JPH063000B2 - Profile control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to improvement of controllability of basis weight profile control.

<Prior Art> An outline of a papermaking process will be described with reference to FIG. The raw material pulp P merges with the return raw material from the white water silo 3 through the seed box 1 and the seed valve 2, and is supplied to the head box 5 by the pump 4. The raw material in the head box is discharged in a sheet form from the gap of the slice lip 6 onto the wire part 8, squeezed by the press part 9, heated and dried by steam in the dry part 10, and then passed through a calendar 11 and reel 12. It is rolled up into a product. Reference numeral 7 is a plurality of (for example, 60) slice bolts for operating the gap of the slice lip.

13 scans the product in the paper width direction, and the basis weight of the paper (1 m ²
Is a B / M meter for measuring the water content) and the moisture content, and the absolute dry basis weight profile of the paper is calculated based on the measured values by dividing the lateral width direction of the paper into a plurality of points, for example, 360 points.

Absolute dry basis weight profile measured value PV of each point calculated
The difference between the set value SV and the set value SV is control-calculated by the profile control device 14, and the slice opening 7 corresponding to the measurement point is operated by the operation output MV to adjust the lip opening, and the absolute dry basis weight profile of the product is set to the absolute dry value. Feedback control is performed so as to match the basis weight profile.

A man-machine interface 15 communicates with the control device 14 and has a profile display function.

Figure 6 is intended to show the relationship of measurement points upstream of the slice bolt and the downstream side in the sheet 16, for example, 60 pieces of sliced bolts 7 _1, 7 2 _... 7 ₆₀ The measurement points 360 points PV
1, PV2 ... PV360 correspond.

As the measurement value corresponding to the operating end of the slice bolt 7 ₁ , the average value ▲ ▼ _{1 of 6} measurement values PV ₁ , PV ₂ ... PV ₆ is used, and the deviation between this measurement value and the set value of the profile is controlled and calculated. slice bolt 7 ₁ the operation output is operated. The operation of other slice bolts is similar.

The example of FIG. 6 is a 60-point profile method in which a plurality of measurement points are mechanically associated with specific slice bolts and the average value of the plurality of measurement points is calculated. , A general method for determining the range of the measurement points included in the i-th slice. First, the measurement point PV _i corresponding to the i-th slice is first analyzed by a statistical method (for example, in Japanese Patent Application No. 61-232181). (Disclosure) and the like, and it is determined so as to include n measurement points symmetrically on both sides of this slice. Therefore, the number of measurement points included in one slice bolt is 2n + 1, which is always an odd number.

FIG. 8 shows an example of the result of profile control by such a configuration. (A) shows slice bolts 7 ₁ , 7 _2.
... 7 shows the relationship between the position of ₆₀ , profile set value SV, and profile PF that connects measured value PV, and (B) shows the manipulated variables MV ₁ , MV ₂ ... MV ₆₀ to each slice bolt. .

The paper flows at a speed of 400 to 1000 m / min, but the B / M meter, which is a sensor, has a speed of 5 to 10 m / min in the paper width direction, so the flow direction (time series) is relative to the measured data. Smoothing processing (filtering) is being performed.

When starting to make paper or when the operating conditions change due to changing the paper type, the deviation becomes large as a whole, and the basis weight profile deteriorates. Conventionally, the operator manually operates at such a time, and when the 2σ value (twice of the standard deviation of the profile deviation) becomes small to some extent, the operation is switched to the automatic control.

The conventional control method uses a distribution control method based on sample PI, and its outline will be described with reference to the functional block diagram of FIG.

Reference numeral 17 is a filtering processing function in the flow direction of the profile measurement value, and 18 is a deviation calculation function for each slice, and the measurement value PV and the setting profile SV subjected to the filtering processing are set.
Deviation is obtained for each measurement point and the deviation signal for each measurement point is processed for each corresponding slice to calculate the deviation e for each slice. For example, when there are 40 slices and 360 measurement points, the deviation e is calculated by averaging the 9 measurement points corresponding to each slice.

Reference numeral 19 denotes a non-linearization processing function with respect to deviations. For deviations less than a certain value, zero deviation processing is performed, and for deviations greater than a certain value, expansion processing that gives a gain depending on the magnitude is executed, and a control deviation E is transmitted. To do.

Reference numeral 20 denotes a speed type PI calculation function, which performs proportional and integral calculations on the control deviation E and transmits a speed type operation output ΔU.

Reference numeral 21 denotes a distribution calculation function, which transmits an operation output ΔU ′ obtained by multiplying ΔU by a coefficient and distributing to adjacent slices based on the interference waveform of the slice.

