JP3047947B2 - Plant monitoring equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plant monitoring apparatus provided with a display device such as a CRT or a liquid crystal display, and more particularly, to the control of various control devices and a group of plants existing in a factory and the operation status of the plant group. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plant monitoring device capable of efficiently performing monitoring using a display screen, and mainly relates to an early warning based on model prediction.

[0002]

2. Description of the Related Art Conventionally, there has been a distributed control device for controlling and operating a plant using a CRT display device.
In these devices, the process amount and the deviation from the set value handled by various internal instruments configured in the control device, focus on the control output, and the like, when those values exceed a preset alarm value, It is configured to report an alarm for each instrument unit. When a large number of alarms are triggered due to the occurrence of an alarm, considerable experience is required to distinguish the true cause of the abnormality and make an appropriate decision. There were problems such as giving. In predictive control introduced to improve controllability, a process of a controlled process is predicted using a model of a controlled process in order to control a plant. In order to determine the manipulated variable, the predicted values of the control variable and the manipulated variable need to be monitored with a certain monitoring width.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to combine control equipment and a plant group existing in a plant into a predetermined range into one unit, configure a control unit for each unit, and control the control unit. Control variables (target values of control for the control unit, and the control unit operates the control so that the control variables become this value) and operation outputs obtained by performing predictive control based on the plant model for each time. Predict the time at which the deviation between the actual control variable and the predicted value obtained for the operation output exceeds the predetermined monitoring width, perform an appropriate alarm display early, and also provide the operator with a treatment method. An object of the present invention is to provide a guide display to prevent an abnormality beforehand, and when an abnormality occurs, promptly report the cause of the abnormality, thereby enabling prompt treatment.

[0004]

A plant model predictive control means for inputting a variable generated as a disturbance and a control variable and outputting predicted values of an operation variable and an operation output, and for monitoring a state of operation control of the plant. 1) Various control devices and a group of plants existing in the plant are collectively arranged in a predetermined range on a display screen as one information processing unit, and Display means for displaying alarm information related to the control unit handling the signal so that the alarm information can be identified for each control unit division;

[0005] 2) With the manipulated variables output from the model prediction control means as target set values (the continuous curve thereof is referred to as a reference trajectory), actual control variables and operation outputs as a result of control operations performed by the control unit are described. A trend prediction calculating means for obtaining a predicted value from the fluctuation tendency; 3) a predicted value of the operation variable and the operation output output from the model prediction control means, and a predicted value of the control variable output from the trend prediction calculating means. And a comparison operation means for comparing the predicted value of the operation output (each continuous curve is referred to as a predicted trajectory), predicting a point in time exceeding a predetermined monitoring width, and outputting alarm information to the display means. Features.

[0006]

With the above configuration, a process model, that is, a motion of a control variable is predicted using a plant model to control the plant, a predicted trajectory is created, and the next manipulated variable is generated based on the predicted result. Is determined, and a reference trajectory is created. The control unit controls the predicted trajectory to approach the reference trajectory. Since this operation is repeated automatically,
The predicted values of the control variables and the manipulated variables had to be monitored with a certain monitoring width, but they have been realized as follows and will be described in detail.

[0007]

[Example] The terms used here have the following meanings. The control variable is a measurement quantity required directly or indirectly in the control operation of the plant, and as information from the plant,
It is a variable that is also used as input for creating a plant model and for alarming. The continuous curve obtained by the prediction calculation means based on this variable is called a predicted trajectory. The variable added as a disturbance is a control variable that is difficult to predict, such as an uncertain change in the amount of used steam. The operation variable is a variable indicating the amount to be controlled directly or indirectly in the control operation of the plant, and a target set value or a target operation value (a continuous curve thereof) to the secondary controller output by the predictive control means is output. Etc.). The operation output is an output that determines an operation amount output by the prediction control unit or the controller.

The present invention will be described below with reference to the drawings. FIG.
FIG. 1 is a configuration block diagram of a system showing an embodiment of the present invention. In this figure, a plant PLT1 is a representative example of a plant including a large number of control devices and devices, and various sensors and control valves are installed in the plant PLT1. SU1 is a control unit for controlling the plant PLT1, receives signals from various sensors, and outputs an operation output for control to an operation terminal such as an automatic control valve. The target set value (S
V) is given from the model prediction control means.

Reference numeral 1 denotes an alarm monitoring device, which usually employs an operator station provided with a display device such as a CRT for monitoring control operation and control status. The alarm monitoring device 1 is connected to each control unit SU1 and the like via a communication bus. Reference numeral 11 denotes a data collection unit, which collects and temporarily stores data of actually measured control variables, operation variables, and the like as an interface with the control unit in order to collect various data handled by the alarm monitoring device 1 cyclically. 12 is an alarm information display means,
On a display screen such as T, various control devices and plant groups (including various internal instruments in the control unit) existing in the plant PLT1 are collectively displayed within a predetermined range.

