A DCS-based analog quantity change judgment method, device and storage medium

Abstract

The present invention discloses a method, device and storage medium for judging analog quantity changes based on DCS, and the method includes: starting to execute the main program, synchronously judging the analog quantity changes; setting a delay time before judging the analog quantity changes; cyclically executing data acquisition and recording and processing capacity judgment through the DCS controller, comparing whether the analog quantity value recorded by the controller in the previous cycle is consistent with the analog quantity value recorded in this cycle; timer action and timing judgment; outputting corresponding protection actions; and resetting and ending. In this way, on the basis of the DCS system using the instantaneous value of the analog quantity as the process control endpoint judgment, the judgment of the change of the real-time value of the analog quantity is added, so as to ensure the validity of the analog quantity as the endpoint judgment condition, so that the DCS system can generate relevant protection actions in time when an abnormal situation occurs, avoid damage to the relevant controlled equipment, make the process control more reliable and safe, reduce the load of manual participation and monitoring in the process control, and improve the degree of automation.

Description

Technical Field

[0001] The present invention relates to the field of automation technology, and in particular to a method, device and storage medium for judging analog quantity changes based on DCS. Background Art

[0002] DCS refers to a distributed control system, which is based on a microprocessor and adopts an instrument control system that has decentralized control functions, centralized display operations, and takes into account the principles of separate autonomy and comprehensive coordination design. Analog quantities in DCS systems are a continuously changing quantity that is often used in various conditional judgment scenarios, and corresponding instructions are sent based on the judgment results to control the actions of on-site equipment. However, in this process, there are many scenarios where the instantaneous value of analog quantities is judged, and the characteristic that analog quantities can change continuously is often ignored, resulting in insufficient judgment conditions, which in turn leads to the consequence of imperfect settings of related equipment protection measures.

[0003] For example, in the process of conveying fluid materials to a storage tank using liquid level as a judgment, the liquid level reaching the upper limit is usually used as the basis for judging the end point of the process. That is, after the material is conveyed to the storage tank, the DCS system issues a command to start the relevant valves and pump equipment. As the material continues to enter the storage tank, when the instantaneous value of the liquid level reaches or exceeds the preset upper limit, the DCS system issues a stop command to close the relevant valves and pumps. However, in abnormal circumstances, such as liquid level signal disconnection or damage to the liquid level measuring instrument. Even if the amount of material entering the storage tank has reached the preset value, the DCS control system cannot effectively judge the end point of the process due to abnormal or malfunctioning judgment conditions, resulting in material overflowing the storage tank or damage to the pump due to long-term operation.

[0004] The same problem may occur in applications such as using weighing equipment to determine liquid material delivery, or using thermometers to determine temperature rise and fall, and similar applications where the instantaneous value of analog quantity is used as the DCS system to determine the process control endpoint. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a method, device and storage medium for judging analog quantity changes based on DCS.

[0006] The present invention provides a DCS-based analog quantity change judgment method, comprising the following steps:

[0007] Step S1, start, execute the main program, and synchronously start the auxiliary program for analog quantity change judgment;

[0008] Step S2, delay, setting the instrument for judging the analog quantity on the target device, and setting the delay time before judging the change of the analog quantity;

[0009] Step S3, real-time value judgment, the DCS controller cyclically executes data acquisition and recording and processing capacity judgment, and compares whether the analog value recorded by the controller in the previous cycle is consistent with the analog value recorded in this cycle;

[0010] Step S4, the timer is activated, and the timer inside the DCS controller is called to start timing. If the analog value changes, the timer is reset; if the analog value does not change, the timer starts timing normally.

[0011] Step S5, timing judgment, judging whether the accumulated time of the timer exceeds the set value, if it is timed out, the protection action of the subsequent steps is performed; if it is not timed out, no protection action is performed, but the analog value of this cycle, that is, the instantaneous value of this cycle is recorded, which is used for the subsequent program cycle to continue to judge whether the analog value changes;

[0012] Step S6, protection action, performing corresponding protection action output;

[0013] Step S7, reset. If not reset, the program continues to generate protection action; if reset, the protection action is eliminated, and it is consistent with the non-timeout action in step S5. After recording the analog value of this cycle, continue to loop and execute the subsequent analog value change judgment;

[0014] Step S8, end, the analog quantity change judgment program and the main program end at the same time. If no protection action is generated, the operation process ends normally, and the analog quantity judgment ends; if a protection action is generated, the protection action execution ends together with the main program.

