JP4256236B2 - Control apparatus and control method - Google Patents

Description

  The present invention relates to a process control technique, and particularly to a control device and a control method for a multi-loop control system including a typical control system and other control systems.

When a controller is used to control a system of a plurality of control loops (hereinafter referred to as multi-loops), it is basically the simplest implementation form to treat each control loop as a completely independent control system.
However, for example, in the temperature raising process in temperature control, there are many demands and restrictions unique to the multi-loop, such as “the temperature raising times of the plurality of control loops are substantially the same”. As a means for solving the restriction that “the temperature rising times are substantially the same”, a control device that automatically tunes another control loop to the control loop that heats up the latest has been proposed (for example, Patent Documents). 1).

  In addition, a phenomenon called interference may occur between multi-loop control systems. For example, in temperature control, the case where the operation of one control system affects the temperature of another adjacent control system corresponds to the interference system. In this case, if each control loop is handled as a completely independent control system, the disturbance of the control system due to interference cannot be properly removed, resulting in deterioration of the control characteristics. As means for solving such interference of each control system, a design apparatus has been proposed in which a multi-loop control system is combined to design a controller as a multi-variable control system (see, for example, Patent Document 2).

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
JP 2002-49406 A JP 2001-109504 A

  For example, it is assumed that there is a multi-loop control system as shown in FIG. In the example of FIG. 5, the temperature inside the firing furnace 21 is controlled by the controllers 24 and 25, and the controller 24 measures the temperature of the area A <b> 1 in the firing furnace 21 to calculate the operation amount, and the firing furnace The heater 22 in 21 heats the area A <b> 1 according to the operation amount output from the controller 24. The controller 25 measures the temperature of the area A2 in the firing furnace 21 to calculate the operation amount, and the heater 23 in the firing furnace 21 heats the area A2 according to the operation amount output from the controller 25. That is, the controller 24 and the firing furnace 21 constitute one control system, and the controller 25 and the firing furnace 21 constitute another control system.

In such a multi-loop control system, the thermal characteristics of the two control systems are completely different, there is little temperature interference between the control systems, and “the temperature rise time of each control loop is substantially the same” as described above. In the case where there is a restriction, the technique as in Patent Document 1 is effective.
In addition, when the two control systems must be changed to completely different temperatures at completely different timings, a controller designed by the method of Patent Document 2 is effective.

  However, the multi-loop control system shown in FIG. 5 constitutes a cooperative system. A cooperative system is a system in which setting values of a plurality of control systems are changed to substantially the same value at substantially the same timing. That is, the firing furnace 21 shown in FIG. 5 is used for the purpose of firing a plurality of fired products simultaneously, and the thermal characteristics of the two control systems are quite similar. The given set value is changed to substantially the same value at substantially the same timing.

  In such a cooperative system, when the interference between a plurality of control systems is strong, the method of Patent Document 1 has a problem that the control is easily disturbed due to the influence of the interference. Particularly problematic is disturbance in control such as a resonance state due to repeated mutual interference between a plurality of control systems. In this case, disturbance in the control amount (temperature in the example of FIG. 5) continues for a long time. . The reason why such control disturbance occurs is that the up and down movement of the operation amount of each control system is staggered.

  On the other hand, according to the design apparatus of Patent Document 2, a controller that performs control can be designed so as to suppress this interference even when there is strong interference between a plurality of control systems in a cooperative system. There is a problem that the design effort of the system is complicated and a high level of specialized knowledge is required. In other words, as a control method for a cooperative system limited to simple operations with simple characteristics, design complexity and expertise are extremely excessive and are not realistic.

  The present invention has been made to solve the above problems, and in a multi-loop control system that is an interference system and a cooperative system, control disturbance due to repeated mutual interference between the control systems is suppressed, and the complexity of the design is reduced. It is an object of the present invention to provide a control device and a control method that do not cause the need for highly specialized knowledge.