Reference numeral 13 denotes a model prediction control means, which receives signals (control variables) from various sensors including disturbances, which are sent from the plant PLT1 via a communication bus, and obtains them in advance. A prediction operation is performed based on the plant model, and an operation variable (reference trajectory) serving as a target set value is created and output as a set value (SV) to the control unit SU1 or the like that controls the plant PLT1. In addition, a predicted value of the operation output of the control unit SU1 is created and output. The output is always updated with new control variable inputs.

Reference numeral 14 denotes a trend predicting operation means, which outputs a sensor output value and an operation output of a control variable obtained as a result of a control operation from the control unit SU1 or the like in which the operation variable (SV) is set by the model prediction control means 13. Receiving the value, a predetermined calculation is performed from the tendency curve to obtain a predicted value of the control variable and the operation output. 15 is a comparison operation means,
The predicted values (reference trajectory) of the operation variables and the operation output obtained from the plant model of the model prediction control means 13 and the predicted values (the predicted trajectory) of the actual control variables and the operation output based on the control results obtained from the trend prediction calculation means 14 And predicts a point in time at which the actual control variable and the operation output exceed a predetermined monitoring width, and outputs the result to the alarm information display means 12 described above.

FIG. 2 shows a CRT as an alarm information display means.
An example of the overview screen displayed above is shown. Specifically, reference numeral 21 denotes a set of display units each representing information processing of one plant or apparatus as one unit. The display contents include a device name, an operation switch for switching between start and stop of operation, automatic and manual, and a distinction between normal, warning, and abnormal operation. Switching is performed using a touch switch or the like. Reference numeral 22 denotes a display unit for displaying an alarm factor which is required to be intensively dealt with. Details will be described with reference to FIG.

Reference numeral 23 is a display unit for displaying a related alarm. Displays related alarms for incidental facilities. FIG. 3 is a detailed screen specified on the overview screen. Reference numeral 31 denotes a detailed screen of a portion displayed as the priority corresponding unit 22 in the overview screen FIG. 2, and designates display together with the display unit 21 which is displaying an alarm. The display of this detail screen can be selected automatically or manually. Reference numeral 32 denotes a detailed screen displayed by designating the display unit 21 and the priority corresponding unit 22 for which an alarm is displayed in the overview screen FIG.

From the target device, the cause of the
The importance of the alert or related content when input is made
This is a screen created so as to report in detail according to.
Shows trends in control variable fluctuations and countermeasures for plant operation.
Is shown. For details, on the graph screen,
If the supply of oil continues to increase, steam consumption tends to decrease.
Therefore, at the time point (a), the prediction at the time point (b)
Drum water level is monitoring width SD ₁Shows predictions that will exceed
ing. FIG. 4 shows a control variable M as an example.₁Forecast for
And compare it with model-based predictions to determine alarm information.
The flow of the output signal is shown.

FIG. 5 shows the output (reference trajectory) of the manipulated variable obtained based on the model prediction by a dotted line, and the monitoring width by a solid line.
The predicted value (predicted trajectory) of the output of the control variable obtained from the trend prediction calculating means is indicated by a solid line, and the two are compared to indicate that alarm information is output when the predicted trajectory departs from the monitoring width. The partially enlarged view shows a method of obtaining a predicted trajectory. The reference trajectory created at time T _0, advance the sampling of a predetermined time t ₁ at intervals had been, t _2, t ₃ and the control variable after the predicted value obtained in t ₇ is the value of FIG at t ₈ That is, the prediction by the linear approximation has shown. FIG. 6 is an instrumentation block diagram of a steam generator as a typical example of a plant. This shows that the feed water is evaporated and heated in the heating furnace and consumed as steam.

Next, the operation of the present apparatus will be described. In FIG. 5, regarding a method for obtaining an operation variable (reference trajectory) serving as a control target value, the operation variable obtained based on a plant model is represented by the following function. Operational variable Y ₁ = F ₁ (Tt) Obtained for each control variable. Determination of the model function F ₁ representing the characteristics of the plant to be actually used are by procedure as statistical model method, a simulation method and other conventional presentation. The plant control method is predictive DDC control using a plant model,
Alternatively, there is a PID control or other method of obtaining an operation variable based on predictive control and designating a control target value, but a conventionally published method is appropriately used.

Regarding a method of obtaining a predicted trajectory A predicted value obtained by calculation from the result of the control operation of the control unit SU1 is expressed by the following equation. The predicted control variable Y ₃ = K ₃ * F ^′ ₃ (Tt, M) + AF3 (Tt, M) represents a function having the value of the control variable M at time Tt.

T is the time at which the model was created, and t is the sampling time of the control variables thereafter. It is shown by t _7, t ₈ and the like. F ^′ ₃ (Tt, M) is a time derivative obtained for the control variable indicated by the control unit at the time Tt. K ₃ is a gain constant which mainly corrected due to the plant characteristics and operating conditions. A is the initial value representing the control variable when the calculated time differential coefficient at time t _7.

