JP2001325004A - Plant controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plant controller, capable of improving controllability to a plant to which an existing control system is introduced. SOLUTION: An output switching means 5 outputs an additional control operation quantity ui calculated by an addition control means 4, when a change in the process value is detected by a detecting means 6, and stops the output of the additional control manipulated variable ui when the change of the process value is restored. A manipulated variable generating means 3 calculates and outputs a operation quantity to a plant 1, based on the already set operation quantity of an existent control means 2 and the additional control manipulated variable of the addition control means 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plant control apparatus for controlling a plant based on process values of a commercial power plant or a general industrial plant.

[0002]

2. Description of the Related Art In a plant control, there is a large amount of control with a long delay and a dead time. For example, to control the amount of steam supplied to the turbine in response to an increase in the load on the power plant, the flow rate of the feedwater supplied to the boiler must be increased to increase the fuel flow rate, but a large delay occurs before the generation of steam. There is dead time.

[0003] Since the boiler has a large heat capacity, there is a large delay time and a dead time between the change in the steam flow rate command value and the generation of steam in accordance with the command value, making it difficult to control the plant. When a general PID control plant control device is used for such a plant, the gain must be reduced, and good controllability is hardly realized.

FIG. 15 is a block diagram of a conventional plant control device. Some of the process values P measured in the plant 1 may be controlled to a certain value or controlled to follow a certain set value P0. This is performed by the existing control means 2, which calculates and outputs the existing operation amount S to the plant 1 from the process value P and the set value P0.

Generally, the PID control method is overwhelmingly used as a control method of the existing control means 2. This is because the tuning system has few tuning parameters, a parameter adjustment method has been established to some extent, and the control system is easy to handle. Especially before plant operation, detailed plant characteristics are often unknown, so it is difficult to introduce a control system based on advanced design techniques. At this point, a PID control system having robustness is often used at the beginning of plant operation.

In a PID control type plant control device,
The control effect of the PID control on a plant having dynamic characteristics such as a large time constant and a dead time is limited. Predictive control is effective for plants having such dynamic characteristics. In particular, after the plant is started, a high-precision prediction model that simulates the operation characteristics of the plant can be created based on the operation data. Therefore, model prediction control is often used.

[0007]

However, when the shift from the existing PID control system (the existing control means 2) to the model predictive control system is considered after the operation of the plant, the plant is already operated by the PID control system. Therefore, it is necessary to consider the following problems when shifting to a model predictive control system.

[0008] In many cases, the plant 1 is operated continuously for 24 hours, and it is quite difficult to stop the plant for replacing the control system. In addition, even if detailed control design and study were performed in advance, readjustment of the new control system was unavoidable when incorporated into the plant, and the control performance was lower than that of the existing control system until readjustment was completed. There is a risk that it will.

[0009] If the plant has been operated for many years and there is a change in plant characteristics, the PID control system is a fairly common control method and can be easily readjusted even on site.
Adjustment of model predictive control is often performed by an expert, and it is difficult to readjust. Therefore, it is not possible to sufficiently guarantee controllability until readjustment.

[0010] In addition, at the time of initial introduction, there is a concern about reliability, and controllability may not be pursued until risk is taken. In addition, model predictive control that requires a large amount of computation is difficult to implement in DCS from the viewpoint of cost, and if implemented in a PC or the like, the reliability is inferior to DCS. Therefore, it is necessary to consider a backup method.

Due to these problems, controllability is not sufficient in the past, and even if there is an alternative control method which seems to be effective, operation must be continued with the existing control system (particularly, PID control system). In many cases, it was not possible.

An object of the present invention is to provide a plant control apparatus capable of improving controllability of a plant into which an existing control system is introduced.

[0013]

According to a first aspect of the present invention, there is provided a plant control apparatus for calculating and outputting an existing manipulated variable based on a process value of a plant and its set value, and the process value and its setting. Additional control means for calculating and outputting an additional control operation amount based on the value, and detection means for detecting whether the process value has changed in a predetermined manner,
An output switching unit that outputs the additional control operation amount calculated by the additional control unit when the detection unit detects the change in the process value, and stops the output of the additional control operation amount when the change in the process value returns. Means, and an operation amount generating means for obtaining and outputting an operation amount to the plant based on the existing operation amount of the existing control means and the additional control operation amount of the additional control means.

