A method and system for controlling valve opening

Abstract

This invention provides a method and system for controlling valve opening, belonging to the field of valve control technology. First, the invention acquires the real-time total torque signal and real-time valve opening signal. Based on a preset valve torque coefficient characteristic, the total torque is converted into a virtual pressure measurement value characterizing the transient pressure at the valve inlet. Then, an explicit algebraic relationship based on the Zhukovsky direct water hammer formula, the valve flow coefficient gradient, and the water hammer wave reflection characteristic time is used as the control law. With the virtual pressure measurement value, real-time opening, and the upper limit of allowable water hammer pressure as inputs, the maximum allowable valve closing angular velocity without causing pressure overshoot is calculated in real time. Finally, the valve is controlled to close at a rate not exceeding this velocity. This invention replaces pipeline pressure sensors with software algorithms and online simulation with analytical formulas, resulting in extremely low computational load. It can achieve adaptive active water hammer suppression under all operating conditions on conventional controllers, balancing safety and operational efficiency.

Description

Technical Field

[0001] This invention relates to the field of valve control technology, and in particular to a method and system for controlling valve opening. Background Technology

[0002] Water hammer is a transient pressure fluctuation in liquid transportation pipelines caused by rapid changes in flow velocity. The resulting pressure peak can be several times the normal operating pressure of the pipeline, and in severe cases, it can lead to pipeline rupture, equipment damage, and safety accidents. In industrial systems such as long-distance water transmission, pump station outlets, and power plant circulating water systems (especially older systems requiring safety upgrades), valve-closing water hammer is a major source of pressure shocks. How to effectively suppress water hammer pressure peaks without significantly extending valve-closing time has been a long-standing technical challenge in this field.

[0003] Currently, the control methods for suppressing water hammer at valve closure can be mainly divided into the following three categories.

[0004] The first type is the fixed-curve control method. This method pre-sets the relationship curve between valve closing stroke and time, typically employing a segmented deceleration strategy of "fast at the beginning and slow at the end." For example, the valve closes at a higher speed in the first half of its stroke, and then the closing speed is significantly reduced in the second half to minimize sudden changes in flow at the end. The drawback of this method is that its closing curve is fixed before the system is put into operation, and it cannot be adaptively adjusted according to actual pipeline conditions, fluid parameters, or changes in upstream and downstream pressure. To ensure safety under various operating conditions, the fixed curve is often designed to be extremely conservative, leading to an unnecessary extension of the valve closing time and affecting system operating efficiency.

[0005] The second category is feedback control methods based on online pressure sensors. This method installs a high-frequency dynamic pressure sensor at the valve inlet upstream of the pipeline to monitor the transient water hammer pressure in real time. This pressure signal is used as feedback to automatically reduce the valve closing speed when the pressure approaches a safe threshold. The drawback of this method lies in the difficulty of engineering implementation: high-frequency dynamic pressure sensors are expensive, and installation requires drilling holes in existing pipelines, welding pipe supports, laying cables, and calibration. Especially for existing pipelines, the construction period is long, costly, and difficult to coordinate. Furthermore, the pressure sensor is in long-term contact with the medium, and is prone to clogging, drifting, or damage in fluids containing impurities, prone to scaling, or corrosive substances, resulting in a large maintenance workload and reduced long-term system reliability.

[0006] The third category is predictive control methods based on online water hammer numerical simulation. This type of method deploys a one-dimensional water hammer simulation model using the method of characteristics within the controller. Simulations are performed based on real-time valve position signals and pipeline conditions to predict future pressure peaks at different valve closing speeds. The optimal valve closing speed for the current moment is determined through iterative search or optimization algorithms. However, its fundamental drawback lies in the excessively high computational load. Each control cycle requires tens to hundreds of steps of numerical integration of partial differential equations, potentially accompanied by multiple iterative optimizations. This places extremely high demands on the controller's computational power, making it difficult to stably implement high-frequency real-time control on conventional PLCs or embedded microprocessors.

[0007] Therefore, there is an urgent need for a method and system for controlling valve opening to solve the technical problems existing in the prior art: the fixed curve method is conservative and cannot adapt to changes in working conditions; the feedback method with added pressure sensors is difficult to construct and maintain and has high system costs; and although the online simulation method does not require additional sensors and is adaptive, it has excessive computational load and is difficult to implement in engineering. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and system for controlling valve opening. Without relying on additional pipeline pressure sensors or performing online water hammer simulation, it only utilizes the inherent torque and valve position dual feedback signals of the valve to achieve real-time active suppression of water hammer with pressure margin adaptation with extremely low algebraic calculations, thereby enabling low-cost deployment on edge controllers. It achieves a comprehensive balance between response speed, engineering economy, long-term reliability and control performance that is difficult to achieve with the prior art.

[0009] To achieve the above objectives, this application proposes a method for controlling valve opening. During valve closing, online water hammer numerical simulation is not performed in each control cycle; instead, the following steps are executed: Signal acquisition steps: Acquire the real-time total torque signal and real-time valve opening signal of the valve; Virtual pressure generation step: Based on the preset valve torque coefficient characteristics, the real-time total torque signal is converted into a virtual pressure measurement value that characterizes the current transient pressure at the valve inlet; Analytical decision-making steps: A preset explicit algebraic relationship is used as the control law. The explicit algebraic relationship is constructed based on water hammer analytical constraints. The virtual pressure measurement value, the real-time valve opening signal, and the preset upper limit of allowable water hammer pressure are used as inputs to solve in real time the maximum allowable valve closing angular velocity that will not cause pressure over-limit in the current state. Opening control steps: Control the valve to perform the closing action at a rate not exceeding the maximum allowable valve closing angular velocity.

[0010] As a further solution, the virtual stress generation step specifically includes: By subtracting the friction torque component from the real-time total torque signal using a preset friction torque model, the transient fluid dynamic torque acting on the valve disc is obtained. By querying a preset torque coefficient characteristic curve that describes the mapping relationship between valve opening and fluid dynamic torque coefficient, the instantaneous torque coefficient corresponding to the real-time valve opening signal is obtained. The virtual pressure measurement value is calculated by adding the ratio of the transient hydrodynamic torque to the instantaneous torque coefficient to the preset constant pressure head on the downstream side of the valve.

[0011] As a further solution, the explicit algebraic relation used in the analytical decision-making step is constructed based on the Zhukovsky direct water hammer formula, the valve flow coefficient gradient, and the reflection characteristic time of water hammer wave propagation. Its physical meaning is: to ensure that the increase in direct water hammer pressure caused by the change in total flow rate due to angular velocity within the reflection characteristic time under valve opening does not exceed the safety margin between the current virtual pressure measurement value and the upper limit of the allowable water hammer pressure.

