JP2014029617A - Plant control device, plant control method and plant control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably perform gain setting when a state quantity command largely changes in a feedback control system.SOLUTION: A plant control device for performing feedback control on the basis of the state quantity deviation of a plant to be controlled includes: an inter-stand tension control section 10 for performing feedback control of at least one of proportional control, integral control and differential control based on a state quantity deviation; a steady-state deviation compensation device 201 for performing the integral control of a control gain which is lower than a control gain by the inter-stand tension control section 10 on the basis of the state quantity deviation; a control operation restriction device 200 for, when the absolute value of the state quantity deviation is equal to or less than a predetermined value, restricting the feedback control by the inter-stand tension control section 10, and makes the steady-state deviation compensation device 201 execute the integral control; and a control gain correction device 203 for adjusting the control gain of the inter-stand tension control section 10 on the basis of the control response of the plant to be controlled to the integral control by the steady-state deviation compensation device 201.

Description

  The present invention relates to a plant control device, a plant control method, and a plant control program, and more particularly to adjustment of a control gain in a state where a state quantity deviation is large.

  As shown in FIG. 17, the plant control is performed by detecting or predicting the actual state quantity of the plant to be controlled 300 by some means and controlling it by the control device 301 so that it matches the state quantity command. The control device 301 generally performs PID (Proportional Integral Derivative) control. PID control includes proportional control, integral control, and differential control, but in practice, necessary functions are used in combination according to the characteristics of the plant 300 to be controlled and the required control characteristics.

  There are various types of plants to be controlled by plant control. For example, there is a hot tandem rolling mill. In a hot tandem rolling mill, the rolling operation is performed by controlling the tension and rolling load applied to the material to be rolled using the roll gap, which is the interval between the upper and lower work rolls, and the roll speed of the equipment before and after the rolling mill. Is called.

  A looper that supports the material to be rolled between the stands is installed between the rolling mill stands. This looper pushes the material to be rolled between the stands, whereby the tension of the non-rolled material changes. The tension of the material to be rolled can be detected by measuring the pressure of the material to be rolled applied to the looper. The height at which the looper supports the material to be rolled is controlled to a desired height by the pressure from the hydraulic cylinder. In this control, proportional-integral control is used. In order to prevent the material to be rolled from sagging between the rolling mill stands and to prevent a reduction in sheet width due to over tension, tension control is necessary. For this reason, tension control is performed using proportional integral control.

  As a technique of such a control system, there has been proposed a method of switching between prior control by open loop and proportional integral feedback control (for example, see Patent Document 1). According to the technique disclosed in Patent Document 1, it is possible to avoid the difficulty of gain setting related to load followability in feedback control by using advance control by open loop, and feedback from the open loop if the deviation is within a predetermined range. Although the load followability is prevented from being deteriorated by switching to the control, it is premised that the feedback control is not used when the deviation is large.

Japanese Patent Laid-Open No. 9-209712

  A plant to be controlled such as a production facility in a factory in plant control may have to stop operation when the control becomes abnormal. When such a situation occurs, the production activity at the control target plant is suspended, so that the effect to be generated becomes large, for example, when the product cannot be provided to the customer or the production in the subsequent process is affected. Therefore, control abnormalities in plant control must be avoided.

  For example, in a hot tandem rolling mill, since the material to be rolled having various product specifications is rolled, the characteristics of the control target plant 300 are varied, and the control gain of the control device 301 is varied. Therefore, it is necessary to set the control gain according to the product specifications. However, the control device 301 is not accurate because the model of the rolling phenomenon that is the plant 300 to be controlled and the parameters such as deformation resistance, friction coefficient, and plate temperature used in the model are inaccurate. There is a problem that the error in setting the control gain is large.

  FIG. 18 shows the difference in response due to the control gain when the state quantity command is changed stepwise. As shown in FIG. 18, if the control gain setting to the plant control device 301 is not appropriate, it takes time for the state quantity result to match the state quantity command (when the control gain is too small), or the state quantity oscillates. Or it diverges (in the case of excessive control gain). In any of these cases, the product quality in the controlled plant is affected.

