PLC automatic control system for valve array opening and closing and pipeline cleaning

Abstract

The present application relates to the technical field of industrial automation control, in particular to a PLC automation control system for valve array opening and closing and pipeline cleaning, comprising a PLC controller, an input module, an output module, a valve actuator array, a pressure sensor array, a pipeline system and a main control system; a pipeline identification subsystem, a timing control subsystem, a pressure closed-loop control subsystem and a safety and scheduling subsystem run in the PLC controller; used for establishing a pipe network parameter table and a pipeline time delay model, generating an instruction issuing time and a valve opening degree instruction, and correcting an opening degree timing curve according to multi-point actual measurement pressure, triggering water hammer suppression control when the pressure change rate reaches a preset threshold, and limiting the number of concurrent control valves and the valve opening degree change rate in a single cycle, so as to ensure the synchronization and stability in the cleaning process.

Description

Technical Field

[0001] This invention relates to the field of industrial automation control technology, specifically a PLC automated control system for valve array opening and closing and pipeline cleaning. Background Technology

[0002] In the process of industrial pipeline cleaning and valve linkage control, as the number of pipeline branches increases, the distribution of pressure measurement points becomes more dispersed, and the requirements for the coordination of actuators increase, the control system usually needs to complete the opening and closing scheduling of multiple valves, pressure feedback acquisition, and action rhythm adjustment within a preset control cycle to ensure the continuity and stability of the cleaning process. However, existing valve array control methods often rely on fixed timing or empirical parameters for control, which do not adequately consider pipeline propagation delays, control cycle delays, and actuator lag. This can easily lead to asynchronous valve actions, superimposed pressure fluctuations, and aggravated local impacts. Especially in multi-branch pipeline cleaning scenarios, the lack of closed-loop correction for real-time pressure changes and effective limitation on the number of concurrent actions can often cause problems such as excessively rapid changes in valve opening, increased water hammer risk, and decreased control accuracy, thereby affecting the cleaning effect and system reliability. Summary of the Invention

[0003] The purpose of this invention is to provide a PLC-based automated control system for valve array opening and closing and pipeline cleaning, addressing the following technical problems: Existing valve control systems are significantly inadequate in handling the propagation delay and action lag during pipeline cleaning, easily leading to asynchronous actions and water hammer risks. There is an urgent need for an automated control system that can accurately handle pipeline delay and pressure feedback, dynamically optimize the synchronous scheduling of multiple valves, and suppress water hammer. This invention's objective can be achieved through the following technical solutions: It includes a PLC controller, an input module and an output module connected to the PLC controller, a valve actuator array connected to the output module, a pressure sensor array connected to the input module, a piping system connected to the valve actuator array and the pressure sensor array, and a main control system that is communicatively connected to the PLC controller; The PLC controller operates a pipeline identification subsystem, a timing control subsystem, a pressure closed-loop control subsystem, and a safety and scheduling subsystem. The pipeline identification subsystem is used to establish a pipeline network parameter table corresponding to each valve based on the node topology relationship from the control reference point to each valve, valve number, equivalent pipeline length, pipe diameter, and local resistance parameters, and to determine the pressure wave propagation speed and establish a pipeline time delay model based on the pressure sampling data collected by the pressure sensor array. The timing control subsystem is used to receive cleaning tasks and generate target action times for each valve. Based on the PLC control cycle delay, input and output delay, pipeline delay model and set time margin, it generates command issuance times and outputs valve opening commands according to preset opening timing curves. The pressure closed-loop control subsystem is used to collect multi-point measured pressure at different pressure measurement nodes in the pipeline and compare it with the target pressure corresponding to the current cleaning stage, and correct the opening time sequence curve according to the pressure deviation; the safety and scheduling subsystem is used to trigger water hammer suppression control when the pressure change rate within the preset sampling window reaches the preset threshold, and limit the number of valves controlled concurrently in a single cycle and limit the valve opening change rate according to the PLC scanning cycle, basic calculation time, and single valve scheduling time.

[0004] In some possible implementations, the pipeline identification subsystem includes a pipeline parameter acquisition module, a fluid parameter calculation module, and a time delay model construction module; the pipeline parameter acquisition module is used to read the node topology relationship from the control reference point to each valve, the equivalent pipeline length, pipe diameter, and local resistance parameters, and generate a pipeline parameter table; The fluid parameter calculation module is used to calculate the pressure wave propagation speed based on the pressure sampling data collected by the pressure sensor array; the time delay model construction module is used to generate the pipeline time delay model corresponding to each valve based on the pipeline parameter table and the pressure wave propagation speed.

