JPH0762625B2 - Noise loss detection method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention sequentially inputs an output signal of a detector and includes the output signal due to a plant abnormality (valve sticking, pipe clogging, etc.) or a failure of the instrument itself. TECHNICAL FIELD The present invention relates to a noise disappearance detection method and apparatus for detecting an abnormality in a plant or a failure of the instrument itself by detecting that a noise component related to process vibration is reduced.

[Conventional technology]

Conventionally, when an operator detects an abnormality in a plant, a detector, or the like, it often causes a serious abnormality in a process, and it is difficult to detect the abnormality in the initial stage. Especially after DCS instrumentation, it is becoming difficult to detect anomalies because it is difficult to grasp the temporal variation of detected values from only digital values. Also, providing a dedicated device for detecting an abnormality inevitably imposes a great financial burden.

Therefore, a change in the output signal of the detector installed in each part of the plant is detected, and when this output signal hardly changes, it is considered that an abnormality has occurred in the plant or the detector and a predetermined alarm or the like is generated. A device capable of doing so has been proposed.

For example, as shown in FIG. 4, this device has an upper and lower limit abnormality determination value (H
Even if it exists in (between L and LL), the output value continues to hardly change and is judged to be abnormal by the judgment method in which the difference from a certain reference value continuously decreases.

[Problems to be Solved by the Invention]

However, when considering the mode of occurrence of an abnormality in the plant due to an abnormality in the detector or clogging of piping, it is not sufficient to simply monitor the unchanged state of the output signal of the detector, as is the case in the prior art. That is, in an actual abnormality, the output signal of the detector itself changes to increase or decrease, but the vibration component that should originally be included in the output signal decreases due to the abnormality, This is because the conventional technology cannot avoid the problem that such an abnormality cannot be detected. This is because the reference value is fixedly used when an abnormality occurs, and the reference value is not updated only by comparing the detected value with the reference value.

In other words, there are two types of process fluctuations, one is low-frequency fluctuations when the operating conditions of the process are changed, or when there is disturbance in the process. It changes slowly. on the other hand,
Fluctuations that include high-frequency components such as noise when the liquid level is swaying or when flow rate pulsation due to pumping occurs even during stable operation without any change in the process There is.

When the latter fluctuation is observed, it can be said that the output value is normal. Therefore, it is desirable that the former low-frequency fluctuation and the latter high-frequency fluctuation can be separately monitored for highly accurate noise disappearance detection.

To explain this more specifically, let us assume, for example, a case where a differential pressure type level meter as a detector arranged in a plant detects a liquid level inside a predetermined vessel. The level gauge and the vessel are connected by a conduit.

Generally, if the inside of the conduit is clogged, it is likely that the output signal of the level meter will remain unchanged, but in reality, the pressure inside the conduit is temporally changed due to condensation and contraction of the gas phase inside the clogged conduit. It often changes and the detector output signal often continues to increase and decrease. However, even in such a case, although the high-frequency vibration component contained in the output signal is reduced, the conventional technique cannot detect the disappearance of noise while the output signal is increasing or decreasing. There was a problem.

Therefore, an object of the present invention is to eliminate the above-mentioned conventional problems,
If the noise disappearance phenomenon occurs in the detected value signal due to some abnormality, it is processed by a relatively easy method for the data sampled sequentially, and it is promptly detected to notify the operator. It is an object of the present invention to provide a noise disappearance detection method and an apparatus therefor.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the noise disappearance detection method according to the first aspect of the present invention stores a past value from a data collection unit that sequentially collects output signals of a detector in a data storage unit and collects the data in the data collection unit. When the absolute difference between the latest current value and the past value stored in the data storage means and successively updated for a certain period of time is calculated by the calculation means, and the output value of the calculation means is smaller than the set value, If the counter number is greater than the set value, the counter number is cleared, and when the counter number exceeds a preset threshold value, a predetermined alarm is issued and the output signal of the detector fluctuates. However, the feature is that the disappearance of the noise component is detected.

In the noise disappearance detection method according to the second aspect of the present invention, the past value from the data collection means that sequentially collects the output signal of the detector is stored in the data storage means, and the latest current value collected by the data collection means is stored. And an absolute difference between the past value stored in the data storage means and sequentially updated a predetermined time before, calculated by the calculation means, and when the output value of the calculation means is smaller than the set value, the counter number is added. , If it is larger than the set value, the counter number is cleared, and if the counter number exceeds a preset threshold value, a predetermined alarm is issued to detect the disappearance of noise components and, if necessary, Given a threshold update instruction signal given, after the threshold update instruction signal is input,
It is characterized in that the maximum value of the counter output in a predetermined period is output as the threshold value.

