JP5221276B2 - PLANT MONITORING CONTROL DEVICE, ITS CONTROL METHOD, AND ITS PROGRAM - Google Patents

Description

  The present invention relates to a plant monitoring control apparatus that monitors and controls a plant, and more particularly, to a technique that can easily perform setting of a model structure and calculation of parameters associated with the setting.

  Generally, a plant monitoring control device that monitors and controls a plant in an industrial industry such as a power plant or petrochemical is used. This plant monitoring and control device measures and displays various process values such as temperature, pressure, and flow rate in order to safely operate the plant as described above, thereby notifying the user of the monitoring state of the plant. .

  Specifically, in order to control a plant, the plant monitoring and control device acquires various process values through sensors provided at the main locations of the plant, and based on these process values, calculates an operation amount for the plant. Calculate and output. That is, in the plant monitoring and control apparatus, not only the notification of the monitoring state of the plant but also the calculation of the operation amount for the plant operation control is performed.

  Therefore, the manipulated variable output from the plant monitoring and control device is required to be a value that allows the plant to operate and has excellent responsiveness. Taking a thermal power plant as an example of a plant, the amount of power supplied from a thermal power plant to consumers through the power system changes every moment according to demand. Sent to. Then, in the plant monitoring and control apparatus, an operation amount is calculated based on the command value, and based on the operation amount, the thermal power plant outputs the amount of power increased or decreased as required to the customer through the power system.

  In order to output the manipulated variable as described above, the plant monitoring and control apparatus generally employs a method that employs a model having high plant responsiveness. That is, by using this model, the plant monitoring and control apparatus reproduces a response that the plant will react with the model, and calculates an operation amount. Thus, in the method of employing a model, it becomes possible to keep the responsiveness of the plant better than when the model is not employed.

  Here, the plant monitoring and control device is intended to operate safely by monitoring and controlling the plant. Therefore, as described above, the plant is operable and the operation is excellent in responsiveness. It is necessary to calculate and output the quantity. Therefore, in order to achieve such an object, a model in which an error between an output signal response to an input signal and an actual response becomes smaller has been conventionally employed.

  Methods for creating a model to which the plant will respond are roughly divided into the following two types. First, there is a method of creating a physically feasible structure from the plant volume, metal mass, etc. and adopting it as a model. However, in practice, it is difficult to create a structure with few physical errors, so that it is not usually adopted as a method for creating a model.

  Second, a mathematical model that specifies the modeling range of the plant in advance and minimizes the error between the response of the output signal to the input signal and the actual response from the input / output time response waveform of the modeling range. The method (identification method) that adopts is listed. A method that employs a mathematical model that minimizes this error is generally used.

  For example, as a method of adopting a mathematical model, there has been proposed a process of detecting the order of a delay system to be approximated and setting each parameter according to the detected order model (see Patent Document 1). In this case, the number of delay systems to be used is calculated by numerical analysis using a model, and by using a predetermined model based on the calculated order, each parameter setting calculation is performed so that the response error is reduced. Has been done.

In addition, since the acquisition of the model that matches the output signal and the adjustment control of the control device for reducing the response error are in a technically close relationship, a process for automatically controlling the adjustment of the control device to improve the response accuracy is also possible. (See Patent Document 2).
JP 2005-258717 A JP 2005-31920 A “Control Engineering with Matlab” ISBN 4-501-31990-9 22

  By the way, in the invention according to Patent Document 1 as described above, the object is to accurately approximate the response of the plant, but a model is not created in consideration of the structure of the control block to be controlled. In particular, the invention according to Japanese Patent Application Laid-Open No. H10-260260 performs a process of detecting the order of the delay system to be approximated when setting a model, and therefore requires a considerable time to calculate each parameter.

  Similarly, the invention according to Patent Document 2 does not employ a model that takes into account the structure of the control block. Further, in the present invention, this structure is limited to the first-order delay and dead time, and each parameter The accuracy is not necessarily sufficient for calculating.