The present invention relates to a typical first control system C1 and n (n is an integer of 1 or more) second control systems Ci (i is an integer from 2 to 2 + n-1) other than the first control system. ), A main measurement unit for measuring the control amount PVm of the first control system C1, and a main setting for setting the set value SPm of the first control system C1. , A main control calculation unit for calculating the operation amount MVm of the first control system C1 based on the control amount PVm and the set value SPm, and n pieces for measuring the control amount PVui of the second control system Ci Sub-measurement unit, n sub-setting units for setting the set value SPui of the second control system Ci, and the manipulated variable MVui of the second control system Ci based on the control amount PVui and the set value SPui. N sub-control operation units for calculating the main control operation unit The n coefficient processing units for multiplying the output manipulated variable MVm by a predetermined coefficient Rui, the manipulated variable RuiMVm coefficient-processed by this coefficient processor, and the manipulated variable MVui output from the sub-control computing unit are added. n addition processing units, a main output unit that outputs the operation amount MVm output from the main control calculation unit to the control target of the first control system C1, and the operation amount that is added by the addition processing unit a n sub output section for outputting the RuiMVm + MVui the control target of the second control system Ci, operation of the main control arithmetic unit is PID calculation, calculation of the sub-control arithmetic unit in the PI operation In addition, the control characteristic of the sub-control calculation unit is adjusted to be less sensitive than the control characteristic of the main control calculation unit.

The control method of the present invention includes a main measurement procedure for measuring the control amount PVm of the first control system C1, a main setting procedure for setting the set value SPm of the first control system C1, and the control amount. A main control calculation procedure for calculating the manipulated variable MVm of the first control system C1 based on PVm and the set value SPm, a sub-measurement procedure for measuring the control variable PVui of the second control system Ci, and the second A sub-setting procedure for setting the set value SPui of the control system Ci, a sub-control calculation procedure for calculating the manipulated variable MVui of the second control system Ci based on the control amount PVui and the set value SPui, and the main control A coefficient processing procedure for multiplying the operation amount MVm calculated by the calculation procedure by a predetermined coefficient Rui, an operation amount RuiMVm coefficient-processed by this coefficient processing procedure, and an operation amount calculated by the sub-control calculation procedure An addition processing procedure for adding Vui, a main output procedure for outputting the manipulated variable MVm calculated by the main control calculation procedure to the control target of the first control system C1, and an addition processing procedure by the addition processing procedure an operation amount RuiMVm + MVui a sub output procedure to output the control target of the second control system Ci, operation of the main control algorithm is PID calculation, calculation of the sub-control algorithm is the PI calculation The control characteristic according to the sub-control calculation procedure is adjusted to be less sensitive than the control characteristic according to the main control calculation procedure.

  According to the present invention, by providing the coefficient processing unit and the addition processing unit for each second control system, the operation amount of the representative first control system is distributed to the other second control system, In order to compensate for the excess or deficiency of the operation amount to be distributed, a sub-control operation unit is provided in the second control system, so control disturbance such as a resonance state due to repetitive mutual interference between multiple control systems is suppressed. can do. Moreover, since only one multi-loop control system is required for the 1-input 1-output type controller (main control operation unit and sub-control operation unit), the controller design does not become complicated and it is highly specialized. It does not require technical knowledge.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the basic principle of the present invention will be described. The present invention provides an interference system (a system in which a change in the operation amount MV of a certain control system strongly affects the control system PV of another control system) and a cooperative system (the set values SP of a plurality of control systems are substantially the same timing). This applies to a multi-loop control system that is a system that is changed to the same value). In addition, all the multi-loop control systems perform the reverse operation as indicated by PID (the control amount PV increases as the manipulated variable MV increases), or all of the multi-loop control systems indicate the normal operation as indicated by PID. It is an indispensable condition to operate (the control amount PV decreases as the operation amount MV increases).

  In such a multi-loop control system, one important control system is a representative control system C1, and a one-input one-output type controller CNm (for example, a PID controller) is installed for this representative control system C1. The general control system C1 is configured to execute normal control. Here, in the case of a cooperative system in which all the control systems operate in reverse or a cooperative system in which all the control systems operate normally, the operation amount MVu2 of the control system C2 other than the representative control system C1 is the operation amount of the representative control system C1. Focusing on the fact that the movement is almost the same as the amount MVm, the operation amount MVu2 ′ = Ru2MVm obtained by multiplying the operation amount MVm by an appropriate positive ratio Ru2 is applied to the control system C2.

