual opening model of the flow accurately describes the relationship between the flow and the opening, after the valve opening is adjusted to the target value, the ammonia flow rate through the valve will approach the desired flow rate (120 kg / h). At the same time, the flow measurement device will monitor the actual flow rate in real time and feed the flow signal back to the DCS controller. The controller can perform further fine-tuning according to the deviation between the actual flow rate and the desired flow rate to ensure that the fluid output at the valve is stable at the desired flow rate value.

[0066] Therefore, by building a valve flow characteristic optimization logic (i.e., the actual opening model of the flow) in the DCS controller, generating the calculation formula for the flow per unit value f and the valve opening u(k) according to the fifth-degree polynomial, and adding the upper and lower amplitude limits of the output to the range of 0 to 100, the desired flow rate of the valve can be controlled. In addition, the function of "automatically controlling the valve flow" is in a parallel relationship with the conventional valve command control function and supports manual switching to cope with emergencies.

[0067] Optionally, before "predicting the target opening of the valve adjustment required to output the desired flow rate through the actual opening model of the flow" in step 104, it specifically further includes: Step 105, obtain the valve flow characteristic curve output by the actual flow opening model according to historical operation data.

[0068] Step 106, determine the characteristic parameters of the valve flow characteristic curve. After the characteristic parameters show no abnormality, predict, through the actual flow opening model, the target opening of the valve adjusted to output the desired flow. Among them, the characteristic parameters include at least one of curve monotonicity, upper and lower limits of the curve, and curve change shape.

[0069] In the above embodiment of the present application, the actual flow opening model can generate a visual picture of the valve flow characteristic curve. After manually confirming that the curve monotonicity, upper and lower limits, and curve change shape are normal, the newly generated six fifth-degree polynomial coefficients (a5, a4, a3, a2, a1, a0) are sent back to the DCS controller in a communication manner. That is, after manually confirming that the fifth-degree polynomial coefficients are correctly input, they are manually activated to take effect and new valve flow characteristic optimization parameters are put into use for subsequent flow control. Specifically, the model fits the relationship between flow and opening according to the input historical operation data and generates a valve flow characteristic curve. For example, the model can use the per-unit value of flow as the abscissa and the actual opening of the valve as the ordinate to draw the corresponding curve in the coordinate system. For example, by calculating the valve opening values corresponding to different per-unit values of flow and connecting these points to form a continuous curve, this curve intuitively shows the characteristics of the valve flow changing with the opening.

[0070] Next, determine the characteristic parameters of the valve flow characteristic curve, specifically including: For the inspection of curve monotonicity, observe the generated valve flow characteristic curve and judge its monotonicity. Under normal circumstances, as the per-unit value of flow increases, the valve opening should increase or decrease monotonically (usually increase). For example, when the per-unit value of flow gradually increases from 0 to 100, the valve opening gradually increases from 0% to 100%. Here, the monotonicity can also be verified by mathematical methods, such as calculating the derivative of the curve. If the derivative is always positive or always negative within the entire domain, the curve has monotonicity. If it is found that the curve is non-monotonic, it may mean that there is an abnormality in the data acquisition process or a problem with the model fitting, and further inspection and processing are required.

[0071] For the determination of the upper and lower limits of the curve, the upper and lower limits of the per-unit value of flow rate and valve opening are determined from the curve. The range of the per-unit value of flow rate is usually 0 - 100, and the corresponding range of valve opening should theoretically be 0% - 100%. However, in actual operation, due to the mechanical characteristics of the valve and system limitations, there may be certain deviations. For example, by observing the curve, it is found that the valve opening starts to change when the per-unit value of flow rate is at least 5; when the per-unit value of flow rate is at most 95, the valve opening is close to the maximum value. At the same time, check whether the actual range of the valve opening is within the reasonable design range, such as whether it is between 0% - 100%. If it exceeds this range, the reasons need to be analyzed.

[0072] For the analysis of the curve change shape, analyze the change shape of the curve to determine whether it conforms to the theoretical flow characteristics of the valve. Common valve flow characteristics include linear, equal percentage, quick opening, etc. types. For example, the slope of the linear characteristic curve remains basically unchanged, that is, the flow rate and the opening are in a linear relationship; the slope of the equal percentage characteristic curve gradually increases as the opening increases. If the change shape of the curve does not match the expected valve type, it may be necessary to readjust the model or check the actual working state of the valve.

