CN114082789B

CN114082789B - Rolling mill control device and rolling mill control method

Info

Publication number: CN114082789B
Application number: CN202110540034.XA
Authority: CN
Inventors: 段野芳和; 服部哲
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2020-08-24
Filing date: 2021-05-18
Publication date: 2023-09-19
Anticipated expiration: 2041-05-18
Also published as: KR20220025649A; DE102021205063A1; JP7481201B2; JP2022036755A; KR102479459B1; CN114082789A

Abstract

The invention provides a plant control device and a plant control method capable of suppressing deviation errors without using feedback control. The FF control device (611) uses a control output corresponding to the disturbance deviation to perform feedforward control of the process performed by the control target plant (600). An on/off timing determination device (612) adjusts the timing at which the FF control device (611) performs feedforward control, based on the state quantity actual results (xFB) associated with the control target plant (600).

Description

Rolling mill control device and rolling mill control method

Technical Field

The present disclosure relates to a rolling mill control device and a rolling mill control method.

Background

In a rolling mill as a plant for producing a thin metal material by rolling a material to be rolled, if there is a variation in hardness of the material to be rolled, there is a case where a variation in plate thickness (plate thickness failure) of the material to be rolled occurs depending on the position due to the variation in hardness. The uneven hardness means that the hardness of the rolled material is different. Since the hardness of the material to be rolled becomes the deformation resistance during rolling, if there is a variation in hardness in the rolling direction in which the material to be rolled is conveyed during rolling, the flattening mode of the material to be rolled varies depending on the position, and the plate thickness after rolling varies depending on the position, resulting in plate thickness variation.

In addition, in the production of a metal material by rolling, in general, a material to be rolled is put into a rolling mill a plurality of times in order to process the thickness of the material to be rolled from the original thickness to a desired product thickness. Therefore, if there is a variation in hardness of the material to be rolled, a variation in plate thickness occurs every time the material is put into the rolling mill.

Patent documents 1 to 3 disclose techniques capable of suppressing plate thickness variations generated in a tandem rolling mill including a plurality of rolling mills. In the techniques described in patent documents 1 to 3, a plate thickness variation generated by a rolling mill in a preceding stage is detected, and a feed-forward control of the rolling mill in a subsequent stage is controlled based on the plate thickness variation, thereby suppressing the plate thickness variation. In such feedforward control, the control gain of the feedforward control is adjusted in accordance with the plate thickness fluctuation of the rolling mill in the front stage. In addition, the technique described in patent document 3 adjusts the control output timing in addition to the control gain when the deviation between the state quantity such as the sheet thickness and the target value is large.

Prior art literature

Patent document 1: japanese patent No. 3384330

Patent document 2: japanese patent No. 5581964

Patent document 3: japanese patent No. 6404195

Disclosure of Invention

Problems to be solved by the invention

In general, in a plant control device that controls a plant to be controlled, feedback control for suppressing a deviation error (a difference between a state quantity and a command value) generated in a state quantity for a long period of time may be performed in addition to feedforward control for suppressing a state quantity fluctuation having a short fluctuation period such as a plate thickness fluctuation.

However, even if feedback control is performed in addition to feedforward control, a deviation error may temporarily occur due to the timing of starting and ending the control output.

The feedback control includes an integration control using a control output obtained by integrating the state quantity, but in the integration control, a phase shift of 90 degrees occurs between the state quantity variation and the control output. Therefore, when both the feedforward control and the feedback control are performed, the control output timing of the feedforward control may deviate from an appropriate value due to the influence of the phase deviation of the feedback control, and the control effect of the feedforward control may be reduced.

In this way, even if feedback control is used, not only the deviation error may not be reduced, but also the control effect of feedforward control may be reduced. Therefore, a technique for suppressing the deviation error without using feedback control is desired.

Patent documents 1 to 3 do not disclose any suppression of the deviation error without using feedback control.

The present disclosure addresses the problem of providing a plant control device and a plant control method that can suppress a deviation error without using feedback control.

Means for solving the problems

A plant control device according to an aspect of the present disclosure, which controls processing performed by a control object based on a factor value related to a fluctuation factor that fluctuates a state quantity related to the control object, includes: a first control unit that performs feedforward control of the process using a control output corresponding to the factor value; and a determining unit that adjusts timing at which the first control unit performs the feedforward control, based on the state quantity.

Effects of the invention

According to the present invention, the deviation error can be suppressed without using feedback control.

Drawings

Fig. 1 is a diagram showing an example of a plant system to which a plant control device according to an embodiment of the present disclosure can be applied.

Fig. 2 is a diagram for explaining a rolling phenomenon occurring in a material to be rolled by a rolling mill.

Fig. 3 is a diagram showing a model showing the rolling phenomenon described in fig. 2.

Fig. 4 is a diagram for explaining an example of plate thickness control.

Fig. 5 is a diagram for explaining an example of tension control.

Fig. 6 is a diagram showing an outline of a conventional plant control system.

Fig. 7 is a diagram showing a plant control device according to embodiment 1 of the present disclosure.

Fig. 8 is a diagram showing an example of the FF control device.

Fig. 9 is a diagram showing an example of the on/off timing determining device.

