JP2002358115A - Method and device for controlling and diagnosing process of plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process controlling and diagnosing method capable of controlling equipment to be operated according to process change amounts, and detecting the abnormality of a fluctuating process regardless of a large amount of data. SOLUTION: The process value of a plant 9 is inputted through an input and output device 7, and a discontinuous operation command signal based on the process value is outputted by an interlock control part 6 of a controller 2 for control so that the plant control can be executed. At the time of outputting the operation command signal, the controller 2 for control calculates a simulated process value by a process simulating part 4 based on a normal process value stored in a data storage part 32 of a normal process value outputting part 3, and compares the simulated process value with the actual process input value, and judges whether or not the process value in the plant is normal from the deviation of those process values. Thus, it is possible to execute the more precise diagnosis of the abnormality or deterioration of the process in a small- scaled device constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to plant control in relatively small-scale plant equipment such as a district cooling and heat supply plant.
The present invention relates to a process control / diagnosis method for a plant capable of diagnosing abnormality or deterioration of a device to be operated, or a reduction in efficiency thereof, based on a change amount in the control process, and a device therefor.

[0002]

2. Description of the Related Art In recent years, in relatively small-scale plants such as energy-saving equipment and district cooling and heat supply plants, the efficiency of such equipment and the difference in electricity rates between day and night have been increasing.
A method is used in which profits are generated by utilizing a very small cost difference and profits are made. Therefore, a decrease in efficiency due to deterioration of plant equipment directly leads to a decrease in profit, resulting in a hindrance to management. For this reason, it is extremely important to detect an abnormality, deterioration, a decrease in efficiency, or the like in the plant equipment and quickly repair or improve it.

In order to meet these demands, conventional methods for diagnosing process abnormalities include, for example, a memory element built in a controller for plant control, in which an upper limit value and a lower limit value (upper / lower limit value) for a process input value are set. Is stored, and when the process input value actually exceeds the upper / lower limit value set in the arithmetic element, the signal bit is set to “1” to detect an abnormality. A scheme is being attempted.

[0004] For example, the liquid in a tank is kept at 50 ° C to 80 ° C.
If there is a control system that keeps the temperature of C and reports the process as abnormal when the temperature falls below 40 ° C,
Pre-set the control temperature range in the control controller to 80 ° C
５０50 ° C., and the lower limit of the abnormal set value is set to 40 ° C. As a result, the controller outputs a command to supply heat to the tank when the tank temperature becomes 50 ° C. or less to the control system.
Continue to output commands until C is reached. Then, when the tank temperature reaches 80 ° C. or higher, a heat supply stop command is output. Thereafter, so-called discontinuous control is performed in which the above processing is repeated when the tank temperature is in the range of 50 ° C to 80 ° C. By the way, according to the conventional process abnormality diagnosis method, when the tank temperature becomes 40 ° C. or less due to, for example, a malfunction of the heat supply equipment or a decrease in efficiency in the above-described situation, the abnormality detection bit is set. A method of detecting an abnormality by establishing “1” has been adopted. That is, a diagnosis method for recognizing an abnormality only when the set value is exceeded is used.

However, in the case of the above-mentioned prior art, the amount of increase or decrease in temperature due to the abnormality is determined by the upper and lower limit values set in the controller (in the above example, the lower limit value of 4).
If the temperature does not reach 0 ° C.), no abnormality is detected, and it is not possible to detect deterioration of the equipment or a decrease in efficiency. It should be noted that it is possible to detect an abnormality by adjusting the upper and lower limits described above, however, it is practically difficult to determine a set value for responding to the occurrence state of any abnormality including deterioration. In order to achieve this, it is necessary to hold an enormous number of set values in the control controller, and this may lead to an increase in the size of the control device.

[0006] In order to detect an abnormal tendency in a plant, a method of comparing a process input value from equipment with reference data has been proposed by other companies, but is extremely complicated and large-scale. It was difficult. For example, as a method of constantly monitoring a plant and detecting an abnormal trend of a process, as shown in Japanese Patent Application Laid-Open No. 8-313885, input / output during normal operation is input / output for each component of the plant. There is already known a method of calculating abnormality by a polynomial expression based on characteristics, and comparing the calculated input / output characteristics of plant components with actually obtained observation values to detect an abnormality. However, such a method is a method of diagnosing a process with a focus on abnormality diagnosis, and in general, a dedicated diagnostic device must be installed in order to diagnose up to process deterioration and efficiency reduction. Was.