FIG. 10 is an interference waveform diagram for adjacent slices centering on the i-th slice. The distribution coefficients α _{i + 2 to} α _i-2 for the two slices before and after the self are the responses of each slice due to interference. For values b _{i + 2 to} b _i-2 , α _{i + 2} = b _{i + 2} / Δ α _{i + 1} = b _{i + 1} / Δ α _i = b _i / Δ α _i-1 = b _{i -1} / Δ α _i-2 = b _i-2 / Δ where Δ = | b _{i + 2} | + | b _{i + 1} | + | b _i | + | b _i-1 | + | b _{i- 2} |.

With the distribution coefficient calculated in this way, the operation output ΔU ′ to each slice is ΔU ′ = α _{i + 2} · ΔU _{i + 2} + α _{i + 1} · ΔU _{i + 1} + α _i · ΔU _i + α _i-1・ ΔU _i-1 + α _i-2・ ΔU _i-2 .

Reference numeral 22 denotes an output check function, which executes an opening limit limiting process between slices on the operation output after the distribution calculation and outputs it to a process, that is, a slice bolt.

<Problems to be Solved by the Invention> The conventional control method is control by one mode of the above-described distribution control, and as tuning, stable control with less overshoot and less overshoot is prioritized. There are the following problems.

(1) Since there is only one filter constant in the flow direction filtering process of the measurement value process, it is a large constant that sufficiently suppresses the flow direction fluctuation, and the response to the profile change becomes slow.

(2) Since there are one type of PI control parameter and control cycle,
If the profile deviation is large after the beginning of paper making and after changing the type, it takes a long time to converge.

Therefore, adjustment is performed by the operator's manual, and the operator's burden is heavy.

An object of the present invention is to provide a profile control device capable of solving such a problem.

<Means for Solving the Problems> The present invention which achieves such an object is provided by a papermaking process (2
Regarding the quality of the paper manufactured in 3), the quality is measured by a sensor (13) that scans in the paper width direction, and the measured value distribution in the paper width direction (hereinafter referred to as “profile measurement value”) matches the set profile. A profile control device for operating the slice of the papermaking process as described above, which has the following configuration.

That is, when the deviation profile between the profile measurement value and the setting profile has a value larger than a predetermined value, the transient mode is set, and in the other cases, a means for determining the steady mode, the profile measurement value and the setting profile are set. Deviation deviation means (18) for obtaining the deviation profile of each measurement point, processing the deviation signal for each measurement point for each corresponding slice, and shortening the control cycle in the transient mode as compared with the mode in the steady state. And a control calculation means (20) for inputting the deviation profile for each slice obtained by the deviation calculation means and performing control calculation using a gain that converges faster in the transient mode than in the steady-time mode even if it tends to overshoot. is doing.

The slice is operated according to the output of the control calculation means.

<Operation> According to the invention having such a configuration, the transient mode / steady-time mode determination means determines whether or not the control state is stable depending on the degree of unevenness of the deviation profile. And
The deviation calculating means shortens the control period in the transient mode and accelerates the convergence as compared with the steady mode. In the transient mode, the control calculation means performs the control calculation by using the gain which converges faster than the steady mode, and operates the slice.

<Embodiment> The features of the present invention will be described prior to the description of the functional configuration of the embodiment.

(1) There are two control modes: a control mode when the basis weight profile is defective (transient mode) and a control mode in which the basis weight profile is in a target range (steady-state mode). Change the point.

... The filter constant for the basis weight profile measured value is switched to a value that approaches 1 in comparison with the steady-state mode.

That is, when the filter constant α in the steady mode and the filter constant α ′ in the transient mode are set, the processing of Y _n = α ′ · X _n + (1-α ′) · Y _n-1 is executed. Here, 0 ≦ α ≦ α ′, X _n is a measured value, and Y _n is a measured value after filtering.

… In the transition mode, the control cycle is made earlier than in the steady mode.

As shown in FIG. 2, in the steady mode, as shown in (B), the control cycle is once every 3 scans of the B / M meter.
In the transient mode, this is set for each scan as shown in (A) to prevent hunting.

... In the transition period mode, the sample PI control with the dead zone is executed. At the same time, the proportional gain and integral gain are switched and changed, so that the value will converge quickly even if there is an overshoot. That is, the sample PI control operations are performed by _{ΔU = K P {(E n} -E n-1) + K I · E n}. Here, K _P is a proportional gain, K _I is an integral gain, E _n is a current control deviation, and E _n-1 is a previous control deviation.