In the plant control device according to the first aspect of the present invention, the output switching means outputs the additional control operation amount calculated by the additional control means when the detecting means detects a change in the process value, and outputs the process value. Is stopped, the output of the additional control manipulated variable is stopped. The manipulated variable generation means includes:
An operation amount for the plant is obtained and output based on the existing operation amount of the existing control means and the additional control operation amount of the additional control means.

According to a second aspect of the present invention, in the plant control apparatus according to the first aspect, the additional control means includes a prediction model setting means for providing a prediction model representing a characteristic of the plant; It is characterized by comprising evaluation function constraint condition setting means for giving a function and a constraint condition, and optimal calculation means for calculating and outputting an additional control operation amount that satisfies the constraint condition and minimizes the evaluation function.

In the plant control apparatus according to the second aspect of the present invention, in addition to the operation of the first aspect, the additional control means is provided by the prediction model and the evaluation function constraint condition setting means provided by the prediction model setting means. The optimal operation amount is sequentially calculated and output by the optimal calculation means based on the evaluation function constraint condition and the set value and the process value.

According to a third aspect of the present invention, in the plant control apparatus according to the first or second aspect, the detecting means detects a change in the process amount when the process value deviates from a preset range. It is characterized by detecting that there is.

In the plant control apparatus according to the third aspect of the present invention, in addition to the operation of the first or second aspect of the present invention, the detecting means may determine the process amount when the process value deviates from a preset range. It detects that there has been a change and outputs a switching signal to the output switching means.

According to a fourth aspect of the present invention, in the plant control apparatus according to the first or second aspect of the present invention, the detecting means is configured to output the process amount when the rate of change of the process value is out of a preset range. Is detected as having changed.

According to a fourth aspect of the present invention, in addition to the operation of the first or second aspect, the detecting means detects when the rate of change of the process value deviates from a preset setting range. It detects that the process amount has changed, and outputs a switching signal to the output switching means.

According to a fifth aspect of the present invention, in the plant control device according to the first or second aspect of the present invention, the output switching means calculates by the additional control means after a lapse of a predetermined time after the change of the process value is restored. The output of the added additional control operation amount is stopped.

According to a fifth aspect of the present invention, in addition to the function of the first or second aspect of the present invention, the output switching means includes an additional control operation calculated by the additional control means when a process value changes. The output of the additional control operation amount calculated by the additional control means is stopped after a predetermined time has elapsed after the change in the process value is restored. Thereby, the validity period of the control by the additional control means can be adjusted.

According to a sixth aspect of the present invention, in the plant control apparatus according to the first or second aspect, the output switching means performs the calculation by the additional control means after a predetermined time has elapsed after the change in the process value has been restored. The output of the additional control operation amount is gradually attenuated to stop the output.

According to a sixth aspect of the present invention, in addition to the function of the first or second aspect of the present invention, the output switching means includes an additional control means which is operated by the additional control means when the process value changes. An operation amount is output, and after a predetermined time elapses after the change in the process value is restored, the additional control operation amount calculated by the additional control means is gradually attenuated, and the output is stopped. This prevents a sudden change.

According to a seventh aspect of the present invention, in the plant control device according to the first or second aspect, the output switching means includes an additional control operation amount calculated by the additional control means when a change in the process value is restored. Is subjected to a predetermined change rate limit, and the output is stopped.

According to a seventh aspect of the present invention, in addition to the function of the first or second aspect, the output switching means further comprises an additional control means which is operated by the additional control means when the process value changes. An operation amount is output, and when the change in the process value is restored, the output is stopped by applying a predetermined change rate limit to the additional control operation amount calculated by the additional control means. This prevents a sudden change.

According to an eighth aspect of the present invention, in the plant control device according to the first or second aspect of the present invention, the operation amount generating means includes an existing operation amount from the existing control means and an additional control operation from the additional control means. The amount is added to the output and output as an operation amount.

