CN1704487A - Process for controlling temperature of strip steel - Google Patents

Abstract

The invention provides a process for controlling temperature of strip steel comprising the steps of, (1) forecasting the strip temperature of a certain future time based on strip temperature dynamic model, (2) calculating the needed gas flow variance so as to minimize the difference between the temperature of the destination strip steel and the forecasted strip temperature, (3) calculating gas flow configuration value according to the real gas flow and the gas flow deviation(4) sending the gas flow configuration value to the instrument control apparatus, (5) carrying out static model and dynamic model self-learning according to the real strip temperature, and calculating the gas flow configuration value again.

Description

A kind of method of controlling belt steel temperature

Technical field

The present invention relates to a kind of method of controlling belt steel temperature, be used for the belt steel temperature control of tinuous productions such as cold rolling mill continuous annealing unit, pot galvanize unit.

Background technology

Belt steel temperature control is one of core control techniques of whole production line, play important effect to improving the quality of products, generally be to adopt the process furnace mathematical model to control the temperature of band steel, present existing process furnace mathematical model major part all is to decide according to concrete production technique producer, production technique producer difference, its corresponding annealing furnace mathematical model mechanism is also inequality, and response speed is slow, and control accuracy is not high yet.

Summary of the invention

Technical problem to be solved by this invention provides a kind of method that can fast, accurately control belt steel temperature, its by parameter configuration applicable to different production lines.

In order to solve the problems of the technologies described above, the present invention has adopted following technical proposals: a kind of method of controlling belt steel temperature is provided, and it comprises the steps:

A, master data, the speed setting value of central sections, the actual temperature of band steel, the target temperature of band steel, the self study parameter of technology digital model according to logical plate order, steel plate, utilize the generalized predictive control principle, according to band temperature with the warm dynamicmodel prediction a certain moment in future;

It is principle that the difference of B, the temperature that makes the object tape steel and pre-measuring tape temperature reaches minimum value, calculates the gas flow deviation that needs;

C, calculate the gas flow set(ting)value according to actual gas flow in conjunction with the gas flow deviometer again;

D, the gas flow set(ting)value is sent to the instrument operating device;

E, when warm attitude, carry out the self study of static model and dynamicmodel, and carry out the gas flow set(ting)value once more and calculate according to actual band temperature.

The present invention has following advantage: the mathematical model of process furnace has been utilized generalized predictive control principle (GPC), and for the system of continuous change target value, GPC is only control theory.Based on GPC, according to warm dynamicmodel prediction certain band temperature constantly in the future, and make the object tape temperature and the difference of measuring tape temperature in advance reach minimum value to be principle, to try to achieve gas flow.Pre-measuring tape temperature is steel width going along with, variation in thickness or strip speed and change, and the object tape temperature changes with the product volume.This model provides response fast stable again Controlling System.This model is from thermodynamic balance equations and system state equation, derive the static model and the dynamicmodel of heating furnace zone temperature control, calculate the increment of gas flow again according to the predictive control principle, and, revise the coefficient of mathematical model with the least square method of recursion of band forgetting factor.Practical application effect is good, and target belt steel temperature and actual temperature are no more than 3 degree during system stability.

1, utilize generalized predictive control principle (GPC) control belt steel temperature, response speed is very fast, the control accuracy height;

2, related with production technique little, tube annealing furnace technology manufacturer is not different with production technique, all can use present method as long as parameter is done configuration.

3, distribute gas flow automatically, this method can be distributed each stove district gas flow automatically according to steel grade, specification.

4, eliminate because the strip running deviation that furnace temperature causes if having irrational furnace temperature deviation between each stove district of process furnace, causes the sideslip of band steel easily, this method can be by distributing each stove district gas flow automatically, and eliminate this furnace temperature deviation.

Description of drawings

Fig. 1 is a kind of schema of controlling the method for belt steel temperature of the present invention.

Fig. 2 is the calculating of band steel target temperature and the relation of actual Central Line speed.

