JPH06274778A - Plant monitoring/diagnosing device and its fault sign detecting method - Google Patents

Abstract

PURPOSE:To immediately carry out an operation to prevent occurrence of faults by a plant monitoring/diagnosing device by detecting the fault signs while a plant is operating in a normal range. CONSTITUTION:When a control means is started at the time point TO, a CPU inputs a controlled quantity measurement signal and stores it in a storage. When the controlled quantity measurement signal exists between the upper and lower limit values of the fault sign detecting use threshold value, a normal operation is decided. The CPU holds the measurement signal at a certain time interval up to the time point T1. When it is detected that the measurement signal exceeded the fault sign detecting use upper limit value at the time point T1, the CPU start to diagnose the contents of the fault sign and checks the contents of the fault sign that may possibly occur. No fault sign processing is carried out during the time points T1-T2. A normal state of a plant is decided during the time points T2-T3, and the measured value is repetitively held. When it is decided that the measurement signal exceeded the detecting upper limit value at the time point T5, the CPU deals with the fault processing in accordance with the fault sign contents stored in the storage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plant monitoring / diagnosing apparatus for monitoring an operating state of a plant within a normal operating range to detect an abnormal sign and a method for detecting the abnormal sign.

[0002]

2. Description of the Related Art There is known a plant control device which measures a physical property value indicating an operating state of a plant, for example, temperature or pressure, and automatically sets a manipulated variable of the plant based on the measurement result. In such a plant control device, it has become possible to execute from the measurement result to the diagnosis of the abnormality and the details of the abnormality. Although various proposals have been made for the abnormality detection method used in the plant control device, they have the following common points. That is, statistical processing is performed on the measurement signal to create a characteristic parameter that represents the operating state of the plant, and when the parameter value is within a predetermined allowable range, it is determined to be normal, and when the parameter value exceeds the allowable range. This is a point to judge as abnormal. Among such anomaly detection methods, those for the purpose of early detection of anomalies include, for example, Japanese Patent Laid-Open No. 4-305794. This proposal discloses an abnormality detection method in which the difference between the standard deviation of the command signal and the standard deviation of the measurement signal is calculated, and when the difference exceeds a certain value, it is judged that an abnormality has occurred.

[0003]

In many plants, a limit check method in which a measurement signal indicating the state of the plant is input to a plant control device, and when the measurement signal deviates from a predetermined reference value, it is determined to be abnormal Has been adopted.

When an abnormality is detected by the plant control device,
It is important to take appropriate measures against the abnormality.
In many plants, especially in chemical plants, an interlock system that automatically shuts down an apparatus or system in which an abnormality is detected is incorporated in order to give the highest priority to safety.

In the case of a large-scale chemical plant, the shutdown of one plant may induce the shutdown of a plurality of plants connected by a pipeline, which requires extremely high reliability and safety. It is required to detect a symptom of abnormality before detecting the abnormality that the interlock system operates, and to investigate the cause and take corrective action.

Therefore, in view of the above points, an object of the present invention is to detect abnormal signs when the plant is operating in a normal range, and to deal with abnormal signs, for example,
It is an object of the present invention to provide a plant monitoring / diagnosing apparatus and a plant abnormality sign detecting method capable of immediately executing an operation for preventing occurrence of abnormality.

[0007]

In order to achieve such an object, the invention of claim 1 inputs a measurement signal indicating the state of the plant, extracts a feature from the input measurement signal, and extracts the extracted feature. And a first reference used for normality detection to detect an abnormality of the plant with a plant control device, within the normal range indicated by the first reference, a specific range in which the plant shows an abnormality sign and its range Is determined in advance, and the sign of abnormality of the plant is detected by comparing the extracted feature with the second criterion prior to the detection of the abnormality of the plant.

According to a second aspect of the present invention, a measurement signal indicating the state of the plant is input, features are extracted from the input measurement signal, and the extracted features are compared with a first reference used for normality determination. In a plant control device for detecting an abnormality in a plant, a storage unit for storing a second reference that defines a specific range in which the plant shows an abnormality sign within the normal range indicated by the first reference, and the detection of the abnormality in the plant. Prior to the above, there is provided an abnormal sign detecting means for detecting an abnormal sign of the plant by comparing the extracted characteristic with the second reference.

[0009]

According to the first aspect of the present invention, when an abnormality occurs in the plant, attention is paid to the fact that the measurement signal goes from the normal range to the abnormal range, and a change in the measurement signal is detected to detect an abnormality sign within the normal range. To do. According to the second aspect of the present invention, the second reference used for determining the abnormal sign is stored in the storage means, so that it can be compared with the measurement signal that changes in time series.