[0012] As a further solution, the explicit algebraic relation is specifically as follows: in, Based on the maximum allowable valve closing angular velocity; It is the acceleration due to gravity; This refers to the cross-sectional area of ​​the upstream pipeline. The length of the upstream pipeline; Valve opening degree The valve flow coefficient gradient below; For fluid density; This is a virtual pressure measurement value; The preset constant pressure head downstream of the valve; To the upper limit of permissible water hammer pressure; This is for the safety factor.

[0013] As a further solution, the analytical decision-making step also includes: determining whether the current motion state belongs to an indirect water hammer condition by comparing whether the time required for the valve to close at the current angular velocity at a constant speed for the remaining stroke is greater than the phase length of the water hammer wave; if so, it belongs to an indirect water hammer condition, and a preset indirect water hammer correction factor is used. The explicit algebraic relationship is modified, and the modified maximum allowable valve closing angular velocity is calculated; the modified maximum allowable valve closing angular velocity is larger than the basic maximum allowable valve closing angular velocity.

[0014] As a further solution, the indirect water hammer correction factor Defined as dimensionless characteristic time ratio algebraic functions The corresponding physical meaning is the ratio of the indirect water hammer peak value to the direct water hammer peak value; the dimensionless characteristic time ratio Defined as: in, Indicates the current angular velocity The valve opening is closed at a constant speed. Time required, current angular velocity The actual angular velocity from the previous control cycle is used for estimation to avoid online iterative solutions. This indicates that water hammer and growth are mutually reinforcing. denoted as the length of the upstream pipe, and 'a' represents the water hammer wave velocity.

[0015] As a further solution, the modified maximum allowable valve closing angular velocity is expressed as: in, This indicates the maximum allowable valve closing angular velocity after correction. This indicates the effective value of the indirect water hammer correction factor after lower limit protection processing, and the value is the indirect water hammer correction factor. The larger of the preset correction factor lower limit.

[0016] As a further solution, the virtual pressure generation step also includes a low-frequency, steady-state self-calibration sub-step: When the valve is detected to be in a preset steady-state condition, a slowly varying compensation offset δ is calculated and updated using the deviation between the system-obtainable reference pressure information and the current virtual pressure measurement value. This compensation offset is then applied to the calculation of the virtual pressure measurement value in subsequent control cycles, correcting the virtual pressure measurement value to: The ratio of the transient hydrodynamic torque to the instantaneous torque coefficient is added to the preset constant pressure head downstream of the valve and the compensation offset δ.

[0017] As a further solution, the opening control step also includes a comprehensive safety arbitration sub-step: When the virtual pressure measurement value has reached or exceeded the product of the allowable water hammer pressure limit and the safety factor, regardless of the output of the analytical decision step, the allowable maximum valve closing angular velocity is immediately set to zero or a preset safe reversal speed. When the real-time valve opening signal is less than the preset end opening threshold, the maximum allowable valve closing angular velocity is compared with a preset end safe slow closing velocity, and the smaller value is taken as the final valve closing command.

[0018] On the other hand, the present invention also provides a system for controlling valve opening, for implementing a method for controlling valve opening as described in any of the preceding claims, comprising: Torque sensing module, used to acquire the total torque signal of the valve in real time; Valve position sensing module, used to acquire valve opening signals in real time; The virtual pressure conversion module is configured to convert the real-time total torque signal into a virtual pressure measurement value that characterizes the current transient pressure at the valve inlet, based on a preset valve torque coefficient characteristic. The analytical decision controller has preset pipeline characteristic constants, allowable water hammer pressure upper limit, and characteristic relationship between valve flow coefficient and opening degree. It is configured to: during valve closing process, not perform online water hammer numerical simulation in each control cycle, but use a preset explicit algebraic relationship as the control law. The explicit algebraic relationship is constructed based on water hammer analytical constraints. With the virtual pressure measurement value, the real-time valve opening signal, and the preset allowable water hammer pressure upper limit as input, it solves in real time the maximum allowable valve closing angular velocity that will not cause pressure over-limit in the current state. The execution drive module, connected to the analytical decision controller, is configured to receive and execute valve closing commands that do not exceed the maximum allowable valve closing angular velocity.

[0019] Compared with related technologies, the method and system for controlling valve opening provided by the present invention have the following advantages: 1. This invention completely eliminates the need for dedicated pressure sensors, instead utilizing the valve's inherent torque and position sensing modules. Through calibrated torque coefficient characteristics, the torque signal is converted into a virtual pressure measurement value characterizing the transient pressure at the valve inlet, essentially replacing hardware sensors with software algorithms. Torque and position sensors are standard configurations or low-cost add-ons for electric valve actuators, installed externally to the valve body, avoiding direct contact with the fluid medium and eliminating the risk of clogging or corrosion. This significantly reduces system hardware costs and allows for the modification of existing valves without production disruptions.

[0020] 2. This invention analyzes the physical constraints of water hammer, transforming the "future pressure peak" information, which can only be obtained through simulation, into a single explicit algebraic formula determined by the current virtual pressure measurement, valve opening, and preset pipeline constants. Each control cycle requires only a few table lookups, multiplications, divisions, and square root operations, without any iteration or time advancement, with computation time on the order of microseconds. This allows the control algorithm of this invention to be easily deployed on various low-end controllers (such as ordinary PLCs or embedded microprocessors), and it is extremely tolerant of the choice of control cycle.

[0021] 3. This invention compares the time required for the valve to close at the current angular velocity at its remaining stroke with the magnitude of the water hammer effect, automatically determining whether the current operating condition is direct or indirect water hammer in each control cycle. When determined to be an indirect water hammer condition, a preset indirect water hammer correction factor is introduced to modify the basic formula, thereby reasonably increasing the calculated maximum allowable valve closing angular velocity. This solves the problem of overly conservative speed margins in existing analytical decision-making methods that use the direct water hammer assumption, further improving valve closing efficiency without sacrificing safety margin.

[0022] 4. This invention incorporates a comprehensive safety arbitration sub-step in the driving process. When the virtual pressure measurement value reaches or exceeds the product of the allowable water hammer pressure limit and the safety factor, regardless of the output of the analytical decision step, the maximum allowable valve closing angular velocity is immediately set to zero or a preset safe reversal speed. This judgment has the highest priority, ensuring that the pressure will not exceed the safety limit under any circumstances. Simultaneously, when the valve opening is less than a preset end-opening threshold, the valve closing speed is forcibly limited to a preset safe slow-closing speed at the end of the stroke, preventing shocks caused by numerical anomalies or mechanical inertia at the valve's end of the stroke.