[0005] In some possible implementations, the timing control subsystem includes a task parsing module, a time delay compensation module, and a synchronization mapping module. The task parsing module receives cleaning tasks including pre-rinsing, main cleaning, pulse cleaning, and evacuation stages and generates the target action time for each valve. The time delay compensation module generates the instruction issuance time based on the PLC control cycle delay, input / output delay, the pipeline time delay model, and the set time margin. The synchronization mapping module maps the instruction issuance time to a synchronization phase and generates continuously changing valve opening instructions based on a preset opening timing curve.

[0006] In some possible implementations, the pressure closed-loop control subsystem includes a pressure acquisition and processing module, a pressure comparison module, and a phase correction module; the pressure acquisition and processing module is used to acquire multi-point measured pressures arranged at different pressure measurement nodes in the pipeline and calculate the arithmetic mean pressure value; the pressure comparison module is used to compare the target pressure of the current cleaning stage with the arithmetic mean pressure value and output the pressure deviation value; the phase correction module is used to correct the synchronization phase according to the pressure deviation value.

[0007] In some possible implementations, the safety and scheduling subsystem includes a water hammer suppression module, a valve grouping scheduling module, and an opening limit module. The water hammer suppression module is used to determine whether to trigger water hammer suppression control based on the pressure change rate calculated from the change amplitude of adjacent pressure sample values ​​within a preset sampling window and the sampling interval. The valve grouping scheduling module is used to determine the number of valves that can be controlled concurrently in a single cycle based on the PLC scanning cycle, basic operation time, and individual valve scheduling time. The opening limit module is used to limit the change rate of valve opening commands based on the upper limit of the valve opening change rate.

[0008] In some possible implementations, a parameter self-updating mechanism is also included, which includes: the main control system obtaining the actual action time based on the valve position feedback signal fed back by the valve actuator array and generating an action error record; the pipeline identification subsystem updating the delay compensation parameter based on the action error record; and the timing control subsystem using the updated compensation parameter to correct the command issuance time of the next cycle.

[0009] In some possible implementations, when the water hammer suppression control is triggered, the safety and scheduling subsystem extends the opening and closing time of valves that have not yet performed actions and adjusts the acceleration and deceleration parameters, reduces the number of valves controlled concurrently in a single cycle, and increases the preset time margin of the timing control subsystem.

[0010] In some possible implementations, the data interaction between the pipeline identification subsystem, the timing control subsystem, and the pressure closed-loop control subsystem includes: the pipeline identification subsystem sending pressure wave propagation time and sampling time information to the timing control subsystem; the pressure closed-loop control subsystem sending a phase correction amount for correcting the synchronization phase to the timing control subsystem; and the timing control subsystem and the safety and scheduling subsystem working together to output the command issuance time and the final opening control signal.

[0011] The beneficial technical effects of this invention are as follows: 1. This system establishes a pipeline time delay model through a pipeline identification subsystem, and generates the command issuance time by combining control cycle delay and input / output delay. This solution solves the problem of asynchronous valve action caused by neglecting pipeline propagation time delay and control lag in existing technologies. Through precise time delay compensation, the coordinated opening and closing of valve arrays in multi-branch scenarios is realized, ensuring the continuity of the pipeline cleaning process. 2. This system uses a pressure closed-loop control subsystem to correct the opening timing curve based on the measured pressure deviation. The safety and scheduling subsystem limits the number of valves and the opening change rate in a single cycle when the pressure change rate exceeds the limit. This scheme overcomes the defect of existing control systems that lack real-time pressure correction, which increases the risk of water hammer. Through dynamic limiting and scheduling, the superposition of pressure fluctuations is effectively suppressed, and the reliability of system operation is improved. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the PLC automated control system for valve array opening and closing and pipeline cleaning in this application. Detailed Implementation

[0014] 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.

[0015] Reference Figure 1 One embodiment of this application provides a PLC automated control system for valve array opening and closing and pipeline cleaning, including a PLC controller, an input module and an output module connected to the PLC controller, a valve actuator array connected to the output module, a pressure sensor array connected to the input module, a pipeline system connected to the valve actuator array and the pressure sensor array, and a main control system communicatively connected to the PLC controller; The PLC controller operates a pipeline identification, timing control, pressure closed-loop control, and safety and scheduling subsystem. The pipeline identification subsystem acquires control reference points and establishes a pipeline parameter table based on the node topology relationship from the control reference points to each valve, valve number, equivalent pipeline length, pipe diameter and local resistance parameters. It also determines the pressure wave propagation speed and establishes a pipeline time delay model based on the pressure sampling data collected by the pressure sensor array. The timing control subsystem receives the cleaning task and generates the target action time for each valve. Based on the PLC control cycle delay, input and output delay, pipeline time delay model and set time margin, it generates the instruction issuance time and outputs the valve opening instruction according to the preset opening timing curve. The pressure closed-loop control subsystem collects the measured pressure at multiple points located at different pressure measurement nodes in the pipeline and compares it with the target pressure corresponding to the current cleaning stage, and corrects the opening time sequence curve according to the pressure deviation. The safety and scheduling subsystem triggers water hammer suppression control when the pressure change rate within the preset sampling window reaches a preset threshold, and limits the number of valves and the valve opening change rate to be controlled concurrently in a single cycle according to the PLC scanning cycle, basic calculation time, and single valve scheduling time.

