JP4069310B2 - Control system automatic recovery circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a normal system selection circuit for a duplex process signal in a plant control device, and particularly when a deviation occurs between the duplex process signals and the control system is switched from automatic control to manual control. The present invention relates to a control system automatic restoration circuit that automatically restores a control system to automatic control after selecting a system.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, many process signals (temperature, pressure, flow rate, etc.) are input to a control device in order to perform automatic control and monitoring of the plant in the control device of the plant. In recent control devices, the progress of digitization has made it easy to diagnose process signal abnormalities. As a result, there are many examples in which a circuit that has been diagnosed as abnormal is installed by detecting a sudden change or a shake of the process signal input to the control device.
Moreover, when the importance of the control circuit of a use destination is high in the input process signal, the device of the same signal is duplicated, and the device which uses a highly reliable process signal for the control circuit is devised.
A conventional control circuit using a duplex process signal is shown in FIG. In FIG. 3, the duplicated process signals 1 and 2 are digitally converted into the control device and taken in every calculation cycle. In response to the captured signal, the abnormality diagnosis circuits 3 and 4 determine whether or not the signal is broken or suddenly changed. The monitor relay 5 detects an abnormal state in which a process signal that cannot be determined as abnormal by the abnormality diagnosis circuits 3 and 4 changes gradually. When the deviation between the process signals 1 and 2 exceeds a preset allowable range, it is determined as abnormal.
The abnormal state of the duplex process signal generated during automatic control can be broadly classified into three. One is a case where one system of the process signal is determined to be abnormal by the abnormality diagnosis circuits 3 and 4, and in this case, the normal system side signal is automatically selected by the bumpless switch 6, Intermitts control. The second is a case where both of the process signal systems are determined to be abnormal by the abnormality diagnosis circuits 3 and 4, and this case is dealt with by interrupting the control by the process signal and quickly controlling the operation end manually. Migrate to The third is a case where the deviation between the process signals 1 and 2 is determined to be large by the monitor relay 5, and in this case, since it cannot be determined which is the normal system, automatic control by the process signal is interrupted once. Then, after maintaining the control of the operation end, after determining and selecting the normal system, the automatic control is promptly restored.
The processing flow at the time of these three abnormality diagnoses is shown in FIG. In particular, when a large process signal deviation occurs, it is necessary to select a normal system and promptly shift to automatic control, so that each operation is processed according to the procedure.
The operation procedure will be described with reference to FIG. When the process signal deviation becomes large, the control system automatically switches to manual control. The first step of the operation is to determine which of the duplicated process signals is normal based on the plant status and the value of the process signal at this time, and to operate a CRT operation button (hereinafter abbreviated as CRT). )) To select the normal system. In the second step, since the situation of a large deviation continues, the “diagnosis exclusion” operation is performed by the CRT in order to exclude this diagnosis circuit. In the third step, when the deviation is large, the control system is switched to manual, and the signal that has maintained the large deviation in order to output an alarm is reset by an “abnormal reset” operation of the CRT. By operating so far, even if the large deviation state continues, the control system can be restored to automatic control. In the fourth step, it is confirmed that the switching to the normal system process signal has been completed, and the control system is restored to automatic control by the “automatic” operation of the CRT.
In the above-described abnormality diagnosis device for process signals, reference related known techniques for abnormality diagnosis mechanisms are described in Japanese Patent Application Laid-Open Nos. 59-11681 and 54-118879, and a duplex process. A reference-related known technique for detecting a failure of a signal is described in Japanese Patent Laid-Open No. 58-12452.
[0003]
[Problems to be solved by the invention]
When the doubled process signal has a large deviation, in order to make the best use of the benefits of duplexing, even if the large deviation continues, the automatic control by the normal process signal is promptly performed. Need to recover.
However, in the above-mentioned conventional technology, it is necessary to operate without error in accordance with a predetermined procedure after selecting a normal system when the deviation is large, so that the operation burden on the operator is large, thereby causing a human error. There was a problem.