According to an eighth aspect of the present invention, in the plant control device according to the first or second aspect, the operation amount generating means includes an existing operation amount from the existing control means and an additional control operation from the additional control means. The amount is added and output as an operation amount.
Thus, the control by the additional control unit is added to the control by the existing control unit.

According to a ninth aspect of the present invention, in the plant control device according to the first or second aspect of the present invention, the operation amount generating means includes an existing operation amount from the existing control means and an additional control operation from the additional control means. One or both of the amounts are multiplied by a predetermined gain, added, and output as an operation amount.

According to a ninth aspect of the present invention, in addition to the operation of the first or second aspect, the operation amount generating means includes an existing operation amount from the existing control means and an additional control from the additional control means. One or both of the operation amounts are multiplied by a predetermined gain and added, and output as an operation amount. Thus, the ratio between the existing control and the additional control can be adjusted.

[0031] The plant control device according to claim 10 is
In the invention of claim 1 or claim 2, the operation amount generating means restricts upper or lower limits to one or both of an existing operation amount from the existing control means and an additional control operation amount from the additional control means. It is characterized in that it is added after limiting the rate of change, and is output as an operation amount.

According to a tenth aspect of the present invention, in addition to the function of the first or second aspect, the operation amount generating means includes an existing operation amount from the existing control means and an additional control from the additional control means. One or both of the manipulated variables are subjected to upper / lower limit or rate-of-change limits and then added and output as manipulated variables.

[0033] The plant control device according to claim 11 is:
In the invention according to claim 1 or 2, when the operation amount generation means detects an abnormality of the existing control means or the additional control means, the operation amount generation means determines the non-abnormal operation amount of the existing operation amount or the additional control operation amount. Is output.

In the plant control apparatus according to the eleventh aspect, in addition to the function of the invention of the first or second aspect, the operation amount generating means detects the abnormality of the existing control means or the additional control means. The non-abnormal one of the amount or the additional control operation amount is output as the operation amount. Thus, the existing control means and the additional control means can back up each other.

[0035]

Embodiments of the present invention will be described below. FIG. 1 is a block configuration diagram of a plant control device according to the first embodiment of the present invention. The first embodiment is different from the conventional example shown in FIG. 15 in that additional control means for calculating and outputting an additional control operation amount based on a process value and its set value is provided, and a detecting means detects a change in the process value. When detected, the additional control operation amount calculated by the additional control means is input to the operation amount generation means via the output switching means, and the operation amount to the plant is calculated and output in consideration of the existing operation amount of the existing control means. It is something to do.

The existing control means 2 calculates an existing manipulated variable S based on the process value P from the plant 1 and its set value P0, and outputs it to the manipulated variable generating means 3. On the other hand, the additional control means 4 calculates an additional control operation amount ui based on the process value P and the set value P0, and outputs it to the operation amount generation means 3 through the output switching means 5. The additional control means 4 performs model predictive control as a control method suitable for the plant 1 having a large delay time and a dead time.

The output switching means 5 switches between outputting and not outputting the additional control manipulated variable ui according to the switching signal a from the detecting means 6. The detecting means 6 outputs a switching signal a when the process value P detects a predetermined change.

The manipulated variable generating means 3 obtains the manipulated variable R for the plant 1 from the existing manipulated variable S of the existing control means 2 and the additional control manipulated variable ui of the additional control means 4 and outputs the manipulated variable R to the plant 1. The operation is performed with the operation amount R. As a result, appropriate control can be performed even for the plant 1 having a large delay time or a dead time.

FIG. 2 is a block diagram showing a case where the plant control device is applied to a power plant for business use. When the plant 1 is a power plant, the plant 1 includes a steam generating means 7 such as a boiler or a nuclear reactor for generating steam, and a steam consuming means 8 such as a steam turbine operating using the generated steam as a power source.