[0016] In this embodiment, the PLC controller acts as the main control unit. It receives pressure sampling data from the pressure sensor array through the input module and sends opening control signals to the valve actuator array through the output module. The main control system is used to issue cleaning tasks and receive valve positioning feedback signals, and participate in parameter correction. The pipeline identification subsystem is used to organize and convert pipeline topology and fluid propagation delay, and its output is a pipeline parameter table and pipeline delay model that can be directly called by the timing control subsystem; the timing control subsystem is used to decompose the cleaning task into target action time and further convert it into command issuance time and valve opening command. The pressure closed-loop control subsystem is used to compare the multi-point pressure sampling values ​​with the target pressure of the current cleaning stage, and use the difference to correct the phase and opening timing; the safety and scheduling subsystem is used to limit and group subsequent actions when the pressure changes too quickly, there are too many concurrent actions within the scanning cycle, or the valve opening changes too quickly, so as to ensure the synchronization and stability of the cleaning process. In one embodiment, the pipeline identification subsystem includes a pipeline parameter acquisition module, a fluid parameter calculation module, and a time delay model construction module. The pipeline parameter acquisition module is used to read the node topology relationship, equivalent pipeline length, pipe diameter, and local resistance parameters from the control reference point to each valve and generate a pipeline parameter table. The fluid parameter calculation module is used to calculate the pressure wave propagation speed based on the pressure sampling data collected by the pressure sensor array. The time delay model construction module is used to generate a pipeline time delay model corresponding to each valve based on the pipeline parameter table and the pressure wave propagation speed.

[0017] In a multi-branch pipeline cleaning scenario, the PLC controller first reads the node topology relationship between the control reference point and each valve, the valve number, the actual pipeline length, pipe diameter, and local resistance parameters. It then combines these local resistance parameters with the pipe diameter and friction coefficient to calculate an additional equivalent length. The calculation formula is as follows: ,in The equivalent length is calculated by adding K, the local resistance parameter, D, the pipe diameter, and f, the friction coefficient, and adding them to the actual pipe length to obtain the equivalent pipe length. Based on this, a pipe network parameter table corresponding to each valve is formed. The system utilizes the initial hydraulic transients generated when a single reference valve is initially opened or the pipeline is initially filled with water during the pre-flushing stage as a disturbance source. The pressure sensor array continuously collects pressure sampling data from different pressure measurement nodes in the pipeline within a preset sampling window. The fluid parameter calculation module identifies pressure response abrupt changes by calculating the differential slope between two adjacent pressure sampling values ​​at each node. Before performing the pre-flushing task, the system extracts a sequence of pressure difference values ​​for a preset number of consecutive sampling periods when the system is idle and without cleaning operations. The mean and standard deviation of this sequence are calculated, and the mean is added to three times the standard deviation as the environmental steady-state noise threshold for dynamically adapting to the background noise of the current physical pipeline. When the pressure differential slope of a pressure measuring node first exceeds the steady-state noise threshold of the environment, the corresponding sampling timestamp is recorded as the moment when the node detects the pressure response change. Based on the order in which adjacent nodes detect the change, the time difference between the two adjacent pressure measuring nodes detecting the pressure response change is obtained, and the equivalent pipeline length between the two nodes in the pipeline parameter table is divided by the time difference to accurately calculate the pressure wave propagation speed under the current actual working conditions. To avoid abnormal results caused by time differences being lower than the preset time difference threshold, being zero, or being misjudged due to noise, the system only uses node pairs that are topologically adjacent, have the correct sequence of abrupt changes, and have a time difference greater than one pressure sampling period for calculation. If multiple valid node pairs exist within the same sampling window, the propagation speed corresponding to each node pair is calculated separately, and outliers exceeding the preset physical feasible range are removed. The preset physical feasible range is defined by the lower limit being the sound velocity at room temperature in water and the upper limit being the theoretical pressure wave velocity in an absolutely rigid pipeline as the boundary judgment condition, and the median value is taken as the current pressure wave propagation speed. If there are no valid node pairs in the current window, the pressure wave propagation speed confirmed in the previous control cycle remains unchanged; then the time delay model construction module divides the equivalent pipeline length from the control reference point recorded in the pipeline parameter table to each valve by the pressure wave propagation speed to obtain the physical propagation time corresponding to each valve, and uses it as the basic compensation parameter of the pipeline time delay model. For example, when the measured pressure wave propagation speed is 1200 m / s, and the pipeline parameter table indicates that the first equivalent pipeline length from the control reference point to the target valve is 600 m, the calculated physical propagation time is 0.5 seconds. This processing method can directly convert the physical delay required for the pressure change in the pipeline to travel from the control reference point to each valve position into a specific compensation time that can be called upon by the timing control, thus avoiding the problem of inaccurate delay prediction caused by the calculation deviation of the ideal fluid formula. In one embodiment, the timing control subsystem includes a task parsing module, a time delay compensation module, and a synchronization mapping module. The task parsing module receives cleaning tasks including pre-rinsing, main cleaning, pulse cleaning, and evacuation stages and generates the target action time for each valve. The time delay compensation module generates the instruction issuance time based on the PLC control cycle delay, input / output delay, the pipeline time delay model, and the set time margin. The synchronization mapping module maps the instruction issuance time to a synchronization phase and generates continuously changing valve opening instructions according to a preset opening timing curve.