  Therefore, when the state of the controlled object changes and the state quantity deviation becomes large as a result, for example, when the controlled object plant 300 is newly started up or when production of a new product is started, the control device 301 is increased. It takes a lot of time to adjust, and there is a possibility that production of the control target plant is stopped due to control failure caused by excessive or excessive control gain, or product failure occurs.

  The problem to be solved by the present invention is that when a control target plant is newly started up or production of a new product is started, operation such as product failure or production stoppage due to excessive or insufficient control gain of the control device 301 An object is to provide a plant control method and a plant control apparatus that can prevent the occurrence of an abnormality and simultaneously adjust the control gain of the control apparatus 301 automatically.

  The present invention addresses the above-described problem, and an object of the present invention is to suitably perform gain setting when the state of a controlled object changes greatly in a feedback control system.

  One aspect of the present invention is a plant control device that performs feedback control based on a state quantity deviation of a plant to be controlled, and includes at least one of proportional control, integral control, and differential control based on the state quantity deviation. A first control unit that performs control, a second control unit that performs integral control of a control gain lower than the control gain of the first control unit based on the state quantity deviation, and an absolute value of the state quantity deviation is A control switching unit that restricts feedback control by the first control unit and causes the second control unit to perform integral control when the value is equal to or less than a predetermined value; and the control for integral control by the second control unit. A gain adjusting unit that adjusts a control gain of the first control unit based on a control response of a target plant.

  According to another aspect of the present invention, there is provided a first control unit that performs feedback control of at least one of proportional control, integral control, and differential control based on a state quantity deviation of a plant to be controlled; A plant control method for controlling the plant to be controlled by switching to a second control unit that performs integral control with a control gain lower than the control gain by the first control unit, the absolute value of the state quantity deviation being When the value is equal to or less than a predetermined value, the feedback control by the first control unit is limited, the second control unit is caused to perform integration control, and the control target of the control target for the integration control by the second control unit is controlled. The control gain of the first control unit is adjusted based on a control response of the plant.

  According to another aspect of the present invention, there is provided a first control unit that performs feedback control of at least one of proportional control, integral control, and differential control based on a state quantity deviation of a plant to be controlled; A plant control program for controlling the plant to be controlled by switching to a second control unit that performs integral control with a control gain lower than the control gain by the first control unit, the absolute value of the state quantity deviation being When the value is equal to or less than a predetermined value, the step of limiting the feedback control by the first control unit and causing the second control unit to perform integral control; and the control for the integral control by the second control unit And causing the information processing apparatus to execute a step of adjusting a control gain of the first control unit based on a control response of a target plant.

  By using the present invention, it is possible to suitably perform gain setting when the state of the controlled object greatly changes in the feedback control system.

It is a figure showing the whole rolling device composition concerning the embodiment of the present invention. It is a figure which shows operation | movement of the looper in the rolling apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the feedback control in a general rolling apparatus. It is a figure which shows the frequency response of the control gain in a general rolling apparatus. It is a figure which shows the convergence, oscillation, and divergence of the state quantity by the difference in control gain. It is a figure which shows the structure of the plant control which concerns on embodiment of this invention. It is a figure which shows the structure of the feedback control in the rolling apparatus which concerns on embodiment of this invention. It is a figure which shows the setting aspect of the control gain which concerns on embodiment of this invention. It is a figure which shows the response of the state quantity by the difference in the control gain which concerns on embodiment of this invention. It is a figure which shows the frequency response of the control gain in the rolling apparatus which concerns on embodiment of this invention. It is a figure which shows the response of the state quantity at the time of performing the steady deviation compensation which concerns on embodiment of this invention. It is a figure which shows the aspect of tension control which concerns on embodiment of this invention. It is a figure which shows the aspect of tension control which concerns on embodiment of this invention. It is a figure which shows the aspect of tension control which concerns on embodiment of this invention. It is a figure which shows the structure concerning learning of the control gain which concerns on embodiment of this invention. It is a figure which shows the hardware constitutions of the information processing apparatus which comprises the plant control apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the plant control which concerns on a prior art. It is a figure which shows the response of the state quantity deviation by the difference in the control gain which concerns on a prior art.