Fig. 10 is a diagram showing an example of the control result of the plant control device.

Fig. 11 is a diagram showing another example of the control result of the plant control device.

Fig. 12 is a diagram showing another example of the control result of the plant control device.

Fig. 13 is a diagram showing a plant control device according to embodiment 2 of the present disclosure.

Description of the reference numerals

11 to 14: rolling mill

21-24: driving device

31 to 34: roll gap control device

41-44: plate thickness gauge

51 to 54: tension meter

61 to 64: plate thickness control device

71 to 74: tension control device

100: tandem rolling mill

600: control object complete equipment

601: control device

602: phase shift factor

603: controlling sources of interference

611: FF control device

612: on/off timing determining device

701: differential circuit

702: multiplier unit

703: integrating circuit

711: delay circuit

801: state quantity deviation measuring device

802: on/off timing operation device

901: control device

902: selection device

Detailed Description

Embodiments of the present disclosure are described below with reference to the accompanying drawings.

Example 1

Fig. 1 is a diagram showing an example of a plant system to which a plant control device (see fig. 7) according to embodiment 1 of the present disclosure can be applied. Fig. 1 shows a tandem rolling mill 100 including a plurality of rolling mills for rolling a material 200 to be rolled as a control target plant. The tandem rolling mill 100 shown in fig. 1 is a tandem rolling mill in which 4 rolling mills 11 to 14 are arranged in series, but the rolling mill is not limited to 4 rolling mills.

Each of the rolling mills 11 to 14 has a plurality of rolls that sandwich the material to be rolled 200, and performs a rolling process of rolling the material to be rolled 200 using these rolls. In the example of the figure, each of the rolling mills 11 to 14 includes, as rolls, 1 pair of work rolls 1 that directly sandwich the material to be rolled 200, 1 pair of intermediate rolls 2 disposed outside each of the work rolls 1, and 1 pair of backup rolls 3 disposed outside each of the intermediate rolls 2. The rolling mill 11, the rolling mill 12, the rolling mill 13, and the rolling mill 14 sequentially convey the material to be rolled 200. Hereinafter, the rolling mill 11 is sometimes referred to as a #1 rolling mill 11, the rolling mill 12 as a #2 rolling mill 12, the rolling mill 13 as a #3 rolling mill 13, and the rolling mill 14 as a #4 rolling mill 14.

Fig. 2 is a diagram for explaining a rolling phenomenon occurring in a material 200 to be rolled by each of the rolling mills 11 to 14. As shown in fig. 2, the rolling of the material to be rolled 200 is performed by flattening the material to be rolled 200 with 1 pair of work rolls 1 that sandwich the material to be rolled 200. At this time, an entry-side tension T directed toward the front side of the work roll 1 is applied to the material to be rolled 200 in the rolling direction, which is the conveying direction of the material to be rolled 200 _b And an outlet side tension T toward the rear side of the work roll 1 _f . Further, a rolling load P determined according to the distance between the work rolls 1, that is, the nip S, is applied to the material to be rolled 200 in the vertical direction. Thereby, the rolled material 200 is rolled, and the plate thickness of the rolled material 200 changes from the inlet side plate thickness H to the outlet side plate thickness H. When the forward slip ratio based on the rolling phenomenon is f and the backward slip ratio is b, the speed of the work roll 1, that is, the speed of the work roll is V _R In the case of (a), the entry side velocity V of the rolled material 200 _e Side speed V _o Is V (V) _e ＝V _R (1+b)、V _o ＝V _R (1+f)。

Fig. 3 is a diagram showing a model showing the rolling phenomenon described in fig. 2. Inlet side tension T applied to rolled material 200 in rolling mill _b Tension T on the outlet side _f According to the speed V of the entry side of the self-rolling mill and the rolling mill before and after the self-rolling mill _e Side speed V _o But vary. In addition, if the tension changes, the rolling load P, the outlet-side sheet thickness h, and the inlet-side velocity V _e Side speed V _o And (3) a change. Therefore, the rolling phenomenon is to make the thickness H of the entering side plate and the speed V of the working roll _R And the nip S as input, taking the entrance side tension T _b Tension T at the outlet side _f And a complicated phenomenon in which the thickness h of the outlet side plate is outputted, and the rolling phenomenon in the front and rear rolling mills is also associated with the tension, and thus is very complicated.

The description returns to fig. 1. Each of the rolling mills 11 to 14 is provided with driving devices 21 to 24 for driving the work rolls and nip control devices 31 to 34 for controlling the nips of the work rolls 1. The driving devices 21 to 24 include, for example, a motor (not shown) for driving the work roll 1 and a motor speed control device (not shown) for controlling the speed of the work roll by operating the motor.

Further, plate thickness gauges 41 to 44 for measuring the plate thickness of the rolled material 200 and tension gauges 51 to 54 for measuring the tension applied to the rolled material 200 are provided on the exit sides of the rolling mills 11 to 14. The plate thickness of the rolled material 200 is particularly important from the viewpoint of the quality of the product produced by rolling the rolled material 200. In addition, the tension applied to the rolled material 200 for the stability of the rolling operation is particularly important, and also the accuracy of the plate thickness.

