JP3868085B2 - Automatic control device with dual detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic control device that performs control operations by measuring state quantities with a duplex detector in various plants and apparatuses, and more particularly, automatic control for switching a duplex detector while continuing automatic control. Relates to the device.
[0002]
[Prior art]
In control devices such as various plants, a state quantity to be controlled is detected by a detector, and automatic control centering on feedback control is widely used based on the detection signal, but all operation control operations are automatically controlled. The manual operation by the operator is also used at the same time. As shown in FIG. 4, typical feedback control in the plant and apparatus includes a detection unit 41, a control unit 42, an operation unit 43, and a manual setting unit 44 of a detector 45.
[0003]
The state quantity of the control target detected by the detector 45 is taken into the detection unit 41, and noise and abnormal signals are removed, and only the normal detector 45 signal is sent to the control unit 42 as a detection signal. The control unit 42 takes in the detection signal and adjusts the output signal of the controller so as to have a predetermined set value. An output signal from the control unit 42 is sent to the operation unit 43 to move the operation end 47. Here, if the detection unit 41 determines that there is no normal detection signal, the control unit 42 cannot continue the control, so that the output signal to the operation unit 43 is sent to the manual setting unit via the changeover switch 46. Switch to the signal from 44. The switched state is generally referred to as “manual mode”, and the operator directly adjusts and controls the operation end 47.
[0004]
Therefore, in the feedback control system, when the detector 45 fails, normal automatic control cannot be performed. Therefore, the same two detectors are provided in the same place, and automatic control is performed until the abnormality of the detector occurs. When this occurs, a duplex system is often employed in which the mode is once shifted to the manual mode, and the automatic control is resumed after artificially switching to the normal detector.
[0005]
FIG. 2 shows a control circuit of the conventional duplex detection unit 41.
In FIG. 2, the same detectors 1 and 2 are connected to the signal switch 3 via the output signal lines 11 and 13, respectively, and the signal switch 3 sends the selected detection signal to the control unit 42. ing.
First, the detection signals from the detectors 1 and 2 enter the comparative upper / lower limit detector 7 via the output signal lines 11 and 13, respectively, and both the detector abnormal signals (B) and (C) are not output. When there is a difference (deviation) greater than or equal to a predetermined value, the detector abnormality signal (D) is output after the time set by the on-delay timer-15.
[0006]
Furthermore, when the detector abnormality signals (B) and (C) are not output and there is a difference (deviation) of a predetermined value or more between both detectors 1 and 2, the AND gate 62 and the inverting circuits 51 and 52 are provided. As a result, a deviation signal is output, and after a time set by the on-delay timer-15, the detector abnormality signal (D) is output and the mode is shifted to the manual mode.
[0007]
On the other hand, the detection signals from the detectors 1 and 2 enter the upper and lower limit detectors 5 and the sudden change detector 6 via the output signal lines 11 and 13, respectively. Detected. That is, the upper / lower limit detector 5 outputs an output signal when the detection signal is out of a preset range, and the sudden change detector 6 also outputs an output signal when a sudden change in the detection signal is detected. When these output signals are output for each of the detectors 1 and 2, detector abnormality signals (B) and (C) are output via the OR gates 61 and 60, respectively.
[0008]
Then, when the detector abnormality signal (B) is output when the detector 1 is selected by the switch 3, the detector abnormality signal (C) when the detector 2 is selected by the switch 3. Is issued, and when the detector abnormality signal (D) is issued, it is determined that an abnormality has occurred in the detector, the automatic control is interrupted, and a transition is made to the manual mode.
Here, whether to select the detector 1 or 2 is determined by whether or not the detector 1 selection signal A is established.
[0009]
That is, in the figure, when the selection signal (A) of the detector 1 is established in the switching device 3, the AND gate 63 takes the AND of the abnormal signal (B) and the selection signal (A) to enter the manual mode. Transition.
When the selection signal (A) of the detector 1 is not established in the switch 3, in other words, when the detector 2 is selected by the switch 3, the abnormal signal (C ) And the inverted selection signal (A) are taken to shift to the manual mode.
[0010]
In the manual operation, the detector abnormality signals (B) and (C) are input to the corresponding AND gates 65 and 66 via the inverting circuits 54 and 55, respectively, so that the detector abnormality signal (B) is output. If the detector 1 is not manually selected, the selection signal (A) of the detector 1 is output via the signal generator 17 and the detector abnormality signal (C) is output conversely. If the detector 2 is not selected by manual operation, the selection signal (A) of the detector 1 is not output via the signal establishment unit 17, in other words, the detector 2 is selected.