Embodiment 1 FIG.
Hereinafter, an embodiment of the present invention will be described taking tension control between rolling mill stands in a hot rolling mill as an example. FIG. 1 is a diagram showing a tension control system according to the present embodiment. As shown in FIG. 1, the inter-stand tension control unit 10 applies a tension applied to the material to be rolled 8 between the i-1 stand rolling mill 1 and the i stand rolling mill 2 of the hot tandem rolling mill to the looper 7. The roll speed of the i-1 stand rolling mill 1 is controlled by detecting the tension meter 9 installed and changing the speed command for the i-1 stand speed controller 11.

  The looper 7 has a looper arm 15 that can be rotated around a looper fulcrum 14 in a mechanically fixed position, and a hydraulic pressure for changing the position of the looper roll 16 by rotating the looper arm 15 around the looper branch 14. It comprises a cylinder 13 and a cylinder position detector 17 for detecting the cylinder position. The looper roll 16 receives tension applied to the material to be rolled 8 by pushing up the material 8 to be rolled. By measuring the force applied to the looper roll 16 with the tension meter 9, the inter-stand tension control unit 10 acquires the tension applied to the material 8 to be rolled.

  2A and 2B show the operation of the looper 7. When the material to be rolled tip 30 is between the i-1 stand rolling mill 1 and the i stand mill 2, the looper roll 16 collides with the material to be rolled 30 and the machine is damaged. As shown to Fig.3 (a), it waits in the position lower than the passage position of the to-be-rolled material 8. FIG. When the workpiece 30 reaches the i-stand rolling mill 2, the looper roll 16 moves to a position where the workpiece 8 is lifted as shown in FIG. The tension can be measured with the tension meter 9.

  Since the tension of the material 8 to be rolled is transmitted from the looper roll 16 to the hydraulic cylinder 13 via the looper arm 15, when the tension of the material 8 to be rolled fluctuates, a difference occurs between the pressure of the hydraulic cylinder 13 and the cylinder position changes. To do. As a result, the position of the looper roll 16 changes. Since the position fluctuation of the looper roll 15 becomes a tension fluctuation and affects the stability of the rolling operation, looper position control is performed to keep the position constant. The looper position control device 20 controls and controls the pressure of the hydraulic cylinder 13 using the cylinder position measured by the cylinder position detector 17 so that the position of the looper roll 16 is constant.

  FIG. 3 is a block diagram showing a configuration of tension control between stands in a conventional hot tandem rolling mill. The inter-stand tension control unit 10 outputs a control command to the i-1 stand speed control device 11 so as to remove the deviation between the tension command and the actual tension using proportional integral control, and the i-1 stand roll speed. To change. That is, in the present embodiment, the inter-stand tension control unit 10 functions as a first control unit. Note that feedback control by proportional control, integral control, and differential control can be used as the control by the first control unit. When the i-1 stand roll speed is changed, the actual tension is changed by the speed-tension response 31. This change is detected by the tension meter 9 and used as the actual tension.

  The fluctuation of the actual tension results in the fluctuation of the hydraulic cylinder 13 due to the plate tension-cylinder pressure 32 which is a mechanical system. When the pressure of the hydraulic cylinder 13 fluctuates, the cylinder position changes, and the looper mechanical system 35 causes the looper position to change. The inter-stand plate path length varies depending on the fluctuation, that is, the looper position-the inter-stand plate path length 34.

The plate length variation between the stands becomes a tension variation due to the plate length change-tension response 33, and the actual tension changes. Here, the speed-tension response 31 is expressed by the following formula (1), and the plate path length change-tension response 33 is expressed by the following formula (2).

  The speed-tension response 31 and the plate path length change-tension response 33 are due to a rolling phenomenon, and change depending on the material, sheet thickness, rolling speed, and the like (hereinafter referred to as a rolling schedule) of the material 8 to be rolled. Conversely, if these values are known, the response of the i-1 stand speed control device 11 can be measured and does not depend on the rolling schedule. Therefore, the setting of the control gain of the inter-stand tension control unit 10 is an example in FIG. Is possible as shown.

