Balancing and throttling integrated valve control method based on PID control technology

Abstract

The invention relates to the technical field of valve control, in particular to a balancing and throttling integrated valve control method based on a PID (Proportion Integration Differentiation) control technology, which comprises the following steps of: calculating a current system pressure drop characteristic according to an established fluid network model and medium data acquired in real time, and dynamically setting a balance adjustment reference opening degree as a throttling control target interval median according to the current system pressure drop characteristic. And then the opening degree of the valve is adjusted based on a PID algorithm in the target interval so as to achieve flow control. And continuously monitoring the matching degree of the adjusted parameter and the current system pressure drop characteristic, triggering the balance adjustment process when the matching degree is insufficient, correcting the reference opening degree, updating the throttling control target interval, and performing readjustment as a new constraint range of the PID algorithm. According to the method, self-adaptive cooperation of the valve balancing function and the throttling function is achieved, and the control precision and the system stability under the complex variable working conditions are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of valve control technology, and in particular to a valve control method based on PID control technology that integrates balanced throttling. Background Technology

[0002] In the control of fluid distribution systems, hydraulic balance and flow regulation are crucial aspects. Existing technologies typically employ a discrete control strategy, where static hydraulic balance is achieved by pre-setting a fixed opening degree for the balancing valve, and then a separate regulating valve performs PID throttling control within its fixed characteristic curve range based on the target flow deviation. This method of decoupling balancing and regulation in time or space means that the control parameters depend on the initial design conditions or commissioning status of the system.

[0003] When the actual operating conditions of the system deviate from the initial state due to load changes, equipment start-up and shutdown, or other branch adjustments, the pressure drop characteristics of the entire pipeline network will dynamically change. At this time, the preset balance opening value is mismatched with the actual system hydraulic conditions, while the throttling control loop continues to adjust within its original fixed operating range. This leads to a severe disconnect between the characteristics of the valve—the object of regulation by the PID controller—and the actual system. The controller often operates in the nonlinear saturation region of the valve flow characteristics, causing regulation oscillations, slow response, or increased steady-state error. The system struggles to quickly stabilize to the target flow rate, resulting in a decline in overall control quality and energy efficiency.

[0004] There is a need for a control method capable of online sensing of changes in the overall hydraulic characteristics of the system and automatically and collaboratively adjusting the balance reference and throttling control operating range accordingly. This would enable valve control parameters to adapt to the dynamically changing pipeline environment, achieving integrated closed-loop operation of balancing and throttling functions. This invention aims to provide such a method. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a valve control method based on PID control technology that integrates balanced throttling.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a valve control method integrating balance and throttling based on PID control technology, comprising: establishing a fluid network model of the pipeline connected to the target valve; acquiring real-time medium pressure data, flow data, and valve opening data within the pipeline; calculating the current system pressure drop characteristics based on the medium pressure data, flow data, and valve opening data; determining the balance adjustment reference opening and the throttling control target range of the target valve based on the fluid network model and the current system pressure drop characteristics; setting the balance adjustment reference opening as the median value of the throttling control target range; and within the throttling control target range, based on a preset system control target value... The valve opening is adjusted based on the proportional-integral-derivative (PID) algorithm to regulate the flow rate, resulting in a real-time flow regulation command. The adjusted pipeline medium pressure and flow rate are collected, and their matching degree with the system pressure drop characteristics is determined. When the matching degree is lower than a threshold, a balancing regulation process is triggered. During the balancing regulation process, the balancing regulation reference opening is corrected, and the throttling control target range is updated accordingly. This updated throttling control target range is used as the new constraint range for the PID algorithm. Within the new constraint range, the PID algorithm readjusts the valve opening based on the updated system pressure drop characteristics until the pipeline medium pressure and flow rate meet the system control target value and remain in this state.

[0007] As a further aspect of the present invention, the calculation of the current system pressure drop characteristics based on the medium pressure data, flow data, and valve opening data specifically involves: synchronously acquiring the pressure value of a first measuring point upstream of the valve, the pressure value of a second measuring point downstream of the valve, and the instantaneous volumetric flow rate in the pipeline; calculating the real-time pressure difference data before and after the valve based on the pressure value of the first measuring point upstream of the valve and the pressure value of the second measuring point downstream of the valve; obtaining the inherent flow characteristic curve of the target valve, and interpolating the current flow coefficient of the valve on the inherent flow characteristic curve based on the instantaneous volumetric flow rate and the real-time pressure difference data; calculating the friction coefficient and local resistance coefficient of the pipeline system under the current operating conditions using fluid dynamics formulas based on the real-time pressure difference data and the instantaneous volumetric flow rate; and constructing a current system pressure drop characteristic equation describing the correspondence between system pressure drop and flow rate by combining the friction coefficient, local resistance coefficient, real-time pressure difference data, and pipeline geometric parameters.

[0008] As a further aspect of the present invention, determining the balance adjustment reference opening and throttling control target range of the target valve based on the fluid network model and the current system pressure drop characteristics specifically involves: calling the resistance characteristic parameters of the parallel branches in the fluid network model, and combining them with the current system pressure drop characteristics to calculate the theoretical flow rate required for the branch where the target valve is located to achieve hydraulic balance under the total system flow design value; solving the theoretical opening value required by the target valve to satisfy the theoretical flow rate value based on the theoretical flow rate value and the current system pressure drop characteristic equation, and setting the theoretical opening value as the balance adjustment reference opening; setting an opening range with the balance adjustment reference opening as the center and a width of a preset value, and initially defining the opening range as the throttling control target range; during system operation, monitoring the actual flow distribution of the parallel branches in real time, and if the distribution deviation persists, fine-tuning the balance adjustment reference opening according to the direction and magnitude of the deviation; and synchronously updating the center position of the throttling control target range based on the fine-tuned balance adjustment reference opening, while keeping the range width unchanged, thereby completing the dynamic determination of the balance adjustment reference opening and the throttling control target range.