[0007] Conventionally, as a plant monitoring device capable of storing an abnormality before the process value itself exceeds a certain reference value (upper / lower limit value), for example, Japanese Patent Laid-Open No. As known from Japanese Patent Application Laid-Open No. 160326, comparison data of a process to be monitored is stored in a storage device in a time-series manner in advance, and an actually obtained process value is compared with the comparison data. Will be Also, JP-A-63-271507
According to the publication, in addition to the conventional qualitative diagnosis by tree processing, as a diagnostic processing system for quantitatively estimating the cause of the abnormality, the physical model of the device for which the abnormality has been estimated is used to determine the behavior of the object to be diagnosed. A diagnosis processing system of an abnormality diagnosis device that evaluates the cause of an abnormality by simulating a dynamic response is already known.

[0008]

However, in the above prior art, in particular, in the above-described abnormality detection method based on the upper and lower limit values, no consideration is given to the detection of an abnormality of the apparatus within the set value range.

Further, a plant monitoring apparatus capable of storing and detecting an abnormality before detecting an abnormality based on upper and lower limits described below always monitors a fluctuating process. There is a problem that it is necessary to have a large amount of comparison data, and as a result, it is necessary to install dedicated equipment. Also, in a diagnostic processing system that simulates a dynamic response of a diagnosis target by a physical model, it is assumed that an abnormality is detected by qualitative diagnosis by tree processing, and eventually, an abnormality is detected within a set value range. Is not considered.

In view of the above-mentioned problems in the prior art, the present invention provides a method for detecting the abnormality, deterioration, or failure of equipment to be operated based on the amount of change in plant equipment before detecting abnormality based on upper and lower limits. By making it possible to diagnose the efficiency reduction with high accuracy and to reduce the number of comparison data held in the control system for use in such diagnosis, particularly the equipment for the diagnosis, it is possible to perform comparison. It is an object of the present invention to provide a process control / diagnosis method for a plant which can be applied to process control in plant equipment having a small scale and a device therefor.

[0011]

In order to solve the above-mentioned problems and to achieve the object of the present invention, first, an input / output device and a controller for controlling input a process value from a plant. And, in a control device that controls the plant by outputting a discontinuous operation command signal to the operation target device of the plant based on the input process value, the control device for the operation target device of the plant When outputting a non-continuous operation command signal, a simulated process value is calculated based on a normal process value set and stored in advance, and the simulated process value is compared with an actual process input value input from the input / output device. This is a plant process control / diagnosis method for determining whether or not a process value in a plant is normal based on a deviation between the two.

In order to achieve the above object,
According to the present invention, an input / output device and a controller for control are used to input a process value from a plant, and based on the input process value, a discontinuous operation with respect to an operation target device of the plant. In the control device that controls the plant by outputting an operation command signal, the control controller further stores a preset operation command signal when outputting a discontinuous operation command signal to an operation target device of the plant. A process simulation unit that calculates a simulated process value based on the normal process value, and compares the simulated process value with an actual process input value input from the input / output device. A process control / diagnosis device for a plant, comprising: a process value comparison unit that determines whether or not the above is true.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic configuration of a control device that performs process abnormality diagnosis on a process together with process control in a plant according to the present invention.

The control device 1 includes a monitored object (plant) 9
And an input / output device 7 for inputting a process value from and outputting a discontinuous operation command signal to a device to be controlled in the plant 9. The control device 1
Is provided with a controller 2 for outputting a device operation command signal to a device to be controlled in the plant 9. In the controller 2, a plant operation determined in advance by a planning document is shown. An interlock control unit 6 having an operation unit 61 storing software is provided.

For example, when the liquid in the tank is kept at 50 ° C. to 80 °
In the case of a control system that maintains the temperature of C, the control temperature range is set in advance in the interlock control unit 6 of the control controller 2 as 80 ° C to 50 ° C. Thereby, the interlock control unit 6 of the control controller 2 sends the tank temperature of 5 to the control target device in the plant 9.
When the temperature falls to 0 ° C. or lower, a command to supply heat to the tank is output via the input / output device 7, and thereafter, the command is continuously output until the tank temperature reaches 80 ° C. Then, when a signal (process value) from a device to be controlled in the plant 9 is input and the tank temperature becomes 80 ° C. or higher, a heat supply stop command is output. Thereafter, so-called discontinuous control is performed in which the above processing is repeated when the tank temperature is in the range of 50 ° C to 80 ° C.

The control controller 2 operates in response to an operation command output from the interlock control unit 6 to a device to be controlled, for example, a heater start / stop command signal (hereinafter referred to as a "trigger signal"). A normal process value output unit 3 to be started is provided. The normal process value output unit 3 includes a device operation command signal detection unit 31 that detects the timing of the trigger signal output from the interlock control unit 6 as the start of process fluctuation, as is apparent from the drawing. A data storage unit 32 that stores in advance a process value (normal process value) that fluctuates due to the normal operation of the device, a data reading unit 33 that reads a normal process value from the data storage unit 32, and A data transmission unit 34 for transmitting the process value to the process simulation unit 4 described below.

