JPH0684596B2 - Papermaking process controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a controller for a papermaking process.

(Prior Art) Generally, a papermaking process has the following structure. As shown in FIG. 7, a seed box 1 in which pulp containing ash (clay) is stored, a clay tank 2 in which a certain concentration of clay mixed with water is stored, and a seed valve 3 are provided. Pulp and clay are supplied through the clay addition valve 4. The flow rates of pulp and clay are adjusted by the valve openings of the seed port valve 3 and the clay addition valve 4, respectively, and are mixed with a fluid (white water) containing low-concentration pulp and clay circulating in the process, and the cleaning step 5 Is supplied to.

The main function of the selection step 5 is to remove foreign matter in the white water. The white water that has exited this selection step 5 is jetted from the head box 6 and dehydrated by the wire 7 with a vacuum force.
The sheet 8 is formed. This sheet 8 is still high in water content.

The sheet 8 coming out of the wire 7 is dried by the dryer 9 into the low-moisture paper 10, which is wound by the winder 12 through the absolutely dry basis weight and ash content measuring device 11.

The white water 13 that has not gone out of the sheet 8 after coming out of the selection step 5, the head box 6 and the wire 7 is recovered and reused.

When the wire 7 and the dryer 9 run out of paper, the broke 14 is stored in the broke tank 15 and the mixing process 16 is performed.
To be fed back to.

(Problems to be Solved by the Invention) However, in the conventional control device for such a papermaking process, mutual interference occurs between the seed port valve at the operating end, the clay addition valve, and the basis weight that is the controlled amount, and the ash content. Therefore, if the target value is changed for a specific control amount, or if a disturbance is applied and deviates from the target value, the main manipulated variable must be manipulated so that the control amount matches the target value. By doing so, the other controlled variables are changed. Therefore, it is difficult to match all the control amounts to their respective target values, and there is a problem that it takes a lot of time until then.

Also, if there is dead time in the process, increasing the control gain of the arbitrary transfer function controller will make the process unstable, so the control gain must be reduced,
As a result, there is a problem that the responsiveness deteriorates.

Furthermore, since the control gain is small, the response to the disturbance added to the process is poor, and automatic operation by the computer is performed only during steady operation, large disturbance is added and the operation amount must be changed significantly. When changing machines, etc., the operator manually operates.
In the manual control by the operator, the quality of control performance is determined by the operation method of the operator and largely depends on the experience and intuition of the operator, so that there is a problem that good control cannot always be performed.

The present invention has been made to solve such a conventional problem, and eliminates interference from the control signal to the controlled variable not only in a steady state but also in a transient state such as during grade change. An object of the present invention is to provide a highly stable controller for a papermaking process which is excellent in quick response by compensating for time.

[Structure of the Invention] (Means for Solving the Problem) The present invention measures the basis weight and ash content of a paper sheet moving at a predetermined speed with a detector, and sets the basis weight and ash content as control amounts. The main operating end for the amount is the seed valve and the main operating end for the ash is the clay addition valve, but the ash content also changes when the seed opening flow rate changes due to the change of the seed opening valve opening, and the clay flow rate changes due to the change of the clay addition valve opening. A controller for a papermaking process having a mutual interference property in which a basis weight also changes depending on a cross controller, a dead time compensation device, and an arbitrary transfer function controller, wherein the cross controller is the arbitrary transfer function controller and the papermaking device. It is placed between the process and the control signal input from the arbitrary transfer function controller to remove unnecessary interference to the grammage and ash content, and to correspond to the grammage and ash content respectively. An operation amount that makes a one-to-one correspondence with a control signal is output to the papermaking process, and the dead time compensation device internally has a model equivalent to the papermaking process, and the control amount is measured by a detector from the operation end. Model output signal obtained by inputting the control signal of the arbitrary transfer function controller to the model that does not include the dead time And the measured control amount are added, the dead time obtained by inputting the model output signal to the model representing only the dead time is subtracted from the model signal. The dead time is compensated by removing the effect of the signal including the dead time. However, the control amount after dead time compensation is fed back to the arbitrary transfer function controller, and the arbitrary transfer function controller performs proportional / integral control for each of the basis weight and the ash content. Or a proportional / integral / derivative control. Based on the feedback amount from the dead time compensation device and the target value, a control signal for shifting the feedback amount to the target state is output to the cross controller to set the control amount to the target value. It is characterized by matching with.