  In general, in order to reduce the error between the response of the output signal to the input signal and the actual response, it is desirable to adopt a complex model with a high order.However, if the model order is high, the order is set. Labor is required, and accordingly, setting of each parameter requires labor and time.

The present invention has been proposed in order to solve the above-described problems, and its purpose is that the structure of the control block such as delay / advance order and gain is determined in advance when the control block is designed. Taking into account the control block structure and the number of constants, the model structure is set by accepting the structure of the specified model under a predetermined condition and quickly calculating only the constants of the specified structure. and a plant monitoring control device capable of easily performing the calculation of the parameters associated with the setting, is to provide a control method thereof, and a control program.

In order to achieve the above-described object, the present invention has the following structural features in a plant monitoring control apparatus that calculates an operation amount for monitoring and controlling a plant using a model.
(1) A model creation device that creates the model having a model structure represented by a transfer function with gain, delay time constant, advance time constant, and dead time as constants, and information from the model creation device A display operation unit for displaying and receiving an operation from a user. (2) The model creation device displays a plurality of constants used when configuring the model on the display operation unit, and is designated by the user from the plurality of constants displayed on the display operation unit. Display control means for displaying a constant to be selected in a selectable manner, and a constant for designating a transfer function indicating the model structure based on the constant selected by the user among the constants displayed on the display operation unit Determining means.
(3) the minimum number of constants be three, the three constants, gain, the time constant of the primary and secondary delay.

  Moreover, this invention also includes the aspect which grasped | ascertained the plant monitoring control apparatus shown above from the viewpoint of the control method and the control program.

  According to the present invention as described above, the control block structure including the gain, the delay order, the advance order, and the dead time is determined in advance in consideration of the fact that the control block structure is determined in advance when the control block is designed. Since a transfer function having a predetermined number of constants can be displayed and a transfer function based on the selected constant can be specified, the model can be set easily and quickly even when compared to the case of detecting the order of the model. It becomes possible. In addition, with the setting of the model, it is possible to easily calculate a parameter that is a value of each constant constituting the model.

[This embodiment]
[1. Constitution]
Next, the configuration of the plant monitoring control device according to the present embodiment will be described below with reference to FIGS.

[1.1. overall structure]
First, an overall configuration of a plant and a plant monitoring control apparatus that monitors and controls the plant will be described with reference to FIG. As shown in FIG. 1, the plant 1 is provided with a plurality of sensors 2 for observing the state of the plant 1, and a measurement signal that is a process value of the plant 1 through the sensor 2 is transmitted to the plant monitoring control device 3. Sent to.

  The data collection device 4 in the plant monitoring control device 3 converts the measurement signal from the sensor 2 installed in the plant 1 into a time series signal and stores it in the plant database 5. Although the specific configuration of the model creation device 6 will be described later, the model creation device 6 creates a model based on an instruction from the setting device 7, and based on this model and the input / output signals from the plant database 5, The response which is the value of each parameter which comprises a model, and the operation amount which controls the plant 1 is calculated.

  The setting device 7 (corresponding to a “display operation unit”) receives an operation from the user on the screen and displays an output from the model creation device 6. In addition to the touch panel on the screen that receives an operation from the user, a hard key for operation outside the screen may be provided. It is also possible to notify the output of the model creation device 6 by voice.

[1.2. Specific configuration of model creation device]
Next, a specific configuration of the model creation device 6 will be described below with reference to FIG. The model is created by using an input signal, an output signal, and a model structure in the modeling range, and the “model structure” is defined by constants such as gain, delay order, advance order, and dead time.