[0015] In the step S3, a dead zone range is set for the comparison value, that is, the change of the measured analog value within the dead zone range is considered invalid; it is judged whether the value recorded in this cycle is smaller than the difference between the value of the previous cycle and the dead zone or whether it is larger than the sum of the previous cycle and the dead zone. If it exceeds the dead zone range, it is considered that the analog value has changed; if it does not exceed the dead zone range, it is considered that the analog value has not changed.

[0016] In the step S1, the main program is a material dispensing program during the liquid dispensing process.

[0017] In the step S2, after the material is fed into the storage tank, as the conveying equipment is started, the liquid needs to be transported through the pipeline to enter the storage tank, and the operation of the liquid level meter for measuring the liquid material in the storage tank is performed.

[0018] In step S6, the protection action includes generating an alarm, or issuing a stop command to shut down corresponding machine pumps and valve equipment during the material conveying process.

[0019] After the material is unloaded from the tank truck, the feed valve and the feed pump are opened to determine whether the liquid level in the storage tank has reached the preset limit. The limit is determined according to the specific height of the storage tank or the feeding demand. When the liquid level is greater than or equal to the preset limit, the feed valve and the feed pump are closed, and the feeding process of the storage tank is completed.

[0020] Preferably, when the equipment is turned on to feed materials, while judging whether the liquid level value has reached the preset limit, it is also judged whether the liquid level value has changed within a preset time.

[0021] If the liquid level remains unchanged for longer than the preset time, this state is considered to be an abnormal operating condition, an alarm is generated, and the device is shut down to end the feeding process.

[0022] Preferably, after the equipment is started to discharge materials, the materials need to be transported into the storage tank through the pipeline for a certain period of time, at which time the liquid level in the storage tank begins to change, and a certain delay time is set before starting to judge the change of the liquid level;

[0023] Determine whether the liquid level has timed out. If the tank volume is large and material is continuously pumped into the tank, the time it takes for the liquid level to change from one value to another is long. Therefore, the corresponding protection action cannot be performed immediately when the liquid level remains unchanged. Instead, determine the duration of the unchanged liquid level. If it exceeds a reasonable time, it is determined as an abnormal condition and the protection action is performed.

[0024] The present invention provides a DCS-based analog quantity change judgment device, comprising a memory and a processor, wherein the memory stores computer-readable instructions, and when the processor executes the computer-readable instructions, the DCS-based analog quantity change judgment method in the embodiment of the present invention is implemented.

[0025] A computer-readable medium provided by the present invention stores a computer program, wherein when the computer program is executed by one or more processors, the DCS-based analog quantity change judgment method in the embodiment of the present invention is implemented.

[0026] With respect to the prior art, the present invention has the following beneficial effects:

[0027] The present invention adds the judgment of the change of the real-time value of the analog quantity on the basis of the DCS system taking the instantaneous value of the analog quantity as the process control endpoint judgment, thereby ensuring the validity of the analog quantity as the endpoint judgment condition to continue to exist, and enabling the DCS system to generate relevant protection actions in time when an abnormal situation occurs to avoid damage to related controlled equipment; whether the analog quantity changes and the corresponding time judgment are introduced, and the judgment conditions in the process control are increased, making the process control more reliable and safe, reducing the load of manual participation and monitoring in the process control, and improving the degree of automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is a schematic diagram of the flow of judging the analog quantity change based on DCS according to the present invention;

[0029] Figure 2 It is a process flow diagram of the punching process in an embodiment of the present invention;

[0030] Figure 3 It is a basic logic block diagram of the punching process in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Embodiment 1

[0033] The present invention provides a DCS-based analog quantity change judgment method, comprising the following steps:

[0034] Step S1, start, execute the main program, and synchronously start the auxiliary program for analog quantity change judgment;

[0035] Step S2, delay, setting the instrument for judging the analog quantity on the target device, and setting the delay time before judging the change of the analog quantity;

[0036] Step S3, real-time value judgment, the DCS controller cyclically executes data acquisition and recording and processing capacity judgment, and compares whether the analog value recorded by the controller in the previous cycle is consistent with the analog value recorded in this cycle;

[0037] Step S4, the timer is activated, and the timer inside the DCS controller is called to start timing. If the analog value changes, the timer is reset; if the analog value does not change, the timer starts timing normally.

