JPH0933514A - Method and system for detecting abnormality in water quality measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect abnormal trend of measurement, which may be missed inadvertently by an operator and can not be detected based on the upper and lower limits of computer, automatically by means of a computer by making a decision that the measurement is abnormal when the variation in the daily average of past measurements deviates from the upper (or lower) limit of decision criterion continuously by a set number of times or more. SOLUTION: A variation operating unit 20 determines variation in the past daily average value operated by a daily average operating unit 19. A decision criterion memory 21 stores decision criteria for the variation in daily average value. A trend operating unit 22 decides whether the variation in daily average value operated by the unit 20 exceeds the decision criteria stored in the memory 21 or not. An abnormal number of time memory 23 stores the number of times for deciding that the measurement is abnormal when the variation in the daily average value exceeds a same value (upper limit, lower limit) stored in the memory 21 continuously. An abnormal value decision unit 24 compares the output value from the unit 22 with a reference value stored in the memory 23 and makes a decision that the measurement is abnormal when the reference value is exceeded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device for detecting an abnormality of a measuring instrument used in a plant such as a water and sewage treatment device.

[0002]

2. Description of the Related Art In plants such as water and sewage treatment equipment,
A large number of measuring instruments installed in the plant are monitored in the central monitoring room, and when an abnormality occurs in each measuring instrument, the abnormality of the measuring instrument is detected by the upper and lower limit values of the standard deviation standard. FIG. 2 is a block diagram showing an abnormality detection device for a measuring instrument in a conventional sewage treatment system. The sewage containing pollutants is first introduced into the settling tank 2 from the pipeline 1, the sedimentable substances in the pollutants are separated by sedimentation, and the supernatant water is discharged to the aeration tank 3. In the aeration tank, the returned sludge drawn out from the final settling tank 4 is returned via the pipe line 5 and blower (not shown) into the aeration tank from the diffuser pipe (not shown).
The air sent by the pump is supplied, and the pollutants are adsorbed and decomposed by the activated sludge and guided to the final settling basin. In the final settling tank, activated sludge is settled and separated, and clear water is treated as treated water in pipeline 6.
The sludge is discharged from the sterilizing tank through a sterilization tank (not shown), and the settled sludge is returned to the aeration tank, and a part of the sludge is sent to a sludge treatment process (not shown) for treatment. 7 is an inflow sewage flowmeter, 8 is an inflow water pH meter, 9 is an inflow water suspended matter concentration meter, 10 is an aeration tank inflow water UV meter, 11 is a DO meter, 1
2 is an MLSS concentration meter, 13 is a water thermometer, 14 is an oxidation-reduction potentiometer, 15 is a pH meter of treated water, 16 is a suspended matter concentration meter of treated water, and 17 is a UV meter of treated water.

Thus, in a sewage treatment plant,
It is common practice to measure and collect various water quality data. Abnormality detection of these measuring instruments is often performed using a judgment reference value set based on the experience of the operator.
However, the determination reference value must be set for each measuring instrument according to the season, and changing the setting of the determination reference value has been a complicated task for the operator. Therefore, it has become more and more common for computers to set the judgment reference value for each measuring instrument.
In general, the setting of the judgment reference value by the computer is often decided by using the standard deviation or the like. The method of setting the judgment reference value using the standard deviation will be described below as a conventional method. 1
Reference numeral 8 is a measurement value storage device that stores the measurement values obtained from each measuring instrument, and 26 is a standard deviation computing device for obtaining the standard deviation of each measuring instrument. The standard deviation is given by the following formula.

[0004]

[Equation 1]

Reference numeral 27 is a judgment reference value calculation device for obtaining a judgment reference value from the standard deviation obtained from the standard deviation calculation device 26. The judgment reference value is often obtained as follows. If the frequency distribution of the measured values shows a normal distribution, the measured values are within the range of 3 times the standard deviation from the average value with a probability of 99.7%, so the measured values that satisfy the following formula are defined as the normal range.