[0023] 5. The entire control mechanism of this invention relies on pre-determined physical quantities such as torque coefficient, flow coefficient, pipeline geometric parameters, and fluid density, which are calibrated offline. No online parameter identification is performed during operation, and it does not rely on a black-box model. The physical meaning of the control law is clear, and the output behavior can be intuitively predicted. Engineering debugging only requires verification of a small number of preset parameters, making it far simpler than simulation-based solutions and highly suitable for the intelligent transformation of existing aging valve systems. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram illustrating the steps of a method for controlling valve opening provided by the present invention; Figure 2 This invention provides a schematic diagram of a system structure for controlling valve opening. The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Example 1 Please see Figure 1 This embodiment provides a method for controlling valve opening. During valve closing, online water hammer numerical simulation is not performed in each control cycle. Instead, the following steps are executed: Signal acquisition steps: Acquire the real-time total torque signal and real-time valve opening signal of the valve; Virtual pressure generation step: Based on the preset valve torque coefficient characteristics, the real-time total torque signal is converted into a virtual pressure measurement value that characterizes the current transient pressure at the valve inlet; Analytical decision-making steps: A preset explicit algebraic relationship is used as the control law. The explicit algebraic relationship is constructed based on water hammer analytical constraints. The virtual pressure measurement value, the real-time valve opening signal, and the preset upper limit of allowable water hammer pressure are used as inputs to solve in real time the maximum allowable valve closing angular velocity that will not cause pressure over-limit in the current state. Opening control steps: Control the valve to perform the closing action at a rate not exceeding the maximum allowable valve closing angular velocity.

[0029] It should be noted that most existing water hammer suppression control systems are based on simulation strategies. Each control cycle still requires a full-stroke water hammer prediction simulation, resulting in a high computational load. Furthermore, the prediction results are highly dependent on the consistency and accuracy of the simulator's internal state, making it difficult to achieve ultimate real-time response on low-end controllers.

[0030] Even without parameter identification and iterative optimization, a single full-closing predictive simulation still requires hundreds of steps of hydraulic transients at the end of the valve with a time step of milliseconds or even sub-milliseconds, and captures the peak value of the reflected wave. Within a 20ms control cycle, this may consume CPU resources of the actuator closed loop and safety logic, resulting in insufficient system margin.

[0031] Therefore, this embodiment completely eliminates online water hammer prediction simulation by adopting torque-valve position dual feedback fusion. Instead, it directly solves the maximum allowable angular velocity in real time based on the analytical constraints of the current virtual pressure and wave reflection time, reducing the amount of computation to only a few algebraic operations.

[0032] This embodiment replaces online water hammer numerical simulation with purely analytical calculations, thereby achieving water hammer suppression with extremely low computational load. Specifically, this method executes only four steps in each control cycle: The signal acquisition step obtains the valve's real-time total torque and real-time opening degree; the virtual pressure generation step, based on the preset valve torque coefficient characteristics, converts the torque signal into a "virtual pressure measurement value" that characterizes the transient pressure at the valve inlet, thereby obtaining real-time pressure feedback on the water hammer sensitive side without adding a pipeline pressure sensor; the analytical decision step uses an explicit algebraic relationship constructed based on water hammer analytical constraints as the control law, and directly solves for the maximum allowable valve closing angular velocity that will not cause pressure over-limit under the current state, using the virtual pressure measurement value, real-time opening degree, and the upper limit of allowable water hammer pressure as inputs; the opening degree control step then executes the closing action according to this instruction.

[0033] This embodiment analyzes the "constraint relationship between future peak pressure and valve closing speed" that previously required online simulation or iterative optimization to obtain into a set of algebraic formulas composed of current measurements and preset constants. The derivation principle is as follows (Zhukovsky water hammer constraint): The valve closing action generates a direct water hammer pressure wave upstream of the valve. The characteristic time required for this wave to propagate to an upstream constant pressure source (such as a reservoir) and then reflect back to the valve is... Within this time window, the valve experiences changes due to angular velocity. Total change in flow This will trigger a near-linear increase in pressure, the upper limit of which follows the Zhukowski formula: This invention utilizes this physical law to find an angular velocity in the current state. This makes the angular velocity exist The predicted peak pressure generated within the time period just does not touch the safety limit, thus solving for... The constraints.

[0034] Since the formula itself is rigorously derived based on Zhukovsky's direct water hammer relationship and reflection characteristic time, it physically guarantees that the calculated upper limit of angular velocity can always keep the peak water hammer pressure within the allowable safety margin, without the need for verification through hourly numerical simulation.

[0035] Compared to fixed curve control, this method can dynamically adjust the speed according to real-time operating conditions; compared to adding a pressure sensor, it uses the valve's own signal to build pressure feedback; compared to online simulation methods, each cycle only requires table lookup and algebraic operations, with calculation time on the order of microseconds, and can be easily deployed on conventional low-end controllers.

[0036] Furthermore, the virtual pressure generation step specifically includes: By subtracting the friction torque component from the real-time total torque signal using a preset friction torque model, the transient fluid dynamic torque acting on the valve disc is obtained. By querying a preset torque coefficient characteristic curve that describes the mapping relationship between valve opening and fluid dynamic torque coefficient, the instantaneous torque coefficient corresponding to the real-time valve opening signal is obtained. The virtual pressure measurement value is calculated by adding the ratio of the transient hydrodynamic torque to the instantaneous torque coefficient to the preset constant pressure head on the downstream side of the valve.

[0037] Specifically, in this embodiment, by gradually stripping away non-fluid factors from the total valve torque, the fluid dynamic torque generated purely by the pressure difference across the valve is finally separated, and this torque is used to deduce the transient pressure at the valve inlet.

[0038] Specifically, this step first uses a preset friction torque model to subtract the friction torque component generated by mechanical transmission from the collected real-time total torque signal, thereby obtaining the transient fluid dynamic torque that the fluid directly acts on the valve disc.

[0039] Subsequently, by querying the torque coefficient characteristic curve pre-calibrated offline and stored in the system, the instantaneous torque coefficient corresponding to the current real-time valve opening is obtained. This torque coefficient describes the magnitude of the torque generated by a unit pressure difference acting on the valve disc at the current opening.

[0040] Finally, the transient fluid dynamic torque is divided by the instantaneous torque coefficient to obtain the real-time pressure difference value before and after the valve; this pressure difference value is then added to the preset constant pressure head on the downstream side of the valve to calculate the virtual pressure measurement value characterizing the transient pressure at the valve inlet.

[0041] This embodiment creatively reuses a torque sensor, typically used only for overload protection in electric valves, as a "virtual pressure sensor," replacing the high-frequency dynamic pressure sensor installed through a hole in the pipeline with a pure software algorithm. Since the torque sensor is installed outside the valve body and does not contact the fluid medium, long-term reliability issues such as sensor clogging and corrosion are completely eliminated, while significantly reducing system hardware costs and construction difficulty. The entire conversion process involves algebraic operations without any simulation or iteration, ensuring the overall solution's extremely simple computational characteristics.