An exit-side tension roller 15 that generates an exit-side tension of the rolling mill 14 is provided on the exit side of the rolling mill 14. A drive 25 is provided on the exit-side tension roller 15. The driving device 25 includes, for example, a motor (not shown) that drives the exit-side tension roller 15 and a motor speed control device (not shown) that operates the motor and controls the rotational speed of the exit-side tension roller 15.

Further, each of the rolling mills 11 to 14 is provided with plate thickness control devices 61 to 64 and tension control devices 71 to 74 as plant control devices for controlling the rolling process.

The plate thickness control device 61 corresponding to the rolling mill 11 controls the roll gap of the rolling mill 11 by using the roll gap control device 31 to control the plate thickness on the outlet side of the rolling mill 11. The plate thickness control devices 62 to 64 corresponding to the rolling mills 12 to 14 control the plate thicknesses on the outlet sides of the rolling mills 12 to 14 by controlling the speeds of the working rolls of the rolling mills 11 to 13 in the former stage, that is, the speeds of the former stage, using the driving devices 21 to 23 of the rolling mills 11 to 13 in the former stage.

The plate thickness control devices 62 to 64 perform feedforward control using the detection results of the plate thickness meters 41 to 43 on the entry side of the corresponding rolling mills 12 to 14 (plate thickness meters on the exit side of the preceding rolling mills 11 to 13), and feedback control using the detection results of the plate thickness meters 42 to 44 on the exit side of the corresponding rolling mills 12 to 14. For example, in the case of the plate thickness control device 62, feedforward control using the detection result of the plate thickness meter 41 and feedback control using the detection result of the plate thickness meter 42 on the output side are performed.

The tension control devices 71 to 73 control the roll gap of the subsequent rolling mill 12 to 14 by using the roll gap control devices 32 to 34 of the subsequent rolling mill 12 to 14 based on the detection results of the tension meters 51 to 53 on the exit side of the corresponding rolling mill 11 to 13, and control the exit side tension of the corresponding rolling mill 11 to 13. For example, in the case of the tension control device 71, the nip of the rolling mill 12 is controlled based on the detection result of the tension meter 51 on the exit side of the rolling mill 11. The tension control device 74 controls the rotation speed of the exit-side tension roller 15 using the driving device 25 based on the detection result of the corresponding exit-side tension meter 54 of the rolling mill 14, thereby controlling the exit-side tension of the rolling mill 14.

Next, the plate thickness control performed by the plate thickness control devices 61 to 64 will be described in more detail. In the plate thickness control, the rolling mill for plate thickness change and the plate thickness gauge for detecting the plate thickness are physically separated. Therefore, there is a dead time from when the deviation of the plate thickness of the entry side of the rolled material 200 is detected to when the position reaches the rolling mill that performs the actual control operation. Further, there is also a dead time until the plate thickness changed by the rolling mill is detected by the plate thickness meter on the output side.

Fig. 4 is a diagram for explaining an example of the plate thickness control, and shows a configuration example of the plate thickness control device 64 corresponding to the #4 rolling mill 14. In the example of fig. 4, the plate thickness meter 43 measures and outputs a deviation of the exit side plate thickness of the #3 rolling mill 13 from the target value as an entrance side plate thickness deviation Δh, and the plate thickness meter 44 measures and outputs a deviation of the exit side plate thickness of the rolling mill 14 from the target value as an exit side plate thickness deviation Δh. Each target value is preset.

The sheet thickness control device 64 includes a transfer time compensation unit 201 that corrects the dead time from the sheet thickness gauge on the inlet side to the rolling mill, a feedforward control unit 202, a proportional circuit 203, and an integral circuit 204.

The transfer time compensation unit 201 performs phase shift by a phase shift amount T on the input-side plate thickness deviation Δh output from the plate thickness meter 43 on the output side of the #3 rolling mill 13 _FF And (3) transferring phase displacement. Using transfer time T _X3D-4 And a control output timing shift amount (hereinafter, simply referred to as timing shift amount) Δt for feedforward control _FF From T _FF ＝T _X3D-4 -ΔT _FF Representing the phase displacement T _FF . Transfer time T _X3D-4 The time taken for the portion of the rolled material 200 having the thickness deviation Δh of the inlet plate to move from the plate thickness gauge 43 to the position immediately below the work roll 1 of the rolling mill 14 is shown. The timing shift amount DeltaT is determined based on the dead time until the control output 230 reaches the driving device 23, the response time until the control output 230 is input to the driving device 23, and the like, which correspond to the input-side plate thickness deviation DeltaH _FF 。

The feedforward control section 202 multiplies the thickness deviation Δh of the inlet plate subjected to the transfer process by the transfer time compensation section 201 by the control gain G _FF And generates a feedforward control output 210.

The proportional circuit 203 and the integral circuit 204 constitute a feedback control section that performs feedback control. The proportional circuit 203 multiplies the outlet plate thickness deviation Δh measured by the outlet plate thickness gauge 44 of the rolling mill 14 by the control gain G _FB And output. The integrating circuit 204 performs an integrating process on the output of the proportional circuit 203 to generate a feedback control output 220. This isIn this case, the control gain G is determined in consideration of dead time from the rolling mill to the exit-side plate thickness gauge _FB 。

The feedforward control output 210 and the feedback control output 220 are added to each other, and are input to the driving device 23 of the rolling mill 13 as the control output 230 of the sheet thickness control device 64.