[0010]

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

Prior to the description of the present invention, the circuit configuration of a plant control system using the plant abnormality sign detection method of the present invention will be described with reference to FIG.

In FIG. 2, the plant 30 receives an operation control signal from the plant control device (DCS) 20 and is operated with a predetermined operation amount. State quantities such as temperature and pressure (hereinafter referred to as control quantities) indicating the operating state of the plant 30 are measured by a measuring instrument, and a measurement signal indicating the measurement result is DCS2.
It is output to 0. The DCS 20 variably sets the manipulated variable based on the measurement signal so that the controlled variable fluctuates along a predetermined response characteristic (including a fixed set value). The plant monitoring / diagnosing device 10 operates as an abnormal sign detecting device, an abnormal sign diagnostic device, and an abnormal detecting device of the plant control device.

In the plant monitoring / diagnosing device 10, the following components are connected to a common bus.

Central processing unit (CPU) 11: executes abnormality sign detection processing, abnormality sign diagnosis processing, and abnormality detection processing based on a system program stored in the system memory 12. As will be described later, the CPU 11 operates as the abnormality sign detecting means of the present invention.

System memory 12: A system program that defines the processing procedure executed by the CPU 11 is stored for each processing content. It also temporarily stores work data related to arithmetic processing. A program for detecting abnormal signs relating to the present invention is also stored in the system memory 12, and the system memory 12 corresponds to the storage means of the present invention.

Keyboard 13: Inputs operation instructions to the CPU 11.

Display device 14: Displays input information from the keyboard and calculation results of the CPU 11 under the control of the CPU 11.

Communication interface (I / F) 15: C
Signals are transferred between the PU 11 and the DCS 20. DC
A control amount measurement signal, a control amount setting signal, and an operation amount operation signal are received from S20, and a new control amount setting signal or a new operation amount operation signal is transmitted to the DCS20.

External storage device 16: Stores plant measurement results in a floppy disk (FD) or hard disk (HD).

The abnormality detection-related processing executed in such a circuit configuration will be described with reference to FIG. Figure 3 CPU
11 shows the procedure of the abnormality sign detection processing and the abnormality detection processing executed by 11, and is stored in the system memory 12 in advance in the form of a programming language. This processing procedure is executed by the CPU 11 by interrupt processing at regular intervals.

When the control procedure of FIG. 3 is started at time T0 of FIG. 1, the CPU 11 inputs the control amount measurement signal, the control amount setting signal, and the operation amount operation signal via the I / F 15, and the system memory 12 stores them. It is temporarily stored in the work area and also stored and stored in the external storage device 16 (S10).

When the control amount measurement signal is between the upper limit value and the lower limit value of the abnormal sign detection threshold value (the second standard of the present invention), a negative judgment is obtained in the judgment processing of S20, and the plant operates normally. And it is judged that there is no abnormal sign, and the CPU
11 completes this procedure. When the measurement signal fluctuates as shown in FIG. 1, the CPU 11 repeatedly executes the above-described procedure (S10 → S20 → end) at a constant time interval until time T1 to store the measurement signal. When it is detected in step S20 in FIG. 3 that the measurement signal exceeds the upper limit value for abnormality sign detection at time T1 in FIG. 1, the CPU 11 confirms the flag. This flag is information indicating on / off whether or not the abnormality symptom diagnosis process is executed. When the measurement signal exceeds the upper limit value for abnormality sign detection for the first time as at time T1 in FIG. 1, the flag is off, so the CPU 11 turns off the flag when the measurement signal first exceeds the abnormality sign detection range. (S30).

Here, the CPU 11 starts the diagnostic processing of the content of the abnormal sign, and combines a plurality of kinds of measurement signals with the equipment showing the contents of the abnormal sign that may occur, for example, sudden rise, slow abnormality and the abnormal sign. Find out from. The diagnosis result is temporarily stored in the system memory 12 (S40). Further, the flag is set to ON. The CPU 11
While the DCS 20 side is performing the diagnosis of the content of the abnormal sign, the plant 10 considers that the plant 10 is operating normally,
Control during normal operation continues.