  The model creation device 6 includes display control means 61 that outputs the information from the model creation device 6 to be displayed on the setting device 7, and the display control means 61 particularly has eight constants ( Here, a model structure limited to G, T1, T2, T3, T4, T5, T6, and 8 constants) is displayed on the setting device 7. Further, the display control unit 61 needs to display at least three constants (three constants G, T1, and T2). That is, the present embodiment is characterized in that the structure of the transfer function displayed on the setting device 7 is limited to a constant of 3 to 8.

In this case, was the 3 the minimum number of constants, in performing the parameter calculation maintaining sufficient accuracy, minimum, because shall consideration Shinano time constant of gain and 1,2-order lag In addition, the maximum number of constants is set to 8 in order to keep the processing time required for parameter calculation within a practical and quick range. Each constant of the model structure displayed on the setting device 7 is in a mode that can be selected by the user.

  The model creation device 6 also includes constant determination means 62 that receives the constant selected by the user in the setting device 7 and specifies a transfer function based on the selected constant. For example, as shown in FIG. 3, when the constants G, T1, and T2 are selected from the model structure displayed on the setting device 7, the constant determination unit 62 receives the constants G, T1, and T2, Specify the transfer function shown below.

[Equation 1]

  Further, the parameters that are not set are handled as shown in FIG. 4, and for example, the constant T3 is not checked in the setting device 7 shown in FIG. 3, so that “T3 = 0” is handled. Further, as shown in FIG. 4, since the other unchecked constants are the same, “T3 = 0” “T4 = 0” “T5 = 0” “T6 = 0” “L = 0” The formula holds.

[Equation 2]
1 + T3s = 1
1 + T4s = 1
1 + T5s = 1
1 + T6s = 1
e- ^LS = 1

  From the above, the transfer function shown in [Formula 1] is established. In particular, the present embodiment is characterized in that the constant of the model structure displayed by the display control means 61 via the setting device 7 is limited to a predetermined number (for example, 6). A feature is that a constant under a condition corresponding to a number is received and a transfer function is designated within the condition.

  The model creation device 6 further includes constant value receiving means 63 for receiving the values of the constants constituting the transfer function designated by the constant determining means 62, and the constant value receiving means 63 is set by the user through the setting device 7. In addition to accepting an input constant value as an initial value, an updated constant value described later is also accepted.

  Further, response calculation for calculating a response based on the model based on the constant value received by the constant value receiving unit 63, the transfer function specified by the constant determining unit 62, and the input signal of the modeling range based on the transfer function. Means 64 are provided. Further, there is provided an error calculating means 65 for calculating an error corresponding to the time series by comparing the response calculated by the response calculating means 64 with the output signal corresponding to the input signal in the modeling range based on the transfer function. doing. The output signal corresponding to the input signal in the modeling range is obtained from the plant database 5. Since the obtained response and the output signal are signals having the same time width, the error calculation means 65 calculates the error for each sampling period, for example, and calculates the sum of absolute values. Note that the calculation method is not limited to such a calculation method as long as the method expresses the error.

  An error determination unit 66 that determines whether or not the error calculated by the error calculation unit 65 is equal to or less than a predetermined threshold value, and when the error determination unit 66 determines that the error is equal to or less than a predetermined threshold value. The parameter determination unit 67 determines the constant value received by the constant value receiving unit 63 as a parameter constituting the model. The response calculated by the response calculation unit 64 based on the model is output to the setting device 7 through the display control unit 61 together with the parameters.

  The model creation device 6 also includes an update unit 68 that updates the initial value to an appropriate value when the error determination unit 66 determines that the error is not less than a predetermined threshold. For this update, the method is not particularly limited, and for example, it is common to perform an operation using an optimization method.

[2. Action]
Next, a procedure for creating a model and determining a response calculated by the model in the plant monitoring control apparatus according to the present embodiment will be described below with reference to FIG. The plant database 5 stores measurement signals from a plurality of sensors 2 installed in the plant 1. Further, the model structure displayed on the setting device 7 has an 8 constant (8 constants of G, T1, T2,...) As shown in FIG.