[0009] As a further aspect of the present invention, the step of adjusting the valve opening to regulate the flow rate within the throttling control target range based on a preset system control target value and a proportional-integral-derivative (PID) algorithm specifically involves: setting a system control target value, wherein the system control target value is the desired pipeline flow rate or downstream pressure value; using real-time collected flow rate data or downstream pressure data in the pipeline as the process variable input for the PID algorithm; the PID algorithm calculates the deviation between the process variable and the system control target value, and generates a control output quantity to eliminate the deviation based on preset proportional gain, integral time, and derivative time parameters; mapping the control output quantity to the target valve opening change quantity, and determining whether the target opening change quantity exceeds the throttling control target range; if it does not exceed the target range, directly converting the target opening change quantity into a drive signal and sending it to the valve actuator; if it exceeds the target range, using the boundary value of the throttling control target range as the target opening, generating a corresponding drive signal and sending it to the valve actuator to ensure that the valve opening always operates within the target range.

[0010] As a further aspect of the present invention, the step of collecting the adjusted pipeline medium pressure and flow rate and determining its matching degree with the system pressure drop characteristics specifically involves: after the valve opening is adjusted and stabilized, collecting new upstream pressure values, downstream pressure values, and new volumetric flow rate values; calculating a new real-time pressure difference based on the new upstream and downstream pressure values; substituting the new volumetric flow rate value and the new real-time pressure difference into the current system pressure drop characteristic equation to calculate the theoretical pressure difference under the current system pressure drop characteristic equation; calculating the absolute difference between the new real-time pressure difference and the theoretical pressure difference, and dividing the absolute difference by the theoretical pressure difference to obtain the relative error of the pressure difference; comparing the relative error of the pressure difference with a preset matching degree threshold; if the relative error of the pressure difference is less than the matching degree threshold, it is determined that the matching degree meets the requirements; if the relative error of the pressure difference is greater than or equal to the matching degree threshold, it is determined that the matching degree is lower than the threshold, triggering the balance adjustment process.

[0011] As a further aspect of the present invention, the step of correcting the balance adjustment reference opening during the balance adjustment process and updating the throttling control target interval accordingly involves the following steps: When the matching degree is determined to be lower than the threshold, the deviation direction of the system resistance characteristics relative to the model is determined based on the sign of the differential pressure relative error; if the differential pressure relative error is positive, it indicates that the actual system pressure drop is greater than the model calculated value, and the balance adjustment reference opening is corrected in the increasing direction by a correction amount related to the error magnitude; if the differential pressure relative error is negative, it indicates that the actual system pressure drop is less than the model calculated value, and the balance adjustment reference opening is corrected in the decreasing direction by a correction amount related to the error magnitude; the corrected balance adjustment reference opening is obtained, and the original interval width is maintained by using the corrected balance adjustment reference opening as the new center, and the throttling control target interval is redefined; the redefined throttling control target interval is used as the new constraint range and updated in the opening limit parameters of the proportional-integral-derivative algorithm.

[0012] As a further aspect of the present invention, during system operation, the actual flow distribution of parallel branches is monitored in real time. If the distribution deviation persists, the balance adjustment reference opening is fine-tuned according to the direction and magnitude of the deviation. Specifically, this involves: continuously acquiring real-time flow data of the branch where the target valve is located and its parallel branches, calculating the actual proportion of each branch's flow to the total flow; comparing the actual proportion of each branch with the preset design proportion of the fluid network model, and calculating the flow distribution deviation rate of the branch where the target valve is located; if the absolute value of the flow distribution deviation rate exceeds the allowable range and continues to exceed the preset stabilization time, it is determined that the distribution deviation persists; judging the direction of the deviation based on the positive or negative value of the flow distribution deviation rate: a positive deviation indicates that the flow of this branch is too high, and a negative deviation indicates that the flow of this branch is too low; calculating the adjustment amount required for the balance adjustment reference opening based on the magnitude of the flow distribution deviation rate using a preset fine-tuning coefficient, and fine-tuning the balance adjustment reference opening in the same or opposite direction.

[0013] As a further aspect of the present invention, the control output quantity is mapped to the target opening change of the valve, and it is determined whether the target opening change exceeds the throttling control target range. Specifically: the control output quantity of the proportional-integral-derivative algorithm is a dimensionless value. Through a preset scaling transformation coefficient, the value is converted into an increment or decrement of the valve opening as the target opening change quantity; the current actual opening of the valve is obtained, and the current actual opening is added to the target opening change quantity to obtain the desired target opening value; the upper limit opening value and the lower limit opening value of the currently effective throttling control target range are read; the desired target opening value is compared with the upper limit opening value and the lower limit opening value; if the desired target opening value is greater than the upper limit opening value, it is determined that the target opening change quantity causes the opening to exceed the upper limit of the range; if the desired target opening value is less than the lower limit opening value, it is determined that the target opening change quantity causes the opening to exceed the lower limit of the range; if the desired target opening value is between the upper limit opening value and the lower limit opening value, it is determined that the target opening change quantity does not exceed the throttling control target range.

[0014] As a further aspect of the present invention, the balance adjustment reference opening is corrected in the direction of increasing or decreasing by a correction amount related to the magnitude of the error. Specifically, the absolute value of the relative error of the pressure difference is used as the error amplitude, and a preset reference opening correction gain coefficient is introduced. The error amplitude is multiplied by the reference opening correction gain coefficient to obtain the initial correction amount. To prevent overcorrection, a maximum allowable correction amount threshold is set for the initial correction amount. If the initial correction amount exceeds the maximum allowable correction amount threshold, the maximum allowable correction amount threshold is used as the final correction amount; otherwise, the initial correction amount is used as the final correction amount. The correction direction is determined according to the sign of the relative error of the pressure difference. That is, when the error is positive, the final correction amount is positive and is added to the current balance adjustment reference opening; when the error is negative, the final correction amount is negative and is subtracted from the current balance adjustment reference opening. The final correction amount, after direction and amplitude processing, is applied to the current balance adjustment reference opening to complete the correction.