For example, in the case of a thermal power plant, a steam flow rate command value signal R 1 is output from the manipulated variable generating means 3 to the steam generating means (boiler) 7 as a manipulated variable. The steam generation means 7 controls the fuel flow rate and the like based on the steam flow rate command value signal R1, and generates steam by the combustion. Since the evaporator of the boiler has a large heat capacity, there is a large delay time and a dead time from when the steam flow rate command value signal R1 changes to when steam generated according to the command value is generated.

When the steam pressure signal P1 of the boiler is used as the control value as the process value P, the additional control means 4 for performing model predictive control adds the steam pressure signal P1 of the boiler and its set value P0 to the consumption value. The steam flow signal P2 and other process quantities that affect the boiler steam pressure (eg,
Disturbance signal G as auxiliary fuel flow, feedwater temperature, etc.
And take control. The target value of the steam pressure is the set value P0
Given by

When the existing control means 2 is not included as a target to be predicted, the existing operation amount S becomes a disturbance with respect to the model prediction control, and this may be taken into the additional control means 4 as a disturbance signal G.

FIG. 3 is a block diagram of the additional control means 4. The additional control means 4 performs model predictive control suitable for a plant having a large delay time or a dead time, and includes a prediction model setting means 9 for providing a prediction model representing characteristics of the plant 1 and a process value and an operation amount. Evaluation function constraint condition setting means 10 for giving an evaluation function and a constraint condition
And an optimal calculation means 11 for calculating and outputting an additional control operation amount ui that satisfies the constraint condition and minimizes the evaluation function.

The prediction model setting means 9 gives a prediction model representing the characteristic of the object to be predicted by the following prediction model formula. This may be a plant alone or a combination of a plant and a control system, depending on the range of equipment and control devices to be predicted.

[0045]

(Equation 1)

The evaluation function constraint condition setting means 10 gives an evaluation function as a scale for measuring the deviation of the control amount (process value P) and the operation amount (additional control operation amount ui) from the target values. If necessary, it is possible to set constraints on the control amount and its increment, and on the operation amount and its increment.

[0047]

(Equation 2)

The optimum calculation amount increment Δu that satisfies the above-mentioned constraint conditions and minimizes the evaluation function (minimizes the deviation from the target value) is obtained by the optimum calculation means 11. Various methods have been proposed as specific calculation methods. For example, a system as disclosed in JP-A-5-120256 can be applied.

When Δu obtained by the optimum calculation is integrated in the time direction, ui which is the optimum additional control operation amount ui is obtained by the following formula.

[0050]

(Equation 3)

FIG. 4 is a block diagram of the detecting means 6. The detecting means 6 outputs a switching signal a when the process value changes by a predetermined amount. For example, in the case of boiler steam pressure control, change detection can be performed by monitoring the consumed steam flow rate signal P2 as the process value P. The threshold value of the process value P is set in advance by the constant setting unit 12 and stored in the constant storage unit 13. The comparing means 14 compares the sequential process value P with a threshold value of the constant storage means 13, and if the threshold value is exceeded, the switching signal a
An ON signal is output, and if it is less than the threshold value, an OFF signal is output as the switching signal a.

Thus, the ON state is set according to the operation state of the plant (whether a certain process value exceeds or does not exceed a threshold value).
/ OFF signal can be switched and output.

The configuration of the detecting means 6 as shown in FIG. 5 may be used. The change rate calculating means 15 calculates the change rate ΔP of the process value P per unit time. The comparing unit 14 compares whether the rate of change ΔP exceeds or does not exceed the threshold value set and stored in the constant setting unit 12 and the constant storage unit 13. If the threshold value is exceeded, an ON signal is output as the switching signal a, and if less than the threshold value, an OFF signal is output as the switching signal a.

As a result, for example, the consumed steam flow rate signal P2, which greatly affects the boiler steam pressure, is changed to the process value P.
And ON / OFF signals can be switched and output according to the rate of change. Note that the above constant setting means 1
2 may be given as a function of inputting a process value of a plant and outputting a threshold value.