  However, there is no guarantee that the control amount PVu2 of the control system C2 will converge to the set value SPu2 just by multiplying the operation amount MVm by the ratio Ru2, and therefore, to correct the operation amount MVu2 ', the control system C2 has one input and one output. A type controller CNu2 is installed in the same manner as the representative control system C1. At this time, the relationship between the controller CNm and the controller CNu2 is designed so that the controller CNm is dominant (for example, a PI controller in which the controller CNu2 is adjusted to a low sensitivity with respect to the PID controller CNm). Then, the operation amount MVu2 calculated by the controller CNu2 is considered as a correction amount, and the operation amount MVu2 'is corrected as follows: MVu2' = Ru2MVm + MVu2.

  As described above, with the operation amount MVm of the controller CNm applied to the representative control system C1 as the dominant operation amount of the cooperative system, the operation amount of the control system C2 other than the representative control system C1 is the controller for correction. By applying the operation amount MVu2 ′ = Ru2MVm + MVu2 combined with the correction amount by CNu2, the operation amounts given to the individual control systems in the multi-loop control system can be made substantially the same behavior. Thereby, disturbances such as a resonance state due to repeated mutual interference can be suppressed.

  Based on the above principle, the structure of the control apparatus of this Embodiment is demonstrated. FIG. 1 is a block diagram showing the configuration of a control device according to the first embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the control device of FIG. The control apparatus according to the present embodiment includes a main measuring unit 1 that measures the control amount PVm of the representative control system C1, a main setting unit 2 that sets the set value SPm of the representative control system C1, and the control amount PVm and the setting. Based on the value SPm, the main control calculation unit 3 that calculates the manipulated variable MVm of the representative control system C1, the sub-measurement unit 4 that measures the control amount PVu2 of the control system C2 other than the representative control system C1, and the control system C2 The sub-setting unit 5 for setting the set value SPu2 of the control system, the sub-control calculation unit 6 for calculating the operation amount MVu2 of the control system C2 based on the control amount PVu2 and the set value SPu2, and the operation output from the main control calculation unit 3 A coefficient processing unit 7 that multiplies the amount MVm by a predetermined coefficient Ru2, an addition processing unit 8 that adds the operation amount Ru2MVm coefficient-processed by the coefficient processing unit 7 and the operation amount MVu2 output from the sub-control operation unit 6; Main control calculation The main output unit 9 that outputs the operation amount MVm output from 3 to the control target of the representative control system C1, and the sub that outputs the operation amount Ru2MVm + MVu2 added by the addition processing unit 8 to the control target of the control system C2 And an output unit 10. Such a control device can be realized by a computer having an arithmetic device, a storage device, and an interface, and a program for controlling these hardware resources.

  Next, the operation of the control device of FIG. 1 will be described with reference to FIG. The set value SPm for the control target of the representative control system C1 is set by the operator of the control device. This set value SPm is input to the main control calculation unit 3 via the main setting unit 2 (step 101 in FIG. 2). The main measuring unit 1 includes a sensor for measuring the control amount PVm to be controlled by the representative control system C1, and the control amount PVm measured by the sensor is input to the main control calculation unit 3 (step 102). .

The main control calculation unit 3 performs a control calculation represented by a transfer function expression using a Laplace operator s as in the following equation, for example, whose control algorithm is PID (step 103).
MVm = (100 / Pbm) {1+ (1 / Tims) + Tdms} (SPm-PVm)
... (1)

In equation (1), Pbm is a proportional band, Tim is an integration time, and Tdm is a differentiation time. In the main control calculation process of step 103, the main control calculation unit 3 calculates the manipulated variable MVm according to equation (1), then performs upper and lower limit processing as shown in the following equation, and calculates the manipulated variable MVm after the limit process as a coefficient. The data is output to the processing unit 7 and the main output unit 9.
if MVm> MVHm then MVm = MVHm (2)
if MVm <MVLm then MVm = MVLm (3)

  In the expressions (2) and (3), MVHm is the upper limit value (for example, 100% in the present embodiment) of the manipulated variable MVm, and MVLm is the lower limit value (for example, 0%) of the manipulated variable MVm. Equation (2) means that when the calculated operation amount MVm is larger than the operation amount upper limit value MVHm, limit processing is performed in which the operation amount upper limit value MVHm is set to the operation amount MVm. Further, equation (3) means that when the calculated operation amount MVm is smaller than the operation amount lower limit value MVLm, limit processing is performed in which the operation amount lower limit value MVLm is set to the operation amount MVm.