[0011]
Therefore, with the above-described conventional control method, when any one of the detectors 1 and 2 is abnormal, the operation is shifted to manual operation, and thus automatic control is not continued.
Therefore, only when there is no difference between the signals of the detectors 1 and 2 until a predetermined time, and when it is possible to automatically determine which detector of the detectors 1 and 2 is abnormal For example, a control method that can select and switch a detection signal automatically sent from the control device to the controller without manual operation has been put into practical use.
[0012]
Such a control method will be described with reference to FIG.
3, the same reference numerals as those in FIG. 2 denote the same functional circuits or members.
In the figure, reference numeral 20 denotes an automatic switching permission determination circuit, which calculates a difference between the detector 1 and the detector 2 before a predetermined time by a subtractor 21 and a dead time delay element 23 and sets a difference set in advance by an upper / lower limit detector 25. The automatic switching signal (E) is output only when no occurs.
When the automatic switching signal (E) is output and the detector abnormality signal (C) is output, the selection signal (A) of the detector 1 is sent via the AND gate 67, the OR gate 69, and the signal establisher 17. Similarly, when the detector abnormality signal (B) is output, the selection signal (A) of the detector 1 is not output via the AND gate 68, the OR gate 70, and the signal establisher 17 in the same manner. Detector 2 is selected.
[0013]
Therefore, this conventional technique outputs the automatic switching signal (E) only when the difference set in advance by the upper / lower limit detector 25 does not occur, and performs switching by the switch 3 while continuing the automatic control. It is a technique. However, even if this method is used, the chance that the detection signal is automatically switched does not increase dramatically.
[0014]
[Problems to be solved by the invention]
As described above, when two detectors 1 and 2 are used in the duplex system, it is rare that they become abnormal at the same time. Even if one detector 1 becomes abnormal, if the other detector 2 is normal, the signal from the normal detector 2 can be selected and used to continue automatic control. What is necessary is just to switch a signal.
[0015]
However, this has the following problems. That is, there is a possibility that the value of the detection signal of the detector 1 that has become abnormal is considerably different from the detection signal of the normal detector 2 until it is determined that the detection signal is abnormal. Until the detector 1 is determined to be abnormal, it is automatically controlled based on the signal from the detector 1, so that the operating device may be considerably away from the normal position.
Accordingly, when the automatic control is switched to the one based on the detection signal of the detector 2 when the abnormality of the detector 1 is determined, the operation end 47 is forcibly pulled back to the position based on the normal detection signal. Disturbances continue to be applied to the control system, causing a significant loss of control system stability. Therefore, as described above, even when the detector is duplicated, when the detector becomes abnormal, it is a general technique to temporarily shift to the manual mode as shown in FIG. Alternatively, as shown in FIG. 3, automatic switching is performed without manual operation only when there is no difference between the detection signals of both detectors until a predetermined time ago. The opportunity to switch will not increase dramatically.
[0016]
However, in the conventional control method, it is extremely burdensome for the operator to perform an appropriate manual operation at the time of occurrence of an abnormality that is unknown when it occurs.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a control device including a detection unit that switches to a signal of a normal-side detector as much as possible without causing a manual mode transition when a detector abnormality occurs. Is.
[0017]
[Means for Solving the Problems]
In order to solve the above problems, the present invention switches the first detector 1 and the second detector 2 and the first and second detectors 1 and 2 as shown in FIG. A first output signal line 11 and a second output signal line 13 connected to the device 3, a circuit 31 for holding a signal after switching between the first and second detection signals, and a first output signal and a second output signal, respectively. The abnormality determination circuits 5 and 6 provided on the lines 11 and 13 respectively communicate with the first and second output signal lines 11 and 13 and receive the signals of the first and second detectors 1 and 2, respectively. A circuit 7 for detecting a signal deviation and a temporary holding signal generating circuit 32 for generating a signal for temporarily holding the automatic control circuit when the deviation occurs are configured.
[0018]
According to such an invention, the state of various plants and devices is measured with a duplex detector, and the controller performs an operation so that the control amount measured with one of the detectors becomes a target set value, In an automatic control device that adjusts the operating device based on the output, when one of the duplicated detectors fails, the operating device fluctuates even if switching to the other detector while continuing automatic control. In addition, it is possible to obtain a switching control system that does not cause disturbance to the apparatus.