[0073] Next, after confirming that the characteristic parameters are normal, predict the target opening. For example, manual confirmation can be carried out, and the generated valve flow characteristic curve is visually displayed on the operation interface for the operator to view. The operator checks whether the monotonicity, upper and lower limits, and change shape of the curve are normal based on experience and understanding of the system. If the operator confirms that the curve is normal, the newly generated 6 fifth-degree polynomial coefficients ( 、 、 、 、 、 ) are sent back to the DCS controller in a communication manner. For example, these coefficients are transmitted from the model calculation module to the DCS controller through the Modbus communication protocol.

[0074] In particular, manual activation can also be performed. The operator manually activates the newly input fifth-degree polynomial coefficients on the DCS operation interface to make them effective. At this time, the DCS controller will use the new valve flow characteristic optimization parameters for subsequent flow control. When the desired flow rate needs to be output, the DCS controller can calculate the corresponding per-unit value of flow rate according to the new fifth-degree polynomial model and the desired flow rate, and then predict the target opening of the valve adjustment required to output this desired flow rate through the model. For example, set the desired flow rate to a certain specific value, calculate the corresponding per-unit value according to the per-unit value of flow rate calculation formula, then substitute it into the new fifth-degree polynomial model, calculate the target opening, and then control the valve to adjust to the target opening to achieve the output of the desired flow rate.

[0075] The traditional thermal power control system DCS does not automatically construct a valve flow model using historical data. By applying the technical solution of this embodiment, the correspondence between flow and opening can be made smoother through model construction, improving the control accuracy of valve flow. By using the existing OPC real-time data communication interface, the opening and flow data of important valves in the DCS are sent to the on-line optimization system of the valve flow characteristic curve of the thermal power unit (i.e., the actual opening model of the flow) in a communication manner for on-line analysis, generating new valve flow characteristic curve parameters, and then sending them back to the DCS through the existing OPC real-time data communication interface. Through the real-time effect of the DCS control logic, it can avoid using the test method for regular calibration, without affecting the production plan of the generating unit, reducing the maintenance cost, and at the same time, it can optimize the valve flow characteristic curve on-line according to the actual operation status of the equipment at any time, improving the automatic control quality.

[0076] Further, as Figure 1 a specific implementation of the method, an embodiment of the present application provides a valve flow control device, as Figure 3 shown, the device includes: A historical data acquisition module 201, configured to acquire the historical operation data of the valve. Among them, the historical operation data includes the actual opening adjusted by the valve when responding to each opening command covering the full opening range, and the flow at each time point within the time period corresponding to the opening command covering the full opening range of the fluid at the valve, and the opening range is 0% to 100%; A flow per-unit processing module 202, configured to perform per-unit processing on the flow of the fluid at the valve, so that the per-unit processed flow is scaled to the same range as the opening range of the opening command, obtaining the flow per-unit value; A flow-opening model construction module 203, configured to construct a flow-actual opening model by fitting the relationship between the flow per-unit value and the actual opening of the valve by the least squares method; A valve flow control module 204, configured to determine the expected flow of the fluid flowing out of the expected valve, and predict the target opening that the valve needs to adjust to output the expected flow through the flow-actual opening model, so that when the fluid passes through the valve adjusted to the target opening, the output is the expected flow.

[0077] It should be noted that for other corresponding descriptions of each functional unit involved in the valve flow control device provided by the embodiment of the present application, reference can be made to Figures 1 to 2 the corresponding description in the method, which will not be elaborated here.

[0078] Based on the method as Figures 1 to 2 shown above, correspondingly, an embodiment of the present application also provides a storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the above as Figures 1 to 2The valve flow control method shown above.

[0079] Based on such an understanding, the technical solution of this application can be embodied in the form of a software product. This software product can be stored in a non-volatile storage medium (which can be a CD-ROM, USB flash drive, mobile hard disk, etc.), and includes several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in various implementation scenarios of this application.