(Operation) In the controller of the papermaking process of the present invention, the papermaking process is replaced by a set of 1-input 1-output system by removing mutual interference by the cross controller, and the 1-input 1-output system wastes each by the dead time compensator. The control signal can be output from the arbitrary transfer function controller so as to compensate for the time and bring the controlled variable to the target value.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In the controller of the papermaking process of the embodiment of the present invention,
In the papermaking process shown in the figure, the valve opening degrees of the seed inlet valve 3 and the clay addition valve 4 are used as manipulated variables, and the basis weight of the final paper 10 and the ash content are controlled variables. Then, optimal valve opening control is performed in order to reach the final valve opening that achieves the target grammage and ash content as quickly as possible.

FIG. 1 shows a controller according to an embodiment of the present invention, which includes an arbitrary transfer function controller 17, a cross controller 18, a dead time compensator 19, and a disturbance compensation feedforward controller 20. In the figure, 21 is a process to be controlled, 22 is a disturbance process,
Both of these processes 21 and 22 are papermaking processes.

Now, the absolute dry basis weight and the ash content of the paper flowing at a certain constant speed are scanned and measured by the detector 11, and the absolute dry basis weight and the ash content are used as control amounts. The main operating end for the absolute dry basis weight is the opening of the seed inlet valve 3, and the main operating end for the ash is the opening of the clay addition valve 4. The basis weight and ash content can be adjusted by operating these valve openings. Done.

However, in the papermaking process, there is mutual interference in which the ash content changes by operating the seed inlet valve 3 and interference in which the absolute dry basis weight changes by operating the clay addition valve 4, which further changes the papermaking speed. Both the absolute dry basis weight and the ash content change due to the disturbance caused. Moreover, it has a dead time, a first-order lag time constant and a gain with respect to the control amount from the two operation ends of the seed port valve 3 and the clay addition valve 4.

Controlled process 21 is G _P (S), disturbance process 22 is G
_{Assuming that D} (S), the controlled variable is Y (S), the manipulated variable is U (S), and the disturbance is D (S), these relationships are expressed by the following equations.

Y (S) = Y _C (S) + Y _D (S) (1) Y _C (S) = G _P (S) · U (S) (2) Y _D (S) = G _D (S) · D (S) ... (3 ) where, Y (S) = [B D A] T ... (4) U (S) = [F T F C] T ... (5) D (S) = ΔV S … (6) However, S: Laplace operator B _D : Absolute dry basis weight of paper (g / m ² ) A: Ash of paper (g / m ² ) F _T : Flow rate at seed opening by seed opening valve operation (m ³ / min) F _C : Clay flow rate by clay addition valve operation (m ³ / min) V _S : Machine speed (m / min) K: Process gain T: Process time constant L: Process dead time L ₁₁ ＝ L ₁₂ ＝ L ₂₁ ＝ L ₂₂ ； L _V1 ＝ L _V2 ； L ₁₁ ＞ L _V1 I am trying.

Cross controller for the above controlled processes
18 G _C (S) is defined as follows. That is, when the transfer function from the control signal R (S) output from the arbitrary transfer function controller 17 to the controlled variable Y (S) is G _CP (S), G _CP (S) = G _C (S) · G _P (S) (9) is established, and G _C (S) is determined so that G _CP (S) becomes a diagonal matrix. At this time, Y _C (S) = G _CP (S) · R (S) (10) is expressed as follows, It becomes one input and one output system from R ₁ to B _D and R ₂ to A.

As one of the methods for obtaining G _C (S) that satisfies the above equation (9), only the gain is extracted from G _P (S) to create a process gain matrix G _K.

Next, taking the inverse matrix of G _K , and multiplying G _P (S) with G _C (S) = G _K ^-1 (13), the relation between R (S) and Y _C (S) is , Y _C (S) = G _C (S) G _P (S) R (S) (14)

In steady state, And completely de-interacted.