Based on the above definitions, FIG. 5 shows a control variable M ₁ obtained from the result of the control operation of the control unit SU1.
For, the predicted value obtained by the trend prediction calculation means 14 (predicted orbit) Y _3, shows the time of leaving the manipulated variable (see trajectory) Y ₁ calculated based on the model predictions from the monitoring width SD1 centered, this The predicted value Y ₁ on the reference orbit,
When foreseen to exceed predetermined monitoring width SD ₁ from, that determine the Y ₃ -Y ₁ ≧ SD ₁ become time t _8, shows that the prior notice as a warning. The predicted trajectory from the operation output of the control unit is obtained in the same manner.

Each of the graphs shows a predicted value of the fluctuation after the time t obtained at the time point T ₀ (the starting point of the graph). Results of actual control traversing the control unit SU1 is as solid lines to the current time, the operation output of the trend prediction calculation means from the variation trend of the control variable at the current time t ₇ is predicted to exceed the area monitoring width at t ₈ The alarm is issued.

Further, a counter 16 for the number of predictions exceeding the monitoring width is provided so that an alarm can be output only when a prediction warning has occurred more than a specified number of times.

FIG. 7 shows an example of instrumentation of the plant PLT1 and the steam generator described above, and corresponds to the control variables and the operation variables of FIG. 1, respectively. The goal of this model predictive control is to supply high-quality steam while maintaining the steam pressure, temperature and drum water level as control variables at predetermined values despite the steam flow rate fluctuating due to demand. In this process, the reference trajectory is corrected by predictive control so as to obtain the optimal control result by predicting the influence of other operation variables and disturbance factors.

[0023]

According to the present invention, the instantaneously changing predicted value curve obtained based on the control result departs from the allowable width of the control variable curve (reference trajectory) obtained based on the plant model. And a signal is generated in advance, so that a guide display can be provided for the operator's treatment operation together with the early warning display, so that abnormalities can be prevented before operating the plant. Even when an abnormality occurs, there is a notice of the cause of the abnormality, so that there is a remarkable effect that prompt treatment can be performed. Further, since the predicted value is calculated from the initial input / output response model, it is possible to detect a deterioration failure of the input / output device that appears as a drift or the like that gradually occurs over a long period of time.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a system showing an embodiment of the present invention.

FIG. 2 is a drawing of an overview screen in which display units and the like are arranged.

FIG. 3 is a drawing of a detailed alarm and operation guide displayed as a result of selecting a priority corresponding unit.

FIG. 4 is a diagram illustrating an operation variable based on a plant model and a predicted value of a control variable obtained for a control result of a control unit;
Predicting a time when comparing both exceeds monitoring width SD ₁ is a diagram showing that outputs the alarm information.

FIG. 5 shows that a prediction value (prediction trajectory) of a control variable obtained by a trend calculation from an operation variable (reference trajectory) output from a model prediction control unit predicts a time at which the prediction variable deviates by a certain monitoring width. It is a drawing. A method of obtaining a predicted trajectory using control variables as an example is also shown.

FIG. 6 is a diagram showing a steam generation plant, control variables, and operation variables.

[Explanation of symbols]

SU1 control unit PC pressure regulator elements FIC flow indicator control elements LIC level adjustment element M ₁ ~M ₇ control variable (measured value) that handles signal plant PL1 SD _1, SD ₂ control monitoring width variable SV _2, SV _3, SV ₅ Manipulated variable (set value) (MV ₂ ), (MV ₄ ) Predicted value of manipulated output (valve opening) Y ₁ Function indicating manipulated variable obtained from model predicting means Y ₃ Function indicating predicted value of control variable 1 Alarm Monitoring device 11 Data collection means 12 Alarm information display means 13 Model prediction control means 14 Trend prediction calculation means 15 Comparison calculation means 16 Counter 17 Flow meter and other sensors 18 Operating terminals such as automatic control valves 21 Display unit 22 Highest priority unit 23 Related management unit 31 Detail screen for the priority corresponding unit on the overview screen 32 Designation of the priority corresponding unit A screen showing the alarm factors to be led, countermeasures, etc.

Claims (1)

(57) [Claims] 1. A plant model predictive control means for inputting a variable generated as a disturbance and a control variable and outputting a predicted value of an operation variable and a control output as a target value of control of a control unit; A plant monitoring apparatus comprising: a display unit for monitoring a situation; 1) on a display screen of the display unit, various types of control devices and device groups existing in the plant are grouped within a predetermined range to form one information Display means for displaying, as a unit of processing, alarm information relating to a control unit which handles signals per unit so as to be identifiable for each control unit division; 2) actual control variables and operations as control results by the control unit A trend prediction operation means for obtaining a predicted value from the fluctuation tendency of the output; and 3) an operation variable and an operation output output from the model prediction control means. The predicted value of the force is compared with the predicted value of the control variable and the predicted value of the operation output output by the trend prediction calculating means, respectively, to predict the time point exceeding a predetermined monitoring width, and to output alarm information to the display means. A plant monitoring device comprising: a comparison operation means.