A noise disappearance detection device, which is a third invention for carrying out the method according to the first invention, includes a data collecting unit that sequentially collects output signals of the detector, and a detection value detected by the data collecting unit. Data storage means for storing past values, and operation for computing and outputting the absolute difference between the latest current value collected by the data collection means and the past value stored in the data storage means and successively updated for a certain period of time Means and the output signal of the arithmetic means are input and compared with a preset set value. If the output value of the arithmetic means is smaller than the set value, the counter number is incremented, and if it is larger than the set value, the counter is incremented. Counter means for clearing the number; limiter means for inputting an output signal of the counter means and outputting a trigger signal when the output signal exceeds a predetermined threshold; and the limiter means It is configured as characterized in that the output signals of the detection value; and a notification unit that receives an output signal generating an alarm when the trigger signal input detects the loss of the noise component also vary.

A noise disappearance detection device according to a fourth aspect of the present invention for carrying out the method according to the second aspect includes a data collecting unit that sequentially collects output signals of the detector, and a detection value detected by the data collecting unit. The data storage means for storing the past value of, the latest current value collected by the data collection means, and the past value stored in the data storage means and successively updated for a certain period of time are constantly input, An arithmetic means for arithmetically outputting the absolute difference and an output signal of the arithmetic means are input and compared with a preset set value. If the output value of the arithmetic means is smaller than the set value, the counter number is incremented and the set value is set. Counter means for clearing the number of counters when it is larger than the limit value, and a limiter for inputting the output signal of the counter means and outputting a trigger signal when the output signal exceeds a predetermined threshold value. A notification means for inputting the output signal of the limiter means and issuing an alarm when the trigger signal is input, and a threshold update instruction signal given as necessary and the output of the counter means for inputting the threshold update instruction. After the input of the signal, there is provided threshold value updating means for outputting the maximum value of the counter output in a predetermined period to the limiter means as a threshold value of the limiter means. .

[Action]

According to the above configuration of the present invention, when the output signal of the detector causes the noise disappearance phenomenon due to the abnormality of the plant or the failure of the detector itself, the latest current value of the detected value and the past value of a certain time before The absolute difference of is calculated and output, and the time during which the value is continuously smaller than the predetermined normal value,
When it becomes longer than the set time determined to be a predetermined abnormality, the operator can be informed that the noise disappearance phenomenon has occurred.

In addition to the above operation, the threshold value updating means inputs the output of the counter and a threshold value updating instruction signal given as necessary, and is predetermined from the input of the threshold value updating instruction signal. The maximum value of the counter output during the period is output to the limiter means as a new threshold value of the limiter means.

When detecting the noise disappearance, it is necessary to reduce the threshold value of the count number in order to detect the noise as soon as possible, but in this case, however, it may cause a false alarm. On the other hand, it is extremely difficult to set a threshold value for judging an abnormality in advance. According to the present invention, when setting the threshold value, it is possible to empirically determine the normal range by taking in data and corresponding to changes in the characteristics of each detector and the operating conditions.

Furthermore, since the magnitude of the fluctuation of the detection signal and the threshold value of the count number have a correlation with each degree of freedom,
If one parameter is set, the other parameter is determined following this. This requires that after determining one parameter, one should consider what would happen if the other parameter were changed. According to the present invention, such processing can be easily performed, and appropriate values of two parameters can be determined. In other words, it is possible to avoid improper setting of parameters, which is a factor of time delay until false alarm or alarm is issued.

It should be noted that the noise disappearance referred to in the present specification mainly refers to a case where a high-frequency vibration component originally included in process vibration or the like is significantly reduced.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment showing an embodiment to which the method according to the first invention is applied
In the figure, the output signals detected by the detector 1 are sequentially collected by the data collecting means 2. In the data storage means 3, the output signals of the data collection means 2 are sequentially input, stored as past value data, and output to the calculation means 4.
The calculation means 4 uses the output signal of the data collection means 2, which is the latest current value [Snew] of the detector, and the past value stored in the data storage means 3 as the past value before a certain time, which is sequentially updated. The previous value [Sold] of the detector to be used and the output signal of the data storage means 3 are respectively inputted, and the following equation (1) is used.
The absolute difference calculation shown in is sequentially performed every time data is collected, and the result [A] is output to the counter means 5.

A = | Snew−Sold | (1) The counter means 5 inputs the output signal of the arithmetic means 4 and sets a predetermined set value [Aset] (set a value smaller than the normal signal fluctuation width). When the output signal of the calculating means 4 is smaller than the set value, the counter number [C] is incremented, and when the output signal of the calculating means 4 is equal to or larger than the set value, the counter number [C] is cleared. . That is, when A <Aset, C = Cold + 1 (2a), and when A ≧ Aset, C = 0 (2b).