The output switching means 5 receives the additional control operation amount ui from the additional control means 4 according to the switching signal a from the detection means 6.
Is switched between output and non-output to the manipulated variable generating means 3. Depending on the operation method of the plant 1, the additional control manipulated variable ui is always effective, or conversely, the additional control manipulated variable ui is always effective. You may not be able to do so.

Switching signal a = ON: outputting additional control operation amount ui Switching signal a = OFF: not outputting additional control operation amount ui

FIG. 6 is a block diagram of the manipulated variable generator 3. The operation amount generating means 3 shown in FIG. 6 is one of the simplest examples. The additional control operation amount ui and the existing operation amount S are added by the adding means 16 and output as an operation amount R to the plant. For example, as an operation amount for controlling the boiler steam pressure P1 of the plant 1, a value obtained by adding an existing operation amount S realized by PID control or the like and an additional control operation amount ui realized by model prediction control or the like is added. Output.

FIG. 7 is a characteristic diagram showing control characteristics when controlling the steam pressure in the power plant. Time point T1
The existing control when the consumed steam flow rate increases from to the time T2 is as follows. When there is no generation of the steam flow rate corresponding to the consumed steam flow rate, the pressure of the steam decreases. If the plant has a dead time, even if the control operation amount (existing) increases immediately after the steam pressure starts to decrease, the actual increase in the generated steam flow rate (existing) is delayed by the dead time.

If there is a dead time, the control operation amount (existing) can only change slowly, and the generated steam flow rate (existing) only increases slowly. Therefore, the deviation between the steam pressure (existing) and the steam pressure target value remains large for a while. This means that in the existing control (for example, PID control), the gain is increased to reduce the dead time,
This is because it becomes oscillating, and it is necessary to suppress the gain.

On the other hand, in the model predictive control, when the consumed steam flow rate increases from time T1 to time T2, the detecting means 6 turns on the switching signal a to detect a process change, for example, as a change rate exceeding a certain threshold value. . Then, the output of the additional control means 4 realized as the model predictive control is output to the manipulated variable generation means 3 through the output switching means 5. In the operation amount generating means 3, a steam flow rate command value signal R 1 which is the sum of the existing operation amount S and the additional control operation amount ui is output to the plant 1. This steam flow command value signal R1
Is shown as the control operation amount (existing + model prediction) in FIG.

As a result, as apparent from the characteristic diagram of FIG. 7, the model predictive control can be effected in a feed-forward manner while the change in the consumed steam flow rate is large. This can be compensated by the control and the return of the steam pressure to the target value can be expedited.

The time when the control by the additional control means 4 is valid is from when the output switching means 5 detects the change in the process value to when the change in the process value is restored. It is also possible that a predetermined time has elapsed since the start of the process.

FIG. 8 is a block diagram of the output switching means 5 in that case. The output switching means 5 has a timer means 17 (off-delay timer) inside, and when the switching signal a is turned on, the timer means 17 outputs an ON signal as it is, and the ON / O
The FF switching means 18 immediately outputs the additional control operation amount ui.
When the switching signal a is turned off, the timer means 17 starts counting time, and outputs an OFF signal at a certain time. At this time O
The N / OFF switching unit 18 does not output the additional control operation amount ui. As a result, even when the plant state change is completed, the time for which the additional control means 4 is enabled can be adjusted without immediately stopping the control of the additional control means 4.

Further, as shown in FIG.
May be provided with a damping means 19. The switching signal a
When it is turned ON, the ON / OFF switching means 18 immediately outputs the additional control operation amount ui. When the switching signal a is turned off, the timer means 17 starts counting time and outputs this time to the attenuation means 19. The damping means 19 refers to the gain function based on the time and outputs the additional control manipulated variable output ui 'to the switching signal a.
Can be gradually attenuated from the value when is turned off. As a result, it is possible to prevent the additional control manipulated variable output ui 'from suddenly becoming zero.
It is possible to prevent a sudden OFF of the additional control from becoming a disturbance.

As shown in FIG. 10, the output switching means 5 can be provided with a change rate limiting means 20. When the switching signal a is turned ON / OFF, the additional control manipulated variable output ui 'suddenly turns ON / OFF.
It is possible to prevent the additional control from being turned off, and to prevent the additional control OF / OFF from being disturbed with respect to the existing control.