Embodiment

As shown in Figure 1: the method for control belt steel temperature of the present invention comprises the steps:

1, according to the master data of logical plate order, steel plate, the speed setting value of central sections, the actual temperature of band steel, the target temperature of band steel, the self study parameter of technology digital model, utilize generalized predictive control principle (GPC), according to band temperature with the warm dynamicmodel prediction a certain moment in future;

2, to reach minimum value be principle to the difference of the temperature that makes the object tape steel and pre-measuring tape temperature, calculates the gas flow deviation that needs;

3, calculate the gas flow set(ting)value according to actual gas flow in conjunction with the gas flow deviometer again;

4, the gas flow set(ting)value is sent to the instrument operating device;

5, when warm attitude, carry out the self study of static model and dynamicmodel, and carry out the gas flow set(ting)value once more and calculate according to actual band temperature.

Below in conjunction with above-mentioned steps, describe treating processes of the present invention in detail: wherein, be with being calculated as follows of steel target temperature in the step 1:

1) normal determining with the steel target temperature

Standard is determined by basic thermal cycling code with the steel target temperature normally

TSoa＝TSol+TSmo

TSoa: the band steel is at the target temperature of HC outlet

TSol: suitably with the standard target temperature of steel

TSmo: the operator revises temperature value by the standard target of the normal band of VDU input steel

2) transitional zone steel target temperature determines

The virtual band steel target temperature of standard is determined by production line operation person

TSoa＝TSol+TSmo

TSoa: the band steel is at the target temperature of HF outlet

TSol: suitably with the standard target temperature of steel

TSmo: the operator revises temperature value by the virtual band steel standard target of VDU input

3) the determining of band steel target temperature (thermal cycling code C1, R2)

The relation of the calculating of target belt steel temperature and actual Central Line speed is as shown in Figure 2: the target belt steel temperature is determined according to the thermal cycling code, different then actual Central Line speed have different target belt steel temperatures, the relation of actual Central Line speed and target belt steel temperature determines that by practical experience wherein Central Line's speed refers to the strip speed of stove section.

Wherein, the belt steel temperature static model are as follows:

$\mathrm{SVF}\≡\frac{\mathrm{TSS}-\mathrm{TSi}}{\mathrm{TF}-\mathrm{TSi}}$

$=1-\exp \left[\frac{-1}{s_1\·(\mathrm{TV}-{\mathrm{TV}}_{\mathrm{ave}})+s_2\·\mathrm{TV}\·(\mathrm{TV}-{\mathrm{TV}}_{\mathrm{ave}})+s_3\·\mathrm{TV}\·(\mathrm{TF}-{\mathrm{TF}}_{\mathrm{ave}})+s_4}\right]$

Wherein:

T: sampling time

S: exchange area

TH: belt steel thickness

WD: strip width

VS: band steel wire speed

TF: furnace temperature

TSi: heating zone inlet band temperature

TSS: be with warm static value (stable state is promptly worked as TF, and TH, VS are constants)

TV: areal velocity (TH * VS)

The mean value of TVave: TV

The mean value of TFave: TF

SVF: furnace temperature coefficient

s ₁..., s ₄: model self study parameter

P: band steel proportion

C _ρ: band steel specific heat

σ ₀: the Stefan-Boltzmann coefficient

φ: band steel radiation coefficient

It is as follows to draw the belt steel temperature dynamicmodel according to static model:

$\mathrm{yhat}\left(t\right)=a1y(t-1)+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{biu}(t-d-i+1)+\underset{i=1}{\overset{4}{\mathrm{\Σ}}}\mathrm{ciwi}\left(t\right)$

$y_{\mathrm{hat}}\left(t\right)=a_{1}y(t-1)+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{b}_{i}u(t-d-i+1)+\underset{i=1}{\overset{4}{\mathrm{\Σ}}}{c}_i{w}_i\left(t\right)$

Output is plate temperature deviation, and input is that the gas flow deviation is multiplied by a time-varying coefficient; Disturbing then is a series of dynamic disturbance that the variation at strip speed, thickness, width causes.