[0015] As a further aspect of the present invention, within the new constraint range, the proportional-integral-derivative (PID) algorithm readjusts the valve opening based on the updated system pressure drop characteristics. Specifically, after completing the correction of the balance regulation reference opening and the update of the throttling control target range, a new set of pressure and flow data when the system is stable is collected. Using the newly collected pressure and flow data, the coefficients in the current system pressure drop characteristic equation are updated to obtain the updated system pressure drop characteristic equation. Within the new constraint range, the PID algorithm generates a new control command based on the system control target value and the system dynamics reflected by the updated system pressure drop characteristic equation. The valve actuator responds to the new control command, adjusts the opening, and the system operates under the new opening and collects feedback data. The PID algorithm continuously performs closed-loop regulation based on the feedback data until the process variable stabilizes within the error band allowed by the system control target value, thus completing the readjustment process.

[0016] Compared with existing technologies, the advantages and positive effects of this invention are as follows: By collecting real-time data on pipeline medium pressure, flow rate, and valve opening, and calculating the current system pressure drop characteristics, the baseline opening for balance regulation is dynamically determined and set as the median of the throttling control target range. This scheme allows the starting reference point and working range center of throttling control to drift in real time with the actual state of the pipeline network, rather than being fixed at a single point. When changes in system operating conditions lead to changes in hydraulic characteristics, the baseline opening and target range are adjusted accordingly, ensuring that the throttling control algorithm always operates within an optimal linearity region that matches the current system. This improves the initial response speed and static accuracy of flow regulation, effectively avoiding sluggish regulation, fluctuations, or static errors caused by the operating point being located in the saturation region or severely nonlinear region of the valve characteristic curve, and enhancing the ability of a single valve to maintain a set flow rate under varying operating conditions. During the throttling control process, the adjusted pipeline parameters are continuously collected, and their matching degree with the current system pressure drop characteristic model is determined. When the matching degree is lower than a threshold, it means that the actual operating conditions have changed significantly, triggering an independent balance regulation process. This process corrects the baseline opening of the balance adjustment and simultaneously updates the target range of the throttling control, using this new range as the new constraint range for the PID algorithm for readjustment. This constructs a two-layer closed-loop control structure based on physical model matching supervision, endowing the control system with overall hydraulic adaptive capabilities. The outer loop balance adjustment ensures that the inner loop throttling control always operates under reasonable parameter conditions. Even in the face of large and continuous disturbances in the system, the control process can quickly converge to a new stable operating point through self-iterative optimization, improving the robustness and environmental adaptability of the entire control method in the face of complex and variable pipeline systems. Attached Figure Description

[0017] Figure 1 The flowchart shows the valve control method based on PID control technology that integrates balanced throttling as described in this invention.

[0018] Figure 2 This is a flowchart illustrating the process of adjusting the opening degree based on the PID algorithm within the target range.

[0019] Figure 3 A diagram showing the correction between flow distribution deviation and baseline opening;

[0020] Figure 4 This is a graph showing the changes in pipeline pressure.

[0021] Figure 5 This is a diagram illustrating the valve opening adjustment process using a PID control algorithm. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] See Figure 1A fluid network model of the pipeline connected to the target valve is established to obtain real-time medium pressure data, real-time flow data, and real-time valve opening data. These data form the basis for calculating the resistance characteristics of the system under current operating conditions. Based on the medium pressure data, flow data, and valve opening data, the current system pressure drop characteristics, describing the relationship between system pressure drop and flow rate, can be calculated. Based on the fluid network model and the calculated current system pressure drop characteristics, the baseline opening required for the target valve to achieve hydraulic balance can be determined, i.e., the balance adjustment baseline opening. A range around this baseline opening, allowing the valve to adjust, is set as the throttling control target interval. This balance adjustment baseline opening is set as the median value of the throttling control target interval. Within the determined throttling control target interval, the control system dynamically adjusts the valve opening using a proportional-integral-differential algorithm based on the preset system control target value, thereby regulating the pipeline flow rate and generating real-time flow regulation commands. After executing the adjustment command, new data on the pressure and flow rate of the medium in the pipeline are collected, and the degree of matching between this new data and the previously established current system pressure drop characteristics is determined. When the matching degree is lower than a preset threshold, a balancing adjustment process is triggered. During the triggered balancing adjustment process, the balancing adjustment reference opening is corrected, and the throttling control target range is updated synchronously based on the corrected reference opening, causing the entire range to shift. The updated throttling control target range will serve as the new constraint range for the proportional-integral-derivative (PID) algorithm. Within the new constraint range, the PID algorithm, combined with the updated system pressure drop characteristics, readjusts the valve opening. This process is repeated until the pipeline medium pressure and flow rate meet the system control target value requirements, and the system operates stably in this state.

[0025] In one embodiment of the present invention, a pressure transmitter is installed at a first measuring point upstream of the valve, a flow meter is installed in the pipe section where the valve is located, and another pressure transmitter is installed at a second measuring point downstream of the valve. The data acquisition system synchronously records the measured values ​​of these three instruments, namely the pressure value at the first measuring point upstream of the valve, the instantaneous volumetric flow rate in the pipeline, and the pressure value at the second measuring point downstream of the valve. The difference between the pressure value at the first measuring point upstream of the valve and the pressure value at the second measuring point downstream of the valve is the real-time pressure difference data before and after the valve. The inherent flow characteristic curve of the target valve stored in the control system database is obtained. This curve has the valve opening degree as the abscissa and the flow coefficient as the ordinate. Based on the measured instantaneous volumetric flow rate value and the calculated real-time pressure difference data, interpolation is performed on the inherent flow characteristic curve to calculate the current flow coefficient corresponding to the valve at the current opening state.