[2.1. Example 1]
In the first embodiment, a case will be described in which constants G, T1, and T2 are selected as model structures by the user via the setting device 7, that is, a case where a model structure having a secondary gain and delay order is designated. In this case, the control block to be controlled has, for example, a three-constant configuration as shown in FIG.

  First, the display control means 61 is configured to select eight constants (G, T1, T2,... As shown in FIG. 3 in order to allow the user to select constants G, T1, T2 as model structures. (8 constants) is displayed in advance via the setting device 7 (STEP 501). When constants G, T1, and T2 are selected by the user via the setting device 7, the constant determination means 62 accepts the selected constants G, T1, and T2 (STEP 502) and transmits the transmission shown in the above [Equation 1]. A function is designated (STEP 503).

  On the other hand, the user arbitrarily sets initial values of G, T1, and T2 of the model structure based on this transfer function via the setting device 7, and the constant value receiving unit 63 receives this value (STEP 504). And the response calculation means 64 calculates the response with respect to the said input signal from this initial value, the said specified transfer function, and the input signal of the modeling range based on the said transfer function acquired from the plant database 5 (STEP505). ).

  The calculated response is a signal having the same time width as the input signal acquired from the plant database 5 and is uniquely determined. For example, the response is calculated by using the method described in Non-Patent Document 1. Is possible.

  Next, the error calculation means 65 compares the response calculated by the response calculation means 64 with the output signal corresponding to the input signal acquired from the plant database 5, and calculates the error between them (STEP 506). Then, the error determination unit 66 determines whether the error calculated by the error calculation unit 65 is equal to or less than a predetermined threshold (STEP 507).

  When the error determination unit 66 determines that the error is equal to or less than a predetermined threshold (YES in STEP 507), the parameter determination unit 67 uses the constant value received by the constant value reception unit 63 as a parameter constituting the model. Determine (STEP508). Then, the determined parameter and the response calculated by the response calculation means 64 are output to the setting device 7 by the display control means 61 (STEP 509).

  On the other hand, when it is determined by the error determination means 66 that the error is not equal to or less than the predetermined threshold (NO in STEP 507), the updating means 68 updates the constant value set to the initial value (STEP 510), The processing from STEP 504 to STEP 507 is repeated.

  When the updating unit 68 updates the constants G, T1, and T2 using an optimization method, it is possible to set the upper and lower limits of the constants. For example, if the input / output waveforms all indicate temperature and the gain G is known to be in the following range, the values of the constants G, T1, and T2 are determined within a range that satisfies the constraint.

[Equation 3]
0.01 <G <0.1

In addition, when updating the initial value by the updating unit 68, it is possible to provide a constraint other than the upper and lower limits, and for example, it may be limited to the case where the time constants T1 and T2 are equal.
[Equation 4]
T1 = T2

  FIG. 7 shows the calculation results of the time constants T1 and T2 at the gain G = 0.077 when the updating operation by the updating unit 68 is performed in consideration of the limitation on the gain G shown in the above [Equation 3]. FIG. 7 shows the calculation result under the condition that the model structure is a gain G and a second-order delay (when G, T1, and T2 are selected).

  Here, FIG. 7A shows an input signal acquired from the plant database 5, and FIG. 7B shows an output signal corresponding to the input signal acquired from the plant database 5 and a response by the obtained model. The relationship with the response calculated by the calculation means 64 is shown. FIG. 7C shows an error between the output signal and the response calculated by the response calculation means 64.

  Therefore, as shown in FIG. 7, the constants updated by the updating unit 68 and received by the constant value receiving unit 63 are G = 0.077, T1 = 101.6, T2 = 101.6, and the maximum It can be seen that error = 0.337 and average error = 0.063553.

[2.2. Example 2]
Next, a description will be given of a second embodiment which is a processing procedure when five constants G, T1, T2, T4, and L are selected by the user through the setting device 7. In the second embodiment, the rest of the configuration and processing are the same as those in the first embodiment, and a description thereof is omitted. Moreover, the control block which is a control target has, for example, a five-constant configuration as shown in FIG.