[0080] Based on the above method as Figures 1 to 2 shown above, and Figure 3 the virtual device embodiment shown above, to achieve the above object, an embodiment of this application also provides a computer device, which can specifically be a personal computer, server, network device, etc. This computer device includes a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to implement the valve flow control method as Figures 1 to 2 shown above.

[0081] Optionally, this computer device may further include a user interface, a network interface, a camera, a radio frequency (RF) circuit, sensors, an audio circuit, a WI-FI module, and so on. The user interface may include a display screen (Display), an input unit such as a keyboard (Keyboard), etc. Optionally, the user interface may further include a USB interface, a card reader interface, etc. The network interface may optionally include a standard wired interface, a wireless interface (such as a Bluetooth interface, a WI-FI interface), etc.

[0082] Those skilled in the art can understand that the structure of a computer device provided in this embodiment does not constitute a limitation to this computer device, and it may include more or fewer components, or combine some components, or have different component arrangements.

[0083] The storage medium may further include an operating system and a network communication module. The operating system is a program for managing and saving the hardware and software resources of a computer device, and supports the operation of information processing programs and other software and / or programs. The network communication module is used to implement communication between components inside the storage medium, as well as communication between this entity device and other hardware and software.

[0084] Through the description of the above embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus a necessary general hardware platform, or the historical operation data of the acquisition valve can be implemented through hardware. The historical operation data includes the actual opening degrees respectively adjusted when the valve responds to each opening command covering the full opening range, and the flow rates at each time point within the time period corresponding to the opening commands covering the full opening range of the fluid at the valve; the flow rate of the fluid at the valve is normalized to obtain a normalized flow rate value; the relationship between the normalized flow rate value and the actual opening degree of the valve is fitted by the least squares method to construct a flow actual opening degree model; the target opening degree adjusted by the valve required to output the expected flow rate is predicted through the flow actual opening degree model. By constructing the actual opening degree model, the correspondence between the flow rate and the opening degree can be made smoother, and the control accuracy of the valve flow rate is improved.

[0085] Those skilled in the art can understand that the drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the drawings are not necessarily essential for implementing this application. Those skilled in the art can understand that the modules in the device in the implementation scenario can be distributed in the device in the implementation scenario according to the description of the implementation scenario, or can be correspondingly changed to be located in one or more devices different from this implementation scenario. The modules in the above implementation scenario can be combined into one module, or further split into multiple sub-modules.

[0086] The above serial numbers of this application are only for description and do not represent the advantages or disadvantages of the implementation scenarios. The above-disclosed are only several specific implementation scenarios of this application. However, this application is not limited thereto, and any changes made by those skilled in the art should fall within the protection scope of this application.

Claims

1. A valve flow control method, characterized in that, The method includes: Collecting historical operation data of the valve, where the historical operation data includes the actual opening degrees respectively adjusted by the valve when responding to each opening degree command covering the full opening range, and the flow rates at each time point within the time period corresponding to the opening degree command covering the full opening range of the fluid at the valve, and the opening range is from 0% to 100%; Performing normalization processing on the flow rate of the fluid at the valve so that the normalized flow rate is scaled to the same range as the opening range of the opening degree command, obtaining the normalized flow rate value; Fitting the relationship between the normalized flow rate value and the actual opening degree of the valve by the least squares method to construct a flow rate-actual opening degree model; Determining the expected flow rate of the fluid flowing out of the expected valve, and predicting the target opening degree adjusted by the valve required to output the expected flow rate through the flow rate-actual opening degree model, so that when the fluid passes through the valve adjusted to the target opening degree, the output is the expected flow rate.

2. The method according to claim 1, wherein The constructing of the flow rate-actual opening degree model by fitting the relationship between the normalized flow rate value and the actual opening degree of the valve by the least squares method includes: Fitting the normalized flow rate value and the actual opening degree of the valve according to the least squares fitting formula to obtain a flow rate-actual opening degree model, where the flow rate-actual opening degree model is: ； is the actual opening degree of the valve, is the per-unit value of the flow rate, , , , , , are the first to sixth polynomial coefficients of the actual opening degree model of the flow rate respectively.