[0042] Furthermore, the explicit algebraic relation used in the analytical decision-making step is constructed based on the Zhukovsky direct water hammer formula, the valve flow coefficient gradient, and the reflection characteristic time of water hammer wave propagation. Its physical meaning is: to ensure that the increase in direct water hammer pressure caused by the change in total flow rate due to angular velocity within the reflection characteristic time under valve opening does not exceed the safety margin between the current virtual pressure measurement value and the upper limit of allowable water hammer pressure.

[0043] Specifically, this embodiment analyzes the complex dynamic relationship between the peak water hammer pressure and the valve closing speed into an algebraic constraint that can be directly calculated from the measured quantity at the current moment.

[0044] Specifically, the explicit algebraic relationship is constructed based on three core physical elements: the first is the Zhukovsky direct water hammer formula, which describes the quantitative relationship between the change in flow rate in the pipeline and the increase in pressure at the valve before the pressure wave is reflected back; the second is the valve flow coefficient gradient, which characterizes the rate of change in flow capacity caused by a unit change in angle at the current opening; and the third is the reflection characteristic time of the water hammer wave propagation, that is, the time required for the pressure wave to propagate from the valve to the upstream constant pressure source and then reflect back to the valve.

[0045] By combining these three factors, a causal chain can be established: "When the opening is closed at a certain angular velocity at the current opening, how much flow change will occur within the reflection characteristic time, and how much direct water hammer pressure will be increased."

[0046] The physical constraint of this explicit algebraic relation means that the maximum allowable valve closing angular velocity solved by the controller must ensure that the increase in direct water hammer pressure corresponding to the total flow change caused by this angular velocity within the reflection characteristic time does not exceed the safety margin between the current virtual pressure measurement value and the upper limit of the allowable water hammer pressure.

[0047] In other words, the formula is not an empirical fit, but a hard constraint based on the physical laws of water hammer—ensuring how quickly the valve can close without exceeding the safety limit due to water hammer within the remaining "pressure space" between the current measured pressure and the upper limit. When the pressure margin is large, the allowable speed is fast; when the pressure is close to the upper limit, the margin approaches zero, and the allowable speed also automatically approaches zero, forming an adaptive dynamic protection.

[0048] Furthermore, the explicit algebraic relation is specifically as follows: in, Based on the maximum allowable valve closing angular velocity; It is the acceleration due to gravity; This refers to the cross-sectional area of ​​the upstream pipeline. The length of the upstream pipeline; Valve opening degree The valve flow coefficient gradient below; For fluid density; This is a virtual pressure measurement value; The preset constant pressure head downstream of the valve; To the upper limit of permissible water hammer pressure; This is for the safety factor.

[0049] Specifically, the first factor This characterizes the sensitivity of a specific pipe and valve to changes in flow rate at the current opening degree—the longer the pipe and the greater the valve flow coefficient gradient, the smaller the permissible angular velocity; the second factor This reflects the contribution of the current flow pressure difference to the rate of change of flow rate; the third factor. The real-time pressure margin is the most direct variable determining the upper limit of speed. When the valve inlet pressure is low and the margin is sufficient, the formula outputs a higher speed, enabling the valve closing process to proceed quickly. As the closing progresses, the pressure gradually increases and the margin narrows, the output speed automatically and smoothly decreases, forming an adaptive deceleration that does not require a preset curve.

[0050] It should be noted that this formula is derived based on Zhukovsky's conservative assumptions about direct water hammer. It assumes that during the characteristic reflection time... All flow changes caused by valve closure are converted into an initial pressure rise (i.e., the most severe water hammer condition), without considering the canceling effect of subsequent reflected waves. This conservatism ensures that even under the most unfavorable operating conditions, when the valve is closed at the rate output by the formula, the peak water hammer pressure will not exceed the safety limit. Therefore, this formula is not an empirical fit, but an analytical control law with explicit physical constraints, and its conservative margin provides a reliable guarantee for engineering safety.

[0051] Furthermore, the analytical decision-making step also includes: determining whether the current motion state belongs to an indirect water hammer condition by comparing whether the time required for the valve to close at the current angular velocity at a constant speed for the remaining stroke is greater than the phase length of the water hammer wave; if so, it belongs to an indirect water hammer condition, and a preset indirect water hammer correction factor is used. The explicit algebraic relationship is modified, and the modified maximum allowable valve closing angular velocity is calculated; the modified maximum allowable valve closing angular velocity is larger than the basic maximum allowable valve closing angular velocity.

[0052] Specifically, the above scheme is based on "ideal frictionless direct water hammer based on Zhukovsky," which implicitly assumes that the valve completes a significant flow change before the reflected wave returns, meaning the effective valve closing time is less than or equal to the water hammer phase length. However, in actual industrial control, due to safety constraints, most of the valve's stroke is within the range of the reflected wave. The test was conducted under the condition that the water hammer type was indirect water hammer, and the actual maximum pressure rise would be significantly lower than the Zhukovsky prediction. Therefore, if the direct water hammer constraint is simply used, the calculated allowable angular velocity will be too small, resulting in an unnecessary extension of the valve closing time.

[0053] This improvement, while retaining the torque-valve position dual feedback virtual pressure generation and final command fusion unchanged, only enhances the accuracy of constraint calculations in the analytical decision controller. An indirect water hammer correction coefficient related to the current motion state is introduced. ( The explicit formula for the maximum permissible angular velocity is modified as follows: Among them, the indirect water hammer correction factor Defined as dimensionless characteristic time ratio algebraic functions The corresponding physical meaning is the ratio of the indirect water hammer peak value to the direct water hammer peak value; the dimensionless characteristic time ratio Defined as: in, Indicates the current angular velocity The valve opening is closed at a constant speed. Time required, current angular velocity The actual angular velocity from the previous control cycle is used for estimation to avoid online iterative solutions. This indicates that water hammer and growth are mutually reinforcing. denoted as the length of the upstream pipe, and 'a' represents the water hammer wave velocity.

[0054] For a classic indirect water hammer scenario with an upstream constant-pressure reservoir, linearly closed valves, and negligible friction, the peak pressure can be solved using the Allievi chain equation. The ratio ψ of the initial peak pressure to the direct water hammer peak pressure exhibits a clear functional relationship with the time ratio τ. This relationship can be achieved by offline fitting of the numerical solution to the Allievi equation, storing it in the controller as a piecewise polynomial or in a lookup table. Online calculations require only algebraic evaluation, without any iterative simulation.

[0055] To avoid iteration, the angular velocity of the previous cycle is used, taking advantage of the high-frequency control cycle. Since the control cycle (10~20ms) is much smaller than the water hammer phase length, the velocity change is continuous. This explicit recursion is sufficient for stable tracking and completely avoids solving the equation, thereby reducing the hardware computing power requirements.