  The set value SPu2 for the control target of the control system C2 other than the representative control system C1 is also set by the operator in the same manner as the set value SPm. This set value SPu2 is input to the sub control calculation unit 6 via the sub setting unit 5 (step 104). The sub-measurement unit 4 includes a sensor that measures the control amount PVu2 to be controlled by the control system C2, and the control amount PVu2 measured by the sensor is input to the sub-control calculation unit 6 (step 105).

The sub-control operation unit 6 has a control algorithm of PI, for example, and performs a control operation represented by a transfer function expression using a Laplace operator s as in the following equation (step 106).
MVu2 = (100 / Pbu2) {1+ (1 / Tiu2s)} (SPu2-PVu2)
... (4)

In Expression (4), Pbu2 is a proportional band, and Tiu2 is an integration time. In the sub-control calculation process of step 106, the sub-control calculation unit 6 calculates the manipulated variable MVu2 by Expression (4), then performs upper / lower limit processing as shown in the following expression, and adds the manipulated variable MVu2 after the limit process. Output to the processing unit 8.
if MVu2> MVHu2 then MVu2 = MVHu2 (5)
if MVu2 <MVLu2 then MVu2 = MVLu2 (6)

  In the expressions (5) and (6), MVHu2 is the upper limit value (for example, 10% in the present embodiment) of the manipulated variable MVu2, and MVLu2 is the lower limit value (for example, −10%) of the manipulated variable MVu2. Equation (5) means that when the calculated operation amount MVu2 is larger than the operation amount upper limit value MVHu2, limit processing is performed in which the operation amount upper limit value MVHu2 is set to the operation amount MVu2. Further, equation (6) means that when the calculated operation amount MVu2 is smaller than the operation amount lower limit value MVLu2, limit processing is performed in which the operation amount lower limit value MVLu2 is set to the operation amount MVu2.

  The reason why the sub-control operation unit 6 is provided with the PI operation function while the main control operation unit 3 is provided with the PID operation function is as described in the basic principle described above. This is because the control characteristic of the control control unit 3 is made to be less sensitive than the control characteristic of the main control calculation unit 3 (the operation amount MVm calculated by the main control calculation unit 3 is the dominant operation amount of the cooperative system). For the same reason, the proportional band Pbu2 of the equation (4) is set to Pbu2 = 2Pbm, the integration time Tiu2 is set to Tiu2 = 2Tim, for example, the operation amount upper limit value MVHm = 100% of the main control calculation unit 3, With respect to 0%, the manipulated variable upper limit value MVHu2 is, for example, 10%, and the manipulated variable lower limit value MVLu2 is, for example, -10%.

  The coefficient processing unit 7 executes coefficient processing for multiplying the manipulated variable MVm output from the main control calculation unit 3 by a predetermined coefficient Ru2 (Ru2 is a positive real number), and adds the result Ru2MVm of the coefficient processing to the addition processing unit. 8 (step 107). The addition processing unit 8 executes a process of adding the output Ru2MVm of the coefficient processing unit 7 and the operation amount MVu2 output from the sub-control operation unit 6, and sets the result of this addition processing as the operation amount MVu2 ′ of the control system C2. The data is output to the sub output unit 10 (step 108).

The main output unit 9 outputs the operation amount MVm output from the main control calculation unit 3 to the control target of the representative control system C1 (step 109), and the sub output unit 10 operates the operation output from the addition processing unit 8. The quantity MVu2 ′ is output to the control target of the control system C2 (step 110). The actual output destination of the main output unit 9 is a control actuator such as a heater of the representative control system C1, and the actual output destination of the sub output unit 10 is a control actuator of the control system C2.
The operations in steps 101 to 110 as described above are repeated every control cycle until the control is stopped by an instruction from an operator or the like (YES in step 111).