3. The method according to claim 1, characterized in that, The valve corresponds to a distributed control system controller and an opening degree adjusting mechanism, and a flow rate-actual opening degree model is built in the distributed control system controller. The making the output be the expected flow rate when the fluid passes through the valve adjusted to the target opening degree includes: Making the distributed control system controller generate a target opening degree command according to the calculated target opening degree and send it to the opening degree adjusting mechanism of the valve. The opening degree adjusting mechanism drives the valve to be adjusted to the target opening degree according to the received target opening degree command, so that the fluid output at the valve is the expected flow rate. When the opening degree of the valve is adjusted, the flow rate of the fluid passing through the valve changes.

4. The method according to claim 1, wherein The performing of the normalization processing on the flow rate of the fluid at the valve so that the normalized flow rate is scaled to the same range as the opening range of the opening degree command, obtaining the normalized flow rate value includes: For the flow rates at each time point within the time period corresponding to the opening degree command covering the full opening range of the fluid at the valve, obtaining the maximum flow rate and the minimum flow rate, and determining the range of the flow rate of the fluid at the valve based on the difference between the maximum flow rate and the minimum flow rate. The determined range is: R = q max -q min , R is the range, q max is the maximum flow rate, q min is the minimum flow rate; For any time point within the time period corresponding to the opening degree command covering the full opening range, calculating the difference between the flow rate at this time point and the minimum flow rate to obtain the flow rate offset at this time point. The calculation formula for the flow rate offset is: ， is the flow offset is the flow at the time point Calculating the normalized flow rate value of the flow rate at this time point based on the ratio of the flow rate offset and the range. The calculation formula for the normalized flow rate value is: ， is the per-unit value of the flow rate.

5. The method according to any one of claims 1 to 4, characterized in that Before predicting the target opening degree adjusted by the valve required to output the expected flow rate through the flow rate-actual opening degree model, the method further includes: Obtaining the valve flow rate characteristic curve output by the flow rate-actual opening degree model according to the historical operation data; Determine the characteristic parameters of the valve flow characteristic curve. After the characteristic parameters show no abnormality, predict the target opening degree adjusted by the valve required to output the desired flow through the actual flow opening degree model, where the characteristic parameters include at least one of curve monotonicity, upper and lower limits of the curve, and curve change shape.

6. The method according to claim 5, wherein When collecting the historical operation data of the valve, collect the flow in batches for each preset opening degree interval within the opening degree range. The collected flow is obtained by taking the average of the flow values collected by multiple sampling points corresponding to the valve. The number of sampling points is greater than the preset number.

7. The method according to claim 6, wherein The actual flow opening degree model is a cubic polynomial or a quintic polynomial or a septic polynomial. When the actual flow opening degree model is a cubic polynomial, it contains 4 polynomial coefficients. When the actual flow opening degree model is a quintic polynomial, it contains 6 polynomial coefficients. When the actual flow opening degree model is a septic polynomial, it contains 8 polynomial coefficients.

8. A valve flow control device, characterized in that, The device includes: A historical data collection module for collecting the historical operation data of the valve, where the historical operation data includes the actual opening degrees adjusted by the valve when responding to each opening degree command covering the full opening degree range, and the flow at each time point within the time period corresponding to the opening degree command covering the full opening degree range at the valve. The opening degree range is 0% to 100%; A flow per-unit processing module for performing per-unit processing on the flow of the fluid at the valve, so that the per-unit processed flow is scaled to the same range as the opening degree range of the opening degree command to obtain the flow per-unit value; A flow opening degree model construction module for constructing an actual flow opening degree model by fitting the relationship between the flow per-unit value and the actual opening degree of the valve through the least squares method; A valve flow control module for determining the desired flow of the fluid flowing out of the desired valve, and predicting the target opening degree adjusted by the valve required to output the desired flow through the actual flow opening degree model, so that when the fluid passes through the valve adjusted to the target opening degree, the output is the desired flow.

9. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the valve flow control method according to any one of claims 1 to 7.

10. A computer device, comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, characterized in that, When the processor executes the computer program, it implements the valve flow control method according to any one of claims 1 to 7.

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