By inserting the cross controller 18 between the arbitrary transfer function controller 17 and the control target process 21, the synthesis process viewed from the arbitrary transfer function controller 17 has one input and one input.
The output system is a process in which the order of G _P (S), that is, two, is collected, and a simple control algorithm for the one-input one-output system is applied to the arbitrary transfer function controller 17.

Next, the dead time compensation device 19 will be described. The miss method is used as one of the dead time compensation methods.

FIG. 2 (a) shows a 1-input 1-output control system in which the controlled process 21 is decomposed into an element 23 that does not include dead time and an element 24 that does not include dead time.
The process model 25 is equivalent to 23, and the dead time model 26 is equivalent to the dead time element 24.

That is, a model equivalent to the papermaking process is provided in two modes: a dead time model 26 that represents only the dead time taken from the operating end until the controlled variable is measured by the detector, and a process model 25 that does not include the dead time. , A model output signal Y ₁ (S) obtained by inputting the control signal R (S) of the arbitrary transfer function controller 17 to a model 25 not including dead time,
Subtract the dead time model signal Y ₂ (S) obtained by inputting the model output signal Y ₁ (S) into the model 26 that represents only the dead time from the signal that is added to the measured control amount Y (S). Then, the dead time is compensated by removing the influence of the signal including the dead time, and the control amount Y ₄ (S) after the dead time compensation is fed back to the arbitrary transfer controller 17.

The description expression from the control signal R (S) to Y (S), Y ₂ (S) is as follows.

_{Y (S) = PC (S} ) e -LS R (S) ... (16) Y 2 (S) = G PC * (S) e -L * S R (S) ... (17) where, _PC ( ^{_{S) = G PC * (S}} ), since it is ^{e -LS = e -L * S ...} (18), Y 3 (S) = Y (S) -Y 2 (S) = O ... (19) is To establish. Therefore, the arbitrary transfer function controller 17
The amount Y ₄ (S) returned to is Y ₄ (S) = Y ₁ (S) = G _PC ^* (S) R (S) (20), and the dead time from R (S) The amount does not include. A block diagram equivalent to FIG. 2A after dead time compensation is shown in FIG. 2B.

The cross controller 18 and the dead time compensation device 19 described above.
By applying the above, it is only necessary to construct two arbitrary transfer function controllers 17 individually for two absolute dry basis weights and two ash-less one-input one-output systems. One of these techniques will be described next.

FIG. 3 (a) shows a one-input one-output system with no dead time of dead weight, 27 is an arbitrary transfer function controller of dead weight, and 28 is a control target process without dead time. The arbitrary transfer function controller 29 that realizes the control system shown in FIG. 3 (b) is represented by the proportional-plus-integral controller shown below, where T _DS is the desired time constant of the illustrated closed-loop control system.

The same control system setting method can be applied to the ash control system.

Next, the disturbance compensation feedforward controller 20 will be described. In Fig. 1, the observable disturbance D (S)
Is a change in the machine speed as shown in the equation (6), and affects the absolute dry basis weight and the ash content through G _D (S) of the disturbance process 22. Variation .DELTA.A ^D of variation .DELTA.B _D ^D and ash content of the (3) and (8) bone dry basis weight by machine speed variation from the equation is expressed by the following equation.

An operation amount U _D (S) that cancels the ΔB _D ^D and ΔA ^D is determined, and U _D (S) that satisfies the following expression is the operation amount that compensates for the disturbance.

Y _D (S) + G _P (S) U _D (S) = O (23) where Assuming that the transient characteristic of G _P (S) is ignored, equation (23) becomes as follows.

Here, since L ₁₁ = L ₁₂ = L ₂₁ = L ₂₂ ; L _V1 = L _V2 ,
Solve equation (25) to obtain the following equation.

Here, in the equation (26), since L _V1 <L ₁₁ ... (27), Represents a future event, but since the speed change is scheduled in advance, the change timing of the speed change and the change pattern and amount can be predicted.

Therefore, it is possible to obtain the scheduled variation ΔV _S ^* of the papermaking speed as expressed by the equation (28).

From the above formulas (26) and (28), ΔF _T ^D and ΔF _C ^D are expressed by the following formulas.