Next, tension control by the tension control devices 71 to 74 will be described in more detail. The tensiometer directly detects the tension applied to the material to be rolled, and therefore, it is unnecessary to consider dead time. Thus, basically only the feedback control is implemented. Fig. 5 is a diagram for explaining an example of tension control, and shows a configuration example of the tension control device 73 corresponding to the #3 rolling mill 13.

In the example of fig. 5, the tension control device 73 has a proportional integration portion 301. The proportional-integral unit 301 uses the actual tension value T, which is the tension measured by the tension meter 53 disposed on the exit side of the rolling mill 13 _34FB And a tension command value T inputted from outside _34REF Deviation deltat of (1) ₃₄ Proportional integral control of the rolling mill 14 is performed. Specifically, the proportional-integral unit 301 calculates the deviation Δt ₃₄ The proportional-integral process is performed to generate a control output 310 of the tension control device 73, which is input to the roll gap control device 34 of the rolling mill 14. The proportional-integral control is a control in which proportional control and integral control are combined, and here, the proportional gain of the proportional control is set to C _P The integral gain of the integral control is set as C ₁ 。

As described above, the plate thickness control performed by the conventional tandem rolling mill 100 is a control in which feedforward control as proportional control and feedback control as integral control are combined. The tension control is feedback control using proportional-integral control.

In general, in the integral control of the control state quantity, which is a state quantity related to the control object, the phase of the control output is shifted by 90 degrees from the phase of the control state quantity, and therefore, as a result, there is a problem in that the phase of the control result obtained by the integral control is shifted from the phase of the original control state quantity. For example, in the tandem rolling mill 100, the phase of the plate thickness (plate thickness deviation) on the outlet side of the rolling mill 14 as a result of control is shifted from the phase of the original deformation resistance (hardness). As a result, appropriate control according to the deformation resistance cannot be performed, and the control effect of the feedforward control is reduced.

Therefore, in the case of implementing the feedforward control, as shown in fig. 4, the control gain G in the feedforward control is set _FF And a phase shift amount T _FF (specifically, the timing shift amount DeltaT) _FF ) By adjusting the phase to an appropriate value, a feedforward control output is generated that matches the phase and amplitude of the control state quantity, thereby improving the control effect. These appropriate values vary depending on parameters related to the control object, other controls to be performed on the control object, and the like. In the case of the tandem rolling mill 100, the rolling speed at which the material 200 to be rolled is set as a parameter related to the control target. When the rolling speed is changed, the frequency of variation of the plate thickness deviation is changed, and the response time of the driving device 23, which is the control operation end based on the control output, is changed. Further, as other control, there is exemplified plate thickness control and the like performed on other rolling mills.

However, in the case of implementing both the feedforward control and the feedback control as in the tandem rolling mill 100, since the phase change of the state quantity is controlled by the feedback control as the integral control, it is difficult to adjust the control gain and the phase shift quantity in the feedforward control to appropriate values.

The problems of the conventional plant control system that implements both feedforward control and feedback control will be described in more detail below.

Fig. 6 is a diagram showing an outline of a conventional plant control system. The conventional plant control system shown in fig. 6 (a) includes a control device 501 that controls the control target plant 500, and a phase shift factor 502 that causes a state quantity xFB, which is a state quantity related to the control target and is output from the control target plant 500, to perform a phase shift by detecting a dead time corresponding quantity. The control device 501 further includes a PI control device 511, and the PI control device 511 performs proportional integral control on the control target plant 500 based on a deviation between the state quantity actual result xFB and a state quantity command value xREF, which is a command value of a state quantity inputted from the outside.

The state quantity actual result xFB has a deviation error due to the influence of modeling error, disturbance, and the like of the control target plant 500. The integral control included in the proportional-integral control of PI control device 511 is a control for correcting the deviation error of state quantity actual result xFB and maintaining state quantity actual result xFB at state quantity command value xREF.

In the conventional plant control system shown in fig. 6 (b), the difference is that the control device 501 includes an I control device 521 that performs integral control (feedback control) on the control target plant 500 and an FF control device 522 that performs feedforward control on the control target plant 500, instead of the PI control device 511, as compared with the example shown in fig. 6 (a).

The plant control system shown in fig. 6 (b) corresponds to the plate thickness control in the rolling mill. In comparison with fig. 4, the control disturbance source 550 is set to control disturbance dACT by detecting the deviation of the thickness of the inlet plate of the rolling mill by the inlet plate thickness meter 43. The FF control device 522 corresponds to the transfer time compensation unit 201 and the feedforward control unit 202, and the I control device 521 corresponds to the proportional circuit 203 and the integral circuit 204.

In the example of fig. 6 (b), the control disturbance dACT, which is the disturbance to the control target plant 500 generated by the control disturbance source 550, is known. When the control disturbance dACT is known in this way, the FF control device 522 performs feedforward control on the control target plant 500 based on the deviation between the control disturbance dACT and the disturbance command value dREF for the control disturbance dACT. The I control device 521 performs integral control on the control target plant 500 based on the deviation between the state quantity actual result xFB and the state quantity command value xREF.