In general, it is considered that the order of T _sigma is the order of a few ms, 1 / T _sigma is greater than the response omega _n of the speed control system. Thus, Bode diagram of the loop transfer function to become as shown in FIG. 4, to set the crossover frequency at ω ≦ 1 / T _I. Here, assuming that ω _c = α / T _I (where α ≦ 1.0), the following equation (3) holds.

Therefore, the gain K _P of the inter-stand tension control unit 10 is expressed by the following formula (4).

Obtained in FIG. 4 shows a control response simulation result when the control gain K _P of the interstand tension controller 10 in accordance with the rolling schedule is excessive in FIG 5 (a) ~ (c) . 5A to 5C show control responses when a tension deviation disturbance (tension disturbance) is applied stepwise. FIG. 5A shows a control gain of 5 times and FIG. FIG. 5B shows a case where the actual tension is oscillated (vibrates while the amplitude is constant) 10.35 times, and FIG. 5C shows a case where the actual tension is 20 times the control gain diverges due to vibration.

From the above, in the inter-stand tension control unit 10 of the hot tandem rolling mill, it can be seen that the tension fluctuation oscillates or diverges when the control gain exceeds 10 times. The _KσV in the speed-tension response 31 differs depending on the rolling schedule, and it can be predicted that the difference may be larger than 10 times. Therefore, even when the control gain setting has an error, it can be stably controlled. A control method is required.

  FIG. 6 is a block diagram showing a configuration of the plant control according to the present embodiment with respect to the configuration of the conventional plant control shown in FIG. As shown in FIG. 6, in the plant control according to the present embodiment, in addition to the configuration included in the conventional plant control shown in FIG. 17, the control operation restriction device 200, the steady deviation compensation device 201, and the steady deviation compensation execution propriety A selection device 202, a control gain correction device 203, a control gain learning device 204, a control gain database 205, and a host computer 250 are provided.

  FIG. 7 is a block diagram illustrating a configuration of tension control between stands according to the present embodiment with respect to the configuration of tension control between stands shown in FIG. The control operation limiting device 200, the steady deviation compensation device 201, the steady deviation compensation execution availability selection device 202, the control gain correction device 203, the control gain learning device 204, and the control gain database 205 in the novel configuration described with reference to FIG. 7 is connected to the configuration of the conventional tension control between stands described in FIG.

The control action restriction device 200 sets a control deviation gain as shown in FIG. An output when a deviation gain is applied to a certain input is shown in the lower diagram of FIG. As shown in FIG. 8, while the tension deviation is ΔT _M2 to ΔT _M1 , the control operation limiting device 200 linearly changes from 1.0 to 0 while the tension deviation is ΔT _M1 and ΔT _M1 to ΔT _P1 . control gain is 0.0, between [Delta] T _P1 is [Delta] T _P2, are set to vary linearly from the control gain is 0 to 1.0.

  That is, in this embodiment, when the absolute value of the state quantity deviation is equal to or smaller than a predetermined value, the feedback control by the inter-stand quantity force control unit 10 that is the first control unit is limited, and a second control unit to be described later The steady-state deviation compensator 201, which is Further, when the control is switched, as shown in FIG. 8, the control gain on the first control unit side is gradually changed according to the value of the state quantity deviation. By adjusting the control gain in this way, it is possible to prevent the control from becoming unstable due to abrupt control switching.

Note that in FIG. 8, [Delta] T _M2 and [Delta] T _P2 is started to adjust the state variable deviation to be input to the interstand tension controller 10, the state amount error as state quantity deviation respectively [Delta] T _M1, approaches [Delta] T _P1 approaches zero In this way, ΔT _M1 and ΔT _P1 are restriction completion thresholds that completely eliminate the state quantity deviation input to the inter-stand tension control unit 10.