[0056] Based on this, the modified maximum allowable valve closing angular velocity is expressed as: in, This indicates the maximum allowable valve closing angular velocity after correction. This indicates the effective value of the indirect water hammer correction factor after lower limit protection processing, and the value is the indirect water hammer correction factor. The larger of the preset correction factor lower limit.

[0057] Furthermore, the virtual pressure generation step also includes a low-frequency, steady-state self-calibration sub-step: When the valve is detected to be in a preset steady-state condition, a slowly varying compensation offset δ is calculated and updated using the deviation between the system-obtainable reference pressure information and the current virtual pressure measurement value. This compensation offset is then applied to the calculation of the virtual pressure measurement value in subsequent control cycles, correcting the virtual pressure measurement value to: The ratio of the transient hydrodynamic torque to the instantaneous torque coefficient is added to the preset constant pressure head downstream of the valve and the compensation offset δ.

[0058] Specifically, virtual pressure conversion strictly relies on two prerequisites: 1. Constant pressure head downstream of the valve. 1. The parameters are constant and known; 2. The torque coefficient curve and flow coefficient do not change significantly during long-term operation; however, in actual industrial settings, changes in downstream water level, back pressure fluctuations, or corrosion and scaling of valve sealing surfaces due to years of operation can cause slow time-varying shifts in the actual and characteristic curves. If the original fixed parameters are still used for calculation, the error will accumulate over time, leading to incorrect pressure margin judgments—either too aggressive (risky) or too conservative (further sacrificing efficiency), resulting in a decrease in the long-term reliability of the system.

[0059] Therefore, this embodiment adds a steady-state self-calibrator to the original virtual pressure conversion module. This self-calibrator is triggered only in specific operating conditions where the valve opening is stable and the flow rate is near zero (or stable). It uses other deterministic information from the system itself to update the offset compensation term at a very low frequency using algebraic calculations, thereby correcting the error through the virtual pressure measurement correction formula. Or equivalently update the downstream equivalent pressure benchmark. : in, For hydrodynamic torque, This is the initial offline calibration value for the instantaneous torque coefficient. This is the initial offline calibration value for the downstream constant pressure head. This is the slowly varying compensation offset output by the self-calibrator, updated only when calibration is triggered.

[0060] Thus, all the useful explicit algebraic relations in the analysis are... and All places have been replaced with the compensated version. The calculated virtual pressure remains unchanged in the formula, and the calculation increment is negligible.

[0061] Triggering conditions (logic gating): When the system detects one of the following two operating conditions and continues for more than a preset confirmation time (e.g., 2 seconds), it is considered to have entered the steady-state calibration window: Operating Condition A (Fully Closed / Nearly Fully Closed Zero Flow): Valve Opening Less than the threshold for full shutdown And it remains in this position. At this time, the pressure difference across the valve is entirely determined by the upstream and downstream static pressure, with no influence from dynamic pressure.

[0062] Operating condition B (fully open, zero-disturbance steady-state flow): Maintain valve opening. Furthermore, if the upstream pressure source is stable (which can be confirmed by the upstream pump operating condition signal or other known quantities), the dynamic pressure characteristics flowing through the valve are clearly defined and can be used as a calibration point.

[0063] Calibration algorithm: Operating Condition A Calibration (Directly Corrects Downstream Pressure Equivalent Offset) When the valve closes reliably and leakage is negligible, the hydrodynamic torque Theoretically, it's not zero because the valve still bears the static pressure difference between the upstream and downstream sides. Let's assume the actual downstream pressure at this point is... (i.e., the actual pressure head downstream of the valve), the initial calibration value is The virtual pressure obtained by inverse calculation after correction from virtual pressure measurement should be equal to the actual upstream pressure at this time. .

[0064] If we know the actual upstream pressure at this time (for example, through occasional readings from an upstream pressure transmitter, or based on the constant gravity head), let the known upstream pressure be... (Constant value), then the compensation deviation calculated in this instance. : Calculated compensation deviation This is the compensation offset that should be applied at the moment; Update with low-pass filter : Among them, the filter coefficients ; and These represent the moments before and after the update; Operating Condition B Calibration (Correcting Overall Characteristic Drift) Under full-opening condition, the pressure difference across the valve Smaller and measurable, if an independent upstream pressure measurement is available at this time. Then the theoretical hydrodynamic torque is calculated as follows: ;in, This represents the torque coefficient value when the valve is in the fully open position (100% opening) under initial offline calibration conditions. Measured fluid dynamic torque. With theoretical hydrodynamic torque The deviation reflects the combined drift of the torque coefficient or downstream pressure.

[0065] Define compensation factor ,make: ; take the logarithmic form of the offset Equivalent to: Both use low-pass filtering for updates. .

[0066] If the system is not equipped with any additional pressure sensors, an absolutely conservative safety strategy can be adopted: under operating condition A, it is assumed that the offset should ensure that the virtual pressure is not less than a certain minimum safe value, and only slow corrections in the conservative direction are allowed. This can be achieved by limiting... The symbols and update directions are implemented.

[0067] The key value of this improvement lies in achieving sustained stability of virtual pressure measurement accuracy during long-term operation at near-zero real-time computational cost (self-calibration is triggered only at low frequencies and does not participate in millisecond-level control loop calculations). This self-calibration does not alter the structure of the analytical decision formula itself and can be used in parallel with other improvements such as indirect water hammer correction.

[0068] Furthermore, the opening control step also includes a comprehensive safety arbitration sub-step: When the virtual pressure measurement value has reached or exceeded the product of the allowable water hammer pressure limit and the safety factor, regardless of the output of the analytical decision step, the allowable maximum valve closing angular velocity is immediately set to zero or a preset safe reversal speed. When the real-time valve opening signal is less than the preset end opening threshold, the maximum allowable valve closing angular velocity is compared with a preset end safe slow closing velocity, and the smaller value is taken as the final valve closing command.

[0069] Specifically, before the analytical decision calculation results are output to the execution mechanism, two hard safety barriers, independent of normal analytical decision-making, are set up to ensure that the system behavior is absolutely controllable under extreme operating conditions. This arbitration sub-step contains two independent judgment logics, both implemented with simple comparison operations.

[0070] The first line of defense is the pressure over-limit emergency stop protection. When the virtual pressure measurement value has reached or exceeded the product of the allowable water hammer pressure limit and the safety factor, it indicates that the current water hammer pressure has approached or even exceeded the safety limit.

[0071] At this point, regardless of the maximum allowable valve-closing angular velocity calculated by the analytical decision-making step, the arbitration logic immediately forces this velocity to zero, or outputs a preset safe reversal velocity to slightly open the valve and actively release pressure. This judgment has the highest priority, and its physical meaning is: when the measured pressure has reached the safe boundary, any continued valve-closing action may exacerbate the pressure increase; the only safe measure is to stop closing or even briefly reverse the opening.