FIG. 4 collectively shows the above control method in a block diagram. In FIG. 4, the arbitrary transfer function controller G for absolute dry basis weight corresponds to the arbitrary transfer function controller 17 in FIG. _MB (S) and arbitrary transfer function controller G _MA (S) for ash, which correspond to the cross controller 18, are cross controllers G _C11 (S) to G
_C22 (S), and the dead time compensator 19 corresponds to the dead time compensator for absolute dry basis weight G _BS (S) and the dead time compensator for ash control G _AS (S). Further, the feedforward controller for disturbance compensation G _FDB (S) and the feedforward controller for ash content G _FDA (S) correspond to the disturbance compensation feedforward controller 20.

Note that G _P11 (S) to G _P22 (S) are control target processes, and G _DB (S) and G _DA (S) are disturbance processes.

The results of the simulation performed under the following conditions with the control system having the configuration shown in FIG. 4 are shown in FIGS. 5 and 6. FIGS. 5A and 5B show the case where the target value is changed and no disturbance is applied.

The parameters of the controlled process and the disturbance process are as follows.

○ In the formula (7), K ₁₁ = 7, K ₁₂ = 0.05, K ₂₁ = 1.0, K ₂₂ = 0.05 T ₁₁ = 66, T ₁₂ = 210, T ₂₁ = 210, T ₂₂ = 210 L ₁₁ = 100, L ₁₂ ＝ 100, L ₂₁ ＝ 100, T ₂₂ ＝ 100 ○ In the formula (8), K _V1 ＝ －0.07, K _V2 ＝ －0.006, L _V1 ＝ 30, L _V2 ＝ 30 ○ The machine speed is 850.0 m / min. The target value for absolute dry basis weight is 50.0g
Change the step from / m ² to 75.0 g / m ² and set the ash target value to 6.0 g /
The step was changed from m ² to 10.0 g / m ² .

○ The target values are changed ahead of the dead time so that the absolute dry basis weight and ash content will start changing at 3.0 minutes on the time axis in Fig. 5.

○ The control cycle is 10 seconds.

○ The closed loop control system is designed to have a time constant of 200 seconds for both basis weight and ash content.

6 (a) and 6 (b) show the case where the disturbance is applied without changing the target value.

○ The parameter of the controlled process and the disturbance process is 5th
It is the same as FIG.

○ Ze'inuitsuboryou is constant at 50.0 g / m ^2, ash content was constant at 6.0 g / m ^2, was modified at a constant rate of change in machine speed on 850.0M / min 700 meters / min.

The other controlled variables are the same as in the first example.

Figure 5, in Figure 6, B _D is bone dry basis weight, F _T seeding outlet flow, A is the ash, F _C represents the clay flow.

In Fig. 5, stable response characteristics as designed were obtained, and in Fig. 6, it was revealed that the influence of disturbance application was within 5% for both the absolute dry basis weight and the ash content.

FIG. 8 shows a control system obtained by removing the dead time compensator, the cross controller, and the disturbance compensation feedforward controller from the control system shown in FIG. 4, which is a control system that has been conventionally used.

FIGS. 9A and 9B show the results when the target value was changed and no disturbance was applied.

The conditions at this time were the same as those shown in FIGS. 5A and 5B for each parameter.

FIGS. 10 (a) and 10 (b) show the results when a disturbance is applied without changing the target value.

The conditions at this time were the same as those shown in FIGS. 6 (a) and 6 (b).

Looking at these conventional results, in FIGS. 9 (a) and 9 (b), responsiveness faster than the set time constant of 200 seconds is shown.
Overshoot is occurring. Therefore, in order to obtain good responsiveness without overshoot, the control system must be designed by trial and error by increasing the design time constant. In addition, in Fig. 10 (a) and (b), the effect of disturbance is about 14% for absolutely dry basis weight and about 10% for ash.
Out.

As described above, in the embodiment of the present invention, the decoupling by the cross controller and the dead time compensation are combined to facilitate the design of the arbitrary transfer function controller, and the control performance can be greatly improved.

The present invention is not limited to the above-described embodiment, but can be implemented in other modes, and in particular, the disturbance controller can be added as necessary.