[0018] After receiving the cleaning task, the task parsing module first breaks down the cleaning task into pre-rinsing, main cleaning, pulse cleaning and evacuation stages, and determines the target action time of each valve for each stage; the time delay compensation module generates the instruction issuance time through basic calculation logic, specifically: subtract the PLC control cycle delay, input and output delay, the corresponding physical propagation time in the pipeline time delay model, and the preset time margin used to compensate for network transmission delay fluctuations from the target action time of each valve to obtain the instruction issuance time of each valve; The synchronization mapping module specifically compares the current system running time with the time when the command is issued to obtain the relative action time of each valve, and uses the relative action time as the synchronization phase. In the specific implementation, the above relative action time is based on the remaining waiting time before the time when the command is issued. When the current system running time has exceeded the time when the command is issued, the synchronization phase is processed as 0 and the corresponding stage of the opening output curve is directly entered. The preset opening timing curve adopts a form with a smooth change in the start and end segments to prevent abrupt changes in valve opening, thereby reducing the impact caused by sudden changes in pipeline pressure. The preset opening timing curve is quantitatively constructed through a smooth transition acceleration and deceleration control algorithm, dividing the opening action range into a starting segment of 0% to 20%, a constant speed segment of 20% to 80%, and a stopping segment of 80% to 100%. During the construction process, the system obtains the pre-tested and determined opening-pressure gain coefficient, which is the amount of pipeline pressure change caused by the unit opening change of the valve under steady state; divides the maximum allowable pressure change rate of the pipeline by the opening-pressure gain coefficient to determine the upper limit of the opening speed, and uses this upper limit of speed as the constant first-order change rate of the uniform speed segment, i.e., the opening speed. The target completion time of the starting segment is selected, and the opening speed is divided by the target completion time to obtain the opening acceleration. When the synchronization phase enters the starting segment, the control algorithm calls the opening acceleration 'a', and combines it with the duration 't' of the synchronization phase within this interval, forcing the opening 'O' of this interval to follow a parabolic function. The motion is gradual; and after entering the uniform speed section, it changes linearly with the constant first-order rate of change, thereby providing a specific and executable smooth motion trajectory. For the stopping segment, the system no longer directly applies the formula for the starting segment, but instead uses the opening degree at the end of the previous stage. As the initial value of the stopping segment, record the origin time t0 when entering the stopping segment, and within the stopping segment, according to the function... Gradually reduce the opening change rate, where v is the constant first-order change rate of the uniform speed segment, a is the opening acceleration, and t is the current running time of the system, so that the opening always monotonically approaches the target final value of 100% within the stopping segment, and the opening value and opening change rate at the boundary time are continuous with the previous stage. To avoid the control cycle discretization causing the opening degree to exceed the limit or the end point to fail to reach the target value, the PLC first calculates the candidate opening degree according to the current synchronization phase in each control cycle, and then compares the candidate opening degree with the upper and lower boundaries of the stage. If it exceeds the limit, it is truncated to the corresponding boundary value. When the synchronization phase exceeds the end time of the stop segment, the target opening degree of 100% is directly output. At the junction of the start segment and the stop segment, the system uses the opening degree at the end of the previous stage as the initial value of the current stage, and shifts the time origin of the opening degree timing curve to make the opening degree change of each stage continuous at the boundary. In one embodiment, the pressure closed-loop control subsystem includes a pressure acquisition and processing module, a pressure comparison module, and a phase correction module. The pressure acquisition and processing module is used to acquire multi-point measured pressures arranged at different pressure measurement nodes in the pipeline and calculate the arithmetic mean pressure value. The pressure comparison module is used to compare the target pressure of the current cleaning stage with the arithmetic mean pressure value and output a pressure deviation value. The phase correction module is used to correct the synchronization phase according to the pressure deviation value.

