JPS60105005A - Fault monitoring device for output signal of redundant system - Google Patents

Abstract

PURPOSE:To attain the monitor of faults with extremely small quantity hardware by detecting the presence or absence of a fault by the difference between the output signal of each redundant system and an intermediate value signal and fetching the result of said detection to a memory with a sampling signal which can vary its time width. CONSTITUTION:Signals 221a-221c of systems A-C are supplied to multiplexers 712-714, and then an intermediate value signal 31 given from a signal selector 3 is supplied to a multiplexer 711. Each multiplexer fetches the signal of each channel to a coincidence detecting circuit 72 by a scanning signal 756 and calculates the differences between the signal 31 and signals 221a-221c successively by differential amplifiers 521-523. For the system such as the system A, etc. where the result of said calculation exceeds a range decided by the allowance deviation voltage 531, the output 551a of a window comparator 541 is set at level H and written to a corresponding address of a memory element 731 decided by the signal 756 and with the trigger of a sampling signal 757. Then the written output 551a is transferred to a display element 741, and the element of the system A is lit up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an abnormality monitoring device for redundant system output signals used in plants etc. that require high reliability, and in particular to a system for monitoring abnormalities in redundant system output signals used in plants etc. that require high reliability. The present invention relates to an abnormality monitoring device for redundant output signals suitable in certain cases.

[Background of the invention]

In power plants that require highly reliable operation, their important control systems include, for example, three
A weighted control system is used.

In the figure, the triplex control system selects the most probable one signal from among the three signals output from each of the three control devices 2a, 2b, 2c1, and applies it to the controlled object 4. It basically consists of an output signal selection device 3, and a coincidence determination device 5 that determines whether the signals outputted from the three control devices 2a, 2b, and 2c match each other. Control devices 2a, 2b for each group.

Control units 21a, 21b, and 21c in 2C transmit and receive large amounts of data in a time-division manner with other devices (not shown) via terminals 1a, lb, and lc. Of these, data from other devices is sent to the control unit 21.
a, 21b, and 21c, and are subjected to various control arithmetic processing or directly outputted without any arithmetic operation.
2!2b122c is output as a control signal. Further, the control devices 2a, 2b, 2c take in signals from the sensor 6 via respective input circuits 23a, 23bl 23C, and control the respective ones 22) 21a, 21b.

21C, or use terminals la, l as is.
b, lc to other devices not shown, or input circuits 23a, 23b.

The control units 21a, 21b, and 21c perform control calculations on the sensor output signals taken in from the sensor 23c, and output the results as control signals through the output circuits 22al, 22bl, and 22C.

The signal selection device 3 often uses an intermediate value selection circuit that selects and outputs an intermediate level signal from among three input signals, and an example of this circuit is shown in FIG.

This device has three high value selection circuits 321, 322 and 323 that compare two signals and select and output a high level signal.
It basically consists of a low value selection circuit 34 which selects and outputs the lowest level signal among the three signals selectively output by these circuits.

A control device 2a for each of the three systems shown in FIG.

The signals 2b and 2C are output from each terminal 31a.

31b and 31C. Assuming that the signals applied to these terminals are A thread signal, B system signal, and C system signal, respectively,
The outputs of two of the high value selection circuits 321 to 323 are the maximum of the three signals, and the other output is the intermediate value of the three signals, so the outputs of these three high value selection circuits If the lowest level signal is selected by the low value selection circuit 34, that signal has an intermediate value among the A, B, and C signals, and is outputted to the terminal 35.

For example, if the magnitude relationship of each system signal is that the C system signal, the A system signal, and the B system signal, the output signals 331 and 332 of the high value selection circuits 321 and 322 will be the B system signals.
The output signal 333 of No. 3 becomes an A-system signal. Therefore, the low value selection circuit 34 outputs the A system signal, that is, the 3
This means that the intermediate level signal among the two signals is selectively output.

Next, the coincidence determination device 5 in FIG. 1 is a control device 2a.