[0019]
Some recent detectors have a so-called self-diagnosis function in which the detector itself detects that the detector has failed. When the detector determines a failure (abnormality) through self-diagnosis, a signal out of the predetermined signal range is output to the automatic control device, so the automatic control device side detects it using the detector abnormality signal described above. You can know the abnormality of the vessel. By incorporating such advances on the detector side, the scope of the present invention is further expanded.
The first and second output signal lines are necessary when wired, but when the detector has an abnormality determination function through self-diagnosis or when signals are transmitted and received wirelessly, the first and second output signal lines are required. The first and second output signal lines are not necessary.
[0020]
Therefore, in the present invention described in claim 1, the states of various plants and apparatuses are measured by the first and second detectors which are duplicated, and the control amount measured by one of the detectors becomes a target set value. In the automatic control device that performs the operation in the controller and adjusts the operating device by the output,
A switch for sending said first and second detector output signal switched to the control unit of the signal holding circuit that holds and fixes the output signal to the control unit from said switch, said first and An abnormality determination circuit for determining an abnormality of each detector from an output signal of each of the second detectors, a deviation detection circuit for detecting a deviation between output signals of the first and second detectors, and the abnormality determination circuit Even when no abnormality signal is output from each detector, the signal holding circuit is temporarily activated when the deviation of the detection signal by the deviation detection circuit exceeds a predetermined set value . A temporary holding signal generating circuit for generating a signal, and when the abnormal detector is determined by the abnormality determining circuit during the temporary holding by the signal holding circuit, a signal from a normal detector by the switch Is selected Is, when the abnormal detector is not determined is characterized by comprising configured to shift to the manual mode.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, unless otherwise specified, the types of components and circuits described in this embodiment and their relative arrangement are not intended to limit the scope of the present invention, but are merely illustrative examples. .
FIG. 1 is a circuit diagram of a control system according to an embodiment of the present invention, particularly a portion corresponding to the detection unit of FIG.
In the following description, the same functional parts shown in FIGS. 2 and 3 are denoted by the same reference numerals for understanding of the present invention.
In FIG. 1, detectors 1 and 2 are connected to a switch 3 via output signal lines 11 and 13, respectively. The switch 3 selects one of the detection signals output from the detectors 1 and 2 in a form to be described later, and sends it to the control unit 42 (see FIG. 4) that performs the control operation.
Upper and lower limit detectors 5 and sudden change detectors 6 are connected to the output signal lines 11 and 13, respectively.
[0022]
The control amount to be detected by the detectors 1 and 2 can reasonably be predicted in a range that varies depending on the operating conditions of the plant and the apparatus. Accordingly, the detection signal value range corresponding to the fluctuation range is set as the signal range, and the detection signal outside the signal range can be determined as abnormal by the upper / lower limit detector 5.
In addition, the speed of fluctuation of the control amount can be predicted within a predetermined range. Therefore, the sudden change detector 6 compares the degree of change of the detection signal, for example, a differential value thereof with the set value, and can determine that it is abnormal if it is large. These abnormality detection circuits 5 and 6 are determined in consideration of the characteristics of the control amount of the plant and the apparatus in which the detectors 1 and 2 are used.
[0023]
The output signals of the upper and lower limit detectors 5 and the sudden change detector 6 are divided into detectors 1 and 2 and become detector abnormality signals (B) and (C) through OR gates 61 and 60, respectively.
Then, the abnormality of any of the detectors 1 and 2 can be discriminated by the output of the abnormality detector signal of (B) and (C).
[0024]
On the other hand, the comparison upper / lower limit detector 7 constantly compares the detection signals of the detectors 1 and 2 via the output signal lines 11 and 13, and the deviation between the two detection signals can exceed a predetermined set value. For example, even when the detector abnormality signals (B) and (C) are not output, a deviation signal is output via the inverting circuits 51 and 52 and the AND gate 62, and the deviation signal is set by the on-delay timer 15. If the output continues even after the elapse of time, an abnormal signal (D) indicating that one of the detectors 1 and 2 is abnormal is output.
At this time, since the detector abnormality signals (B) and (C) are not output, the abnormality of any of the detectors 1 and 2 is not determined.
[0025]
That is, only when a deviation occurs between the detectors 1 and 2, it is impossible to immediately determine which detector 1 or 2 is abnormal. Therefore, when a deviation occurs between the detectors 1 and 2 by the comparison upper and lower limit detector 7, a control output fixing command (F) is sent to the switch 31 via the one-shot timer 32 and sent to the control unit 42. The detection signal to be sent is fixed and held.
That is, the detection signal is held by passing the signal after switching to the switch 31, and by holding the signal, control is performed using the signals of the detectors 1 and 2 on the abnormal side, and the operation device is in a normal position. There is no such thing as leaving.