[0019] During the pressure feedback correction process, the pressure acquisition and processing module obtains multi-point measured pressures from different pressure measurement nodes in the pipeline and calculates the arithmetic mean of these pressures. The system calculates the equivalent global target pressure for the current cleaning stage. The specific conversion logic is as follows: the system calculates the cross-sectional area of ​​the flow channel corresponding to each pressure measurement node based on the pipe diameter D recorded in the pipeline parameter table. Where π is the mathematical constant pi, the cross-sectional area of ​​each node is calculated as the proportion of the total cross-sectional area of ​​the currently open pipeline and used as a weighting coefficient. The local target pressures preset for each pressure measurement node are multiplied by their respective weighting coefficients, summed, and the weighted average is used as the equivalent global target pressure, thereby eliminating the interference caused by single-point local head loss or local sensor observation extreme values. Before performing weighted accumulation, the system first normalizes the cross-sectional area ratio of each node to keep the sum of all weights at 1, so as to avoid the target pressure calibration imbalance caused by changes in the number of local open branches; in order to ensure that the comparison objects are consistent in statistical caliber, the arithmetic average pressure value and the equivalent global target pressure are calculated only based on the pressure measurement nodes corresponding to the open branches that actually participate in the control in the current cleaning stage. For nodes that have not yet opened branches, have abnormal communication, or whose sampled values ​​exceed the sensor's calibrated range, they will not be included in the average and weighted calculations in the current cycle. If the number of effective pressure measurement nodes in the current cycle is less than 2, the system will maintain the arithmetic average pressure value and the equivalent global target pressure of the previous control cycle and suspend the phase correction of the current cycle to avoid the closed-loop action being directly driven by isolated abnormal points. The pressure comparison module compares the arithmetic mean with the equivalent global target pressure to obtain the pressure deviation value; the phase correction module then corrects the synchronization phase based on the pressure deviation value; the phase correction module multiplies the difference between the equivalent global target pressure and the arithmetic mean measured pressure by a preset phase compensation gain coefficient to obtain the phase correction amount. The preset phase compensation gain coefficient is a specific parameter obtained by the system through adaptive calibration of hydraulic step response test during the pre-flushing stage. The calibration process is as follows: when the pipeline is under initial steady-state pressure and the pressure fluctuation variance is less than the preset steady-state tolerance threshold in multiple consecutive scanning cycles, the system issues an opening step command of a predetermined amplitude to any reference valve and records the arithmetic mean measured steady-state pressure change of the pipeline network in real time. Based on the constant first-order rate of change of the preset opening time-series curve, the opening offset is converted into an equivalent phase offset duration to obtain the compensation sensitivity under the current operating condition. The specific conversion formula is as follows: ,in This is the equivalent phase shift duration. This is the opening offset. The constant first-order rate of change of the preset opening time-series curve is used as the preset phase compensation gain coefficient; otherwise, or if there is a boundary abnormality such as sensor communication disconnection leading to missing pressure sampling, the empirical gain parameter saved in the previous cleaning batch is switched to avoid a sudden increase in gain due to the divisor being a value close to zero. For example, if the equivalent global target pressure is set to 0.6 MPa and the current arithmetic mean measured pressure is 0.5 MPa, when the phase compensation gain coefficient is 0.2 seconds / MPa obtained during calibration, the calculated phase correction amount is 0.02 seconds. If the deviation value indicates that the arithmetic mean measured pressure is lower than the target pressure, it indicates that the flow resistance of the current cleaning section has increased or the cleaning kinetic energy is insufficient. The system will perform feedforward compensation on the synchronous phase of the subsequent coordinated action valves based on the phase correction amount. For example, the command issuance phase will be advanced by the above 0.02 seconds, so that the subsequent valve opening changes will be quickly adjusted in a direction that is more conducive to increasing the pipeline cleaning pressure. If the measured pressure is higher than the target pressure, the phase correction will delay the phase of the command issuance by the correction amount, so that the change in opening degree is relatively slowed down. The entire closed-loop calculation and correction process is completed by the PLC controller after pure time delay compensation by introducing the pipeline time delay model. The correction result is directly superimposed as the offset and transmitted to the timing control subsystem, and then sent to the valve actuator array by the output module, which ensures the high real-time performance of the control. In one embodiment, the safety and scheduling subsystem includes a water hammer suppression module, a valve grouping scheduling module, and an opening limit module. The water hammer suppression module is used to determine whether to trigger water hammer suppression control based on the pressure change rate calculated from the change amplitude of adjacent pressure sampling values ​​within a preset sampling window and the sampling interval. The valve grouping scheduling module is used to determine the number of valves that can be controlled concurrently in a single cycle based on the PLC scanning cycle, basic operation time, and individual valve scheduling time. The opening limit module is used to limit the change rate of valve opening commands based on the upper limit of the valve opening change rate.