The control controller 2 further includes:
A process simulation unit 4 is provided.
Is the amount of change by a polynomial representing the change (temporal change) of the process value that fluctuates due to the normal operation of the device, based on the normal process value output (transmitted) from the normal process value output unit 3. And outputs the result (hereinafter referred to as “simulated process value”). That is, as a method of precisely diagnosing the soundness of the process operation in the plant 9 in the control device 1, at the timing when an operation command signal is output from the input / output device 7 to the equipment in the plant 9, A simulated process value is predicted based on a process value (normal process value) scheduled at the time of design stored in the process value data storage unit 32, and the simulated process value is compared with an actual process input signal from a plant. Make a comparison.

The process value comparison unit 5 in the control controller 2 includes a comparison unit 51 and an alarm signal output unit 52.
First, in the process value comparison unit 51, the output (simulated process value) from the process simulation unit 4 and
An actual process signal input from the plant 9 via the input / output device 7 is compared by a comparing unit 51. And
The alarm signal output unit 52 outputs a process abnormality notification signal as an abnormality of the process when there is a deviation between the above two values (simulated process value and actual process signal) exceeding an allowable value. 8 outputs an alarm.

Next, FIGS. 2 and 3 show an example in which the control device having the above-described basic configuration is applied to the above-described temperature control system for a tank which is a relatively small-scale plant facility. In this system, water is stored inside the tank 10, and is an example of a district heat supply plant that stores heat in the water and supplies it to consumers.

As apparent from the figure, in this district heat supply plant, a pump 16 heats water in a tank 10 from a heat source 15 such as an exhaust heat recovery boiler.
Then, the heat is exchanged by the heat exchanger 17. On the other hand, when the heat energy from the heat source 15 is insufficient or when the heat demand increases, the system is configured to supply the insufficient heat energy from another power source 13 via the heater 12.

In this system, when the present invention is implemented, a lower limit of 50 ° C. and an upper limit of 80 ° C. are set in the data storage unit 32 as normal process values. As a result, when the temperature in the tank falls below 50 ° C., the calculation unit 61 of the interlock control unit 6 outputs a device operation command signal (trigger signal) for activating the heater 12, whereby the power supply 13 The switch 14 between the heater and the heater 12 is closed.

On the other hand, when this trigger signal is detected by the device operation command signal detecting unit 31 of the normal process value detecting unit 3 (Step S1 in FIG. 3), the normal process value stored in the data storage unit 32 is used. A certain 50 ° C. is read by the data reading unit 33, and via the data transmitting unit 34,
The data is transferred to the process simulation section 4 (step S2). The process simulating unit 4 stores the transferred normal process value 5
Process in which the temperature in the tank changes from 50 ° C. to 80 ° C. by starting the heater 12 based on 0 ° C. (temporal fluctuation)
Is estimated by a polynomial or the like stored in advance (for example, in the data storage unit 32) to calculate an expected temperature,
The data is transferred to the comparison unit 51 (step S3). Then, the comparison unit 51 compares the estimated temperature with the input / output device 7.
Is compared with a process input value (actual in-tank temperature) input via the CPU (step S4), and it is determined whether or not the process is abnormal (step S5). As a result, if it is determined that there is an abnormality, an alarm is output from the alarm signal output unit 52 to the alarm window 8 (step S6).

The above-described comparison may be executed a plurality of times (for example, at a constant cycle) after the trigger signal is generated and the expected temperature is estimated and calculated. Further, in the subsequent determination of abnormality, in any of the above-described plurality of comparison operations, when one of the comparison results is determined to be abnormal beyond the normal range, or when it is determined to be abnormal for a preset number of times, You may make it determine that it is abnormal. Alternatively, it is also possible to add the respective comparison results and add and average the comparison results for comparison.

For example, because the temperature rise is slow due to abnormality or deterioration of the heat exchanger 17, the change in the actual tank temperature, which is the process input value, is normal to the estimated change. If the value deviates from the range, a deviation occurs between the simulation process value calculated by the process simulation unit 4 and the actual process value. Therefore, from this deviation, the alarm signal output unit 52
It is determined whether or not the process is abnormal. If it is determined that the process is abnormal, an abnormality notification signal is output to the alarm window 8.

Although FIG. 2 shows an example of a plant for supplying hot heat by increasing the temperature of water in the tank 10, the present invention is also applicable to a case of a cold heat supply plant. Applicable. That is, in a plant having a cooling device by gas combustion as a heat source and a cooler by an electric drive compressor as another heat source, the heat source 15 in FIG.
The heater 12 can be applied to a cooler by a compressor. Also, in a plant using only a single heater or cooler as a heat source,
The present invention can be applied.