[0072] The second line of defense is the forced slow-closing protection at the end of the stroke. When the real-time valve opening signal is less than the preset end-of-stroke opening threshold, it indicates that the valve has entered the end-of-stroke region. At this time, the maximum allowable valve closing angular velocity calculated by the analytical decision-making step is compared with a preset safe slow-closing speed at the end of the stroke, and the smaller value between the two is taken as the final valve closing command.

[0073] The reason for implementing this protection is that when the valve is near the fully closed position, the flow coefficient gradient may tend to a minimum, leading to a risk of numerical singularities in the basic formula; simultaneously, mechanical inertia is more likely to cause shocks in the final stroke. By forcibly limiting the speed, the valve can be ensured to close smoothly in the last stroke, avoiding any safety hazards caused by calculation anomalies or mechanical factors. The entire arbitration sub-step consists of simple numerical comparison and value retrieval operations, with negligible computational load.

[0074] Example 2 Please see Figure 2 This embodiment also provides a system for controlling valve opening, used to implement a method for controlling valve opening as described in any of the above embodiments 1. The system will be described in detail below with reference to specific embodiments: I. Overall System Composition In one specific embodiment, the system mainly includes a torque sensing module, a valve position sensing module, a virtual pressure conversion module, an analytical decision controller, and an execution drive module: Torque sensing module, used to acquire the total torque signal of the valve in real time; Valve position sensing module, used to acquire valve opening signals in real time; The virtual pressure conversion module is configured to convert the real-time total torque signal into a virtual pressure measurement value that characterizes the current transient pressure at the valve inlet, based on a preset valve torque coefficient characteristic. The analytical decision controller has preset pipeline characteristic constants, allowable water hammer pressure upper limit, and characteristic relationship between valve flow coefficient and opening degree. It is configured to: during valve closing process, not perform online water hammer numerical simulation in each control cycle, but use a preset explicit algebraic relationship as the control law. The explicit algebraic relationship is constructed based on water hammer analytical constraints. With the virtual pressure measurement value, the real-time valve opening signal, and the preset allowable water hammer pressure upper limit as input, it solves in real time the maximum allowable valve closing angular velocity that will not cause pressure over-limit in the current state. The execution drive module, connected to the analytical decision controller, is configured to receive and execute valve closing commands that do not exceed the maximum allowable valve closing angular velocity.

[0075] Among the above modules, the virtual pressure conversion module and the analytical decision controller can be integrated into the same microprocessor, PLC or embedded controller, with a control cycle of 10 milliseconds to 20 milliseconds.

[0076] II. Offline Acquisition of Pre-set Data Before the system is put into operation, the following data are obtained through offline testing or design data and stored in the controller memory.

[0077] Torque coefficient characteristic curve The pressure difference across the valve was measured at different valve openings using a steady-state flow test bench calibration. The torque exerted by the fluid on the valve disc From the relation Calculate the torque coefficient at each opening degree to form a lookup table or polynomial fitting curve indexed by the opening degree.

[0078] Flow coefficient characteristics and its gradient The flow rate is obtained through a standard flow test. The valve is opened at different pressure levels, and the volumetric flow rate Q is measured by passing an incompressible fluid with a known pressure difference. Calculate the flow coefficient at each opening degree; where ρ represents the fluid density. for The derivative with respect to the opening degree can be obtained by... The curve can be obtained by taking the derivative after polynomial fitting or by directly using a difference table.

[0079] The frictional torque model was obtained through no-load operation calibration. Without applying fluid pressure, the valve was driven at different speeds in both forward and reverse directions, and the torque values ​​were recorded. A classic model combining Coulomb friction and viscous friction was employed. The Coulomb friction coefficient was determined by data fitting. and the coefficient of viscous friction b; where, The sign function for angular velocity ω; it takes +1 when ω>0, 0 when ω=0, and -1 when ω<0.

[0080] In the pipe characteristic constants, the pipe length L, pipe inner diameter D, and cross-sectional area A are obtained from design data; the water hammer wave velocity a is calculated based on the pipe material, wall thickness, and fluid elastic modulus, or obtained through field testing; the fluid density... Determined by media analysis. Constant pressure head downstream of the valve. Determined based on the downstream pool water level or system design pressure. Maximum allowable water hammer pressure. The safety factor is determined based on the pipeline design pressure standard. Take a value between 0.90 and 0.95.

[0081] Indirect water hammer correction factor function The method of obtaining the data is as follows: for specific pipeline parameters, different dimensionless time ratios are used. Under the given operating conditions, offline numerical solutions are obtained using the Allevi chain equation or the method of characteristics to calculate various... The ratio of the corresponding peak indirect water hammer pressure to the peak direct water hammer pressure is used to form a fitting function or lookup table, which is then embedded in the controller. Only this value is used during online operation. Perform algebraic evaluation, but do not perform any numerical simulation.

[0082] III. Detailed Steps of the Control Method After the valve receives a closing command, the system executes the following steps within each control cycle. All steps involve algebraic operations, table lookups, and logical judgments, and do not include any online water hammer numerical simulation or iterative optimization process.

[0083] Step S1: Signal Acquisition The torque sensing module and the valve position sensing module simultaneously acquire the total valve stem torque at the current moment. and valve opening The signal is then transmitted to the virtual pressure conversion module and the analytical decision controller.

[0084] Step S2: Virtual Pressure Generation The virtual pressure conversion module first calculates the current angular velocity. Angular velocity is obtained by numerically differentiating the opening signals of adjacent cycles, or directly from the velocity signal fed back by the execution drive module.

[0085] The current friction torque is calculated based on the preset friction torque model: ; Subtracting the frictional torque from the total torque yields the transient hydrodynamic torque acting on the valve disc: ; At the current opening Using the index, query the torque coefficient characteristic curve to obtain the corresponding instantaneous torque coefficient. .

[0086] Calculate the virtual pressure measurement value: ; When the system has steady-state self-calibration enabled and there is an effective compensation offset. At that time, the virtual pressure measurement value is corrected to: ; Compensation offset The method for obtaining this information will be explained separately in step S5 below. This step runs independently at low frequency and does not participate in the high-frequency calculation of each control cycle.

[0087] Step S3: Analytical Decision Calculation The analytical decision controller receives the current virtual pressure measurement value. and current valve opening Perform the following calculations.

[0088] S3.1 Calculation basis: Maximum allowable valve closing angular velocity Based on the explicit algebraic relationship constructed using Zhukovsky's direct water hammer formula and reflection characteristic time, the calculation basis allows for the maximum valve closing angular velocity: All parameters in the formula are determined by preset values ​​or current measured values, and are all known quantities. Through opening Obtained by querying the preset flow coefficient gradient table. When When the value is negative or zero, it indicates an abnormal pressure difference between the upstream and downstream of the valve. In this case, the calculation is no longer based on the formula. Instead, the basic maximum allowable valve closing angular velocity is directly set to the maximum allowable mechanical speed of the actuator, and the subsequent safety arbitration procedure takes over.