In FIG. 8, the case where ΔT _P1 = 0.3, ΔT _P2 = 0.6, ΔT _M1 = −0.3, and ΔT _M2 = −0.6 is taken as an example. From ΔT _M1 to ΔT _P1 , since the control gain = 0, it is substantially a dead band. Therefore, in the following description, it referred to as the dead band between [Delta] T _M1 of [Delta] T _P1.

  9A to 9B show changes in control response when a control deviation gain is added as the control action limiting device 200. FIG. FIG. 9A shows a case of a conventional control system, in which case oscillation occurs as shown in the figure. On the other hand, FIG. 9B is a diagram showing a case where the control operation limiting device 200 is used, and in this case, oscillation is suppressed as shown in the figure. On the other hand, in the case of FIG. 9B, a steady deviation of +0.3 remains because a dead band occurs and tension control is not performed within a control deviation of ± 0.3 where the control gain becomes zero. The steady deviation compensator 201 is provided to remove this steady deviation. As will be described later, the steady deviation compensator 201 performs only integral control in consideration of the ease of gain adjustment.

Since the one-round transfer function of the steady deviation compensator 201 is expressed by the following equation (5), the Bode diagram is as shown in FIG.

The integral control gain K ′ _I can be obtained from the speed-tension response 31 gain K _σV depending on the rolling schedule and the preset integration time constant T ′ _I. Here, _assuming that ω _c = α · ω _n = 1 / T _I (where α ≦ 1.0), the following equation (6) holds.

Therefore, the gain K ′ _I of the steady deviation compensator 201 is expressed by the following equation (7).

Here, the integration time constant _T'I of steady-state error correction, rate - so that the control even when the tension response 31 gain K _{[sigma] v} is different about 10 times does not oscillate, the integration time constant in interstand tension controller 10 T _I Is set to 10 times. In other words, the control gain of the integral control in the steady deviation correction is set to about 1/10 of the control gain in the inter-stand tension control unit 10. The value of 10 times is an example, and a value of several times to several tens of times can be used according to the characteristics of the plant to be controlled.

The simulation of FIG. 9B _assumes that the control gain is 10.35 times because the speed-tension response 31 gain _KσV is smaller than the actual _value, but even in this case, the integral gain of the steady deviation compensator is assumed. Is 1.035 times the optimum gain, and can be controlled stably. FIG. 9C shows a step response when the steady deviation compensator 201 is added. It can be seen that the steady-state deviation compensator 201 removes the steady-state deviation after being controlled by the inter-stand tension controller 10 and the steady-state deviation compensator 201 to a control deviation of 0.3.

FIGS. 11A and 11B are diagrams showing step responses when the steady deviation compensator 201 is added in the cases of FIGS. 5A and 5C, respectively. As shown in FIG. 11 (a), the response of FIG. 11 (a) corresponding to FIG. 5 (a) in which the control gain of the inter-stand tension control unit 10 is within an appropriate range takes time. Since the control operation limiting device 200 and the steady deviation compensating device 201 are added to prevent the control from oscillating or diverging when the control gain of the inter-stand tension control unit 10 is excessive, the control gain is excessive. In some cases, it operates effectively, but when it is appropriate or too small, there is a problem that the control response becomes worse. Therefore, the control gain correcting device 202 that corrects the speed-tension response 31 gain _KσV is applied using the response at the time of control in the steady deviation compensating device 201.

FIG. 12 shows the concept of control gain correction. Although the tension variation between the stands occurs due to various factors, the timing t ₁ at which the to-be-rolled material tip portion bites into the i-stand from the state in which the to-be-rolled material tip portion 30 exists between the stands shown in FIG. In this case, tension between the stands is generated. In this, a large tension difference is generated, after the timing t ₂ when this is removed, interstand tension Without acceleration and deceleration or the like of the rolling mill is stabilized.

