JPH0711473B2 - Abnormality detection method and device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an abnormality detection method and an abnormality detection device for detecting an abnormality in the operation of a plant or equipment used by the plant, for example, an abnormality in measuring equipment, particularly deterioration in measurement accuracy. Regarding

[Prior Art] Conventionally, when automatically controlling various equipment in a plant, a measuring equipment for measuring predetermined physical properties is attached to the equipment to be controlled, and the operation of the equipment is controlled by the control equipment based on the output signal. Is mainly performed.

Further, such failure detection of the measuring device is performed as follows. That is, the level of the sensor signal output from the measuring device is compared with the upper and lower threshold values, and when it is detected that the output of the measuring signal is lost, it is determined that the measuring device is abnormal. When the measured signal exceeds the range of the upper and lower thresholds, the control device judges that it is abnormal.

[Problems to be Solved by the Invention] However, conventionally, this type of abnormality detection method cannot detect an abnormality in a measuring device used in a plant, for example, a temperature sensor, a pressure sensor, or a control device such as a control valve at an early stage. For example, if the pressure guiding tube of the orifice flow meter is partially clogged, the detection gain is reduced and the fluctuation of the sensor signal is reduced, but the conventional detection method cannot grasp the tendency of the abnormality early.

Further, when the control valve is stuck due to a scale or the like, the fluctuation range of the sensor signal becomes small, but the conventional detection method cannot grasp the tendency of the abnormality early.

Therefore, in view of the above points, the object of the present invention is mainly to
An object of the present invention is to provide an abnormality detection method and device capable of early detecting an abnormality of a sensor or a control valve.

[Means for Solving the Problem] In order to achieve such an object, the method of the present invention inputs an input / output signal to be inspected for a certain period of time, and changes the maximum input / output signal within the certain period of time. The width is detected, the detected maximum fluctuation width is compared with a predetermined threshold level, and as a result of the comparison, the input / output signal is output when the maximum fluctuation width becomes smaller than the threshold value. It is characterized by determining that an abnormality has occurred in the.

The device of the present invention comprises an input means for inputting an input / output signal to be inspected, a maximum fluctuation width detecting means for detecting a maximum fluctuation width in the input / output signal within a fixed time, and a maximum fluctuation width detected in advance. It is characterized in that a magnitude comparison with a predetermined threshold value is performed, and as a result of the comparison, an abnormality occurs in the input / output signal when the maximum fluctuation width becomes smaller than the threshold value.

[Operation] In the present invention, it is noted that when an abnormality occurs in the sensor or the control valve, the fluctuation width of the sensor signal or the control signal input to the control valve may be reduced, and the maximum fluctuation of the sensor signal within a certain period of time is considered. The abnormality is detected early by comparing the width with a predetermined threshold value.

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

FIG. 1 shows the basic configuration of the embodiment of the present invention.

In FIG. 1, 10 is an input means for inputting a sensor signal.

Reference numeral 20 is a maximum fluctuation width detecting means for detecting the maximum fluctuation width in the input signal.

30 performs a comparison between the detected maximum fluctuation range and a predetermined threshold value, and as a result of the comparison, it is determined that an abnormality has occurred in the plant when the maximum fluctuation range becomes smaller than the threshold value. It is a determination means.

FIG. 2 shows a concrete circuit configuration of the embodiment of the present invention.

In FIG. 2, the abnormality detecting device 1000 comprises a microcomputer 100, a digital / analog (D / A) converter 110, and a display lamp (LED) 130.

The microcomputer 100 inputs the sensor signal of the orifice flow meter converted into a digital value through the D / A converter 110, and detects whether the orifice flow meter 120 is abnormal.

In this embodiment, the D / A converter 110 operates as the input means of the present invention, and the microcomputer 100 operates as the maximum fluctuation width detecting means and the determining means.

Further, when an abnormality occurs in the orifice flow meter 120, the microcomputer 100 turns on the LED 130 and displays a warning.

The operating principle of the present invention will be described below.

When the flow rate of the fluid is controlled by the sensor signal value of the orifice flow meter 120, the level of the sensor signal fluctuates as shown in P0-P1 in FIG. However, when a part of the pressure guiding tube of the orifice flow meter is clogged, the fluctuation range of the sensor signal becomes small such as between P1 and P2. Focusing on such characteristics, in the present embodiment, the maximum fluctuation width of the sensor signal obtained during a fixed time is detected. While the maximum fluctuation width of detection is larger than a predetermined threshold value, the orifice flow meter 120 is determined to be normal. Further, when the maximum fluctuation width becomes smaller than a predetermined threshold value, the orifice flow meter 120 is determined to be abnormal.

The circuit operation of FIG. 2 based on such an abnormality detection principle will be described with reference to the flowchart of FIG.

FIG. 3 shows a control procedure executed by the microcomputer 100 of FIG. 2, and this control procedure is actually described in a program language executable by the microcomputer 100.
Read-only memory (RO
Pre-stored in M).

When the power is turned on, the control procedure shown in FIG. 3 is started. That is, when the operator inputs an instruction with the dip switch 140 using the minimum fluctuation width to be measured as a threshold value, the microcomputer 100 stores the input data in the internal memory (steps S10 to S20 in FIG. 3).