[0004]
An object of the present invention is to automatically process a recovery operation to automatic control after a normal process signal is selected when a duplex process signal has a large deviation, thereby reducing an operation burden on a driver and a human error. There is.
[0005]
[Means for Solving the Problems]
The above problem is a control system automatic recovery circuit that switches the control system from automatic control to manual control or from manual control to automatic control when a large deviation exceeding a preset allowable range is detected between the duplex process signals. There,
In a state where the deviation between the duplicated process signals is large, the normal process signal diagnosed by the abnormality diagnosing means during the large deviation detecting operation by the deviation detecting means is selected by switching by the operator's manual operation. On the condition that there is a large deviation between the duplicated process signals , in the duplicated process signal, the diagnostic process is switched off so that the abnormal side cannot be mistakenly selected, and at the same time normal When it is detected that the switching operation to the process signal of the system is completed, an automatic recovery means for outputting a control system automatic recovery command is provided, and the switching means is automatically switched by the control system recovery command output by the automatic recovery means. This is solved by switching the control system from manual control to automatic control.
[0006]
The present invention automates the operation of once setting the control system to manual control until the normal system is selected when the duplex process signal has a large deviation and then returning to automatic control after selecting the normal process signal. As a result, it is possible to quickly and without error, restore the plant to automatic control operation.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are control system automatic recovery circuits showing an embodiment of the present invention. FIG. 1 shows a control circuit using a duplex process signal. In FIG. 1, the process signal 1 and the process signal 2 are selected as normal signals by the bumpless switch 6. The bumpless switch 6 selects the process signal 1 side when the 1 selection signal 14 is ON, and selects the process signal 2 side when the 1 selection signal 14 is OFF. The difference between the selected process signal and the control setting signal generator 7 is calculated by the differencer 8. The calculated control deviation signal is input to a PI (proportional + integral) calculator 9, and the output of the PI calculation based on the deviation signal is the control signal A.
Further, the manual setting device 11 outputs a manual signal H corresponding to the manual increase / decrease operation on the CRT operation screen. The manual setting device 11 is a signal that is not influenced by the process signal because the output is calculated only by a signal corresponding to the increase operation or decrease operation of the operator.
Either the control signal A or the manual signal H is selected by the automatic / manual signal switch 10 to become the operation signal 12 and controls the operation end. The signal switcher 10 selects the control signal A side when the automatic signal 13 is ON, and selects the manual signal H side when the automatic signal 13 is OFF. The automatic signal 13 turns ON the flip-flop 21 when the operator operates the automatic 19 on the CRT operation screen, and keeps ON until the flip-flop 21 is reset by operating the manual 20 thereafter. Even when the condition of the signal abnormality 15 is turned ON, the automatic signal 13 is turned OFF by resetting the flip-flop 21. As a result, when the automatic signal 13 is ON, an automatic control signal for controlling the process signal as a feedback signal is an operation command, and when the automatic signal 13 is OFF, a manual signal from the manual setting device is an operation command.
[0008]
Here, in the control circuit of FIG. 1, the abnormality diagnosis of the process signal may be detected by the abnormality diagnosis circuits 3 and 4 or may be detected by the monitor relay 5.
The process signal is digitally converted into a control device every calculation cycle. In response to the captured signal, the abnormality diagnosis circuits 3 and 4 determine whether or not the signal has been broken or suddenly changed, and if this is detected, the signal diagnosis abnormality 16 or 17 is assumed to be abnormal in the process signal. Turn on. If the deviation between the process signals 1 and 2 exceeds a preset allowable range, the monitor relay 5 determines that an abnormality has occurred and turns on the large signal deviation 18.
[0009]
FIG. 2 shows an interlock circuit for preventing the operation end from being affected by the abnormality when the process signal is abnormal in the control circuit using the duplex process signal described above. In the figure, a portion surrounded by a broken line is the circuit of this embodiment provided for automatic recovery when the deviation is large.