y(t)≡TS(t)-TSave

u(k)＝DVF(k)*{FL(k)-FL _ave}

w ₁≡TST(k-1)

w ₂≡DSS(k)

w ₃≡DVF(k)*{WD(k)*TH(k)*VS(k)-WTV _ave}

w ₄≡DVF(k) k＝t+1，...，t+d

$\mathrm{DVF}\left(k\right)\≡\frac{\∂\left(\mathrm{TSS}\right)}{\∂\left(\mathrm{TF}\right)}$

Wherein:

D: the band steel heats up time of lag (seeing Fig. 3-1)

y _Hat(t): the estimated value of y during sampling (t)

TV: areal velocity (TH*VS)

FL: gas flow

WD: strip width

SVF: furnace coefficient

DVF: furnace temperature differential coefficient

DSS: be with warm constant term variable quantity, (after TH * VS changes)

TST: be with warm time lag of first order item (after TH * VS changes, being with warm modifying term)

TS _Ave: the mean value of TS

FL _Ave: the mean value of FL

WTV _Ave: the mean value of WD * TH * VS

a ₁, b ₁-b _m, c ₁-c ₄: model self study parameter

N: constant

Calculate the increment of gas flow according to band steel dynamicmodel:

Among the GPC in generalized predictive control (Generalized Predictive Control), predictive model adopts controlled autoregressive integration gliding model CARIMA (controlled auto_regressiveintegrated moving average), and the optimization aim of generalized predictive control rule is:

$\min J=E\{\underset{j=N1}{\overset{N2}{\mathrm{\Σ}}}\mathrm{\ρ}\left(j\right){\{r(t+j)-y(t+j)\}}^2+w\underset{k=1}{\overset{\mathrm{NU}}{\mathrm{\Σ}}}{\mathrm{\Δu}}^{\′}{(t+k-1)}^2\}$

Wherein

W: the weight of operational ton

ρ (j): with the weight of warm deviation

R: object tape temperature

Y: actual band temperature

N1: invalid period (time of lag)

N2: the time of future position

NU: apart from certain moment of current point

Δ u ': the increment of operational ton (FL (t)-FL (t-1))

Reference value according to gas flow incremental computations gas flow:

FLsv＝FLpv+Δu′(t)

FLsv: the reference value of gas flow

FLpv: the actual value of gas flow

Δ u ' is (t): the gas flow increment

Wherein, the self study coefficient calculations of the static model in the step 5 is as follows:

s _hatj(t)＝s _hatj(t-1)+K _j*ε(t)

$K_j\≡\frac{p_j*{\mathrm{\φ}}_j\left(t\right)}{1+\underset{i=1}{\overset{4}{\mathrm{\Σ}}}{p}_i*{\mathrm{\φ}}_i{\left(t\right)}^2}$

P wherein _jAdaptive gain

Wherein:

TV ：TH×VS

T: sampling time

s _Hat1: the estimated value of parameter 1

s _Hat2: the estimated value of parameter 2

s _Hat3: the estimated value of parameter 3

s _Hat4: the estimated value of parameter 4

p _j: adaptive gain

The self study coefficient calculations of the dynamicmodel in the step 5 is as follows:

Λ (t) is the matrix of N * N, N=n+5

λ _i(t) be forget because of

Son

${\mathrm{\λ}}_i\left(t\right)\≡\sqrt{1-\frac{g_i*\mathrm{\ϵ}{\left(t\right)}^2}{1+\stackrel{\‾}{\mathrm{\φ}}{\left(t\right)}^{T}P(t-1)*\stackrel{\‾}{\mathrm{\φ}}\left(t\right)}}$

Wherein:

g _i: i the member's of response θ constant

λ _i: i the member's of response θ forgetting factor

θ _Hat(t): in sampling t estimated value constantly

N: control region

Above-mentioned model calculation moment point is:

(1) in following Time Calculation band temperature target value

1) every T1 second

2) when central linear velocity changes above XM/MIN.