[0026] In some embodiments, based on the calculated real-time differential pressure data and the measured instantaneous volumetric flow rate, the friction coefficient and local resistance coefficient of the pipeline system are calculated using fluid mechanics formulas. The calculation of the friction coefficient depends on the absolute roughness of the pipe inner wall, the pipe inner diameter, and the Reynolds number of the fluid, while the calculation of the local resistance coefficient depends on the specific type and specifications of pipe fittings such as valves, elbows, and tees. Combining the calculated friction coefficient, local resistance coefficient, real-time differential pressure data, and geometric parameters such as pipe length and inner diameter, a current system pressure drop characteristic equation describing the relationship between system pressure drop and flow rate is constructed. One specific form of the current system pressure drop characteristic equation can be expressed as:

[0027]

[0028] in: This represents the total pressure drop of the system, i.e., the real-time differential pressure data. Indicates the friction coefficient. Indicates the length of the pipe. Indicates the inner diameter of the pipe. Indicates fluid density, This indicates the average flow velocity of the fluid within the pipe. This represents the sum of the local resistance coefficients of all local pipe fittings. Flow velocity. With instantaneous volumetric flow rate The relationship is Through measurement and calculation, it can be determined and The specific values ​​under the current operating conditions are used to establish a flow rate-based system. Independent variable, pressure drop The dependent variable is a functional relationship, i.e., the current system voltage drop characteristic equation.

[0029] It is understandable that the synchronous acquisition of instantaneous volumetric flow rate values ​​ensures time correspondence with pressure data, avoiding characteristic calculation errors caused by data asynchrony. The use of the valve's inherent flow characteristic curve directly links the valve's structural characteristics with the flow state, providing a basis for calculating the current flow coefficient. In practical implementation, the constructed current system pressure drop characteristic equation integrates the characteristics of pipeline friction resistance and all local resistance components, providing a complete mathematical description of the pipeline system's hydraulic characteristics.

[0030] In one embodiment of the invention, the control system invokes a pre-stored fluid network model. This model includes resistance characteristic parameters of other branches connected in parallel with the branch containing the target valve. These parameters are stored in the form of equivalent length, pipe diameter, and sum of local resistance coefficients for each branch. Combined with the current system pressure drop characteristics, the system calculates the flow rate at which the total system flow reaches the design value. In order to achieve the preset hydraulic balance among the branches, the theoretical flow rate that the branch where the target valve is located needs to share is determined. The calculation is based on the principle of flow distribution in parallel pipelines. Given the total system flow and the resistance characteristics of each branch, the theoretical flow rate required for the branch containing the target valve to achieve hydraulic balance is calculated. The calculation formula is:

[0031]

[0032] in: This indicates the total design flow rate of the entire pipeline system. This represents the impedance coefficient of the branch containing the target valve when the valve is at a certain reference opening degree. Indicates the first The impedance coefficient of the parallel branches, This indicates the total number of parallel branches. Impedance coefficient. This comprehensively reflects the pipe resistance characteristics of a branch, which are related to the branch's friction coefficient, local resistance coefficient, pipe length, and diameter. The theoretical flow rate that the target valve's branch should pass under equilibrium conditions is calculated using a formula. The obtained theoretical flow value By combining this equation with the current system pressure drop characteristic equation, we can find the solution that enables the flow rate of the branch containing the target valve to reach [the desired value]. At that time, the theoretical opening value that the valve needs to maintain is set as the reference opening value for the balance adjustment of the target valve in subsequent control.

[0033] In some embodiments, a fixed, preset opening value is extended upwards and downwards from a set balance adjustment reference opening, for example, ±5%, to form an opening range with clear upper and lower limits. This opening range is initially defined as the throttling control target interval. During actual system operation, flow meters installed on each parallel branch monitor and acquire real-time flow data of the branch containing the target valve and all its parallel branches. The control system calculates the actual proportion of the real-time flow of each branch to the total measured flow of the system. The control system compares the actual proportion of each branch with the preset design flow proportion of each branch in the fluid network model to calculate the flow distribution deviation rate of the branch containing the target valve. The calculation method is as follows ,in It is the actual proportion of the target branch traffic. It is the design ratio of the target branch flow.

[0034] It is understandable that if the absolute value of the flow distribution deviation rate continuously exceeds the allowable range of 3%, and this state persists for more than the preset stabilization time of 300 seconds, it is determined that there is a persistent distribution deviation in the branch where the target valve is located. The direction of the deviation is determined by the positive or negative value of the flow distribution deviation rate. When the flow distribution deviation rate is positive, it indicates that the flow rate in the branch where the target valve is located is too high, exceeding the design ratio; when the flow distribution deviation rate is negative, it indicates that the flow rate in the branch where the target valve is located is too low, failing to meet the design ratio. The size is determined by a preset fine-tuning coefficient. Calculate the adjustment amount required for the balance adjustment reference opening. The calculation relationship is Fine-tuning the balance adjustment reference opening in the same or opposite direction is performed. When the flow distribution deviation rate is positive, it indicates that the branch flow is too high, and the balance adjustment reference opening should be adjusted to decrease it. The adjustment amount is... When the flow distribution deviation rate is negative, it indicates that the branch flow is too low, and the balance adjustment reference opening should be adjusted to increase it. The adjustment amount is... Based on the fine-tuned balance adjustment reference opening, the center position of the throttling control target interval is updated synchronously while keeping the interval width unchanged. This allows the throttling control target interval to dynamically shift with the balance adjustment reference opening, thus completing the dynamic determination and updating of the balance adjustment reference opening and the throttling control target interval.