  First, in order to allow the user to select the constants G, T1, T2, T4, and L as the model structure, the display control unit 61 is a model in which a predetermined number of constants that can be selected are predetermined as in the first embodiment. The structure is displayed via the setting device 7 (STEP 501). When the constants G, T1, T2, T4, and L are selected by the user via the setting device 7 (FIG. 9), the constant determination means 62 accepts the selected constants G, T1, T2, T4, and L. (STEP 502), the following transfer function is designated (STEP 503).

[Equation 5]

Here, as shown in FIG. 9 , the parameters that are not set are handled as “T3 = 0”, “ T5 = 0”, and “T6 = 0 ” , and the following equations are established.

[Equation 6]
1 + T3s = 1
1 + T5s = 1
1 + T6s = 1

The subsequent processing is the same as in the first embodiment. In FIG. 10 , the relationship between the input signal acquired from the plant database 5, the output signal corresponding to the input signal, and the response calculated by the response calculating means 64, The error calculated by the error calculation means 65 is shown. As shown in FIG. 10 , the constants updated by the updating unit 68 and received by the constant value receiving unit 63 are G = 0.076, T1 = 27.2, T2 = 11.7, T 4 = −72. 4. L = 12.0, the maximum error = 0.290, and the average error = 0.049281.

[Other Embodiments]
(A) The present invention is not limited to the embodiment in which the user selects a model structure constant on the setting device 7 as described above, but automatically acquires the control block constant to be controlled. In addition, an embodiment in which the constant determination unit 62 accepts it is also included. Since the configuration of the control block to be controlled is often determined in advance at the time of design as described above, it is not necessary for the user to make a selection, and constants are stored in advance corresponding to the control block. By detecting the target, a constant that is the configuration of the control block is automatically read out and accepted by the model creation device 6. Thus, each desired parameter, response, and error can be automatically calculated without having the user select the model structure through the setting device 7 of the plant monitoring control device 3.

(B) Further, the present invention is not limited to the embodiment for calculating the error between the output signal and the response with respect to the single designated model as described above, and the average error is obtained by comparing a plurality of models. The embodiment to calculate is also included. Normally, the model structure is determined at the time of design. For example, the model structure shown in FIG. 6 may be changed to the model structure shown in FIG. In such a case, it is possible to perform model calculation with higher accuracy by comparing a plurality of models (FIGS. 6 and 8) and calculating an average error.

  More specifically, an error comparison means is provided in the model creation device 6 and the processes of the first embodiment and the second embodiment are continuously executed. From the results of FIGS. 7 and 10, the average error of the first embodiment = 0. .063553 and the average error of the second embodiment = 0.049281 is obtained, the error comparison determination means compares the average error, and the calculation result of the second embodiment having a smaller average error is displayed through the display control means 61. Output to the setting device 7. This makes it possible to easily set the best model structure.

1 is an overall view showing a system configuration of a plant monitoring control apparatus according to the present embodiment. The block diagram which shows the specific structure of the model production apparatus which concerns on this embodiment. The example of a screen of the setting apparatus which concerns on this embodiment (when selecting G, T1, T2). The figure which shows the handling on the algorithm at the time of the model structure setting which concerns on this embodiment. The flowchart which concerns on Example 1 of this embodiment. The block diagram of the control block which concerns on Example 1 of this embodiment. The figure which shows an example of the model calculation result of the plant monitoring control apparatus which concerns on Example 1 of this embodiment. The block diagram of the control block which concerns on Example 2 of this embodiment. The example of a screen (G, T1, T2, T4, L) of the setting apparatus which concerns on Example 2 of this embodiment. The figure which shows an example of the model calculation result of the plant monitoring control apparatus which concerns on Example 2 of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plant 2 ... Sensor 3 ... Plant monitoring and control apparatus 4 ... Data collection apparatus
DESCRIPTION OF SYMBOLS 5 ... Plant database 6 ... Model creation apparatus 7 ... Setting apparatus 61 ... Display control means 62 ... Constant determination means 63 ... Constant value reception means 64 ... Response calculation means 65 ... Error calculation means 66 ... Error determination means 67 ... Parameter determination means 68 ... update means