When the timing t ₂ after the tension variation as shown in Figure 12 is in the absence of much, to operate the steady state error compensator 201. Since the steady deviation compensator 201 is configured only by integral control, the control gain is expressed by the above equation (7), and it can be estimated that the difference in response is due to the error of _KσV . Accordingly, the actual value _T'Iact of integration time constant _T'I is obtained in that the tension deviation at the start of control is to measure the time to decay to 37%. By using this, the speed by the following equation (8) - it is possible to determine the actual value K _ShigumaVact tension response 31 gain K _{[sigma] v.} Thus, in this embodiment, it is possible to correct the velocity-tension influence coefficient _KσV based on the control response of the control by the steady deviation compensator 201 as the second control unit.

Figure 13 is a diagram showing the details of the timing t ₂ subsequent steady-state error compensation control shown in FIG. 12. As shown in FIG. 13, the steady deviation compensation execution availability selection device 202 monitors the tension deviation, which is the difference between the actual tension measured by the tension meter 9 and the tension command, and determines whether or not the steady deviation compensation device 201 can be operated. judge. The steady deviation compensation execution availability selection device 202 operates the steady deviation compensation command value 210 of the steady deviation compensation device 201.

As shown in FIG. 13, the steady-state error compensation performed whether selection device 202, steady-state error compensation control was implemented as a steady-state deviation compensation command value = [Delta] T _P1, while the tension deviation between before and after the [Delta] T _{P1 +} and [Delta] T of the [Delta] T _{P1 P1-} When the period of time reaches a preset tension stability determination period, the steady deviation compensation command value 210 is set to zero. Thus, the tension deviation [Delta] T begins to approach the [Delta] T _P1 to zero. This timing is a timing _{t 3} when shown in FIG. At this timing t ₃ , the response measurement execution signal 212 is enabled, and the speed-tension influence coefficient K _σV correction operation by the control gain correction device 203 is started. Although the case where the tension deviation is on the positive side (plus side) has been described here, the same applies to the negative side (minus side).

By such a process, when the tension deviation ΔT is brought close to zero, since the tension deviation ΔT is stabilized to some extent around ΔT _P1 , the tension deviation considered in the integral control is stable, and ΔT _P1 The waveform approaching zero can be stabilized, and the actual time constant _T ′ _Iact for correcting the velocity-tension influence coefficient K _σV can be suitably measured. In the example of FIG. 13, the steady deviation compensation command value is directly controlled. However, the steady deviation compensation command value remains zero and the gain 211 of the steady deviation compensation command value is controlled. It is also possible to realize the same function as 15.

Next, an outline of the operation of the control gain correction device 203 is shown in FIG. When response measurement is started in the steady deviation compensation implementation selection device 202, the actual tension at that time is set to ΔT _START , and a tension deviation ΔT _END = 0.37 × ΔT _START to be measured is obtained. To monitor the tension deviation, tension deviation When equal to or less than the ΔT _END, to end the response measurement. The actual integral control response _{T ′ Iact} can be obtained by measuring the time during which the response measurement has been performed.

By using the thus determined was _T'Iact and the equation (8), speed - it can determine the actual value K _ShigumaVact gain K _{[sigma] v} tension responses 31. Here, K _σV and _{T ′ I} are the speed-tension response 31 gain and the integration time constant used to obtain the control gains of the inter-stand tension controller 10 and the steady deviation compensation controller 201.

FIG. 15 shows an outline of the operation of the control gain learning device 204. A host computer 250 that manages what kind of rolled material to be rolled in the hot tandem rolling mill sets a rolling schedule that is product specifications and operation information for each rolled material. Based on the set value, the control gain learning device 204 uses the speed-tension response 31 gain in the relevant rolling schedule and parameter information K _σV , ΔT _P1 , ΔT _P2 , ΔT _M1 , ΔT _M2 used in the control operation limiting device 200. Are read from the control gain database 205, and parameters ΔT _P1 , ΔT _P2 , ΔT _M1 , ΔT _M2 of the control gain and the control deviation gain are sent to the inter-stand tension control unit 10, the control operation limiting device 200, and the steady deviation compensation device 201. Set.