[0026]
However, since the detection signal sent to the control unit 42 is held, the controller is not adjusted and controlled according to the control amount even though the automatic control is continued during that time. Therefore, the time of the one-shot timer 32 that can hold the signal sent to the control unit 42 is appropriately determined depending on the control target of the plant and the apparatus.
When the detector abnormality signal (B) or (C) is not output during the holdable time and an abnormal detector cannot be determined, the detector abnormality signal (D) is established as described above, and control is performed. The system goes to manual mode.
This case is conventional and cannot be switched automatically with current technology.
[0027]
Next, a circuit that can determine an abnormal detector and avoids disturbance to the operating device even when the detection signal is switched by the switch 3 will be described.
Since the time of the on-delay timer 15 is significantly shorter than the predetermined holding time by the one-shot timer 32, the detector abnormality signal (D) is established almost simultaneously after the establishment of the control output fixing command (F) to the control unit 42. .
In response to this control output fixing command (F), the control unit 42 holds the output signal to the operation unit 43 for a predetermined holding time by the one-shot timer 32.
[0028]
Within the holding time of the detection signal of the one-shot timer 32 described above, the upper / lower limit detector 5 or the sudden change detector 6 determines whether any one of the detectors 1 and 2 is abnormal in the circuits 5 and 6. In this case, the normal signal is selected by the switch 3. At the same time, when the detector abnormality signal (B) or (C) is established, the AND gate 62 takes the AND of the inverted signals (B) and (C) by the inverting circuits 51 and 52 together with the (D) signal. Therefore, the detector abnormality signal (D) is not established, and immediately after that, the output of the one-shot timer 32 is also not established, and the signal of the switch 31 passes the signal of the switch 3 to the control unit 42. A normal detector signal is sent. Further, immediately after the switch 31 passes the signal of the switch 3, the control output fixing command (F) is not established, and the control output of the control unit 42 is released and the holding of the operating device is released.
[0029]
By performing the above switching in series, it is possible to prevent disturbances to the plant and the apparatus by unnecessarily changing the operating device even in the process of switching the detection signal to the normal side. Of course, since these operations are performed without operator intervention, the burden on the operator is reduced.
[0030]
【The invention's effect】
As described above, according to the control method of the present invention, when an abnormality occurs in one of the two detectors, the detection signal to the control unit and the operation device are detected until the abnormal detector can be identified. By temporarily holding this signal, disturbances to the controlled object such as plants and equipment can be reduced, and automatic control can be continued without switching the operating unit to manual mode, which can reduce the burden on the operator. As a result, the reliability and safety of a controlled object such as a plant can be improved.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a control system according to an embodiment of the present invention, particularly a portion corresponding to a detection unit of FIG.
FIG. 2 is a conventional circuit diagram of a portion corresponding to the detection unit of FIG. 4;
FIG. 3 is another conventional circuit diagram of a portion corresponding to the detection unit of FIG. 4;
FIG. 4 is a block diagram showing a typical feedback control system.
[Explanation of symbols]
1, 2 Detector 3 Switching device 5 Upper / lower limit detector 6 Sudden change detector 7 Comparison upper / lower limit detector 11, 13 Output signal line 15 On-delay timer 17 Signal enabler 31 Switcher 32 One-shot timer 41 Detector 42 Control Unit 43 Operation unit 44 Manual setting unit A Detector 1 selection signal B, C, D Detector abnormality signal E Automatic switching permission signal F Control output fixing command

Claims (1)

Measure the state of various plants and equipment with the first and second detectors that are duplicated, perform the calculation with the controller so that the control amount measured with one of the detectors becomes the target set value, In the automatic control device that adjusts the operating device with its output,
A switch for sending said first and second detector output signal switched to the control unit of the signal holding circuit that holds and fixes the output signal to the control unit from said switch, said first and An abnormality determination circuit for determining an abnormality of each detector from an output signal of each of the second detectors, a deviation detection circuit for detecting a deviation between output signals of the first and second detectors, and the abnormality determination circuit Even when no abnormality signal is output from each detector, the signal holding circuit is temporarily activated when the deviation of the detection signal by the deviation detection circuit exceeds a predetermined set value . A temporary holding signal generating circuit for generating a signal, and when the abnormal detector is determined by the abnormality determining circuit during the temporary holding by the signal holding circuit, a signal from a normal detector by the switch Is selected Is abnormal detector automatic control device with a detector which is duplicated characterized by comprising configured to shift to the manual mode when it is not determined.

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