The above-described dead time is generated by the fact that the control target plant 500 performs processing on the material and the location where the result of the processing is detected are physically separated from each other. In the tandem rolling mill 100, as shown in fig. 2, rolling mills 11 to 14 for rolling the material to be rolled 200 and plate thickness meters 41 to 44 for detecting the plate thickness of the material to be rolled 200 are physically separated, and the material to be rolled 200 is transferred from the rolling mills 11 to 14 to the plate thickness meters 41 to 44, and the result (plate thickness) of the material to be rolled 200 is detected. The time required for transferring the rolled material 200 becomes a detection dead time.

In this way, in the conventional plant control system, feedback control including integral control is performed to remove the deviation error. The integration control is a control in which the control output is caused to have a phase delay of 90 degrees from the control state quantity and a phase delay based on the sum of the phase delays of the detection dead time, and if the control output becomes large, interference occurs with the control output of the feedforward control, and the phase shift quantity of the feedforward control is shifted from the set value. As a result, the control effect of the feedforward control is reduced.

In the conventional plant control system, as shown in fig. 6 (b), a timing of switching between the start and end of the control output of the feedforward control and a timing of switching on/off of the mode switch 531 for starting the control device for performing the feedforward control are different from each other, and depending on the timing, a deviation error may occur even if the feedback control is used. In the plant control device of the present embodiment to be described below, these problems can be solved. The mode switch 531 is provided on a field operation panel 532 provided on the field of the control target plant 500, and is operated by an operator or manager of the control target plant 500, for example.

Fig. 7 is a diagram showing a plant control device according to embodiment 1 of the present disclosure. Fig. 7 shows a control device 601 for controlling a plant 600 to be controlled as a plant control device.

The control target plant 600 is a control target of the control device 601, and is, for example, a plant for performing a processing treatment for processing a processing target such as a material. The control target plant 600 outputs a state quantity actual result xFB, which is a state quantity related to the control target. The control target plant 600 is, for example, a tandem rolling mill including rolling mills 11 to 14 for processing a material to be rolled by rolling. In this case, the state quantity result xFB is at least one of a plate thickness of the material to be rolled and a tension applied to the material to be rolled, and the processing is, for example, a rolling process for rolling the material to be rolled.

In the state quantity result xFB, a phase shift occurs due to the phase shift factor 602. The phase shift factor 602 is, for example, a physical distance between a location where the control target plant 600 performs machining on the material and a location where the state quantity result xFB as a result of the machining is detected. In fig. 7, the phase shift factor 602 exists outside the control target plant 600, but may also exist inside the control target plant 600.

The control target plant 600 is also affected by the control disturbance dACT, which is the disturbance to the control target plant 500 generated by the control disturbance source 603. Therefore, the control disturbance dACT becomes a fluctuation factor that fluctuates the state quantity result xFB. Control interference dACT is known. More specifically, at least a statistical value such as an average value of the control interference dACT is known.

The control device 601 includes an FF control device 611 and an on/off timing decision device 612.

The FF control device 611 is a first control unit that performs feedforward control of the processing (for example, rolling processes by the rolling mills 11 to 14) performed by the control target plant 600, using feedforward control output that is control output corresponding to the disturbance deviation, which is the deviation between the disturbance dACT and the disturbance command value dREF. The FF control means 611 starts and ends the timing of the feedforward control is adjusted by the on/off timing determination means 612. The disturbance deviation is a factor value related to a control disturbance dACT, which is a fluctuation factor that fluctuates the state quantity actual result xFB.

The on/off timing determination device 612 is a determination unit that determines the timing at which the FF control device 611 starts and ends the feedforward control based on the state quantity result xFB. In the present embodiment, when the on/off of the mode switch 621 for starting the FF control device 611 is switched, the on/off timing determination device 612 determines the timings of starting and ending the feedforward control based on the state quantity result xFB. The mode switch 621 is provided on a field operation panel 532 provided on the field of the control target plant 600, for example. The control target plant 600 is operated by an operator, a manager, or the like.

Fig. 8 is a diagram showing an example of the FF control device 611 and an FF control device 522 of a conventional plant control system as a comparative example thereof. Specifically, (a) in fig. 8 shows an example of the FF control device 611, and (b) in fig. 8 shows the FF control device 522.

The FF control device 611 shown in fig. 8 (a) includes: a differential circuit 701, a multiplier 702, and an integrating circuit 703.

The differential circuit 701 outputs a differential between the interference dACT and the interference command value dREF. Specifically, the differential circuit 701 includes a delay circuit 711 that delays the disturbance deviation by a unit time (for example, the period when the control disturbance dACT periodically changes), and outputs a value obtained by subtracting the signal delayed by the delay circuit 711 from the original disturbance deviation as a difference in the disturbance deviation.

Multiplier 702 multiplies the output signal from differential circuit 701 by control gain G _FF And output. The integrating circuit 703 integrates the output signal from the multiplier 702 as a feedforward control output S _FFNEW And outputting.