When newly setting up a hot tandem rolling mill facility or rolling with a new rolling schedule, it is necessary to set initial values of K _σV , ΔT _P1 , ΔT _P2 , ΔT _M1 , and ΔT _M2 . In this case, K _σV is set with a value calculated using a rolling model formula, and appropriate values may be set for ΔT _P1 , ΔT _P2 , ΔT _M1 , and ΔT _M2 from past experience. In the present invention, since the control operation limiting device 200 is configured to be able to stably control even when the control gain of the inter-stand tension control unit 10 is excessive, the control gain of the inter-stand tension control unit 10 is increased. It is desirable to set the control gain to (about 5 to 10 times) and learn the control gain.

Further, when the response measurement is completed by the control gain correction device 203 and the speed-tension response 31 gain result _Kσact is calculated, the contents of the execution when the response measurement is completed are executed. And _K σV (k-1) is taken out K _{[sigma] v} of the corresponding rolling schedule from the control gain database, in accordance with the learning gains _{C AD,} and K _{[sigma] v} (k) to learn actual K _ShigumaVact, the position of the corresponding rolling schedule _{Change KσV} to _KσV (k). At the same time, the ratio between K _σV (k) and K _σV (k-1) is calculated, and if the change is between AD _LLIM and AD _ULIM (respectively predetermined values) at which the change is judged to be small, learning is completed. As a result, the control parameter is changed so that the control operation restriction device 200 does not operate.

Specifically, the control deviation gain parameters ΔT _P1 , ΔT _P2 , ΔT _M1 and ΔT _M2 are all set to zero. As a result, the actual result _KσVact obtained by the control gain correction device 203 is reflected in the actual inter-stand tension control unit 10 and, when learning is completed, the operation of the control operation restriction device 200 is stopped, so that the optimum Thus, the inter-stand tension control unit 10 using a simple control gain becomes possible. That is, the control gain correction device 203 functions as a gain adjustment unit. As for the control deviation gain, there is a method in which the dead band is initially set wide and gradually narrowed according to the learning progress of the control gain.

  As described above, even when a hot tandem rolling mill equipment is started up or when a material of a new rolling schedule is rolled, quality anomalies caused by tension fluctuations caused by excessive control gain of the inter-stand tension control unit 10 It is possible to learn the optimal control gain while preventing abnormal operation.

  Note that the control configuration of tension control between stands as shown in FIG. 7 is realized by a combination of software and hardware. Here, hardware for realizing each function of tension control between stands according to the present embodiment as shown in FIG. 7 will be described with reference to FIG. FIG. 16 is a block diagram illustrating a hardware configuration of tension control between stands according to the present embodiment. As shown in FIG. 16, the information processing apparatus according to the present embodiment has the same configuration as an information processing terminal such as a general server or a PC (Personal Computer).

  That is, the information processing apparatus according to the present embodiment includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102, a ROM (Read Only Memory) 103, an HDD (Hard Disk Drive) 104, and an I / F 105. Connected through. Further, an LCD (Liquid Crystal Display) 106 and an operation unit 107 are connected to the I / F 105.

  The CPU 101 is a calculation unit and controls the operation of the entire information processing apparatus. The RAM 102 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 101 processes information. The ROM 103 is a read-only nonvolatile storage medium and stores a program such as firmware.

  The HDD 104 is a nonvolatile storage medium that can read and write information, and stores an OS (Operating System), various control programs, application programs, and the like. The I / F 105 connects and controls the bus 108 and various hardware and networks. The I / F 105 is also used as an interface for each device to exchange information or input information to the rolling mill.

  The LCD 106 is a visual user interface for an operator to check the state of the information processing apparatus. The operation unit 107 is a user interface such as a keyboard and a mouse for an operator to input information to the information processing apparatus. In such a hardware configuration, a program stored in a recording medium such as the ROM 103, the HDD 104, or an optical disk (not shown) is read into the RAM 102, and the CPU 101 performs calculations according to the program, thereby configuring a software control unit. . The function of the control configuration of the tension control between the stands according to the present embodiment is realized by a combination of the software control unit configured as described above and hardware.

Other embodiments.
In the first embodiment, the control deviation gain is used as the control operation limiting device 200, but other control operation limiting means may be used as in a simple dead band. In the first embodiment, the tension control between the stands of the hot tandem rolling mill has been described. However, the same method can be applied to various control target plants including the cold tandem rolling mill.