[0006]

[Equation 2]

Reference numeral 21 is a judgment reference value storage device for storing the result obtained by the judgment reference value computing device 27, and 24 is a measurement value newly stored in the measurement value storage device 18 and a judgment reference value storage device 23 for storing the measurement value. An abnormality determination device that compares the determination reference values that exist and determines whether or not there is an abnormality, and the determination result is displayed on the display device 2
I was trying to output to 5. However, in such data anomaly detection based on the upper and lower limit values, it is possible to detect data anomalies in which the measured value unilaterally increases or decreases due to accumulation of dirt adhering to the water quality measuring device. There were things I couldn't do.

[0008]

The conventional measuring device abnormality detecting device determines a normal range based on the determination reference value storage device 21, and determines that the measurement value is abnormal when the measured value deviates from the range. However, the measured value may unilaterally increase or decrease due to the gradual accumulation of dirt adhering to the water quality measuring device. In such a case, it is difficult to detect a trend abnormality of this kind of measured value because the measured value is within the normal range in the abnormality detection based on the upper and lower limit values of the standard deviation standard. Moreover, it was difficult for the operator to detect such an abnormality because the change in the measured value is small. The present invention provides a method for automatically detecting a trend abnormality of a measured value by a computer, which is easily overlooked by an operator and which is difficult to detect by the abnormality detection based on the upper and lower limit values of the computer.

[0009]

In order to achieve the above object, the present invention is an abnormality detecting method for detecting an abnormality in a water quality measuring instrument used in a sewage treatment plant, in which measured values of the water quality measuring instrument are accumulated. , The past daily average value of the accumulated measurement values is calculated, and when the change amount of the average value continuously exceeds the upper limit value or the lower limit value of the judgment reference value for the set number of times, The feature is that it is determined to be abnormal. Further, in an abnormality detecting device for detecting an abnormality of a water quality measuring instrument used in a water treatment plant, a measurement value accumulating device accumulating the measurement value of the water quality measuring instrument, and a measurement value accumulated in the measurement value accumulating device. A daily average value calculating device for calculating the past daily average value, a change amount calculating device for obtaining a change amount of the average value of the daily average value calculating device, and a determination reference value for the change amount of the daily average value. And a trend calculation device for calculating how many times the change amount of the daily average value exceeds the upper limit value of the judgment reference value or how many times the lower limit value is continuously exceeded. And an abnormality number storage device that stores the number of times an abnormality is determined when the amount of change in the daily average value continuously exceeds the same determination reference value (upper limit value, lower limit value), and the trend calculation device. Judge whether the value exceeds the value in the abnormal count storage device Is characterized in that provided that abnormal value determining device.

[0010]

[Operation] The present invention is one day (24 hours) at a water treatment plant.
This is based on the finding that water treatment is performed cyclically in a cycle, so that if the daily average value is followed, it will be less likely to be affected by short-term fluctuations. By the above means, it becomes possible to detect an abnormality when the measured value unilaterally rises or falls due to the accumulation of dirt attached to the water quality measuring instrument, so that the accuracy of the abnormality detection of the measuring instrument improves.

[0011]