-By determining whether or not the signals outputted multiple times as 2b and 2C match each other within an arbitrary set tolerance, and displaying the results, plant operators can, for example, take appropriate measures in the event of an abnormality. It is intended to make you feel like you. FIG. 3 shows an example of this coincidence determination device 5, in which an operational amplifier 5
21,522°523, window comparator type comparators 541 to 546, and a display device 571,572°57 for displaying the match determination results obtained with the above configuration.
3) Basically consists of: A-C output from the control devices 2a, 2b, and 2c of each of the three systems shown in FIG.
Each signal of the system is connected to each terminal 51a.

51b, 51c, and each operational amplifier 521°52
2 and 523 output the difference between the A-system signal and the B-system signal, the difference between the B-system signal and the C-system signal, and the difference between the C-system signal and the A-system signal, respectively. These output values are output from comparators 541 to 546.
is input. Comparators 541 to 546 are configured as window comparators, and operational amplifiers 521 and 522
, 523 is within the range of the positive reference voltage 531 and the negative reference voltage 5i2.

Therefore, the output signal 551 from the comparators 541-546
．． 552 and 553 are A-system signals and B-system signals.

It indicates whether or not the C-system signals are within the tolerance value set by the reference voltages 531, 532, and these determination results are displayed on the display devices 571, 572, 573 via the buffers 561, 562 and 563. is displayed.

The basic configuration and functions of the conventional triplex control system have been explained above, taking as an example the case where there is one signal selection device 3, that is, the case where there is one control signal, but in reality there are three control devices 2a, 2b. , 2c each output a plurality of signals. Therefore, from a plurality of sets of A yarn signals, B yarn signals, and C system signals, the most probable signal is selected by each separate signal selection device and outputted to the controlled object as a plurality of control signals. In addition, at this time, the A yarn signal, B yarn signal, and C system signal consisting of multiple fiber sets are each processed by a separate coincidence determination device.
The system signals are judged to match each other, and the results are displayed. In this way, using multiple coincidence determination devices to determine the coincidence of the three output signals from the three control devices that are input to each signal selection device and displaying the results makes it possible to detect abnormalities in the system. This is important for plant operators to recognize and take appropriate treatment.

However, in the conventional abnormality monitoring device for redundant system output signals as described above, it is necessary to provide the same number of coincidence judgment devices as the number of control output points. The disadvantage was that the amount of hardware required increased. In particular, the set of control devices 22 to 2C of the redundant control system having the configuration described above is installed in a distributed manner at a plant site, for example, and is used as a remote input/output device for a higher-level computer control device in a central control room, and this and a higher-level computer control device When positioning the system as a system that performs time-division multiplex transmission of as many signals as possible to reduce the number of cables between the field and the central operation, the increase in the amount of hardware for determining the match between redundant system output signals is an implementation problem. becomes.

[Purpose of the invention]

It is an object of the present invention to provide a redundant control system having a plurality of means for selectively outputting the most probable signal among redundant output signals, and to monitor abnormalities of each redundant signal and the selected signal using as little hardware as possible. An object of the present invention is to provide an abnormality monitoring device for redundant system output signals that can be realized in terms of quantity.

[Summary of the invention]

The abnormality monitoring device of the present invention consists of one unit, and a set of a redundant system output signal corresponding to a can control signal and an intermediate value signal selected from the redundant system output signal is sequentially transmitted in a time-divided manner via a multiplexer with a scanning signal corresponding to each control signal. Each time a set corresponding to one control signal is input, it is checked whether the difference between each redundant system output signal and the intermediate value signal is greater than or equal to the set tolerance deviation, and the presence or absence of an abnormality is detected. The result is taken in by a sampling signal to the memory using the scanning signal as an address signal, and the sampling signal is set to be generated in the latter half of the scanning signal, and the scanning signal and the sampling signal are By making the time width variably settable, abnormality monitoring can be performed without being affected by the asynchronous time of a set of redundant system output signals.

[Embodiments of the invention]

Hereinafter, specific examples of the present invention will be described. FIG. 4 is an overall configuration diagram of a system using the device of the present invention, and shows a case where the present invention is applied to an abnormality monitoring device of a triplex control system. The present invention relates to control signal output circuits 22 a and 22 b of each control device.