The manipulated variable generating means 3 includes not only simple addition as shown in FIG. 6 but also gain setting means 21A and 21B and gain storage means 22A and 22B as shown in FIG.
The gain set and stored by
It can also be output as an operation amount R after being applied to one or both of the existing operation amount S and both. In this case, by setting the relative magnitude of the gain, it is possible to adjust the effectiveness of the existing control and the additional control (which is more effective).

Further, assuming that one of the gains is 0,
Only the existing control is effective, or the switching signal a is always
It is also possible to use only the additional control in combination with turning on.

As shown in FIG. 12, the operation amount generating means 3 is provided with upper and lower limit means 23A and 23B or, alternatively, is provided with a change rate limiting means.
The upper and lower limit values and the rate of change can be set appropriately.

FIG. 13 is a block diagram of a plant control device according to the second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG. 1 in that the existing control means 2 and the additional control means 4 respectively output control state signals X and Y to the operation amount generation means 3, When detecting an abnormality of the existing control means 3 or the additional control means 4, the operation amount generation means 3 outputs the existing operation amount or the additional control operation amount which is not abnormal as the operation amount.

In FIG. 13, it is assumed that one of the existing control means 3 and the additional control means 4 has failed. The additional control means 4 and the existing control means 2 are provided with logic for counting up in each control operation cycle, and the results are output as an existing control state signal X and an additional control state signal Y, respectively.

In the manipulated variable generating means 3, as shown in FIG. 14, both signals are monitored by the output switching means 24, and when the count-up stops, it is determined that the control means which has stopped has failed. Judgment is made, and only the output of the remaining normal control means is output as the manipulated variable R. Thus, the remaining control system can be used as a backup.

[0072]

As described above, according to the present invention, the additional control means is provided in addition to the existing control means, and the additional control means can be used for the control of the plant in a feed-forward manner. That is, since two control systems can be used side by side, it is possible to achieve an improvement in control response which was difficult with only the existing control system.

Further, the existing control means is mainly used, and the newly added additional control means is used as a slave, so that the additional control means can be easily tuned, and the additional control means can be easily separated and maintained. Further, when one of the control means goes down due to a failure or the like, the rest can be used as a backup.

By using the model predictive control as the additional control means, it is also effective for a control object including a large delay or dead time, which is difficult to control well with the existing PID control.

The ON / OFF criterion for the additional control system can be freely set based on the state of the plant and the magnitude of the rate of change.
It is possible to improve the response by applying additional control in a feed-forward manner, mainly in an area where the existing control is weak. Further, by providing the attenuation means and the change rate limiting means in the output switching means, it is possible to prevent the ON / OFF of the additional control means from being disturbed by the existing control means, thereby preventing the controllability from deteriorating.

[Brief description of the drawings]

FIG. 1 is a block diagram of a plant control device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a case where the plant control device according to the first embodiment of the present invention is applied to a commercial power plant.

FIG. 3 is a block diagram of an additional control unit according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing an example of a detecting unit according to the first embodiment of the present invention.

FIG. 5 is a block diagram showing another example of the detecting means according to the first embodiment of the present invention.

FIG. 6 is a block diagram illustrating an example of an operation amount generating unit according to the first embodiment of the present invention.

FIG. 7 is a characteristic diagram illustrating control characteristics when controlling the steam pressure in the power plant according to the first embodiment of the present invention.

FIG. 8 is a block diagram showing an example of an output switching unit according to the first embodiment of the present invention.

FIG. 9 is a block diagram showing another example of the output switching means according to the first embodiment of the present invention.

FIG. 10 is a block diagram showing still another example of the output switching means according to the first embodiment of the present invention.

FIG. 11 is a block diagram showing another example of the manipulated variable generator according to the first embodiment of the present invention.

FIG. 12 is a block diagram showing still another example of the manipulated variable generator according to the first embodiment of the present invention.

FIG. 13 is a block diagram of a plant control device according to a second embodiment of the present invention.