[0035] In one embodiment of the present invention, see [reference] Figure 2 The system control target value is preset to the desired pipeline flow rate or downstream pressure value, for example, a constant flow rate of 50 cubic meters per hour. Real-time flow meter readings or downstream pressure transmitter measurements are used as process variable inputs for the proportional-integral-derivative (PID) algorithm. The PID algorithm internally calculates the deviation between the process variable and the system control target value, and generates a control output to eliminate the deviation based on pre-tuned proportional gain, integral time, and derivative time parameters. The control output of the PID algorithm is a dimensionless numerical value, which is converted into a specific increment or decrease in valve opening through a preset scaling coefficient; this conversion result is called the target opening change. The current actual opening indicated by the valve position feedback device is obtained, and the current actual opening is algebraically added to the calculated target opening change to obtain the target opening value that the system expects to achieve in the next control cycle.

[0036] In some embodiments, the upper and lower limits of the currently valid throttling control target range are read from the control system memory. The upper limit is, for example, 65%, and the lower limit is, for example, 55%. The expected target opening value is compared with the upper and lower limits. If the expected target opening value is greater than the upper limit, it is determined that the change in target opening will cause the valve opening to exceed the upper limit of the throttling control target range; if the expected target opening value is less than the lower limit, it is determined that the change in target opening will cause the valve opening to exceed the lower limit of the throttling control target range; if the expected target opening value is between the upper and lower limits, it is determined that the change in target opening does not exceed the throttling control target range. The boundary relationship between the target opening change and the throttling control target range can be represented by the following logical expression:

[0037]

[0038] in: This represents the desired target opening value obtained by converting and superimposing the control output quantities using a proportional-integral-differential algorithm. This indicates the current actual opening degree of the valve. This represents the change in target opening obtained by scaling the control output. The determination process is as follows: If... If the change in the target opening exceeds the limit; If the change in the target opening exceeds the limit; If the change in the target opening degree does not exceed the limit, This is the upper limit opening value of the target interval for throttling control. This is the lower limit opening value of the target interval for throttling control.

[0039] Understandably, if the target opening change is determined to be within the throttling control target range, the control system directly converts the target opening change into a corresponding voltage or current drive signal and sends it to the valve's electric or pneumatic actuator. If the target opening change is determined to be outside the throttling control target range, the control system uses the corresponding boundary value of the throttling control target range as the final command opening. For example, when the desired opening exceeds the upper limit, the upper limit opening value is used as the command; when the desired opening is below the lower limit, the lower limit opening value is used as the command. The control system generates a corresponding drive signal and sends it to the valve actuator. The valve actuator operates according to the received drive signal, adjusting the valve opening to the commanded position, thereby ensuring that any adjustment of the valve opening is constrained within the throttling control target range, preventing excessive throttling from disrupting the system's hydraulic balance.

[0040] See Figure 3This is a graph showing the flow distribution deviation and reference opening correction, illustrating the relationship between the flow distribution deviation rate, the reference opening correction amount, and the corrected reference opening as a function of the control cycle during the balancing adjustment phase. It is a core visualization of hydraulic balance adjustment in valve PID control. By comparing the drastically fluctuating deviation rate with the stable corrected reference opening, it intuitively demonstrates that the system can maintain hydraulic balance under complex operating conditions through gentle and controllable corrections, avoiding over-adjustment. The system monitors the flow distribution deviation rate in real time, triggering a fine-tuning of the reference opening when the deviation exceeds the allowable range and persists for a period of time. To avoid over-correction disrupting system stability, a maximum threshold (±2%) is set for the reference opening correction amount, ensuring a smooth and controllable adjustment process. Through continuous small-amplitude corrections, the reference opening and the throttling control target range dynamically adapt to changes in system operating conditions, thereby achieving long-term hydraulic balance.

[0041] In one embodiment of the present invention, after the valve opening is adjusted and stabilized using a proportional-integral-differential algorithm, the data acquisition system collects a new set of upstream pressure values, new downstream pressure values, and new volumetric flow rate values. A new real-time differential pressure is calculated. The new volumetric flow rate value and the new real-time differential pressure are substituted into the current system pressure drop characteristic equation to calculate the theoretical differential pressure. The absolute difference between the new real-time differential pressure and the theoretical differential pressure is calculated, and this absolute difference is divided by the theoretical differential pressure to obtain the relative error of the differential pressure. The calculated relative error of the differential pressure is compared with a preset matching degree threshold, which is set at 5%. If the relative error of the differential pressure is less than 5%, it is determined that the matching degree between the actual operating state of the system and the model prediction meets the requirements; if the relative error of the differential pressure is greater than or equal to 5%, it is determined that the matching degree is lower than the threshold, triggering a balancing adjustment process. When the matching degree is determined to be below a threshold, the control system determines the direction of deviation of the system resistance characteristics relative to the fluid network model based on the sign of the differential pressure relative error. If the differential pressure relative error is positive, it indicates that the pressure drop of the actual system is greater than the calculated value of the model, meaning that the actual system resistance is greater than expected. If the differential pressure relative error is negative, it indicates that the pressure drop of the actual system is less than the calculated value of the model, meaning that the actual system resistance is less than expected. In some embodiments, refer to Table 1 for the correspondence between the differential pressure relative error and the correction amount of the balance adjustment reference opening.