Claims (8)

In a plant monitoring and control device that calculates an operation amount for monitoring and controlling a plant using a model,
A model creation device for creating the model having a model structure represented by a transfer function with gain, delay time constant, advance time constant, and dead time as constants;
A display operation unit that displays information from the model creation device and receives an operation from a user;
The model creation device includes:
A plurality of constants used when configuring the model are displayed on the display operation unit, and a constant designated by the user can be selected from a plurality of constants displayed on the display operation unit. Display control means for
Constant determining means for designating a transfer function indicating the model structure based on the constant selected by the user among the constants displayed on the display operation unit;
The minimum number of the constants is three, and these three constants are a gain, a time constant of delay of 1st and 2nd orders, and a plant monitoring control apparatus characterized by The maximum number of the constants is 8,
The plant monitoring control according to claim 1, wherein the eight constants are a gain, a time constant of a 1st, 2nd and 3rd order delay, a time constant of a 1st, 2nd and 3rd order advance, and a dead time. apparatus. The model creation device includes:
A response signal calculating means for calculating a response signal that is the manipulated variable by the model based on an input value of each constant of the specified model;
Error calculating means for calculating an error between the response signal calculated by the response signal calculating means and the actual output signal of the specified modeling range;
Error determining means for determining whether the error is equal to or less than a threshold;
A determination unit that determines an input value of each constant as a parameter of the model when the error determination unit determines that the error is equal to or less than a threshold;
The plant monitoring control apparatus according to claim 1 or 2, further comprising: The model creation device includes:
Update means for updating the input value using an optimization method,
The plant monitoring control apparatus according to claim 3, wherein the update unit updates the input value when the error determination unit determines that the error is not equal to or less than a threshold value.   The plant monitoring control apparatus according to claim 4, wherein upper and lower limits are set for the input value.   The plant monitoring control apparatus according to claim 4, wherein a constant value that is the same as the input value is set as a constraint. In a control method of a plant monitoring control device that calculates an operation amount for monitoring and controlling a plant using a model,
The plant monitoring and control device is
A model creation device for creating the model having a model structure represented by a transfer function with gain, delay time constant, advance time constant, and dead time as constants;
A display operation unit that displays information from the model creation device and receives an operation from a user;
Minimum number of constants be three, the three constants, gain, a time constant of the primary and secondary delay,
The model creation device is
A plurality of constants used when configuring the model are displayed on the display operation unit, and a constant designated by the user can be selected from a plurality of constants displayed on the display operation unit. Display control step to
A constant determination step of designating a transfer function indicating the model structure based on the constant selected by the user among the constants displayed on the display operation unit;
The control method of the plant monitoring control apparatus characterized by performing this. A model creation device in which a computer creates a model having a model structure expressed by a transfer function with gain, delay time constant, advance time constant, and dead time as constants, and information from the model creation device is displayed. In addition, a control program for a plant monitoring control apparatus that includes a display operation unit that receives an operation from a user and calculates an operation amount for monitoring and controlling the plant using the model.
Minimum number of constants be three, the three constants, gain, a time constant of the primary and secondary delay,
This control program is
A plurality of constants used when configuring the model are displayed on the display operation unit, and a constant designated by the user can be selected from a plurality of constants displayed on the display operation unit. Display control processing to
Constant determination processing for designating a transfer function indicating the model structure based on the constant selected by the user among the constants displayed on the display operation unit;
A control program for a plant monitoring and control apparatus, characterized in that

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