Embodiments of the present invention will now be described in detail with reference to FIG. FIG. 1 is a block diagram showing an abnormality detection device of a measuring instrument of a sewage treatment system of the present invention. The same parts as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted. 19
Is a daily average value computing device, and it is thought that the data cycle of the sewage treatment process is mainly 24 hours, and the past daily average value was calculated in order to handle the data on a daily basis. Reference numeral 20 denotes a change amount calculating device, which obtains a change amount of the past daily average value calculated by the daily average value calculating device 19. Reference numeral 21 denotes a judgment reference value storage device, which stores a judgment reference value for the amount of change in the daily average value. Reference numeral 22 denotes a trend calculation device, and the change amount of the daily average value calculated by the change amount calculation device 20 is determined by the determination reference value storage device 21.
It is judged whether or not the judgment reference value stored in is exceeded. Reference numeral 23 denotes an abnormality number storage device, which indicates the number of times an abnormality is determined when the amount of change in the daily average value continuously exceeds the same value (upper limit value or lower limit value) stored in the determination reference value storage device 21. I remember. An abnormal value determination device 24 compares the value output from the trend calculation device 22 with the reference value stored in the abnormality count storage device 23. If the value of the trend calculation device exceeds the reference value, an abnormality is detected. Output. A display device 25 is a device for displaying the result output by the abnormal value determination device 24. When the measured value rises or falls unilaterally due to the accumulation of dirt on the sensor part, the change is comparatively small, so it is difficult to detect an abnormality in the measured value by the conventional method, and the calibration of the measuring instrument is difficult. I often noticed something unusual. FIG. 3 is a result of abnormality detection of the SS flowing into the aeration tank according to the present invention. As shown in the figure, a trend abnormality was detected a few days after the measured value began to rise. By incorporating this anomaly detection system, it became possible to detect trends in data that could not be detected by other logic.

[0012]

As described above, the present invention can deal with the abnormality of the measuring instrument when the measured value unilaterally rises or falls due to the accumulation of dirt on the sensor portion, and therefore the accuracy of the abnormality detection of the measuring instrument can be improved. Has the effect of improving.

[Brief description of the drawings]

FIG. 1 is a diagram showing an abnormality detection device of a measuring instrument of a sewage treatment system of the present invention.

FIG. 2 is a diagram showing an abnormality detection device for a measuring instrument of a conventional sewage treatment system.

FIG. 3 is a graph showing changes with time of SS flowing into the aeration tank (abnormality detection results of the present invention).

[Explanation of symbols]

 1 Pipeline 2 First settling tank 3 Aeration tank 4 Final settling tank 5 Pipeline 6 Pipeline 7 Inflow sewage flowmeter 8 pH meter of inflow water 9 Suspended substance of inflow water 10 UV meter of inflow water of aeration tank 11 Dissolved oxygen concentration Total 12 MLSS concentration meter 13 Water temperature meter 14 Redox potential meter 15 pH meter of treated water 16 Suspended substance of treated water 17 UV meter of treated water 18 Measured value storage device 19 Day average value calculation device 20 Change amount calculation device 21 Judgment Reference value storage device 22 Trend calculation device 23 Abnormal number storage device 24 Abnormal value determination device 25 Display device 26 Standard deviation calculation device 27 Determination reference value calculation device

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 20, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Invention title

[Correction method] Change

[Correction content]

Title: Method and apparatus for detecting abnormality in water quality measuring instrument

Claims (2)

[Claims] 1. An abnormality detection method for detecting an abnormality in a water quality measuring instrument used in a sewage treatment plant, wherein the measured values of the water quality measuring instrument are accumulated and a past daily average value of the accumulated measurement values is calculated. Abnormality of the water quality measuring device characterized in that when the variation of the average value exceeds the upper limit value of the judgment reference value continuously for the set number of times or continuously exceeds the lower limit value, it is judged as abnormal Detection method. 2. An abnormality detecting device for detecting an abnormality of a water quality measuring instrument used in a water treatment plant, comprising: a measurement value accumulating device for accumulating the measurement value of the water quality measuring instrument; A daily average value computing device for calculating the past daily average value of the measured values, a variation amount computing device for obtaining the variation amount of the average value of the daily average value computing device, and a criterion value for determining the variation amount of the daily average value And a determination reference value storage device that stores, and calculates how many times the change amount of the daily average value continuously exceeds the upper limit value of the determination reference value or how many times the lower limit value is continuously exceeded. A trend calculator, an abnormality count storage device that stores the number of times an abnormality is determined when the amount of change in the daily average value continuously exceeds the same determination reference value (upper limit value, lower limit value), and the trend The value of the arithmetic unit exceeds the value of the abnormal count memory device. Abnormality detection device water quality measuring instrument, characterized in that a abnormal value determining device to determine whether.