[0020] In terms of safety and scheduling, the water hammer suppression module continuously reads adjacent pressure sampling values ​​within the preset sampling window and calculates the pressure change rate by combining the sampling interval, that is, taking the absolute value of the difference between two adjacent pressure sampling values ​​and dividing it by the sampling time interval between the two. When the pressure change rate reaches a preset threshold, the system triggers water hammer suppression control; to ensure the reliability of the judgment criterion, the length of the preset sampling window is set to 3 to 5 times the PLC control cycle to filter out high-frequency pulsating noise in the fluid pipeline. The calibration basis for the preset threshold is as follows: extract the maximum safe water hammer pressure amplitude that the physical properties of the pipe can withstand, subtract the average steady-state measured pressure of the current operating stage to obtain the maximum pressure difference margin, when the maximum pressure difference margin is positive, divide it by the time of single physical propagation of the pressure wave in the longest single branch in the pipeline network to calculate the critical rise slope of water hammer, and finally multiply the critical rise slope by a safety reduction factor of 0.7 to obtain the preset threshold. If the maximum differential pressure margin is less than or equal to 0, the preset minimum positive threshold is directly used as the preset threshold to avoid the threshold from having a zero or negative value. At this time, the valve group scheduling module extracts the preset scheduling time of a single valve, that is, the fixed hardware time required for the PLC to perform a complete input / output read / write and memory status update of a single valve. Based on the remaining schedulable time after subtracting the system's basic calculation time from the PLC scan cycle, and dividing it by the single valve scheduling time and rounding down, the upper limit of the number of valves that can be controlled concurrently in a single cycle is accurately calculated. For example, if the PLC scan cycle is 10 milliseconds, the system basic operation time is 4 milliseconds, and the scheduling time for a single valve is 2 milliseconds, then the remaining scheduling time is 6 milliseconds. Rounding down, the maximum number of valves that can be controlled concurrently in a single cycle is 3. The system divides the valves to be executed into several groups according to the upper limit of the number and issues them sequentially in different scanning cycles; the opening limit module limits the change range of the valve opening command according to the upper limit of the valve opening change rate; the specific limit rule is: the opening limit module extracts the difference between the opening command of the current control cycle and the previous control cycle, and divides it by the PLC scanning cycle to obtain the expected opening change rate. If the absolute value of the expected opening change rate is greater than the upper limit of the valve opening change rate, the system multiplies the upper limit of the valve opening change rate by the PLC scan cycle to obtain the maximum allowable opening increment. The system then forces the valve opening of the previous control cycle to be added to or subtracted from the maximum allowable opening increment as the actual opening command issued in the current cycle. This achieves a hard cutoff limit on the command step size, thereby effectively reducing transient impacts in the pipeline. If the absolute value of the expected opening change rate is less than or equal to the upper limit of the valve opening change rate, no cutoff limit is applied, and the opening command is issued directly according to the original expected opening change rate. In one embodiment, the system further includes a parameter self-updating mechanism, which includes: the main control system obtaining the actual action time based on the valve position feedback signal fed back by the valve actuator array and generating an action error record; the pipeline identification subsystem updating the delay compensation parameter based on the action error record; and the timing control subsystem using the updated compensation parameter to correct the command issuance time of the next cycle.