First, the process signal 1 selection 1a, process signal 2 selection 2a, diagnosis exclusion 3a, diagnosis use 4a, and abnormality reset 5a on the CRT operation screen are signals that are turned on when operated by the CRT, respectively. The two-signal diagnosis abnormality 17 is turned on when the signals of the one-signal diagnosis abnormality 16 and the two-signal diagnosis abnormality 17 in FIG. 1 is a signal that is turned on when the signal deviation large 18 signal in FIG. 1 is ON, that is, when the deviation large monitor relay 5 determines that the deviation is large.
The flip-flop 9a is set when the one-signal diagnosis abnormality 16 is OFF and the one-selection 1a or two-signal diagnosis abnormality 17 is ON. When the two-signal diagnosis abnormality 17 is OFF, the two-selection 2a or one-signal diagnosis abnormality 16 is detected. Reset when ON. That is, the 1 selection signal 14 which is the output signal of the flip-flop 9a is automatically turned ON when the 1 system side is manually selected or when only the 2 system side is abnormal, and conversely, the 2 system side is manually operated. Is selected, or when only system 1 side is abnormal. Since this 1 selection signal 14 is a switching condition of the bumpless switch 6 of FIG. 1, switching to a normal signal is performed to the bumpless.
Next, the flip-flop 11a is set when the large signal deviation 18 is ON in the case where both the one-signal diagnosis abnormality 16 and the two-signal diagnosis abnormality 17 are both off (normal in both systems) or in either OFF state, and the abnormality reset 5a is operated. Reset when ON.
The signal abnormality 15 is turned on when either the output signal of the flip-flop 11a or the 1 and 2 system diagnosis abnormality 16 is established. By making this signal abnormality 15 a reset signal of the flip-flop 21 in FIG. 1, the automatic 13 is turned OFF, and the automatic / manual switching device 10 selects the manual signal H. As a result, the operation signal 12 is manipulated by an output signal from the manual setting device 11. However, unless the manual setting device 11 is increased / decreased, the signal at the time of switching is held.
[0010]
If the signal error 15 is turned ON because the large signal deviation 18 in FIG. 2 is turned ON, it is immediately determined whether the process signals 1 and 2 are normal, and after selecting the normal system, the signal error 15 is set. It is necessary to restore the control system to automatic control by turning it off. A circuit for automatically processing this restoration operation will be described below.
The flip-flop 10a is set by the operation of the diagnosis exclusion 3a or the signal 20a from the switching detector 18a, and reset by the operation of the diagnosis use 4a.
If it is determined that the selection side is abnormal after the occurrence of a large deviation, the normal system is selected by 1 selection 1a and 2 selection 2a. When the normal system is selected, the switching detector 18a detects the signal change state (1⇔0) and generates a signal that is turned on for one shot (several seconds). The flip-flop 10a that is set when diagnosis is excluded is automatically set by the logical product of this signal and the large deviation 19a that is set when the deviation is large. When the output signal of the flip-flop 10a is turned on, the signal 22a is turned off, and the set / reset condition of the flip-flop 9a cannot be established. This is to prevent the abnormal side from being selected by mistake during the large deviation state. Similarly, when the signal 22a is turned OFF, the set signal 14a of the flip-flop 11a is also turned OFF, and the signal abnormality 15 due to the large deviation is turned OFF even if the large deviation state continues due to the establishment of the reset condition of the abnormal reset 5a. It becomes possible to do. When the flip-flop 10a is set, the flip-flop 11a is automatically reset after several seconds by the timer 21a. As a result, the signal abnormality 15 is turned OFF, and the control system is ready for automatic recovery.