(2) calculate the mixed gas flow rate in the following time

1) above-mentioned institute is free

(3) execution time of parameter self-study

1) 1) every T1 second

The precondition of above-mentioned computing is as follows:

(1) computer mode condition

1) tracking mode ON

2) the chain data communication with instrument is normal

(2) condition of functional design

1) sets the higher limit of a mixed gas flow rate for each combustion zone

2) set the lower value of a mixed gas flow rate for each combustion zone

3) if the band temperature control is under an embargo, this function cancellation computer mode should signal

(3) target calculated value (last calculative value)

1) the band steel is in the target reference value of HF outlet of still

2) mixed gas flow rate reference value

3) model parameter

In addition, also the input data are carried out the bound inspection, will be under an embargo if data exceed the bound computer mode.

Claims (10)

1, a kind of method of controlling belt steel temperature is characterized in that, comprises the steps:

A, master data, the speed setting value of central sections, the actual temperature of band steel, the target temperature of band steel, the self study parameter of technology digital model according to logical plate order, steel plate, utilize the generalized predictive control principle, according to band temperature with the warm dynamicmodel prediction a certain moment in future;

It is principle that the difference of B, the temperature that makes the object tape steel and pre-measuring tape temperature reaches minimum value, calculates the gas flow deviation that needs;

C, calculate the gas flow set(ting)value according to actual gas flow in conjunction with the gas flow deviometer again;

D, the gas flow set(ting)value is sent to the instrument operating device;

E, when warm attitude, carry out the self study of static model and dynamicmodel, and carry out the gas flow set(ting)value once more and calculate according to actual band temperature.

2, the method for control belt steel temperature according to claim 1, it is characterized in that, band steel target temperature described in the steps A is by basic thermal cycling code decision, calculation formula is: TSoa=TSol+Tsmo, wherein, Tsoa is a standard target temperature of suitably being with steel for the target temperature of band steel in the HC outlet, Tsol, and Tsmo is that the operator revises temperature value by the standard target of the normal band of VDU input steel.

3, the method for control belt steel temperature according to claim 1, it is characterized in that described target belt steel temperature determines that according to the thermal cycling code different actual Central Line speed have different target belt steel temperatures, wherein, Central Line's speed refers to the strip speed of stove section.

4, the method for control belt steel temperature according to claim 2 is characterized in that, in following Time Calculation band temperature target value, 1) every T1 second, 2) change when surpassing XM/MIN when central linear velocity.

5, the method for control belt steel temperature according to claim 3 is characterized in that, described belt steel temperature static model are as follows:

$\mathrm{SVF}\≡\frac{\mathrm{TSS}-\mathrm{TSi}}{\mathrm{TF}-\mathrm{TSi}}$

$=1-\exp \left[\frac{-1}{s_1\·(\mathrm{TV}-{\mathrm{TV}}_{\mathrm{ave}})+s_2\·\mathrm{TV}\·(\mathrm{TV}-{\mathrm{TV}}_{\mathrm{ave}})+s_3\·\mathrm{TV}\·(\mathrm{TF}-{\mathrm{TF}}_{\mathrm{ave}})+s_4}\right]$

Wherein: t is the sampling time, and S is an exchange area, and TH is a belt steel thickness, WD is a strip width, VS is band steel wire speed, and TF is a furnace temperature, and Tsi is a heating zone inlet band temperature, TSS is for being with warm static value, TV is an areal velocity, and Tvave is the mean value of TV, and Tfave is the mean value of TF, SVF is the furnace temperature coefficient, s ₁..., s ₄Be model self study parameter, ρ is band steel proportion, C _ρBe band steel specific heat, σ ₀Be the Stefan-Boltzmann coefficient, φ is band steel radiation coefficient.

6, the method for control belt steel temperature according to claim 4 is characterized in that, it is as follows to draw the belt steel temperature dynamicmodel according to static model:

$\mathrm{yhat}\left(t\right)=a1y(t-1)+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{biu}(t-d-i+1)+\underset{i=1}{\overset{4}{\mathrm{\Σ}}}\mathrm{ciwi}\left(i\right)$

$y_{\mathrm{hat}}\left(t\right)=a_{1}y(t-1)+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{b}_{i}u(t-d-i+1)+\underset{i=1}{\overset{4}{\mathrm{\Σ}}}{c}_i{w}_i\left(t\right)$