[Effects of the Invention] As described above, according to the present invention, the papermaking process is made non-interfering by the cross controller into a one-input one-output system, and each input / output system is provided with an arbitrary transfer function controller for control and waste. The time compensator can compensate the dead time from the change of the manipulated variable to the change of the controlled variable, and it has excellent responsiveness and stability not only in the steady state but also in the transient state such as during grade change. The papermaking process can be controlled.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 (a) is a block diagram showing a detailed configuration of the dead time compensating apparatus in the above embodiment, and FIG. 2 (b) is the dead time compensating apparatus. An equivalent block diagram after dead time compensation, FIG. 3 (a) is a block diagram in the case of controlling a 1-input 1-output process without dead time by the arbitrary transfer function controller in the above embodiment, FIG. 3 (b) is A block diagram after synthesizing the blocks of the arbitrary transfer function controller, FIG. 4 is a more detailed block diagram of the above embodiment, FIG. 5 (a),
(B) is a graph showing the result of simulation by the control device shown in the above detailed block diagram, where there is no disturbance and only the target value is changed, and FIGS. 6 (a) and 6 (b) are It is a graph which shows the result of the said simulation, when only a disturbance is considered, without changing a target value, FIG. 7 is a schematic diagram which shows an example of a general papermaking process, FIG. 8 is a conventional example. 9A and 9B are graphs showing the results of the simulation according to the above-mentioned conventional example, where there is no disturbance and only the target value is changed, and FIG. 10A and FIG. (B) is a graph showing the result of the simulation according to the above-mentioned conventional example, in which only the disturbance is considered without changing the target value. 17 ... Arbitrary transfer function controller 18 ... Cross controller 19 ... Dead time compensator 20 ... Disturbance compensation feedforward controller 21 ... Process to be controlled 22 ... Disturbance process

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Yamaguchi, Aomori Prefecture, Hachinohe City, Oji, 3rd Aomori Valley, Aomori Yachi, Mitsubishi Paper Mills, Ltd. (72) Inventor, Hiroaki Kobayashi, Hachinohe City, Aomori, Aomori, 3rd place, Aomori Valley Mitsubishi Paper Mills, Ltd. Hachinohe Mill (72) Inventor Minoru Taniguchi, Aomori, Aomori, Aomori Prefecture, No. 3 Aomori Yachi No. 3 Mitsubishi Paper Mills, Hachinohe Mill (72) Hashimoto Nobuaki, Hachinohe, Aomori, Aomori Valley, Aomori Valley Address Mitsubishi Paper Mills, Ltd. Hachinohe Mill (56) References JP 62-257494 (JP, A)

Claims (1)

[Claims] 1. A grammage and an ash content of a paper moving at a predetermined speed are measured by a detector, and the grammage and the ash content are used as control amounts. Although the operating end is a clay addition valve, the ash content also changes due to the change in the seed opening flow rate due to the change in the seed opening valve opening, and the basis weight also changes due to the change in the clay addition valve opening. A controller of the above, comprising a cross controller, a dead time compensator, and an arbitrary transfer function controller, wherein the cross controller is placed between the arbitrary transfer function controller and the papermaking process, and the arbitrary transfer function controller An operation amount that removes unnecessary interference on the grammage and ash content from the control signal input from the device, and makes one-to-one correspondence between the grammage and ash content and the corresponding control signals. Output to the papermaking process, the dead time compensator internally has a model equivalent to the papermaking process, a model showing only the dead time from the operating end until the control amount is measured by the detector, and the dead time. A model output signal obtained by inputting the control signal of the arbitrary transfer function controller to the model not including the dead time, and a signal obtained by adding the measured control amount to the model. Dead time model obtained by inputting the output signal into a model representing only the dead time. The effect of the signal including the dead time is subtracted to compensate for the dead time, and the control amount after the dead time compensation is adjusted to the arbitrary transfer function controller. And the arbitrary transfer function controller is configured with proportional / integral control or proportional / integral / derivative control for each of the basis weight and the ash content. And a feedback amount and the target value from the compensation device, the control apparatus of a paper process, characterized in that to match the control amount is outputted to the cross controller a control signal for shifting the feedback amount to the target state to the target value.