FIG. 14 is a block diagram illustrating an example of an operation amount generating unit according to the second embodiment of the present invention.

FIG. 15 is a block diagram of a conventional plant control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plant, 2 ... Existing control means, 3 ... Manipulation amount generation means, 4 ... Additional control means, 5 ... Output switching means, 6 ... Detection means, 7 ... Steam generation means, 8 ... Steam consumption means, 9 ... Prediction model Setting means, 10 ... evaluation function constraint condition setting means, 11
... Optimal calculation means, 12 ... Constant setting means, 13 ... Constant storage means, 14 ... Comparing means, 15 ... Change rate calculating means, 16 ...
Addition means, 17 ... timer means, 18 ... ON / OFF switching means,
19: damping means, 20: change rate limiting means, 21: gain setting means, 22: gain storage means, 23: upper and lower limit limiting means, 24: output switching means

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshihiro Yamada 1 Toshiba-cho, Fuchu-shi, Tokyo F-term in Toshiba Fuchu Plant (reference) 5H004 GA16 GB04 HA03 HB02 HB03 KA53 KA54 KA65 KA66 KA69 KB02 KB04 KB06 KB33 KB34 KC10 KC27 KC56 LB03 LB06 LB07 MA02

Claims (11)

[Claims] 1. An existing control means for calculating and outputting an existing operation amount based on a process value of a plant and its set value, and an additional control means for calculating and outputting an additional control operation amount based on the process value and its set value. Detecting means for detecting whether the process value has changed by a predetermined amount, and outputting an additional control operation amount calculated by the additional control means when the detecting means detects a change in the process value. An output switching unit for stopping the output of the additional control operation amount when the change in the process value is restored; and an operation on the plant based on the existing operation amount of the existing control unit and the additional control operation amount of the additional control unit. A plant control device, comprising: a manipulated variable generation means for calculating and outputting a quantity. 2. The additional control means includes: a prediction model setting means for giving a prediction model representing a characteristic of a plant; an evaluation function constraint condition setting means for giving an evaluation function and a constraint condition relating to a process value or an operation amount; 2. The plant control apparatus according to claim 1, further comprising: an optimum calculation unit that calculates and outputs an additional control operation amount that satisfies the following condition. 3. The plant control according to claim 1, wherein the detecting means detects that the process amount has changed when the process value deviates from a preset setting range. apparatus. 4. The apparatus according to claim 1, wherein the detecting unit detects that the process amount has changed when a change rate of the process value deviates from a preset setting range. Plant control equipment. 5. The output switching means stops the output of the additional control operation amount calculated by the additional control means after a predetermined time has elapsed after the change of the process value is restored. Or the plant control apparatus according to claim 2. 6. The output switching means according to claim 1, wherein after a predetermined time elapses after the change of the process value has returned, the additional control operation amount calculated by said additional control means is gradually attenuated to stop the output. The plant control device according to claim 1 or 2, wherein: 7. The output switching means, when the change in the process value is restored, stops the output by applying a predetermined change rate limit to the additional control operation amount calculated by the additional control means. The plant control device according to claim 1 or 2, which performs the control. 8. The operation amount generating unit according to claim 1, wherein the operation amount generation unit adds an existing operation amount from the existing control unit and an additional control operation amount from the additional control unit and outputs the added operation amount. The plant control device according to claim 2. 9. The operation amount generating means multiplies one or both of the existing operation amount from the existing control means and the additional control operation amount from the additional control means by a predetermined gain and adds the operation amount. The plant control device according to claim 1, wherein the output is a quantity. 10. The operation amount generation unit applies an upper / lower limit or a change rate limit to one or both of an existing operation amount from the existing control unit and an additional control operation amount from the additional control unit. 3. The plant control device according to claim 1, wherein the plant control device outputs the operation amount as an operation amount. 4. 11. The operation amount generating means, when detecting an abnormality of the existing control means or the additional control means, outputs the existing operation amount or the additional control operation amount which is not abnormal as the operation amount. Claim 1 or Claim 2
3. The plant control device according to 1.