[0038] Step S5, timing judgment, judging whether the accumulated time of the timer exceeds the set value, if it is timed out, the protection action of the subsequent steps is performed; if it is not timed out, no protection action is performed, but the analog value of this cycle is recorded, which is used for the subsequent program cycle to continue to judge whether the analog value changes;

[0039] Step S6, protection action, performing corresponding protection action output;

[0040] Step S7, reset. If not reset, the program continues to generate protection action; if reset, the protection action is eliminated, and it is consistent with the non-timeout action in step S5. After recording the analog value of this cycle, continue to loop and execute the subsequent analog value change judgment;

[0041] Step S8, end, the analog quantity change judgment program and the main program end at the same time. If no protection action is generated and the operation process ends normally, the analog quantity judgment program ends; if a protection action is generated, the protection action execution ends together with the main program.

[0042] Those skilled in the art will understand that analog quantity refers to the continuously changing quantity or signal in the DCS system. It is usually the working condition detected by the DCS system, such as instrument signals such as temperature, pressure, flow, etc., or the custom variables used to assist control in the DCS system. Figure 1 Shown is the basic logic block diagram of the program algorithm, and the specific algorithm is described as follows.

[0043] (1) Start: The analog quantity change judgment is an auxiliary program of a main program, which is used to assist in judging abnormal working conditions. For example, in the process of liquid feeding, the feeding program is the main program and the analog quantity judgment program is the auxiliary program. Therefore, the analog quantity judgment program starts synchronously with the main program.

[0044] (2) Delay: There is a certain lag in process control. For example, after the material is fed into the storage tank, as the conveying equipment is started, the liquid needs to be transported through the pipeline for a certain period of time before it can enter the storage tank. The instrument for judging the analog quantity is usually installed on the target equipment, such as measuring the liquid level of the liquid material in the storage tank, so there is a certain lag in the change of the liquid level. Therefore, it is unreasonable to judge the change of the analog quantity immediately after the program starts. A certain delay time needs to be reserved for the lag, which needs to be manually estimated and set according to the specific usage scenario.

[0045] (3) Real-time value judgment: The DCS controller has the ability to collect, record and judge data. This process is executed cyclically, so there is a cyclic execution cycle, and each cycle is usually 500ms. The specific method for judging the change of analog quantity in this step is to compare whether the analog quantity value recorded by the controller in the previous cycle is consistent with the analog quantity value recorded in this cycle.

[0046] However, the analog value fluctuates to a certain extent, so this step does not simply compare whether the two values ​​are completely consistent. For example, in the process of transporting liquid materials to the storage tank, the liquid level will not remain stable due to inertial tension and other effects, but will continue to float and rise, and the value measured by the level meter will also fluctuate. Even if the material feeding process is abnormally interrupted due to equipment problems, the material in the storage tank will have to stand for a long time before the liquid level remains stationary, and the value measured by the level meter will fluctuate before the liquid level remains stationary. In addition, the analog value measured by the instrument is transmitted through a standard 4-20mA current signal, which may be interfered by various environmental factors during the transmission process, causing the measured value to fluctuate.

[0047] For the above reasons, it is not reasonable to simply compare the two values ​​recorded in the previous cycle and the current cycle in this step to see if they are consistent. Therefore, a dead zone range is set for the comparison value, that is, the change of the measured analog value within the dead zone range is considered invalid. The dead zone range can be adjusted according to needs in specific usage scenarios. The comparison process of this step also becomes to determine whether the value recorded in this cycle is smaller than the difference between the value of the previous cycle and the dead zone or whether it is larger than the sum of the value of the previous cycle and the dead zone. If it exceeds the dead zone range, it is considered that the analog value has changed; if it does not exceed the dead zone range, it is considered that the analog value has not changed.

[0048] (4) Timer action: In this program, a timer inside the DCS controller is called to perform timing. If the analog value changes, the timer is reset; if the analog value does not change, the timer continues to time normally. This timing process is usually in the form of countdown.

[0049] (5) Timing judgment: In this step, a timing judgment is performed, that is, whether the accumulated time of the timer exceeds the set value. If it times out, the protection action of the subsequent steps is performed; if it does not time out, no protection action is performed, but the analog value of this cycle is recorded, which is used in the subsequent program loop to continue to judge whether the analog value changes.

[0050] (6) Protection action: In this step, the corresponding protection action output is performed, such as generating an alarm, or issuing a stop command to shut down the corresponding machine pump and valve equipment during the material conveying process.