The limiter means 6 receives the output signal [C] of the counter means 5, performs comparison calculation with a preset set value [Cset] (sets a time at which it can be determined that noise has disappeared), and outputs the output signal of the counter means 5. When [C] becomes [Cset] or more, the trigger signal [T] is turned "ON". On the other hand, the counter means 5
When the output signal [C] of [1] becomes less than [Cset], the trigger signal [T] is turned off.

The notification means 7 is a trigger output signal [T] of the limiter means 6.
When is ON, the result is notified to the operator that the noise disappearance phenomenon has occurred through a device such as a CRT terminal, a printer, or a voice notification.

FIG. 2 shows an example of the output signal of each configuration of FIG.

FIG. 2 (A) shows the output signal [Snew] of the data collecting means 2 showing the temporal change of the output signal of the detector 1. 2B shows the absolute difference between the current value from the data collecting means 2 and the sequentially updated previous value from the data storing means 3 with respect to the output signal of the detector 1 shown in FIG. 2A. An example of the output signal [A] of the calculating means 4, the example of the set value [Aset] of the counter 5 in FIG. 2B, and the example of FIG. 2B in FIG. Output signal [C] of the counter means 5 indicating the count value when the input signal to the counter means 5 which is the output signal of the arithmetic means 4 falls below the set value.
For example, FIG. 2C shows the threshold value [Cs of the limiter means 6
et], FIG. 2 (D) is an example of the trigger output signal [T] of the limiter means 6 when the count value shown in FIG. 2 (C) exceeds the threshold value.

Now, as shown in FIG. 2 (A), in FIG.
The case where noise disappears at one place will be described. In the periods other than α, β and γ which are the normal states, the absolute difference [A] between the present value and the previous value, which is the output signal of the calculation means 4, is larger than the set value [Aset], so the output of the counter means 5 [ C] is also small and does not exceed the threshold value [Cset]. However, during the period of α, β, γ in FIG. 2 (A) where the noise disappearance phenomenon occurs, the absolute difference [A] between the current value and the previous value, which is the output signal of the calculation means 4, is the set value [As].
et], which is sufficiently smaller, and the output of the counter means 5 [C]
Increases and exceeds the threshold [Cset]. And
The limiter means 6 outputs a trigger output signal to the notification means 7 to notify the operator that the noise disappearance phenomenon has occurred. When the output signal of the detector returns to the normal state, the trigger signal also becomes "OFF" and the alarm is canceled.

According to such an embodiment, the calculating means 4 is configured to obtain the absolute difference between the latest previous value and the current value of the detected value, and to judge whether this is greater than a predetermined threshold value. Alternatively, there is an effect that even if the detected value signal that tends to decrease, that is, the noise components in the sections α, β, and γ shown in FIG. 2A become small, this can be detected with high accuracy.

Next, an embodiment of the noise disappearance detecting device to which the method according to the second invention is applied will be described with reference to FIG. In addition,
In the following description, the same parts as those in the above embodiment are designated by the same reference numerals, and the description will be omitted or simplified.

The feature of this embodiment is that, as shown in FIG. 3, the output of the counter means 5 and the threshold value update instruction signal [R] are input, and the threshold value update value [u] is set. A threshold updating means 8 for outputting to the limiter means 6 is added.

In the above configuration, (1) The threshold value update instruction signal [R], which is input as necessary when the operating conditions are changed, that is,
The calculation start signal for updating the threshold value and the output of the counter means 5 are input to the threshold value updating means 8. When the threshold value updating means 8 receives the threshold value updating instruction signal [R], it collects the output of the counter means 5 for a predetermined period, and then the maximum value, that is, the threshold value updating value [R]. u] is obtained and the value is output to the limiter means 6.

(2) On the other hand, the limiter means 6 operates in substantially the same manner as in the above-described embodiment until the time when the threshold value update instruction signal [R] is generated, but thereafter, the limiter means 6 operates the threshold value update value. [U] is input as a new threshold value, and when the output value of the counter means 5 exceeds the new threshold value, it is determined that the noise disappearance phenomenon has occurred, and the trigger output signal [T] is output to the notification means 7. .

Therefore, according to such an embodiment, the threshold value of the limiter means 6 is compared with the integrated value of the counter means 5 based on the threshold value updating instruction signal [R] to the threshold value updating means 8. Since the threshold value is determined from the maximum value by statistically observing for a very long period of time, the effect that a more reliable noise disappearance detection device can be obtained is further added.