When the microcomputer 100 inputs the control system start-up signal, the internal register used for detecting the fluctuation range of the sensor signal is set to an initial value. In this embodiment, an initial value "0" is set in the register (MAX) that stores the maximum value of the sensor signal, and a large numerical value such as 10 ¹⁰ is set as the initial value in the register (MIN) that stores the minimum value (step in FIG. 3). S40).

Next, the internal timer is activated to start inputting the sensor signals of the predetermined number of flowmeters 120 every time the internal timer measures a fixed time (step S60 in FIG. 3).

At this time, the microcomputer 100 compares the level of the value stored in the register MAX with the sensor signal, and if the sensor signal is larger, stores the sensor signal in the register MAX in an updated manner (step S71 in FIG. 3). ~ S72).

Further, when the level of the register MIN and the sensor signal is compared and the sensor signal is smaller, the sensor signal is updated and stored in the register MIN (steps S81 → S8 in FIG. 3).
2).

The sampling process of the sensor signal and the comparison process with respect to the sensor signal are repeated a predetermined number of times (loop process of steps S60 to S90 in FIG. 3).

After completing the loop processing a predetermined number of times, the microcomputer 100 executes other processing until the next sampling cycle is reached. The above-mentioned processing is repeated again in response to the time measurement end signal of the internal timer (step S50 in FIG. 3).
~ S100 loop processing). In this way, when the microcomputer 100 executes sampling of the sensor signal and comparison processing with the stored value of the register for a certain period of time, that is, a plurality of cycles, at this point, the register MAX contains the sensor signals sampled so far. The maximum value of is stored, and the minimum value is stored in the register MIN.

Therefore, the microcomputer 100 calculates the stored value of the register MAX and the stored value of the register MIN, that is, the difference between the maximum value and the minimum value of the sensor signal as the maximum fluctuation width of the sensor signal, and then inputs this maximum fluctuation width in advance. The threshold value Y is compared. At this time, the microcomputer 100 operates as the maximum width detecting means of the present invention. As a result of this comparison, if the maximum fluctuation width is smaller than the threshold value, it is determined that the measurement accuracy has deteriorated, and the microcomputer 100 determines that the LED
130 is turned on and a warning is displayed (step S11 in FIG. 3).
0 ~ S130). At this time, the microcomputer 100 operates as the determination means of the present invention.

On the other hand, when the maximum fluctuation range of the sensor signal is larger than the threshold value, the orifice flow meter 120 determines that it is normal, the microcomputer 100 returns the execution procedure to step S40 in FIG. 3, and sets the registers MAX and MIN. After the initialization, the monitoring of the fluctuation range of the sensor signal is continued.

The present invention is not limited to the above-described embodiments, but can be implemented with various modifications as described below.

1) In the above embodiment, in order to generalize the abnormality detection device,
The operator inputs the threshold value to be compared with the maximum fluctuation width, but if the size and automation of the device are to be reduced, a predetermined fraction of the maximum fluctuation width of the sensor signal detected so far is required. Can also be set automatically by updating to a new threshold.

2) In the above-described embodiment, the maximum value and the minimum value of the sampled sensor signals are detected to calculate the maximum fluctuation range, but if it is desired to reduce the influence of noise, sampling is performed during one cycle. The average value of the sensor signals obtained may be obtained, and the maximum value and the minimum value of the average value thus obtained over a plurality of periods may be detected.

3) In the above embodiment, the orifice flow meter is taken as an example of the sensor, but it goes without saying that the present invention can be applied to other sensors. In addition, when the target sensor may be in the operation stop state during operation, by inputting the operation stop signal to the above device and stopping the alarm output while the operation stop signal is generated, It is possible to prevent malfunction of abnormality detection.

[Effects of the Invention] As described above, according to the present invention, an abnormality of a plant, particularly a sensor or a control valve, can be detected at an early stage, so that a malfunction or failure occurs in a system or a plant using the sensor. The effect that the sensor and control valve can be repaired and effected before can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the embodiment of the present invention, FIG. 2 is a block diagram showing a concrete circuit configuration of the embodiment of the present invention, and FIG. 3 is a diagram showing an execution procedure of the microcomputer 100 of FIG. FIG. 4 is a flow chart showing an example, and FIG. 4 is a waveform diagram showing a waveform example of the sensor signal of the embodiment of the present invention. 100 …… Microcomputer, 110 …… D / A converter, 120
...... Orifice flow meter, 130 …… Indicator light (LED).

Claims (2)

[Claims] 1. An input / output signal to be inspected is input for a certain period of time, a maximum fluctuation width in the input / output signal within the constant time is detected, and the detected maximum fluctuation width and a predetermined threshold value are set. And comparing the levels, and as a result of the comparison, it is determined that an abnormality has occurred in the input / output signal when the maximum fluctuation width becomes smaller than the threshold value. 2. Input means for inputting an input / output signal to be inspected, maximum fluctuation width detecting means for detecting the maximum fluctuation width of the input / output signal within a fixed time, and the detected maximum fluctuation width in advance. And a judging means for judging whether or not an abnormality has occurred in the input / output signal when the maximum fluctuation range is smaller than the threshold value as a result of comparison with a predetermined threshold value. Anomaly detection device characterized by.