[0051] (7) Reset: In this step, the program is manually confirmed whether to reset. If not reset, the program will continue to generate protection actions (alarm or stop command, etc.); if reset, the protection action is eliminated, and it is consistent with the action that did not time out in step 5. After recording the analog value of this cycle, continue to loop and execute the subsequent analog value change judgment.

[0052] (8) End: The analog quantity change judgment program and the main program end at the same time. If no protection action is generated and the punching process ends normally, the analog quantity judgment program ends; if a protection action is generated, the protection action may end the main program as well. The content of the protection action can be determined and set according to the specific usage scenario.

[0053] (9) The following parameters in this program can be set openly:

[0054] a. During the delay after the start, the delay time can be set according to the specific usage scenario.

[0055] b. The dead zone in the real-time value change judgment, the dead zone size can be set according to the specific usage scenario.

[0056] c. In timing judgment, the timeout period can be set according to the specific usage scenario.

[0057] d. Protection action. The specific action content needs to be set according to the usage scenario.

[0058] Embodiment 2

[0059] like Figure 2 The figure shows the process flow chart of the feeding process. After the material is unloaded from the tank truck, the feed valve and the feed pump are opened to determine whether the tank liquid level has reached the preset limit, which is determined according to the specific tank height or feeding requirements. When the liquid level is greater than or equal to the preset limit, the feed valve and the feed pump are closed, and the feeding process of the tank is completed. Figure 3 The left side of the figure is the logic block diagram of the process.

[0060] Figure 3 The right side is the basic logic block diagram after adding the algorithm of the present invention. Different from the above-mentioned charging process, when the equipment is turned on for charging, while judging whether the liquid level value has reached the preset limit, it also delays judging whether the liquid level value has changed within the preset time. If the liquid level remains unchanged for more than the preset time, this state is considered to be an abnormal condition, an alarm is generated, and the step of shutting down the equipment is also entered to end the charging process. This realizes the identification and reminder of abnormal conditions, as well as the protection of the charging equipment.

[0061] After the equipment is started, the material needs to be transported to the storage tank through the pipeline for a certain period of time. At this time, the liquid level in the storage tank begins to change, so a certain delay time needs to be set before the change of the liquid level is judged.

[0062] The reason why we judge whether the liquid level remains unchanged for a timeout is that the liquid level rises slowly during normal material injection. If the tank is large and materials are continuously injected into it, it will take a long time for the liquid level to change from one value to another. Therefore, we cannot immediately perform the corresponding protection action when the liquid level remains unchanged. Instead, we judge the duration of the unchanged liquid level. If it exceeds a reasonable time, it is judged as an abnormal condition and the protection action is performed.

[0063] During the feeding process, the liquid level is constantly floating and rising. Even if the feeding is interrupted due to abnormal circumstances, the liquid level value will not be static immediately due to factors such as inertia and tension, but will continue to float for a period of time in a small range. In addition, the current signal that transmits the liquid level value is easily disturbed and causes value fluctuations. Therefore, a reasonable dead zone range must be set. Liquid level changes within the dead zone are considered invalid changes, which is equivalent to no changes.

[0064] During this process, the time for delaying the start of liquid level change, the dead zone of liquid level change, and the timeout time for unchanged liquid level can all be modified and set accordingly according to the actual material discharging situation.

[0065] The judgment method based on the first embodiment can also be applied to judging the liquid material delivery by weighing equipment, judging the temperature rise and fall by thermometer, and other similar applications in which the instantaneous value of analog quantity is used as the process control endpoint judgment of DCS system.

[0066] The present invention also provides a computer-readable storage medium storing a computer program, characterized in that when the computer program is executed by one or more processors, the DCS-based analog quantity change judgment method is implemented. The computer-readable storage medium can be a non-volatile computer-readable storage medium, or a volatile computer-readable storage medium. The computer-readable storage medium stores instructions, and when the instructions are executed on a computer, the computer executes the steps in the process of transporting fluid materials to a storage tank using the liquid level as a judgment in Example 2. Fluid refers to a substance that can flow, and it is an object that will continuously deform under the action of any small shear force.