  In a multi-loop interference system, a factor that causes a disturbance such as a resonance state due to repeated mutual interference is that the operation amount of each control system fluctuates up and down. However, in a cooperative system, assuming a properly controlled operation, there is almost no situation where such a quick operation is basically required. Therefore, it is sufficient that the operation amounts given to the respective control systems are configured to rise and fall together.

  In the present embodiment, by distributing the operation amount of the representative control system to other control systems, the operation amounts given to the respective control systems are all increased or decreased. In order to compensate for the excess or deficiency of the operation amount to be distributed, the control system (sub-control computation) has a low sensitivity control characteristic that does not contribute to the main vertical movement of the operation amount in the control system other than the representative control system. Part). Thereby, in this Embodiment, disorder of control like the resonance state by repetition of the mutual interference between several control systems can be suppressed. Further, in the present embodiment, the controller design becomes complicated because only one multi-loop control system is required for the 1-input 1-output type controller (main control operation unit and sub-control operation unit). There is no need for advanced technical knowledge.

  FIG. 3 is a diagram showing an example in which the control device of the present embodiment is applied to the temperature control of the firing furnace shown in FIG. An operation amount MVm is output from the main output unit 9 to the heater 22 in the firing furnace 21, and an operation amount MVu2 ′ is output from the sub output unit 10 to the heater 23. The main measurement unit 1, the main setting unit 2, the main control calculation unit 3, the main output unit 9, and the firing furnace 21 (heater 22) constitute a representative control system C1, and the sub measurement unit 4, the sub setting unit 5, The sub-control operation unit 6, the coefficient processing unit 7, the addition processing unit 8, the sub-output unit 10, and the firing furnace 21 (heater 23) constitute a control system C2 other than the representative control system C1.

[Second Embodiment]
In the first embodiment, the control system other than the representative control system C1 is only C2, but a plurality of control systems other than the representative control system C1 may exist. FIG. 4 is a block diagram showing the configuration of the control apparatus when there are a plurality of control systems other than the representative control system C1, and the same components as those in FIG. 1 are given the same reference numerals.

  The heaters 22, 23-2, 23-3, 23-4, and 23-5 in the firing furnace 21a heat the regions A1, A2, A3, A4, and A5 in the firing furnace 21a, respectively. The main measurement unit 1, the main setting unit 2, the main control calculation unit 3, the main output unit 9, and the firing furnace 21a (heater 22) constitute a representative control system C1, and the sub measurement unit 4-i (this embodiment) In the embodiment, i is an integer of 2 to 5), sub-setting unit 5-i, sub-control operation unit 6-i, coefficient processing unit 7-i, addition processing unit 8-i, sub-output unit 10-i, and firing furnace. 21a (heater 23-i) constitutes a control system Ci other than the representative control system C1.

  Also in the present embodiment, the operation of the control device is the same as in the first embodiment, and will be described with reference to FIG. The operations of the main setting unit 2 (step 101), the main measurement unit 1 (step 102), the main control calculation unit 3 (step 103), and the main output unit 9 (step 109) are the same as those in the first embodiment.

  The set value SPui for the control target of the control system Ci other than the representative control system C1 is input to the sub-control operation unit 6-i via the sub-setting unit 5-i (step 104). Each of the sub-measurement units 4-i includes a sensor that measures a control amount PVui to be controlled by the control system Ci, and the control amount PVui measured by the sensor is input to the sub-control calculation unit 6-i ( Step 105).

  The sub-control calculation unit 6-i calculates the manipulated variable MVui in the same manner as the sub-control calculation unit 6 of the first embodiment, and then performs upper / lower limit processing similar to that of the first embodiment, and performs limit processing. The subsequent manipulated variable MVui is output to the addition processing unit 8-i (step 106). The coefficient processing unit 7-i executes coefficient processing by multiplying the manipulated variable MVm output from the main control calculation unit 3-i by a predetermined coefficient Rui (Rui is a positive real number), and the result of this coefficient processing RuiMVm Is output to the addition processing unit 8-i (step 107).