[0089] S3.2 Determining Indirect Water Hammer Conditions Read the actual valve closing angular velocity of the previous control cycle (Use initial values ​​for the first calculation).

[0090] Calculate the water hammer phase construction: ; Estimate the time required to close the remaining travel at a constant current angular velocity: ; Calculate the dimensionless characteristic time ratio: ; Determine the type of water hammer: when At this time, it falls under the direct water hammer condition and no correction is required. ; when At this time, it belongs to the indirect water hammer condition, and step S3.3 is executed.

[0091] S3.3 Indirect Water Hammer Correction Query the preset indirect water hammer correction factor function Substitute the current Worth the correction factor .

[0092] By applying a lower limit protection to the correction factor, an effective correction factor is obtained: ;in This is the preset lower limit of the correction factor, typically set to 0.1 to 0.2. When great, When the value approaches a minimum, this protection prevents the correction factor from approaching zero, which could lead to an abnormal increase in output speed.

[0093] Calculate the maximum allowable valve closing angular velocity after correction: Due to indirect water hammer conditions Therefore, the revised maximum allowable valve closing angular velocity can be reasonably increased compared to the basic value, releasing the excessively conservative margin brought about by the original direct water hammer assumption.

[0094] Step S4: Integrated Security Arbitration and Command Output Before outputting the calculated maximum allowable valve closing angular velocity to the actuator module, a comprehensive safety arbitration is performed.

[0095] Pressure over-limit emergency stop judgment: compare the current virtual pressure measurement value. With safety limits .when When this occurs, it indicates that the water hammer pressure has approached or reached the allowable upper limit. Regardless of the result of the analytical decision-making step, the maximum allowable valve closing angular velocity is immediately forced to zero, or a preset safe reversal speed is output to slightly open the valve to release the pressure. This judgment has the highest priority.

[0096] End-of-line forced slow-closing judgment: compare the current valve opening. With the preset end opening threshold .when When this occurs, it indicates that the valve has entered the end-of-stroke region, and the current permissible speed is compared with the preset safe slow-closing speed at the end. The smaller value is selected as the final valve-closing command. End-point opening threshold. It is typically set at 5% to 10% of the total travel, with a safe slow closing speed at the end. The settings are based on the actuator capacity and the pipeline pressure resistance level.

[0097] Command output: After the above arbitration, the final maximum allowable valve closing angular velocity will be determined. Send to the actuator module. The actuator module controls the valve to operate at a speed not exceeding... The angular velocity is used to perform the closing action.

[0098] Step S5: Steady-state self-calibration (executed independently at low frequencies) The steady-state self-calibration sub-step operates independently at a frequency far lower than the control cycle, such as once every minute or every few minutes, and does not participate in the calculation of the real-time control loop.

[0099] Triggering condition judgment: When the system detects that the valve is in one of the following preset steady-state operating conditions and this condition persists for more than the confirmation time (e.g., 2 seconds), self-calibration is triggered: Operating Condition A: Valve fully closed or nearly fully closed ( At this point, the flow rate is zero, and the pressure difference between the upstream and downstream sides is determined solely by the static pressure. Operating Condition B: Valve fully open ( Furthermore, the upstream pressure is stable and can be confirmed by pump operating signals or other independent measurements.

[0100] Calibration calculation: Obtain the available reference pressure information for the system at this time. The reference pressure can be obtained from the value of the upstream pressure transmitter read occasionally, or for systems with a gravity-type constant pressure reservoir upstream, the known reservoir water level can be used directly.

[0101] Calculate the deviation between the current virtual pressure measurement and the reference pressure: ; The compensation offset is updated using a first-order low-pass filter: in, The filter coefficient has a value ranging from 0.01 to 0.05, ensuring that the offset changes slowly and smoothly, avoiding disturbances to normal control.

[0102] Updated compensation offset The data is stored in the virtual pressure conversion module and applied to the calculation of virtual pressure measurements starting from the next control cycle.

[0103] In a more specific embodiment, an electric valve is installed at the end of a water pipeline, with the following parameters: Pipe length Pipe inner diameter Cross-sectional area ; Water jet speed Water-driven growth ; fluid density ; Downstream of the valve is a constant pressure water tank. ; Allowable upper limit of water hammer pressure Safety factor Safety limits ; The valve exhibits linear flow characteristics, with a flow coefficient when fully open. Opening range 0 to 100%, flow coefficient gradient It is a constant; Maximum permissible angular velocity of actuator ; End opening threshold End-of-line safety slow-closing speed ; Lower limit of correction factor .

[0104] Operating Condition 1: When the opening is 60% Current virtual pressure measurement value The actual angular velocity of the previous cycle .

[0105] The calculation of the maximum allowable valve closing angular velocity is as follows: ; Determine the type of water hammer: ; This falls under the category of direct water hammer conditions. .

[0106] Maximum allowable valve closing angular velocity If the speed is less than the mechanical upper limit of 3.0 rad / s and the opening degree is greater than the end threshold, output command. .

[0107] Operating Condition 2: When the opening is 20% As the valve closes, the virtual pressure gradually increases. Currently... , .

[0108] The calculation of the maximum allowable valve closing angular velocity is as follows: ; Determine the type of water hammer: ; It is still a direct water hammer condition. .

[0109] Maximum allowable valve closing angular velocity At this point, the opening degree is below the end threshold of 5%; 20% is above 5%, therefore the end slow-closing is not triggered. Output command. .

[0110] As can be seen from operating conditions one and two, as the pressure margin decreases from 37m to 7m, the output angular velocity automatically and smoothly decreases from 0.85rad / s to 0.15rad / s, achieving adaptive deceleration.

[0111] Operating Condition 3: Opening degree 8% (End stage) current The margin is only 2m. .

[0112] The calculated maximum allowable valve closing angular velocity is approximately 0.04 rad / s. An opening of 8% is greater than the 5% end-of-line threshold, but slow closing is not triggered. The output command is approximately 0.04 rad / s.

[0113] When the opening continues to close to 4% (less than the 5% end threshold), even if the calculated permissible speed is a certain value, the comprehensive safety arbitration will compare it with the end-safe slow-closing speed. Compare and take the smaller value to ensure an absolutely smooth and safe end-to-end closure.

[0114] If the virtual pressure measurement unexpectedly reaches the safety limit of 247m at any time, the emergency stop logic will take effect immediately, setting the speed to zero or reversing.

[0115] In summary, the solution in this embodiment performs only a few lookup, multiplication, division, square root, and logical judgment operations within each control cycle, with computation time on the order of microseconds. Compared to existing solutions that require online simulation of water hammer characteristic lines or rely on additional pressure sensors, this embodiment has significant advantages in terms of computational load, hardware cost, and long-term reliability. Furthermore, through indirect water hammer correction and steady-state self-calibration, valve closing efficiency and long-term measurement accuracy are further improved while ensuring safety.