[0067] Those skilled in the art can understand that the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of software, and the computer software is stored in a storage medium, including several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for judging analog quantity changes based on DCS, characterized in that: The steps include: Step S1, start, execute the main program, and synchronously start the auxiliary program for analog quantity change judgment; Step S2, delay, setting the instrument for judging the analog quantity on the target device, and setting the delay time before judging the change of the analog quantity; Step S3, real-time value judgment, through the DCS controller cyclically executing data acquisition recording and processing capacity judgment, compare the analog value recorded by the controller in the previous cycle with the analog value recorded in this cycle to see if they are consistent, if there is a change, reset the timer, set a dead zone range for the comparison value, that is, it is considered that the change of the measured analog value within the dead zone range is invalid; judge whether the value recorded in this cycle is smaller than the difference between the value of the previous cycle and the dead zone or whether it is larger than the sum of the value of the previous cycle and the dead zone, if it exceeds the dead zone range, it is considered that the analog value has changed; if it does not exceed the dead zone range, it is considered that the analog value has not changed; Step S4, the timer is activated, and the timer inside the DCS controller is called to start timing. If the analog value changes, the timer is reset; if the analog value does not change, the timer starts timing normally. Step S5, timing judgment, judging whether the accumulated time of the timer exceeds the set value, if it is timed out, the protection action of the subsequent steps is performed; if it is not timed out, no protection action is performed, but the analog value of this cycle is recorded, which is used for the subsequent program cycle to continue to judge whether the analog value changes; Step S6, protection action, performing corresponding protection action output; Step S7, reset. If not reset, the program continues to generate protection action; if reset, the protection action is eliminated, and it is consistent with the non-timeout action in step S5. After recording the analog value of this cycle, continue to loop and execute the subsequent analog value change judgment; Step S8, end, the analog quantity change judgment program and the main program end at the same time. If no protection action is generated, the operation process ends normally, and the analog quantity judgment ends; if a protection action is generated, the protection action execution ends together with the main program.

2. A DCS-based analog quantity change judgment method as claimed in claim 1, characterized in that: The delay time after the start, the size of the dead zone range in the real-time value change judgment, the timeout time in the timing judgment and the specific content of the protection action are all set according to the specific usage scenario.

3. A DCS-based analog quantity change judgment method as claimed in claim 2, characterized in that: In the step S1, the main program is a material dispensing program during the liquid dispensing process.

4. A DCS-based analog quantity change judgment method as claimed in claim 3, characterized in that: In step S6, the protection action includes generating an alarm, or issuing a stop command to shut down corresponding machine pumps and valve equipment during the material conveying process.

5. A DCS-based analog quantity change judgment method as claimed in claim 4, characterized in that: Also includes: After the material is unloaded from the tank truck, the feed valve and the feed pump are opened to determine whether the liquid level in the storage tank has reached the preset limit. The limit is determined according to the specific height of the storage tank or the feeding demand. When the liquid level is greater than or equal to the preset limit, the feed valve and the feed pump are closed, and the feeding process of the storage tank is completed.

6. A DCS-based analog quantity change judgment method as claimed in claim 5, characterized in that: Also includes: When the equipment is turned on to feed materials, while judging whether the liquid level value has reached the preset limit, it also delays judging whether the liquid level value has changed within the preset time. If the liquid level remains unchanged for longer than the preset time, this state is considered to be an abnormal operating condition, an alarm is generated, and the device is shut down to end the feeding process.

7. A DCS-based analog quantity change judgment method as claimed in claim 6, characterized in that: Also includes: After the equipment is started and the material is pumped into the storage tank through the pipeline for a certain period of time, the liquid level in the storage tank begins to change. Set the delay time before starting to judge the change of the liquid level. Determine whether the liquid level has timed out. When the tank volume is greater than the preset volume threshold, material is continuously pumped into the tank. There is an intermediate time for the liquid level to change from one value to another. Therefore, the corresponding protection action cannot be performed immediately when the liquid level remains unchanged. Instead, the duration of the unchanged liquid level is determined. If it exceeds a reasonable time, it is determined as an abnormal condition and a protection action is performed.

8. A DCS-based analog quantity change judgment device, characterized in that: The invention comprises a memory and a processor, wherein the memory stores computer-readable instructions, and when the processor executes the computer-readable instructions, the DCS-based analog quantity change judgment method as claimed in any one of claims 1 to 7 is implemented.

9. A computer-readable medium storing a computer program, characterized in that: When the computer program is executed by one or more processors, the DCS-based analog quantity change judgment method as described in any one of claims 1 to 7 is implemented.

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