In the embodiment of the method according to the second aspect of the present invention and the apparatus for implementing the same, the absolute difference between the current value of the detected value and the previous value that is sequentially updated is calculated, and this is compared with a predetermined set value. However, the past value output from the data storage means 3 to the arithmetic means 4 is the arithmetic means 4 when the absolute difference between the present value and the past value in the arithmetic means 4 exceeds the set value.
Outputs a reset signal to the data storage means 3 and stores the detected value from the data collection means 2 given to the data storage means 3 when the reset signal is received as a past value,
The configuration may be updated and output to the calculation means 4.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a noise disappearance detection device that can detect a noise disappearance phenomenon by a relatively simple calculation. Further, when setting the threshold value, the normal range can be empirically determined based on the characteristics of each detector by taking in data. Furthermore, based on the correlation between the magnitude of fluctuation of the detection signal and the threshold value of the number of counts, after determining one of the parameters and changing the other parameter, a study will be made as to what kind of result will occur. It is also possible to do it. Also,
Since this noise loss detection method and its device employ a simple logic, it should be incorporated in the computer set in the plant to monitor the noise loss for a large amount of detected values without imposing a heavy load on the computer. Therefore, it becomes possible to automatically determine the observation time of the detection value necessary for determining the noise disappearance.

[Brief description of drawings]

FIG. 1 is a block diagram of a noise disappearance detection device showing an embodiment to which the method according to the first invention is applied, and FIG. 2 (A)-
(D) is a diagram showing an example of an output signal of each part of the apparatus of FIG. 1,
FIG. 3 is a block diagram of a noise disappearance detecting device showing an embodiment to which the method according to the second invention is applied, and FIG. 4 is a diagram for explaining a conventional example. 1 ... Detector, 2 ... Data collection means, 3 ... Data storage means, 4 ... Calculation means, 5 ... Counter means, 6 ...
Limiter means, 7 ... Notification means, 8 ... Threshold value updating means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Kaseda 11 Minamihama-cho, Chita-shi, Aichi Idemitsu Kosan Co., Ltd. ) Reference JP 62-143742 (JP, A) JP 60-11657 (JP, A) JP 60-1586 (JP, A)

Claims (4)

[Claims] 1. An output signal of a detector for detecting a process amount, which is a noise component originally continuously generated due to process vibration when the plant and the instrument itself are normal, is sequentially input,
In a noise disappearance detection method for detecting a plant abnormality or a failure of the instrument itself by detecting that the noise component included in the output signal has become small due to an abnormality of the plant or a failure of the instrument itself, the output of the detector The past value from the data collecting means for sequentially collecting the signals is stored in the data storing means, and the latest current value collected by the data collecting means and the past before a certain time stored in the data storing means and sequentially updated The absolute difference from the value is calculated by the calculation means. When the output value of the calculation means is smaller than the set value, the counter number is added. When the output value is larger than the set value, the counter number is cleared. Detecting the disappearance of noise components even if the output signal of the detector fluctuates by issuing a predetermined alarm when it exceeds a predetermined threshold value. Noise disappearance detection method characterized by. 2. The noise disappearance detection method according to claim 1, wherein when a counter number exceeds a predetermined threshold value, a predetermined alarm is issued to detect the disappearance of a noise component, and when necessary. A threshold update instruction signal given in response to the input, and after the threshold update instruction signal is input, the maximum value of the counter output in a predetermined period is output as the threshold. Noise loss detection method. 3. An output signal of a detector, in which a noise component inherently continuously occurs due to process vibration when the plant and the instrument itself are normal, is sequentially input, and the output is caused by an abnormality of the plant or a failure of the instrument itself. In the noise disappearance detection device for detecting an abnormality of the plant or a failure of the instrument itself by detecting that the noise component included in the signal has become small, a data collection unit that sequentially collects the output signal of the detector, A data storage means for storing past values of the detected values detected by the data collection means, a latest current value collected by the data collection means, and a past past a certain time stored in the data storage means and sequentially updated. The calculation means for calculating and outputting the absolute difference from the value, and the output signal of the calculation means are inputted and compared with a preset set value, and the output of the calculation means. When the force value is smaller than the set value, the counter number is incremented, and when the force value is larger than the set value, the counter means is cleared, and the output signal of the counter means is input and a predetermined threshold value or more is input. When the output signal of the detection value fluctuates, the limiter means for outputting a trigger signal when it becomes, and the notification means for issuing an alarm when the output signal of the limiter means is input A device for detecting noise disappearance, which detects the disappearance of a noise. 4. The noise disappearance detecting device according to claim 3, wherein the threshold update instruction signal given as necessary and the output of said counter means are input, and after this threshold update instruction signal is input. A noise disappearance detection device comprising: a threshold updating means for outputting the maximum value of the counter output during a predetermined period to the limiter means as a threshold value of the limiter means.