22c and a plurality of intermediate value signals output from the signal selection device 3 which is an intermediate value selection circuit, for example, are connected to one abnormality monitoring device 7.
The abnormality monitoring device 7 is constructed of a multiplexer 71, a coincidence detection circuit 72, a memory circuit 73, a display circuit 74, and a control circuit 75. FIG. 5 shows in detail an embodiment of the abnormality monitoring device 7 of the present invention, and below, each control signal will be numbered and distinguished from channel +0 to channel +N, and the overall operation will be explained in detail. is as follows. First, each channel A thread signal 221a
is input to the multiplexer 712, the B thread signal 221b is input to the multiplexer 713, the C system signal 221c is input to the multiplexer 714, and the intermediate signal 31 of each channel output from the signal selection device 3, which is an intermediate value selection circuit, is input to the multiplexer 711. Ru. Each multiplexer 711-71
4 is a scanning signal generator 754 of the control circuit 75;
The signals of each channel (0 to N) are cyclically taken into the coincidence detection circuit 72 by the scanning signal 756 transferred from
output signals 221a, 221b, 221c of each unit
The difference between the two is calculated in order by the differential amplifiers 521, 522, and 523, and the system in which the result exceeds the range defined by the externally arbitrarily settable tolerance voltage 531 or 532, for example, If it is the A system, the output 551a of the window comparator 541 or 542 will be at H level (L level if it is below the allowable deviation voltage) and will be triggered by the sampling signal 757 transferred from the sampling circuit 755 of the control circuit 75. , the result is written to the corresponding address of the memory element 731 determined by the scanning signal 756. Furthermore, the stored signal is transferred to the display element 741, and the A-system elements are turned on (they are not turned on when the tolerance is at the L level). Further, a signal indicating that the A system of the channel is abnormal at that time is also transferred to the input circuit of the higher-level control device, etc., and monitoring can be performed accordingly.

The above operations are performed cyclically and sequentially for each channel number 0 to N, so even if the number of redundant control signals (number of channels) increases, the coincidence detection circuit 72, multiplexer 71, memory circuit 73, Only one set of control circuits 75 and the like is required, and it is possible to monitor abnormalities of a plurality of redundant system output signals with a small amount of hardware. Further, a light emitting diode, a liquid crystal, or the like can be used as the display device 74, and an optimal display element may be selected depending on the plant.

FIG. 6 is a time chart showing the method of generating the scanning signal 756, and for simplicity, the number of channels is assumed to be 16 (S0 to S15). This scan signal 756 is transmitted in synchronization with a clock signal 758 to the branching unit 75 shown in FIG.
3, in this case, the cycle is set to twice that of the clock (by changing the division ratio, the magnification can be set appropriately), and this frequency is further divided by 2 one after another to produce 4 bits of signals 756a to 756d. Sixteen values are created, and channels are designated by the multiplexer 71 and memory circuit 73 according to these values. Furthermore, the cycle of the clock signal can be set using the changeover switch 751, thereby making it possible to appropriately set the scan time for one channel.

FIG. 7 is a time chart showing the details of the operation example of this embodiment. When a certain channel is scanned and captured, A, B,
The signals of each C group are 4.9V and 5V, respectively.

5. Assume that everything is normal in 1■. These signals are generated with a time lag, as shown at time t1 + '2 + t3, since the operations of each control device are not completely synchronized. Therefore, in this case, the output 551a of the window comparator.

551C generates an H level signal with a time width τ, but this is actually not an abnormality, but is due to a deviation in the generation of signals in each system. Therefore, as shown in FIG. 7, when the scan signal 756 (which has a period three times as long as the clock signal 758 in this figure) captures the change point of each system signal, each system signal has finished changing. If the window comparator outputs 551a to 551c and 31 after t3 are input to the memory element 73 at the falling edge 1)a of the sampling signal 757 shown in the figure, the influence of asynchronous output of the control device can be removed and correct judgment (
normal). Also, time points t4 to t6 in FIG.
So the B and C system output is 10■.