After the comparison between the normal process value and the actual process input signal is performed, the comparison source data in the process value comparison unit 51 is replaced with the normal process value until the next device operation command signal is transmitted. Based on the process simulation section 4
By sequentially calculating the data amount, the amount of data stored in the data storage unit 32 in advance is reduced. In the above-described embodiment, the device operation command signal (start of fluctuation) for starting the heater 12 has been described as the start signal (trigger signal) of the simulation operation in the process simulation unit 4, but instead of this, for example, The device operation signal (at the end) for stopping the operation of the heater 12 can be used as a start signal (trigger signal) for the simulation operation.

Conventionally, other methods using comparison with reference data have been proposed. However, these conventional methods are extremely complicated and large-scale. It has been difficult to realize this in a small-scale control device. On the other hand, according to the method of the present invention, in a control device that controls a control target device in a plant by performing a control operation based on a process input signal, a normal operation that must be set in a control controller in advance. The size of the data storage unit is reduced by limiting the number of process value data (the amount of data held in the data storage unit 32), and expected process fluctuations are continuously calculated and input values ( By comparing with an actual process input signal), it is possible to construct a highly accurate abnormality diagnosis function.

As described above, according to the control device for diagnosing a process abnormality according to the present invention, a change in the process value within the control range is detected regardless of the conventional upper and lower limit values for the process input value. An alarm can be issued before an important abnormality such as interruption of heat supply to the customer is triggered, so that the administrator of the heat supply plant can be informed of signs of abnormality or deterioration of the equipment, Deterioration measures such as washing the exchanger can be quickly implemented.

Further, in particular, according to the present invention, a process simulation section is stored in the control controller, and the comparison reference value (simulation process value) is sequentially calculated. ) Can be detected even for minor abnormalities such as a decrease in the rate of temperature change due to abnormalities or deterioration, and early measures and maintenance can be performed. Further, since data (normal process values) necessary for diagnosis stored in advance can be limited, it is possible to prevent an increase in the scale of the device (particularly, the control device).

For this reason, a decrease in the heat exchange rate due to the attachment of scale (black oxide, etc.) to the heat exchanger in a district cooling and heat supply plant using a heat storage device is detected as a decrease in the rate of temperature change during heat supply. It is possible to provide a means for constantly monitoring facility efficiency and deterioration status without adding special facilities.

[0031]

As is apparent from the above detailed description, according to the method and the apparatus for controlling and diagnosing a plant according to the present invention, prior to the detection of an abnormality based on the upper and lower limit values, the plant equipment is controlled. It is possible to accurately diagnose the abnormality, deterioration, or decrease in efficiency of the operation target device based on the amount of change in, and to reduce the number of comparison data retained in the control system as much as possible. Is made possible, the size of the control device can be reduced, and the present invention can be applied to process control in relatively small-scale plant equipment.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a control device for realizing a plant process diagnosis method of the present invention.

FIG. 2 is a block diagram showing a specific configuration when the control device of the present invention is applied to a temperature control system as an example.

FIG. 3 is a flowchart showing an example of the operation of the control device of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control device 2 control controller 3 normal process value output unit 4 process simulation unit 5 process value comparison unit 6 interlock control unit 7 input / output device 8 alarm window 9 monitored object (plant) 10 tank 11 temperature detector 12 heater Reference Signs List 13 power supply 14 switch 15 heat source 16 pump 17 heat exchanger 31 device operation command signal detection unit 32 data storage unit 33 data readout unit 34 data transmission unit 51 comparison unit 52 alarm signal output unit 61 arithmetic unit

Claims (2)

[Claims] An input / output device and a control controller input a process value from a plant, and output a discontinuous operation command signal to an operation target device of the plant based on the input process value. In the control device that controls the plant by outputting, when outputting a discontinuous operation command signal to the operation target device of the plant, a simulated process value is calculated based on a normal process value set and stored in advance. Then, comparing the simulated process value with the actual process input value input from the input / output device,
A process control / diagnosis method for a plant, comprising determining whether or not a process value in a plant is normal from a deviation between the two. 2. An input / output device and a controller for inputting a process value from a plant, and outputting a discontinuous operation command signal to an operation target device of the plant based on the input process value. In the control device that controls the plant by outputting, the control controller further includes a normal process value set and stored in advance when outputting a discontinuous operation command signal to the operation target device of the plant. A process simulation unit that calculates a simulated process value based on the calculated process value, and compares the simulated process value with an actual process input value input from the input / output device, and determines whether a process value in the plant is normal based on a deviation between the two. A process control / diagnosis device for a plant, comprising: a process value comparison unit that determines whether the process is performed.