Figure 3 is an explanatory diagram related to dead zone processing deviation, the dead zone H _YS provided positive and negative directions with respect to the input deviation e _n, The process of is executed.

In the steady state mode, the control method is switched so that the control by the distribution control method based on the sample PI described in FIG. 9 is executed.

(2) Switching of control mode The switching to the transient mode is performed only when the operator switches.

The switching from the transient mode to the steady mode is automatically performed when the operator switches or when the deviation 2σ becomes equal to or less than the target value.

FIG. 1 shows a functional block diagram of a control device to which such a control method is applied in the case of the transient mode.

The same elements as those described with reference to FIG. 9 are designated by the same reference numerals, and the description thereof will be omitted. A description of the elements peculiar to the transient mode will be added.

Regarding the flow direction filtering processing function 17, the filter constant is changed as described above, and the control cycle for regulating the entire control device is also changed.

Reference numeral 24 denotes the deviation dead zone processing function described in FIG.
It replaces the conventional non-linearization processing function.

The transient PI calculation function 20 is set to the sample value PI control mode, and the proportional and integral gains are also changed.

The distribution process that was conventionally performed on the control calculation output is not performed in the transient mode.

FIG. 4 is a flow chart showing the procedure of signal processing relating to control mode switching. Measurement at step, calculation of deviation corresponding to slice at step and 2σ
After execution of the calculation, 2σ is compared with the target value in a step, and when it is less than the target value, the steady control mode is set.

If 2σ is equal to or larger than the target value, the operator's history of switching to the transient mode is checked in step, and if not switched, the steady mode control is executed as it is, and if switched, the transient mode control is continued.

The application example of the apparatus of the present invention described above is intended for the profile control of the paper in the paper making process, but the following other application examples and modified examples are possible.

(1) The same method can be applied to profile control of paper thickness, profile control of moisture content, and profile control of film thickness.

(2) As a control method for the transient mode, a flow direction filter constant, a control cycle, a dead zone, a proportional gain, and an integral gain are changed as a distribution control method similar to the steady mode.

(3) Not only 2σ but also the maximum value-minimum value (referred to as R) of the profile is used for the determination of switching to the automatic mode, and (2σ ≦ target value) * (R ≦ target value) is used as the switching condition. Good.

<Effects of the Invention> As described above, the present invention has the following effects.

(1) The convergence time to the target value of the deviation 2σ is shortened by switching the control method in the transient mode.

(2) Since the conventional distribution control and the steady-state filter constants and control gains are used after the equilibrium state is reached, good stability and focusing can be ensured.

(3) Since the profile adjustment is quickly performed in the automatic control state by the transient control mode even after the beginning of paper making or the change of the type of paper, the burden on the operator is greatly reduced.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a control device transient mode configuration to which the present invention is applied, FIG. 2 is an explanatory diagram regarding control cycle switching, FIG. 3 is an explanatory diagram regarding deviation dead zone processing, and FIG. 4 is control mode switching. FIG. 5 is a flowchart showing a signal processing procedure relating to FIG.
FIG. 7 is an explanatory diagram of correspondence between slices and measurement points by the 60-point profile method, FIG. 7 is an explanatory diagram of correspondence of measurement points to specific slices in the slice-corresponding profile, and FIG. 8 shows a relationship between manipulated variables and profiles for slices. A characteristic diagram, FIG. 9 is a functional block diagram of a conventional distribution control device,
FIG. 10 is an explanatory diagram of a slice lip interference waveform diagram. Reference numeral 17 ... Flow direction filtering processing function, 18 ... Deviation value calculation function for each slice, 20 ... Velocity type PI calculation function, 2
2 ... Output processing check function, 23 ... Process, 24 ... Deviation dead zone processing function

Claims (1)

[Claims] 1. The quality of paper produced in a papermaking process (23) is measured by a sensor (13) scanning in the paper width direction, and the measured value distribution in the paper width direction (hereinafter referred to as "profile measured value") is measured. ) Is a profile control device that operates the slices of the papermaking process so as to match the set profile, and when the deviation profile between the profile measurement value and the set profile has a value larger than a predetermined value, the transient Mode, and in the remaining cases, means for determining the mode at steady time, and a deviation profile between the profile measurement value and the set profile is obtained for each measurement point, and the deviation signal for each measurement point is processed for each corresponding slice. At the same time, in the transient mode, the deviation calculation means (18) for shortening the control cycle as compared with the steady-time mode and the deviation calculation means were used. The control calculation means (20) for inputting the deviation profile for each rice and performing the control calculation in the transient mode by using the gain which converges faster than the steady-state mode compared with the steady mode is provided. A profile control device for manipulating the slice according to an output.