[0042] Table 1: Example Table of Balance Adjustment Reference Opening Correction Logic

[0043]

[0044] It can be understood that the absolute value of the relative pressure difference error is used as the error amplitude. A preset reference opening correction gain coefficient is introduced, and the error amplitude is multiplied by the reference opening correction gain coefficient to obtain the initial correction amount. To prevent overcorrection in a single adjustment, a maximum allowable correction threshold is set for the initial correction amount. If the initial correction amount exceeds the maximum allowable correction threshold, the maximum allowable correction threshold is used as the final correction amount; if the initial correction amount does not exceed the maximum allowable correction threshold, the initial correction amount is used as the final correction amount. The correction direction is determined based on the sign of the relative pressure difference error. When the relative pressure difference error is positive, the final correction amount is positive and is added to the current balance adjustment reference opening; when the relative pressure difference error is negative, the final correction amount is negative and is subtracted from the current balance adjustment reference opening. Final correction amount. The calculation follows these rules:

[0045]

[0046] in: This represents the relative error of the calculated pressure difference. For a sign function, when When the value is positive, take +1; when the value is negative, take -1, indicating the correction direction. This represents the absolute value of the relative error of the pressure difference, i.e., the error amplitude; This represents the preset reference opening correction gain coefficient; This indicates the preset maximum allowable correction threshold; Indicates the initial correction amount With the maximum allowable correction threshold The smaller value is selected. The final correction amount, after direction and amplitude processing, is applied to the current balance adjustment reference opening, thus completing the correction of the balance adjustment reference opening. The corrected balance adjustment reference opening is obtained. Using the corrected balance adjustment reference opening as the new center, and keeping the original interval width unchanged, the upper and lower limits of the throttling control target interval are redefined. The redefined upper and lower limit opening values ​​of the throttling control target interval are used as the new constraint range and updated in the opening limit parameters of the proportional-integral-derivative algorithm, replacing the original interval parameters.

[0047] See Figure 4This is a pipeline pressure variation curve, visually demonstrating the dynamic changes in upstream pressure, downstream pressure, and differential pressure during valve control, as well as the crucial role of stage transition points. By comparing the actual differential pressure with the theoretical differential pressure, the accuracy of the system's pressure drop characteristic equation is verified, providing a reliable constraint basis for PID control. It clearly shows the switching timing from "pressure drop characteristic judgment" to "balance adjustment," proving the logical rationality of "triggering balance adjustment when the matching degree is below the threshold" in the technical solution. It provides an intuitive reference for setting key parameters such as the matching degree threshold and stage transition conditions in practical engineering, ensuring stable system operation under complex conditions. By observing the correspondence between pressure and differential pressure, the system's adjustment response speed and stability under different operating disturbances can be predicted, providing data support for fault diagnosis and optimized design.

[0048] In one embodiment of the present invention, after completing the correction of the balance adjustment reference opening and updating the throttling control target range, the system operates stably for a period of time while maintaining the new valve opening. Then, the data acquisition system re-acquires a set of system pressure and flow data under stable operating conditions. Using the re-acquired system pressure and flow data, the coefficients in the current system pressure drop characteristic equation are updated to obtain the updated system pressure drop characteristic equation. The general form of the pressure drop characteristic equation can be expressed as a function of the total system resistance and flow rate. The update process involves recalculating the coefficients fitting this function using the new data. The updated system pressure drop characteristic equation can more accurately reflect the real-time hydraulic characteristics of the system after balance adjustment. Within the new constraint range, i.e., the updated throttling control target range, the proportional-integral-differential algorithm generates a new valve opening control command based on the preset system control target value and the system dynamics reflected by the updated system pressure drop characteristic equation.

[0049] In some embodiments, the valve actuator responds to a new control command generated by the proportional-integral-derivative (PID) algorithm, driving the valve to adjust its opening. The system operates at the new valve opening and continuously collects feedback data on flow and pressure. The PID algorithm continuously performs closed-loop regulation based on the real-time collected feedback data, comparing the process variables with the system control target value and calculating the deviation. Based on the deviation, it applies proportional, integral, and derivative operations to generate a control output, which is then combined with the updated throttling control target range to constrain the final opening command. This closed-loop regulation process iterates until the process variables, such as pipeline flow or downstream pressure, stabilize within the error band allowed by the system control target value, thus completing the readjustment of the valve opening. The closed-loop regulation process of the PID algorithm can be described as follows:

[0050]

[0051] in: This indicates that the proportional-integral-differential algorithm is at time 10. The generated dimensionless control output quantity needs to be limited according to the method in the embodiment and the throttling control target range before it is sent to the actuator; Indicates the proportional gain coefficient; This represents the integral gain coefficient, which is the ratio of the proportional gain to the integral time constant. This represents the differential gain coefficient, which is the product of the proportional gain and the differential time constant. Indicates at time The deviation between the system control target value and the measured value of the process variable. Proportional term. Provides control action proportional to the current deviation, integral term Used to eliminate steady-state deviations, differential terms Used to predict the trend of deviation changes and apply damping. Parameters of the proportional-integral-differential algorithm. , , Tuning is required during system debugging to ensure the speed and stability of the adjustment process.

[0052] It is understandable that re-collecting pressure and flow data from a stable system state to update the system pressure drop characteristic equation is to ensure that the system model upon which the control algorithm is based remains consistent with the actual system state, thereby improving control accuracy. The proportional-integral-derivative (PID) algorithm operates within the new constraints, ensuring that throttling control does not disrupt the re-established hydraulic balance. The valve actuator's action is the physical implementation of the control command, and its positioning accuracy affects the final control effect. Continuous closed-loop regulation enables the system to overcome internal disturbances, ultimately stabilizing the process variables near the target value. The error band, for example, set to ±1% of the system control target value, serves as the final criterion for judging the completion of the readjustment process.