Output is plate temperature deviation, and input is that the gas flow deviation is multiplied by a time-varying coefficient; Disturbing then is a series of dynamic disturbance that the variation at strip speed, thickness, width causes.

y(t)≡TS(t)-TSave

u(k)＝DVF(k)*{FL(k)-FL _ave}

w ₁≡TST(k-1)

w ₂≡DSS(k)

w ₃≡DVF(k)*{WD(k)*TH(k)*VS(k)-WTV _ave}

w ₄≡DVF(k) k＝t+1，...，t+d

$\mathrm{DVF}\left(k\right)\≡\frac{\∂\left(\mathrm{TSS}\right)}{\∂\left(\mathrm{TF}\right)}$

Wherein: d heats up time of lag y for the band steel _HatThe estimated value of y (t) during (t) for sampling, TV is an areal velocity, and FL is a gas flow, and WD is a strip width, and SVF is the furnace coefficient, and DVF is the furnace temperature differential coefficient, and DSS is for being with warm constant term variable quantity, and TST is for being with warm time lag of first order item, TS _AveBe the mean value of TS, FL _AveBe the mean value of FL, WTV _AveBe the mean value of WD * TH * VS, a ₁, b ₁-b _m, c ₁-c ₄Be model self study parameter, n is a constant

7, the method for control belt steel temperature according to claim 5, it is characterized in that, calculate the increment of gas flow according to described band steel dynamicmodel: in generalized predictive control, predictive model adopts controlled autoregressive integration gliding model, and the optimization aim of generalized predictive control rule is:

$\min J=E\{\underset{j=N1}{\overset{N2}{\mathrm{\Σ}}}\mathrm{\ρ}\left(j\right){\{r(t+j)-y(t+j)\}}^2+w\underset{k=1}{\overset{\mathrm{NU}}{\mathrm{\Σ}}}\mathrm{\Δ}{u}^{\′}{(t+k-1)}^2\}$

Wherein, w is the weight of operational ton, and ρ (j) is the weight with warm deviation, and r is the object tape temperature, and y is actual band temperature, and N1 is the invalid period, and N2 is the time of future position, and NU is certain moment apart from current point, and Δ u ' is the increment of operational ton.

8, the method for control belt steel temperature according to claim 6 is characterized in that, according to the reference value of gas flow incremental computations gas flow:

FLsv＝FLpv+Δu′(t)

FLsv is the reference value of gas flow, and FLpv is the actual value of gas flow, and Δ u ' is the gas flow increment (t).

9, the method for control belt steel temperature according to claim 4 is characterized in that, the self study coefficient calculations of static model is as follows:

s _hatj(t)＝s _hatj(t-1)+K _j*ε(t)

$K_j\≡\frac{p_j*{\mathrm{\φ}}_j\left(t\right)}{1+\underset{i=1}{\overset{4}{\mathrm{\Σ}}}{p}_i*{\mathrm{\φ}}_i{\left(t\right)}^2}$

Wherein, p _jAdaptive gain, TV are that TV is an areal velocity, and t is the sampling time, s _Hat1Be the estimated value of parameter 1, s _Hat2Be the estimated value of parameter 2, s _Hat3Be the estimated value of parameter 3, s _Hat4Be the estimated value of parameter 4, p _jBe adaptive gain.

10, the method for control belt steel temperature according to claim 5 is characterized in that, the self study coefficient calculations of dynamicmodel is as follows:

Λ (t) is the matrix of N * N, N=n+5

λ _i(t) be forgetting factor,

${\mathrm{\λ}}_i\left(t\right)\≡\sqrt{1-\frac{g_i*\mathrm{\ϵ}{\left(t\right)}^2}{1+\stackrel{\‾}{\mathrm{\φ}}{\left(t\right)}^{T}P(t-1)*\stackrel{}{\stackrel{\‾}{\mathrm{\φ}}}\left(t\right)}}$

Wherein, g _iBe i member's the constant of response θ, λ _iBe i member's the forgetting factor of response θ, θ _Hat(t) be that n is the control region in sampling t estimated value constantly.

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