10.2'l normal), when the A system output becomes OV (abnormal), only the output of the window comparator 551 is at H level at the falling edge of the sampling signal 757, indicating that there is an abnormality in the A system. H level is set in the corresponding memory.

Next, if the intermediate value selection circuit fails by exceeding the allowable deviation voltage from the output signal of each group as shown at time t7 in FIG. 7, the differential amplifiers 521, 522, 52 shown in FIG.
All outputs of 3 must be higher than the set allowable voltage deviation.Outputs 551a, l), c of window comparators 541 to 546
are all at H level, so at the falling point C of the sampling signal 757, the A, B, and C system diagnostic output cuffs 31a.

If both 732a and 733a are at H level, they are written as abnormal. Therefore, if the AND logic (not shown) of the outputs of 731 to 733 is taken, failures in the intermediate value selection circuit can also be monitored.

This abnormality monitoring device can be used offline or manually.
It also has a feature that allows you to check the function of each circuit. That is, in FIG. 5, by switching the changeover switch 751 of the control circuit 75, the clock of the clock signal generator 752 is stopped, and instead of this, the external clock signal 8 is output from the external terminal 8.
1, this clock signal 81 is given to the frequency divider 753 and the sampling circuit 755, and the control output signals 221a, 221b, 221c of each group are separated and a simulated input signal is given instead. Since the abnormality monitoring function operates in the same way as the content, the validity of each circuit can be confirmed, which is also effective in improving reliability.

In the above embodiment, an intermediate value selection circuit is shown as an example of a signal selection device that selects and outputs the most probable signal among the output signals of each system control device, but the present invention is not limited to this. For example, when the redundant system output signal is a digital signal, a 2 out of 3 circuit is usually used as the signal selection device.

Even in this case, an abnormality in the redundant system output signal can be detected by logical judgment, and the abnormality monitoring method and apparatus of the present invention can be easily applied.

〔Effect of the invention〕

According to the present invention, in a redundancy control system that selects and outputs one most probable signal for each of a plurality of sets of redundant output signals, abnormality monitoring of redundant output signals input to each selection output means and This has the advantage that abnormality monitoring of each selection output means can be executed with a small amount of hardware.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional triplex control system, FIG. 2 is an explanatory diagram of a signal selection device, FIG. 3 is an explanatory diagram of a conventional discrepancy determination device, and FIG. 4 is an explanatory diagram of a system to which the present invention is applied. 5 is a diagram showing an embodiment of the present invention, and FIGS. 6 and 7 are time charts showing the operation of the embodiment of FIG. 5. 2a, 2b, 2c--control device, 22a
, 22b. 22c... Control signal output circuit, 3... Signal selection device, 7... Abnormality monitoring device, 71... Multiplexer,
72・°°coincidence detection circuit, 73...memory circuit, 75
...Control circuit. Agent Patent Attorney Masami Akimoto Condolences 2

Claims (1)

[Claims] 1. Selecting the most probable signal among a plurality of control devices and redundant system output signals output one by one from each control device for each control signal, and using the selected signal as a control target. In a device for monitoring redundant system output signals of a redundant control system equipped with a signal selection device to output, a set of each redundant system output signal and selection signal for each control signal is made to correspond to the control signal. An input means that inputs a scanning signal in a single-click manner, and each time a set of signals is acquired, when the difference between each redundant signal and the selection signal exceeds a range that can be set from the outside, the redundant system output signal is output. an abnormality determination means for outputting an abnormality signal indicating that the control signal is abnormal; and an abnormality determination means for temporarily outputting an abnormality signal from the abnormality determination means due to irregularities in the rising times of redundant system output signals from the control device corresponding to one control signal. 1. An abnormality monitoring device for a redundant system output signal, comprising: sampling means for outputting the output of the abnormality determination means as a sampling signal after the apparent abnormality signal disappears. 2. A mechanism is provided to generate the scanning signal and sampling signal from a built-in clock generator or a clock signal input from an external source, and the period of the scanning signal and sampling signal and the generation phase of the sampling signal can be variably set. An abnormality monitoring device for a redundant system output signal according to claim 1, characterized in that it has a structure.