In the above configuration, the FF control device 611 starts and ends the timing of the feedforward control, that is, switches the feedforward control output S as the control output of the FF control device 611 _FFNEW The on/off switching timing of the mode switch 621 is determined by the on/off timing determining means 612 in accordance with the on/off switching of the mode switch. In the present embodiment, the on/off timing determination device 612 outputs the feedforward control output S _FFNEW When on, the control gain G of the multiplier 702 is set to _FF Set to 1, at the feedforward control output S _FFNEW If the switch is turned off, the control gain G of the multiplier 702 is set to _FF Set to 0, thereby controlling the feedforward control output S _FFNEW Is set in the above-described manner.

As will be described later, by appropriately setting the feedforward control output S _FFNEW Is switched between (a) and (b)The timing can correct the deviation error generated in the state quantity. In addition, as long as the feedforward control output S can be appropriately adjusted _FFNEW Based on the feedforward control output S of the on/off timing determination means 612 _FFNEW The control method of the switching timing of (a) is not limited to the above-described example.

The FF control device 522 shown in fig. 8 (b) includes: a differential circuit 701a, a multiplier 702a, and an integrating circuit 703a. The differential circuit 701a has a delay circuit 711a. The differential circuit 701a, the multiplier 702a, the integrating circuit 703a, and the delay circuit 711a have the same functions as the differential circuit 701, the multiplier 702, the integrating circuit 703, and the delay circuit 711 shown in fig. 8 (a). However, the FF control device 522 does not have a configuration corresponding to the on/off timing determination device 612 shown in fig. 8 (a), and the feedforward control output S of the FF control device 522 is switched _FFNEW The on/off switching timing of (a) is the same as the on/off timing of the switching mode switch 531. That is, when the mode switch 531 is turned on, the control gain G of the multiplier 702 _FF 1, when the mode switch 531 is turned off, the control gain G of the multiplier 702 _FF Is 0.

Fig. 9 is a diagram showing an example of the on/off timing determination device 612. The on/off timing determination device 612 shown in fig. 9 has a state quantity deviation measurement device 801 and an on/off timing calculation device 802.

The state quantity deviation measuring device 801 obtains the maximum value x, which is the positive peak value of the deviation between the state quantity actual result xFB and the state quantity command value xREF as the target value, in a fixed period (for example, one cycle of control disturbance dACT) ₊ And a negative peak value, i.e. minimum value x _- . The state quantity deviation measuring device 801 is based on the maximum value x ₊ Minimum value x _- To calculate the central value (maximum value x ₊ Minimum value x _- Mid-point of (c) relative to a reference value _DIFF And amplitude Deltax _ACT ＝x ₊ -x _- . The reference value is 0 in the present embodiment, and the deviation Δx _DIFF Is Deltax _DIFF ＝(x ₊ +x _- )/2. Furthermore, the deviationΔx _DIFF The error amount of the deviation error of the state quantity actual result xFB is shown.

The on/off timing calculation device 802 calculates the deviation Δ of the central value calculated by the state quantity deviation measurement device 801 _xDIFF Amplitude delta _xACT And controlling amplitude delta of interfering dACT _dACT Calculate the feedforward control output S of the FF control device 611 _FFNEW Is set in the above-described manner.

Specifically, first, the on/off timing calculation device 802 calculates a value of α=Δx _DIFF /Δx _ACT To calculate the amplitude Deltax of the central value relative to the state quantity result xFB _ACT Deviation deltax of (a) _DIFF Is a ratio alpha of (a).

Next, the on/off timing calculation device 802 determines the feedforward control output S of the FF control device 611 based on the ratio α _FFNEW Is set in the above-described manner. Specifically, the on/off timing calculation device 802 will cause the feedforward control output S to _FFNEW The timing determination for switching on is the control of the offset d of the interfering dACT _T Satisfy d _T ＝(-α)·Δ _dACT Will cause the feedforward control output S _FFNEW Determination of timing for disconnection as control deviation d of interfering dACT _T Satisfy d _T ＝α·Δ _dACT Is set in the above-described patent document. Since the feedforward control is a control for a known control disturbance dACT, the amplitude Δ of the control disturbance dACT can be calculated in advance _dACT For example, the on/off timing calculation device 802 can be held.

In this case, the amplitude Δx of the central value with respect to the state quantity result xFB _ACT Deviation deltax of (a) _DIFF If the value is positive, the control of timing to start feedforward control interferes with the dACT deviation d _T Negative, control of timing to stop feedforward control interferes with dACT deviation d _T Is positive.

On the other hand, the deviation Δ of the amplitude Δxact of the central value with respect to the state quantity actual result xFB _xDIFF If negative, the timing to start feedforward control interferes with dACT deviation d _T In the positive direction, the timing of stopping the feedforward control interferes with the dACT deviation d _T Is negative.

When the mode switch 621 of the FF control device 611 is on, the on/off timing calculation device 802 monitors the control disturbance dACT, and waits until the deviation d of the control disturbance dACT is detected _T After the determined switching timing, the control gain G of the multiplier 702 of the FF control device 611 is set _FF Set to 1, the feedforward control output S of the FF control device 611 _FFNEW Is set to be on. If the mode switch 621 of the FF control device 611 is off, the on/off timing calculation device 802 monitors the control disturbance dACT, and waits until the deviation d of the control disturbance dACT is detected _T After the determined switching timing, the control gain G of the multiplier 702 of the FF control device 611 is set _FF Set to 0, the feedforward control output S of the FF control device 611 _FFNEW Is disconnected.