Next, the output signal of the timer 21a, the signal 17a for confirming that the large deviation state continues, and the switching that is turned on when it is detected that the switching operation from the abnormal signal to the normal signal is completed when the signal is switched. When three signals of the completion 22 signal are established, the one-shot (several seconds) automatic recovery command 23 is turned ON. Thereby, the flip-flop 21 of FIG. 1 is automatically set, and the control system is automatically switched from manual control to automatic control, and the operation is completed.
Note that when the signal selected when the deviation is large is a normal system, there is no need to select it, and therefore the switching detection circuit 18a due to the selection of the normal system does not operate. In this case, diagnosis exclusion 3a is manually selected. As a result, the subsequent operation is automatically restored to the automatic control as in the case where the normal system is selected and the signal 20a from the switching detection circuit 18a is turned on.
[0011]
Here, FIG. 5 shows a main part of a circuit (a portion surrounded by a broken line in FIG. 2) provided for automatic restoration when the deviation is large as a control system automatic restoration circuit (inside the broken line).
When the duplex process signals 1 and 2 are diagnosed by the monitor relay 5 as having a large deviation, the flip-flop 11a is set and 21 is reset by turning on the deviation large signal 18, and automatically switches to manual control (in the figure). (1) state).
Thereafter, when a normal system (1 selection 1a in the figure) is selected by the normal system selection circuit (flip-flop 9a) in the large deviation state, the normal process signal 1 is selected by the bumpless switch 6. Then, the normal process signal 1 is detected by the switching detection circuit 18a, and the signal 20a from the switching detection circuit 18a is turned on under the condition that the deviation between the duplicated process signals is large. The operation of the exclusion 10a and the operation of the large deviation signal reset 11a are automatically performed, and at the same time, the switching completion detection circuit 22 detects that the selection signal has been switched, and the control system automatic recovery command 23 is turned ON. As a result, the flip-flop 21 is set, the output is turned ON, and the control system is automatically switched from manual control to automatic control ((2) state in the figure).
[0012]
【The invention's effect】
As described above, according to the present invention, when the duplex process signal deviation is large, the control system once switched to manual control can be automatically restored to automatic control after determining the normal system. As a result, the troublesome procedure that has been manually handled by the operator is no longer necessary, and the shift of the automatic control operation of the plant can be executed promptly without any error.
[Brief description of the drawings]
FIG. 1 is a control system automatic recovery circuit showing an embodiment of the present invention. FIG. 2 is a control system automatic recovery circuit showing an embodiment of the present invention. Process flow for conventional abnormality diagnosis [FIG. 5] Main part of control system automatic recovery circuit according to one embodiment of the present invention [Explanation of symbols]
5: Monitor relay, 6: Pan press switcher, 7: Setting signal generator, 8: Differencer, 9: Proportional + integrator, 10: Automatic / manual switcher, 11: Manual setter, 21: Flip-flop circuit 9a, 10a, 11a: flip-flop circuit, 18a: switching detector, 21a: timer

Claims (1)

A duplex process signal is taken in every sampling period, and an abnormality diagnosis means for diagnosing each abnormality by detecting a sudden change or shakeout of the duplex process signal is set in advance between the duplex process signals. The control system automatic recovery circuit has a deviation detecting means for detecting a large deviation exceeding the allowable range and a switching means for switching the control system from automatic control to manual control or from manual control to automatic control when a large deviation is detected. There,
After selecting a normal process signal diagnosed by the abnormality diagnosing means during manual operation of the operator during the large deviation detecting operation by the deviation detecting means in a state where the deviation between the duplex process signals is large, On the condition that there is a large deviation between the duplex process signals , in the duplex process signal, a diagnostic exclusion state that blocks the duplex process signal switching is set so that the abnormal side cannot be selected by mistake. And an automatic recovery means for outputting a control system automatic recovery command when it is detected that the switching operation to the normal process signal is completed, and the switching means is controlled by the control system recovery command output by the automatic recovery means. control system automatic recovery circuit, characterized in that switching from manual control to automatic control system is switched to automatic control.

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