[0053] See Figure 5 This is a diagram illustrating the valve opening adjustment process using a PID control algorithm. It clearly shows the valve opening gradually increasing from approximately 56% to 98% and stabilizing above 95%, intuitively demonstrating that the PID algorithm can effectively track the system control target and achieve smooth and stable opening adjustment. The curve stabilizes after 60 seconds, indicating that the PID output is effectively constrained within the throttling control target range, verifying the core technical logic that "the valve opening always operates within the target range." It clearly demonstrates the complete process from "opening adjustment" to "stable operation," forming a complete technical process chain with charts of other stages such as pressure drop characteristic judgment and balance adjustment, making the logical structure of the entire technical solution readily apparent. By observing the fluctuation amplitude and convergence speed of the opening curve, the system's adjustment response speed and stability under different operating conditions can be predicted, providing data support for troubleshooting and optimization design.

[0054] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A valve control method integrating balanced throttling based on PID control technology, characterized in that, Includes the following steps: Establish a fluid network model of the pipeline connected to the target valve, obtain real-time medium pressure data, flow data and valve opening data in the pipeline, and calculate the current system pressure drop characteristics based on the medium pressure data, flow data and valve opening data; Based on the fluid network model and the current system pressure drop characteristics, the balance adjustment reference opening and the throttling control target range of the target valve are determined, and the balance adjustment reference opening is set as the median value of the throttling control target range. Within the throttling control target range, based on the preset system control target value, the valve opening is adjusted according to the proportional-integral-derivative algorithm to regulate the flow rate, thereby obtaining a real-time flow regulation command; Collect the adjusted pipeline medium pressure and flow rate, determine its matching degree with the system pressure drop characteristics, and trigger the balancing adjustment process when the matching degree is lower than the threshold. During the balance adjustment process, the balance adjustment reference opening is corrected, and the throttling control target range is updated accordingly. The updated throttling control target range is used as the new constraint range of the proportional-integral-differential algorithm. Within the new constraints, the proportional-integral-derivative algorithm readjusts the valve opening based on the updated system pressure drop characteristics until the pipeline medium pressure and flow rate meet the system control target values ​​and remain in operation.

2. The valve control method based on PID control technology for integrated balancing and throttling as described in claim 1, characterized in that, The calculation of the current system pressure drop characteristics based on the medium pressure data, flow data, and valve opening data specifically involves: The pressure value at the first measuring point upstream of the valve, the pressure value at the second measuring point downstream of the valve, and the instantaneous volumetric flow rate in the pipeline are collected simultaneously. The real-time pressure difference data before and after the valve is calculated based on the pressure value at the first measuring point upstream of the valve and the pressure value at the second measuring point downstream of the valve. Obtain the inherent flow characteristic curve of the target valve, and calculate the current flow coefficient of the valve by interpolation on the inherent flow characteristic curve based on the instantaneous volumetric flow rate value and real-time differential pressure data. Based on the real-time differential pressure data and instantaneous volumetric flow rate, the friction coefficient and local resistance coefficient of the pipeline system under the current operating conditions are calculated using fluid mechanics formulas. By combining the friction coefficient, local resistance coefficient, real-time differential pressure data, and pipeline geometric parameters, a current system pressure drop characteristic equation is constructed to describe the relationship between system pressure drop and flow rate.

3. The valve control method based on PID control technology for integrated balancing and throttling as described in claim 1, characterized in that, The step of determining the target valve's balance adjustment reference opening and throttling control target range based on the fluid network model and the current system pressure drop characteristics is as follows: By calling the resistance characteristic parameters of the parallel branches in the fluid network model and combining them with the current system pressure drop characteristics, the theoretical flow rate required to achieve hydraulic balance in the branch where the target valve is located is calculated under the total system flow design value. Based on the theoretical flow rate and the current system pressure drop characteristic equation, the theoretical opening value required by the target valve to satisfy the theoretical flow rate is solved in reverse, and the theoretical opening value is set as the balance adjustment reference opening. Set an opening range with the balance adjustment reference opening as the center and the width as a preset value, and initially define the opening range as the throttling control target interval; During system operation, the actual flow distribution of parallel branches is monitored in real time. If the distribution deviation persists, the opening of the balance adjustment reference is fine-tuned according to the direction and magnitude of the deviation. Based on the fine-tuned balance adjustment reference opening, the center position of the throttling control target interval is updated synchronously while keeping the interval width unchanged, thereby completing the dynamic determination of the balance adjustment reference opening and the throttling control target interval.

4. The valve control method based on PID control technology for integrated balancing and throttling as described in claim 1, characterized in that, Within the throttling control target range, the valve opening is adjusted to regulate the flow rate based on a preset system control target value and a proportional-integral-derivative algorithm. Specifically: Set a system control target value, wherein the system control target value is the desired pipeline flow rate or downstream pressure value; Use real-time flow data or downstream pressure data collected inside the pipeline as process variables input for the proportional-integral-differential algorithm. The proportional-integral-derivative (PID) algorithm calculates the deviation between the process variable and the system control target value, and generates a control output to eliminate the deviation based on preset proportional gain, integral time, and derivative time parameters. The control output is mapped to the target opening change of the valve, and it is determined whether the target opening change exceeds the throttling control target range. If the target opening change is not exceeded, the target opening change will be directly converted into a drive signal and sent to the valve actuator. If the target opening is exceeded, the boundary value of the throttling control target range will be used as the target opening, and a corresponding drive signal will be generated and sent to the valve actuator to ensure that the valve opening always operates within the target range.

5. The valve control method based on PID control technology for integrated balancing and throttling as described in claim 1, characterized in that, The process of collecting adjusted pipeline medium pressure and flow rate, and determining their matching degree with the system pressure drop characteristics, specifically involves: After the valve opening is adjusted and stabilized, new upstream pressure values, downstream pressure values, and new volumetric flow rate values ​​are collected. The new real-time pressure difference is calculated based on the new upstream pressure value and the new downstream pressure value. Substitute the new volumetric flow rate value and the new real-time pressure difference into the current system pressure drop characteristic equation to calculate the theoretical pressure difference under the current system pressure drop characteristic equation. Calculate the absolute difference between the new real-time differential pressure and the theoretical differential pressure, and divide the absolute difference by the theoretical differential pressure to obtain the relative error of the differential pressure; The relative error of the pressure difference is compared with the preset matching degree threshold. If the relative error of the pressure difference is less than the matching degree threshold, the matching degree is determined to meet the requirements. If the relative error of the pressure difference is greater than or equal to the matching degree threshold, the matching degree is determined to be lower than the threshold, triggering the balance adjustment process.