The addition processing unit 8-i executes a process of adding the output RuiMVm of the coefficient processing unit 7-i and the operation amount MVui output from the sub-control calculation unit 6-i, and the result of the addition process is obtained from the control system Ci. The operation amount MVui ′ is output to the sub output unit 10-i (step 108). The sub output unit 10-i outputs the operation amount MVui ′ output from the addition processing unit 8-i to the control target of the control system Ci (step 110). The actual output destination of the sub output unit 10-i is the heater 23-i.
As described above, even when there are a plurality of control systems Ci other than the representative control system C1, the same effect as that of the first embodiment can be obtained.

  The present invention can be applied to process control.

It is a block diagram which shows the structure of the control apparatus used as the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the control apparatus of FIG. It is a block diagram which shows the example which applied the control apparatus of FIG. 1 to the multiloop control system of temperature control. It is a block diagram which shows the structure of the control apparatus used as the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the conventional multiloop control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main measurement part, 2 ... Main setting part, 3 ... Main control calculating part, 4 ... Sub measuring part, 5 ... Sub setting part, 6 ... Sub control calculating part, 7 ... Coefficient processing part, 8 ... Addition processing part, 9 ... main output unit, 10 ... sub output unit.

Claims (2)

A representative first control system C1 and n (n is an integer of 1 or more) second control systems Ci (i is an integer from 2 to 2 + n-1) other than the first control system. In the control device of the multi-loop control system,
A main measuring unit for measuring a control amount PVm of the first control system C1,
A main setting unit for setting a set value SPm of the first control system C1;
A main control calculation unit for calculating an operation amount MVm of the first control system C1 based on the control amount PVm and a set value SPm;
N sub-measuring units for measuring the control amount PVui of the second control system Ci;
N sub-setting units for setting the set value SPui of the second control system Ci;
N sub-control operation units for calculating an operation amount MVui of the second control system Ci based on the control amount PVui and a set value SPui;
N coefficient processing units for multiplying the manipulated variable MVm output from the main control calculation unit by a predetermined coefficient Rui;
N addition processing units for adding the operation amount RuiMVm coefficient-processed by the coefficient processing unit and the operation amount MVui output from the sub-control operation unit;
A main output unit for outputting the manipulated variable MVm output from the main control calculation unit to a control target of the first control system C1,
N sub-output units that output the manipulated variable RuiMVm + MVui added by the addition processing unit to a control target of the second control system Ci ;
The calculation of the main control calculation unit is a PID calculation, the calculation of the sub control calculation unit is a PI calculation, and the control characteristics of the sub control calculation unit are adjusted to be less sensitive than the control characteristics of the main control calculation unit. control device and wherein the that. A representative first control system C1 and n (n is an integer of 1 or more) second control systems Ci (i is an integer from 2 to 2 + n-1) other than the first control system. In the control method of the multi-loop control system,
A main measurement procedure for measuring the control amount PVm of the first control system C1,
A main setting procedure for setting the set value SPm of the first control system C1;
A main control calculation procedure for calculating an operation amount MVm of the first control system C1 based on the control amount PVm and a set value SPm;
A sub-measurement procedure for measuring the control amount PVui of the second control system Ci;
A sub-setting procedure for setting the set value SPui of the second control system Ci;
A sub-control calculation procedure for calculating an operation amount MVui of the second control system Ci based on the control amount PVui and a set value SPui;
A coefficient processing procedure for multiplying the manipulated variable MVm calculated by the main control calculation procedure by a predetermined coefficient Rui;
An addition processing procedure for adding the operation amount RuiMVm coefficient-processed by the coefficient processing procedure and the operation amount MVui calculated by the sub-control operation procedure;
A main output procedure for outputting the manipulated variable MVm calculated by the main control calculation procedure to the controlled object of the first control system C1;
A sub-output procedure for outputting the manipulated variable RuiMVm + MVui added by the addition processing procedure to a control target of the second control system Ci;
The calculation of the main control calculation procedure is a PID calculation, the calculation of the sub control calculation procedure is a PI calculation, and the control characteristics according to the sub control calculation procedure are adjusted to be less sensitive than the control characteristics according to the main control calculation procedure. The control method characterized by the above-mentioned.

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