Fig. 10 to 12 are diagrams for explaining an example of the control result of the simulation-based control device 601. Fig. 10 to 12 show control disturbance dACT and state quantity actual result xFB (specifically, deviation between state quantity actual result xFB and state quantity command value xREF). The horizontal axis is the elapsed time (seconds) from an arbitrary point in time.

Fig. 10 is a diagram showing the control disturbance dACT and the state quantity actual result xFB when the feedforward control is started at a point of time of 6 seconds shown by an arrow in the conventional control device 501 shown in fig. 6 (b). In fig. 10 (a), the control disturbance dACT and the state quantity actual score xFB are positive at the time point of 6 seconds when the feedforward control is started, and in fig. 10 (b), the control disturbance dACT and the state quantity actual score xFB are both 0 at the time point of 6 seconds when the feedforward control is started.

In the case of fig. 10 (a), the state quantity result xFB is a state in which there is almost no deviation error until 6 seconds, but is deviated to the positive side after 6 seconds. In the case of fig. 10 (b), the state quantity result xFB is a state in which there is almost no deviation error even before 6 seconds or after 6 seconds.

Fig. 11 shows a control disturbance dACT and a state quantity actual result xFB in the case where the feedforward control is ended at a point of time of 6 seconds indicated by an arrow in the conventional control device 501 shown in fig. 6 (b). In fig. 11 (a), the control disturbance dACT and the state quantity actual result xFB are negative at the time point of 6 seconds when the feedforward control is ended, and in fig. 11 (b), the control disturbance dACT and the state quantity actual result xFB are both 0 at the time point of 6 seconds when the feedforward control is ended.

In the case of fig. 11 (a), the state quantity result xFB is a state in which there is almost no deviation error until 6 seconds, but is deviated to the positive side after 6 seconds. In the case of fig. 11 (b), the state quantity result xFB is a state in which there is almost no deviation error even before 6 seconds or after 6 seconds.

As shown in fig. 10 and 11, when the deviation of the state quantity actual result xFB is in the vicinity of 0, if the on/off of the feedforward control is switched at a timing when the control disturbance dACT is in the vicinity of 0, the deviation of the state quantity actual result xFB remains unchanged in the vicinity of 0, but if the on/off of the feedforward control is switched at other timings, a deviation error occurs in the state quantity actual result xFB.

Fig. 12 is a diagram showing the control disturbance dACT and the state quantity actual result xFB when the feedforward control is started in the control device 601 of the present embodiment shown in fig. 7 and the conventional control device 501 shown in (b) in fig. 6. Fig. 12 (a) shows a control disturbance dACT and a state quantity actual result xFB in the control device 601 of the present embodiment, and fig. 12 (b) shows a control disturbance dACT and a state quantity actual result xFB in the conventional control device 501. In a state before the start of the feed-forward control, the state quantity actual result xFB is deviated to the negative side. The mode switches 531 and 621 (in fig. 12, simply referred to as mode switches) are turned on (H level) at a timing between 4 seconds and 6 seconds when the control disturbance dACT and the state quantity result xFB reach the peak.

In the conventional control device 501 shown in fig. 12 (b), the control gain G of the multiplier 702 is controlled at the timing when the mode switch 531 is on _FF Since 1, the state quantity result xF deviates to the positive side.

In contrast, in the control device 601 of the present embodiment shown in fig. 12 (a), the on/off timing determination device 612 starts the feedforward control at a timing of 6 seconds corresponding to the above-described switching timing in accordance with the control disturbance dACT and the state quantity actual result xFB. In this case, the amplitude and the deviation error of the state quantity result xFB are reduced.

As described above, according to the present embodiment, the FF control device 611 performs the feedforward control of the control target plant 600 using the control output according to the disturbance deviation. The on/off timing determination device 612 adjusts the timing at which the FF control device 611 performs feedforward control based on the state quantity actual results xFB concerning the control target plant 600. Therefore, since the feedforward control can be performed at the timing of suppressing the deviation error, the deviation error can be suppressed without using the feedback control.

In the present embodiment, the on/off timing determination device 612 determines the deviation Δx of the central value of the deviation of the state quantity actual result xFB from the state quantity command value xREF from the reference value _DIFF The FF control device 611 adjusts the timing of performing the feedforward control. Deviation Deltax _DIFF Since the deviation error is represented, the timing of performing the feedforward control can be appropriately adjusted according to the deviation error, and therefore the deviation error can be more appropriately suppressed.

In particular, in the present embodiment, the reference value is zero, and the on/off timing determination means 612 is at the deviation Δx _DIFF If the disturbance deviation is positive, the feedforward control is started at a timing when the disturbance deviation is negative, and the deviation Δx is calculated _DIFF If negative, the feedforward control is started at the timing when the disturbance deviation is positive. The on/off timing determination device 612 is set to be at the deviation Δx _DIFF If the disturbance deviation is positive, the feedforward control is ended at the timing when the disturbance deviation is positive, and the deviation Δx is calculated _DIFF If the disturbance deviation is negative, the feedforward control is ended at the timing when the disturbance deviation is negative. Therefore, the feedforward control can be started and ended at appropriate timings at which the deviation error is reflected, and therefore the deviation error can be suppressed more appropriately.