Next, the CPU 11 compares the measured value with the upper and lower limit values for abnormality detection (first criterion of the present invention) to determine whether or not an abnormality has occurred (S50). In the example of FIG. 1, since the measured value at time T1 has not reached the upper limit value for abnormality detection, a negative determination (no abnormality) is obtained (S50 → end). From time T1 to time T2, the execution procedure of FIG.
10 → S20 → S30 → S50 → Follow the end route,
Although the abnormal sign is detected, it has not yet been detected. Further, the diagnosis process of the content of the abnormality sign is performed at time T1.
Has already been executed (the flag is on), so at time T1
The abnormality symptom diagnosis process is not performed between the time T2 and time T2. Between times T2 and T3 of FIG. 1, the execution procedure of FIG. 3 is S10 → S.
The route of 20 → end is followed and the plant is judged to be normal. When such an execution procedure is repeatedly executed in the CPU 11 and it is detected in step S50 in FIG. 3 that the measured value exceeds the upper limit for abnormality detection at time T5,
The CPU 11 reads out the abnormality symptom diagnosis result stored in the system memory 12, and executes the abnormality coping process corresponding to the abnormality symptom content by using the conventional method (S60 → end).

As described above, in this embodiment, the abnormal sign is detected when the plant is operating in the normal range and the abnormal sign coping process is executed. It is possible to prevent the occurrence of
Even in the unlikely event of an abnormality, quick and accurate response can be provided.

In addition to this embodiment, the following example can be carried out.

1) As a method of detecting an abnormal sign, in the present embodiment, a fixed threshold value is used for convenience of explanation, but a variable threshold value can be used. The fluctuation threshold is calculated by calculating the moving average value of the measured values taken a certain time before from the present time and determining the current threshold value by multiplying or adding a specific value to the average value. is there. The relationship between the change in the measured value and the variation threshold value is shown in FIG. A fixed threshold for anomaly detection,
A variable threshold can also be used to detect abnormal signs. In addition, it is also possible to calculate a moving average value of the difference between adjacent measurement signals in time series or physically and compare the moving average value with the threshold value to detect the abnormal sign.

2) In the present embodiment, the abnormality is detected by the level of the measurement signal, but in addition to this, it is preferable that the amplitude, frequency, spectrum, etc., and the number of times exceeding the abnormality sign range are used for judging the abnormality sign. Anomalies and abnormal signs may be detected using various characteristic elements. Needless to say, the number of types of abnormal signs is not limited to one, and various types of abnormal signs can be detected.

3) The threshold value used to determine the abnormal sign is calculated from the moving average of the measured values, and the maximum value of the measured values during the past fixed period and the maximum deviation between the set target value and the measured value. It is also possible to multiply by a predetermined magnification.

[0030]

As described above, according to the present invention,
Since the abnormal sign can be detected while the plant is operating in the normal range, it is possible to diagnose a possible abnormal condition and prepare for the occurrence of the abnormal condition. Also, by completely separating the plant control device and the plant monitoring diagnostic device,
Remote specialist staff (eg raw materials, product arrangements, etc.)
It is possible to prepare for the occurrence of an abnormality, and further, the system can be enhanced and developed even during plant operation.

[Brief description of drawings]

FIG. 1 is a waveform diagram showing an abnormal sign and an abnormal sign process according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a system configuration of an embodiment of the present invention.

FIG. 3 is a flowchart showing a processing procedure executed by a CPU 11 of FIG.

FIG. 4 is a waveform diagram showing a variation threshold value.

[Explanation of symbols]

 10 workstation 11 CPU 12 system memory 13 keyboard 14 display device 15 I / O 16 external storage device 20 DCS 30 plant

Claims (2)

[Claims] 1. A measurement signal indicating a state of a plant is input, a feature is extracted from the input measurement signal, and the extracted feature is compared with a first reference used for normality determination, and an abnormality of the plant is detected. When detected by the control device, a predetermined range in which the plant shows an abnormal sign in the normal range indicated by the first criterion and a second criterion that determines the range are determined in advance, and prior to detection of an abnormality in the plant, An abnormal sign detection method for a plant control apparatus, comprising detecting an abnormal sign of the plant by comparing the extracted characteristic with the second criterion. 2. An abnormality of the plant is detected by inputting a measurement signal indicating the state of the plant, extracting features from the input measurement signal, and comparing the extracted features with a first reference used for normality determination. In the plant control device, a storage unit that stores a second reference that defines a specific range in which the plant shows an abnormality sign within a normal range indicated by the first reference; and prior to detection of an abnormality in the plant, A plant monitoring and diagnosing device comprising: an abnormal symptom detecting means for detecting an abnormal symptom of the plant by comparing the extracted characteristic with the second criterion.