[0021] The parameter self-updating mechanism takes effect after each cleaning cycle ends; the main control system obtains the timestamp corresponding to the position feedback signal triggered by the valve actuator hardware as the actual action time, subtracts it from the target action time output by the task parsing module, calculates the difference to obtain the time lag, and stores the time lag as the action error record; The pipeline identification subsystem reads the action error record and determines whether the absolute value of the time lag is greater than the preset control cycle tolerance, such as twice the PLC scan cycle. If it is greater, the system retains the sign of the time lag according to the error ratio correction logic and multiplies it by a preset learning rate coefficient, such as 0.5, to prevent overcompensation, thus obtaining a signed time delay compensation increment. This time delay compensation increment is then directly added to the current basic compensation parameter of the corresponding valve in the pipeline time delay model, thereby completing the update of the time delay compensation parameter. If the absolute value of the time lag is less than or equal to the preset control cycle tolerance, the time delay compensation parameter is not updated. When parsing the task of the next cleaning cycle, the timing control subsystem regenerates the instruction issuance time using the compensation parameters with the above incremental updates. The system gradually incorporates the time lag error into the compensation process through signed accumulation logic to avoid the error from accumulating repeatedly in subsequent cycles. In one embodiment, when the water hammer suppression control is triggered, the safety and scheduling subsystem extends the opening and closing time of valves that have not yet performed actions and adjusts the acceleration and deceleration parameters, reduces the number of valves controlled concurrently in a single cycle, and increases the preset time margin of the timing control subsystem.

[0022] When water hammer suppression control is triggered, the safety and scheduling subsystem extends the opening and closing time of valves that have not yet performed actions and adjusts the acceleration and deceleration parameters, reduces the number of valves controlled concurrently in a single cycle, and increases the preset time margin of the timing control subsystem. For the opening and closing time and acceleration and deceleration parameters, the system forcibly multiplies the target completion time of the starting and stopping segments of all valves that have not yet performed actions by a preset water hammer mitigation coefficient, for example, a value of 1.5, and uses this extended target completion time as a divisor to recalculate the updated opening acceleration in the algorithm. Regarding the number of valves to be controlled concurrently, the system forcibly halves the previously calculated upper limit of the number of valves that can be controlled concurrently in a single cycle and rounds it down to the nearest integer. This new upper limit is used to regroup the valves and queue them for execution. Regarding the preset time margin, the system adds an extra amount of time equal to the time taken for a single physical propagation of the longest single branch in the pipeline network to the original time margin for sequential control, thereby updating the current preset time margin. This processing method smooths out subsequent actions through time scaling rules and quantity truncation boundaries, reducing the risk of water hammer impact in the pipeline. In one embodiment, the data interaction between the pipeline identification subsystem, the timing control subsystem, and the pressure closed-loop control subsystem includes: the pipeline identification subsystem sending pressure wave propagation time and sampling time information to the timing control subsystem; the pressure closed-loop control subsystem sending a phase correction amount for correcting the synchronization phase to the timing control subsystem; and the timing control subsystem and the safety and scheduling subsystem jointly outputting the command issuance time and the final opening control signal.

[0023] The pipeline identification subsystem sends the pressure wave propagation time and sampling time information to the timing control subsystem to form the basis for time compensation of each valve; the pressure closed-loop control subsystem sends the phase correction amount to the timing control subsystem to correct the synchronization phase; the timing control subsystem then links with the safety and scheduling subsystem to output the command issuance time and the final opening control signal. After generating the initial instruction issuance time and the continuously changing opening instruction, the timing control subsystem does not directly issue them to the output module, but instead sends them as input parameters to the safety and scheduling subsystem. The safety and scheduling subsystem performs queue scheduling verification and truncation processing on the initial instruction according to its internal group scheduling upper limit and opening limit rules. If no limit is triggered, the original initial instruction is output. If a limit is triggered, the recalculated delayed issuance time and the actual issuance opening instruction after the limit are returned. After receiving the returned data, the timing control subsystem outputs the final determined command issuance time and the final opening control signal, which is then driven by the output module to synchronously open and close the valve actuator array. Through the above data flow, the controlled object always corresponds to objective physical quantities such as pressure, opening degree and time delay, and a scheduling intervention closed loop is realized at the bottom layer. Therefore, without changing the basic structure of the PLC, the multi-valve array can be made to run at a predetermined rhythm during the cleaning process, and the pressure fluctuations and water hammer impacts caused by asynchronous actions can be reduced.