6. The valve control method based on PID control technology for integrated balancing and throttling as described in claim 1, characterized in that, During the balance adjustment process, the balance adjustment reference opening is corrected, and the throttling control target range is updated accordingly. Specifically: When the matching degree is determined to be lower than the threshold, the direction of deviation of the system resistance characteristics relative to the model is determined based on the sign of the relative error of the pressure difference. If the pressure difference relative error is positive, it indicates that the actual system pressure drop is greater than the model calculated value. In this case, the balance adjustment reference opening will be corrected in the direction of increasing by a correction amount related to the magnitude of the error. If the relative error of the pressure difference is negative, it indicates that the actual system pressure drop is less than the model calculation value. In this case, the balance adjustment reference opening will be corrected in the direction of decreasing by a correction amount related to the magnitude of the error. Obtain the corrected balance adjustment reference opening, and use the corrected balance adjustment reference opening as the new center, while maintaining the original interval width, to redefine the throttling control target interval. The target range for throttling control is redefined as the new constraint range and updated in the opening limit parameters of the proportional-integral-derivative algorithm.

7. The valve control method based on PID control technology for integrated balanced throttling as described in claim 3, characterized in that, During system operation, the actual flow distribution of parallel branches is monitored in real time. If the distribution deviation persists, the balance adjustment benchmark opening is fine-tuned according to the direction and magnitude of the deviation. Specifically: Continuously acquire real-time flow data of the branch where the target valve is located and its parallel branches, and calculate the actual proportion of flow in each branch to the total flow. The actual proportions of each branch are compared with the preset design proportions of the fluid network model to calculate the flow distribution deviation rate of the branch where the target valve is located. If the absolute value of the traffic allocation deviation rate exceeds the allowable range and continues to exceed the preset stabilization time, it is determined that the allocation deviation persists. The direction of the deviation can be determined by the sign of the flow distribution deviation rate: a positive deviation indicates that the flow in this branch is too high, and a negative deviation indicates that the flow in this branch is too low. Based on the magnitude of the flow distribution deviation rate, the required adjustment amount for the balance adjustment reference opening is calculated using a preset fine-tuning coefficient, and the balance adjustment reference opening is fine-tuned in the same or opposite direction.

8. The valve control method based on PID control technology for integrated balancing and throttling as described in claim 4, characterized in that, The control output is mapped to a target valve opening change, and it is determined whether the target opening change exceeds the throttling control target range. Specifically: The control output of the proportional-integral-derivative algorithm is a dimensionless numerical value. Through a preset scaling transformation coefficient, the numerical value is converted into an increment or decrement of the valve opening, which is used as the target opening change. Obtain the current actual opening degree of the valve, add the current actual opening degree to the change in the target opening degree, and get the desired target opening degree value; Read the upper and lower limits of the current effective throttling control target range; Compare the expected target opening value with the upper limit opening value and the lower limit opening value; If the expected target opening value is greater than the upper limit opening value, it is determined that the change in the target opening value caused the opening to exceed the upper limit of the interval. If the expected target opening value is less than the lower limit opening value, it is determined that the change in the target opening value caused the opening to exceed the lower limit of the interval. If the desired target opening value is between the upper limit opening value and the lower limit opening value, then it is determined that the change in the target opening value has not exceeded the throttling control target range.

9. The valve control method based on PID control technology for integrated balanced throttling as described in claim 6, characterized in that, The balance adjustment reference opening is corrected by a correction amount related to the magnitude of the error, either by increasing or decreasing the opening. Specifically: The absolute value of the relative error of the pressure difference is used as the error amplitude. A preset reference opening correction gain coefficient is introduced. The error amplitude is multiplied by the reference opening correction gain coefficient to obtain the preliminary correction amount. To prevent overcorrection, a maximum allowable correction threshold is set for the initial correction amount. If the initial correction amount exceeds the maximum allowable correction threshold, the maximum allowable correction threshold is used as the final correction amount; otherwise, the initial correction amount is used as the final correction amount. The correction direction is determined based on the sign of the relative error of the pressure difference. When the error is positive, the final correction amount is positive and is added to the current balance adjustment reference opening. When the error is negative, the final correction amount is negative and is subtracted from the current balance adjustment reference opening. The final correction amount, after direction and amplitude processing, is applied to the current balance adjustment reference opening to complete the correction.

10. The valve control method based on PID control technology for integrated balancing and throttling as described in claim 1, characterized in that, Within the new constraints, the proportional-integral-differential algorithm readjusts the valve opening based on the updated system pressure drop characteristics, specifically: After completing the correction of the balance regulation reference opening and the update of the throttling control target range, a new set of pressure and flow data when the system is stable is collected; By using the newly acquired pressure and flow data, the coefficients in the current system pressure drop characteristic equation are updated to obtain the updated system pressure drop characteristic equation. Within the new constraints, the proportional-integral-derivative algorithm generates new control commands based on the system control target value and the system dynamics reflected by the updated system voltage drop characteristic equation. The valve actuator responds to the new control command, adjusts the opening degree, and the system operates under the new opening degree and collects feedback data; The proportional-integral-derivative (PID) algorithm continuously performs closed-loop adjustment based on feedback data until the process variable stabilizes within the error band allowed by the system control target value, thus completing the readjustment process.

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