[0116] Note: The unit of the physical quantity pressure head in the above embodiments is meters (m). This is a common representation in fluid engineering, converting pressure by dividing by fluid density ρ and gravitational acceleration g to obtain the equivalent liquid column height.

[0117] The above are only some embodiments of this application and do not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method for controlling valve opening, characterized in that, During valve closing, online water hammer numerical simulation is not performed in each control cycle. Instead, the following steps are executed: Signal acquisition steps: Acquire the real-time total torque signal and real-time valve opening signal of the valve; Virtual pressure generation step: Based on the preset valve torque coefficient characteristics, the real-time total torque signal is converted into a virtual pressure measurement value that characterizes the current transient pressure at the valve inlet; Analytical decision-making steps: A preset explicit algebraic relationship is used as the control law. The explicit algebraic relationship is constructed based on water hammer analytical constraints. The virtual pressure measurement value, the real-time valve opening signal, and the preset upper limit of allowable water hammer pressure are used as inputs to solve in real time the maximum allowable valve closing angular velocity that will not cause pressure over-limit in the current state. Opening control steps: Control the valve to perform the closing action at a rate not exceeding the maximum allowable valve closing angular velocity.

2. The method for controlling valve opening according to claim 1, characterized in that, The virtual pressure generation step specifically includes: By subtracting the friction torque component from the real-time total torque signal using a preset friction torque model, the transient fluid dynamic torque acting on the valve disc is obtained. By querying a preset torque coefficient characteristic curve that describes the mapping relationship between valve opening and fluid dynamic torque coefficient, the instantaneous torque coefficient corresponding to the real-time valve opening signal is obtained. The virtual pressure measurement value is calculated by adding the ratio of the transient hydrodynamic torque to the instantaneous torque coefficient to the preset constant pressure head on the downstream side of the valve.

3. The method for controlling valve opening according to claim 1, characterized in that, The explicit algebraic relation used in the analytical decision-making step is constructed based on the Zhukovsky direct water hammer formula, the valve flow coefficient gradient, and the reflection characteristic time of water hammer wave propagation. Its physical meaning is: to ensure that the increase in direct water hammer pressure caused by the change in total flow rate due to angular velocity within the reflection characteristic time under valve opening does not exceed the safety margin between the current virtual pressure measurement value and the upper limit of the allowable water hammer pressure.

4. The method for controlling valve opening according to claim 3, characterized in that, The explicit algebraic relation is specifically as follows: in, Based on the maximum allowable valve closing angular velocity; It is the acceleration due to gravity; This refers to the cross-sectional area of ​​the upstream pipeline. The length of the upstream pipeline; Valve opening degree The valve flow coefficient gradient below; For fluid density; This is a virtual pressure measurement value; The preset constant pressure head downstream of the valve; To the upper limit of permissible water hammer pressure; This is for the safety factor.

5. The method for controlling valve opening according to claim 4, characterized in that, The analytical decision-making step further includes: determining whether the current motion state belongs to an indirect water hammer condition by comparing whether the time required for the valve to close at the current angular velocity at a constant speed for the remaining stroke is greater than the phase length of the water hammer wave; if so, it belongs to an indirect water hammer condition, and a preset indirect water hammer correction factor is used. The explicit algebraic relationship is modified, and the modified maximum allowable valve closing angular velocity is calculated; the modified maximum allowable valve closing angular velocity is larger than the basic maximum allowable valve closing angular velocity.

6. The method for controlling valve opening according to claim 5, characterized in that, The indirect water hammer correction factor Defined as dimensionless characteristic time ratio algebraic functions The corresponding physical meaning is the ratio of the indirect water hammer peak value to the direct water hammer peak value; the dimensionless characteristic time ratio Defined as: in, Indicates the current angular velocity The valve opening is closed at a constant speed. Time required, current angular velocity The actual angular velocity from the previous control cycle is used for estimation to avoid online iterative solutions. This indicates that water hammer and growth are mutually reinforcing. denoted as the length of the upstream pipe, and 'a' represents the water hammer wave velocity.

7. The method for controlling valve opening according to claim 5, characterized in that, The corrected maximum allowable valve closing angular velocity is expressed as follows: in, This indicates the maximum allowable valve closing angular velocity after correction. This indicates the effective value of the indirect water hammer correction factor after lower limit protection processing, and the value is the indirect water hammer correction factor. The larger of the preset correction factor lower limit.

8. The method for controlling valve opening according to claim 2, characterized in that, The virtual pressure generation step also includes a low-frequency, steady-state self-calibration sub-step: When the valve is detected to be in a preset steady-state condition, a slowly varying compensation offset δ is calculated and updated using the deviation between the system-obtainable reference pressure information and the current virtual pressure measurement value. This compensation offset is then applied to the calculation of the virtual pressure measurement value in subsequent control cycles, correcting the virtual pressure measurement value to: The ratio of the transient hydrodynamic torque to the instantaneous torque coefficient is added to the preset constant pressure head downstream of the valve and the compensation offset δ.

9. The method for controlling valve opening according to claim 1, characterized in that, The opening control step also includes a comprehensive safety arbitration sub-step: When the virtual pressure measurement value has reached or exceeded the product of the allowable water hammer pressure limit and the safety factor, regardless of the output of the analytical decision step, the allowable maximum valve closing angular velocity is immediately set to zero or a preset safe reversal speed. When the real-time valve opening signal is less than the preset end opening threshold, the maximum allowable valve closing angular velocity is compared with a preset end safe slow closing velocity, and the smaller value is taken as the final valve closing command.

10. A system for controlling valve opening, used to implement a method for controlling valve opening as described in any one of claims 1 to 9, characterized in that, include: Torque sensing module, used to acquire the total torque signal of the valve in real time; Valve position sensing module, used to acquire valve opening signals in real time; The virtual pressure conversion module is configured to convert the real-time total torque signal into a virtual pressure measurement value that characterizes the current transient pressure at the valve inlet, based on a preset valve torque coefficient characteristic. The analytical decision controller has preset pipeline characteristic constants, allowable water hammer pressure upper limit, and characteristic relationship between valve flow coefficient and opening degree. It is configured to: during valve closing process, not perform online water hammer numerical simulation in each control cycle, but use a preset explicit algebraic relationship as the control law. The explicit algebraic relationship is constructed based on water hammer analytical constraints. With the virtual pressure measurement value, the real-time valve opening signal, and the preset allowable water hammer pressure upper limit as input, it solves in real time the maximum allowable valve closing angular velocity that will not cause pressure over-limit in the current state. The execution drive module, connected to the analytical decision controller, is configured to receive and execute valve closing commands that do not exceed the maximum allowable valve closing angular velocity.

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