Example 2

In embodiment 1, an example is described in which the timing at which the FF control device 611 performs feedforward control is adjusted in accordance with the on/off switching of the mode switch of the FF control device 611. However, the timing of performing the feedforward control is not limited to the switching of on/off of the mode switch. For example, feedforward control may be performed in response to external factors such as a disturbance detector used for feedforward control and a state (normal or abnormal) of a control operation end. In this case, particularly when an abnormality occurs in the disturbance detector or the control operation end, it is preferable to switch the on/off of the feedforward control as quickly as possible in order to suppress a malfunction of the control target plant 500 or the like. In this embodiment, a control device corresponding to the present subject will be mainly described.

Fig. 13 is a diagram showing a plant control device according to embodiment 2 of the present disclosure. The plant control device 900 shown in fig. 13 includes: control device 601, control device 901, and selection device 902 shown in fig. 7.

The control device 901 is a second control unit having the same function as the conventional control device 501 shown in fig. 6 (b). Specifically, the control device 901 performs feedforward control of the machining process performed by the control target plant 600 using a control output obtained by multiplying the disturbance deviation by the control gain, and performs integral control of the machining process performed by the control target plant 600 using a control output obtained by integrating the deviation between the state quantity actual result xFB and the state quantity command value xREF.

The selection device 902 causes either one of the control devices 601 and 901 to execute control of the processing performed by the control target plant 600, based on a predetermined external factor. The predetermined external factor is, for example, the state of 1 or more predetermined devices (detector, operation end, etc.) used in the control target plant 600, plant control device 900, etc.

For example, the selection device 902 causes the control device 601 to execute when all the predetermined devices are normally operated, and causes the control device 901 to execute when any one of the predetermined devices is abnormal so as to switch the on/off of the control output as soon as possible.

As described above, in the present embodiment, the control target plant 600 can be controlled using an appropriate control device.

The embodiments of the present disclosure described above are illustrative examples for explaining the present disclosure, and the scope of the present disclosure is not limited to only these embodiments. Those skilled in the art will be able to practice the invention in other various ways without departing from its scope.

Further, the present disclosure can be applied to the tandem rolling mill 100 as an example. The present disclosure is applicable to plants other than the tandem rolling mill 100, particularly plants that have large control disturbances and require feedforward control. For example, the present disclosure can be applied to other plants such as plate thickness control in a hot rolling mill and tension control in a steel production line.

The examples of the present disclosure described above are illustrative of the present disclosure, and the scope of the present disclosure is not limited to the embodiments. Those skilled in the art can practice the disclosure in other various ways without departing from the scope thereof.

Claims

1. A rolling mill control device for controlling a process performed by a control object according to a factor value related to a fluctuation factor for fluctuating a state quantity related to the control object,

the rolling mill control device comprises:

a first control unit that performs feedforward control of the process using a control output corresponding to the factor value;

a determining unit that adjusts timing at which the first control unit performs the feedforward control, based on the state quantity;

a second control unit that performs feedforward control of the process using a control output for determining a timing for the factor value, and performs integral control of the process using a control output obtained by integrating a deviation of the state quantity from a target value; and

and a selection unit that causes one of the first control unit and the second control unit to execute control of the process according to a predetermined external factor.

2. A rolling mill control device according to claim 1, wherein,

the determination unit adjusts the timing based on a deviation of a central value of the deviation of the state quantity from a target value from a reference value.

3. A rolling mill control device according to claim 2, wherein,

the reference value is zero.

4. A rolling mill control device according to claim 3, wherein,

the determination unit starts the feedforward control at a timing when the factor value is negative when the deviation is positive, and starts the feedforward control at a timing when the factor value is positive when the deviation is negative.

5. A rolling mill control device according to claim 3, wherein,

the determination unit ends the feedforward control at a timing when the factor value is positive, and ends the feedforward control at a timing when the factor value is negative, when the deviation is positive.

6. A rolling mill control device according to claim 1, wherein,

the control object is a rolling mill for processing a material to be rolled by rolling,

the state quantity is at least one of a plate thickness of the material to be rolled and a tension applied to the material to be rolled,

the process is a rolling process of rolling the material to be rolled.

7. A rolling mill control method performed by a rolling mill control device that performs control of a process performed by a control object based on a factor value related to a fluctuation factor that fluctuates a state quantity related to the control object, the rolling mill control method comprising:

a first control step of performing feedforward control of the process using a control output corresponding to the factor value;

an adjustment step of adjusting timing of performing the feedforward control in accordance with the state quantity;

a second control step of performing feedforward control of the process using a control output for determining timing of the factor value, and performing integral control of the process using a control output obtained by integrating a deviation of the state quantity from a target value;

and a selection step of executing control of the process based on one of the first control step and the second control step, in accordance with a prescribed external factor.