[0024] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A PLC-based automated control system for valve array opening / closing and pipeline cleaning, characterized in that, It includes a PLC controller, an input module and an output module connected to the PLC controller, a valve actuator array connected to the output module, a pressure sensor array connected to the input module, a piping system connected to the valve actuator array and the pressure sensor array, and a main control system that is communicatively connected to the PLC controller; The PLC controller operates a pipeline identification, timing control, pressure closed-loop control, and safety and scheduling subsystem. The pipeline identification subsystem acquires control reference points and establishes a pipeline parameter table based on the node topology relationship from the control reference points to each valve, valve number, equivalent pipeline length, pipe diameter and local resistance parameters. It also determines the pressure wave propagation speed and establishes a pipeline time delay model based on the pressure sampling data collected by the pressure sensor array. The timing control subsystem receives the cleaning task and generates the target action time for each valve. Based on the PLC control cycle delay, input and output delay, pipeline time delay model and set time margin, it generates the instruction issuance time and outputs the valve opening instruction according to the preset opening timing curve. The pressure closed-loop control subsystem collects the measured pressure at multiple points located at different pressure measurement nodes in the pipeline and compares it with the target pressure corresponding to the current cleaning stage, and corrects the opening time sequence curve according to the pressure deviation. The safety and scheduling subsystem triggers water hammer suppression control when the pressure change rate within the preset sampling window reaches a preset threshold, and limits the number of valves and the valve opening change rate to be controlled concurrently in a single cycle according to the PLC scanning cycle, basic calculation time, and single valve scheduling time. The timing control subsystem includes a task parsing module, a time delay compensation module, and a synchronization mapping module. The task parsing module receives cleaning tasks including pre-rinsing, main cleaning, pulse cleaning, and evacuation stages and generates the target action time for each valve. The time delay compensation module generates the command issuance time based on the PLC control cycle delay, input / output delay, the pipeline time delay model, and the set time margin. The synchronization mapping module maps the command issuance time to a synchronization phase and generates continuously changing valve opening commands according to a preset opening timing curve. It also includes a parameter self-updating mechanism, which includes: the main control system obtaining the actual action time based on the valve position feedback signal fed back by the valve actuator array and generating an action error record; the pipeline identification subsystem updating the delay compensation parameters based on the action error record; and the timing control subsystem using the updated compensation parameters to correct the command issuance time of the next cycle. The data interaction between the pipeline identification subsystem, the timing control subsystem, and the pressure closed-loop control subsystem includes: the pipeline identification subsystem sending pressure wave propagation time and sampling time information to the timing control subsystem; the pressure closed-loop control subsystem sending a phase correction amount for correcting the synchronization phase to the timing control subsystem; and the timing control subsystem and the safety and scheduling subsystem working together to output the command issuance time and the final opening control signal.

2. The PLC automated control system for valve array opening / closing and pipeline cleaning according to claim 1, characterized in that, The pipeline identification subsystem includes a pipeline parameter acquisition module, a fluid parameter calculation module, and a time delay model construction module; the pipeline parameter acquisition module is used to read the node topology relationship from the control reference point to each valve, the equivalent pipeline length, pipe diameter, and local resistance parameters, and generate a pipeline parameter table; The fluid parameter calculation module is used to calculate the pressure wave propagation speed based on the pressure sampling data collected by the pressure sensor array; the time delay model construction module is used to generate the pipeline time delay model corresponding to each valve based on the pipeline parameter table and the pressure wave propagation speed.

3. The PLC automated control system for valve array opening / closing and pipeline cleaning according to claim 1, characterized in that, The pressure closed-loop control subsystem includes a pressure acquisition and processing module, a pressure comparison module, and a phase correction module. The pressure acquisition and processing module is used to acquire the measured pressure at multiple points arranged at different pressure measurement nodes in the pipeline and calculate the arithmetic average pressure value. The pressure comparison module is used to compare the target pressure of the current cleaning stage with the arithmetic average pressure value and output the pressure deviation value. The phase correction module is used to correct the synchronization phase based on the pressure deviation value.

4. The PLC automated control system for valve array opening / closing and pipeline cleaning according to claim 1, characterized in that, The safety and scheduling subsystem includes a water hammer suppression module, a valve group scheduling module, and an opening limit module. The water hammer suppression module is used to determine whether to trigger water hammer suppression control based on the pressure change rate calculated from the change amplitude of adjacent pressure sample values ​​within a preset sampling window and the sampling interval. The valve group scheduling module is used to determine the number of valves that can be controlled concurrently in a single cycle based on the PLC scanning cycle, basic operation time, and individual valve scheduling time. The opening limit module is used to limit the change rate of valve opening commands based on the upper limit of the valve opening change rate.

5. The PLC automated control system for valve array opening / closing and pipeline cleaning according to claim 4, characterized in that, When the water hammer suppression control is triggered, the safety and scheduling subsystem extends the opening and closing time of valves that have not yet performed actions and adjusts the acceleration and deceleration parameters, reduces the number of valves controlled concurrently in a single cycle, and increases the preset time margin of the timing control subsystem.

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