DESCRIPTION OF SYMBOLS 1 i-1 stunt rolling mill 2 i stand rolling mill 7 Looper 8 Rolled material 9 Tension system 10 Tension control between stands 11 i-1 Stand speed control device 12 i Stand speed control device 13 Hydraulic cylinder 14 Looper fulcrum 15 Looper arm 16 Looper roll 17 Cylinder position detector 20 Looper position control device 30 Rolled material tip 31 Speed-Tension response 32 Plate tension-Cylinder pressure 33 Plate path length change-Tension 34 Looper position-Stand tension 35 Looper machine system 101 CPU
102 RAM
103 ROM
104 HDD
105 I / F
106 LCD
Reference Signs List 107 Operation Unit 108 Bus 200 Control Operation Limiting Device 201 Steady Deviation Compensation Device 202 Steady Deviation Compensation Execution Selection Device 203 Control Gain Correction Device 204 Control Gain Learning Device 205 Control Gain Database 250 Host Computer 300 Controlled Plant 301 Control Device

Claims (7)

A plant control device that performs feedback control based on a state quantity deviation of a plant to be controlled,
A first control unit that performs feedback control of at least one of proportional control, integral control, and differential control based on the state quantity deviation;
A second control unit that performs integral control of a control gain lower than the control gain of the first control unit based on the state quantity deviation;
A control switching unit that limits feedback control by the first control unit and causes the second control unit to perform integral control when the absolute value of the state quantity deviation is a predetermined value or less;
A plant control apparatus comprising: a gain adjustment unit that adjusts a control gain of the first control unit based on a control response of the plant to be controlled with respect to integral control by the second control unit.   The control switching unit adjusts the state quantity deviation input to the first control unit when the absolute value of the state quantity deviation of the plant is equal to or less than a predetermined limit start threshold value, thereby adjusting the first control. The plant control device according to claim 1, wherein feedback control by the unit is limited.   When the absolute value of the state quantity deviation of the plant is equal to or less than the restriction start threshold, the control switching unit is configured so that the absolute value of the state quantity deviation of the plant approaches a restriction completion threshold smaller than the restriction start threshold. The state quantity input to the first control unit is adjusted such that the state quantity deviation input to the first control unit approaches zero, and the state quantity deviation of the plant is equal to or less than the limit completion threshold. The plant control unit according to claim 2, wherein the deviation is zero.   The second control unit starts integration control based on the input state quantity deviation, and then stabilizes the state quantity deviation within a predetermined range for a predetermined period, so that the state quantity deviation becomes zero. The plant control unit according to claim 1, wherein integration control is started.   The gain adjusting unit adjusts a control gain of the first control unit based on a period until the state quantity deviation is reduced to a predetermined ratio by integral control by the second control unit. The plant control unit according to claim 1. A first control unit that performs feedback control of at least one of proportional control, integral control, and differential control based on the state quantity deviation of the plant to be controlled, and control by the first control unit based on the state quantity deviation A plant control method for controlling the plant to be controlled by switching to a second control unit that performs integral control with a control gain lower than the gain,
When the absolute value of the state quantity deviation is equal to or less than a predetermined value, the feedback control by the first control unit is limited, and the second control unit executes the integral control,
A plant control method, wherein a control gain of the first control unit is adjusted based on a control response of the plant to be controlled with respect to integral control by the second control unit. A first control unit that performs feedback control of at least one of proportional control, integral control, and differential control based on the state quantity deviation of the plant to be controlled, and control by the first control unit based on the state quantity deviation A plant control program for controlling the plant to be controlled by switching to a second control unit that performs integral control with a control gain lower than the gain,
Limiting the feedback control by the first control unit when the absolute value of the state quantity deviation is equal to or less than a predetermined value, and causing the second control unit to perform integral control; and
Adjusting the control gain of the first control unit based on the control response of the plant to be controlled with respect to the integral control by the second control unit, causing the information processing apparatus to execute the plant control program .

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