CN107999545B - Cold rolling mill second flow thickness control method and system based on system identification and parameter self-adaption - Google Patents
Cold rolling mill second flow thickness control method and system based on system identification and parameter self-adaption Download PDFInfo
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Abstract
The invention provides a cold rolling mill second flow thickness control method based on system identification and parameter self-adaptation, which is characterized in that a theoretical value of the strip steel outlet thickness is pre-calculated according to a second flow equation; measuring the actual thickness value of the strip steel outlet by using an outlet thickness gauge to correct the pre-calculated theoretical thickness value of the strip steel outlet; inputting second flow AGC, sampling AGC control quantity and strip steel outlet thickness, and then identifying parameters of a controlled object by using a least square method; and calculating the initial value of the PI parameter according to the parameter of the controlled object by experience, and continuously adjusting the PI parameter by using a self-adaptive method. The second flow thickness control method can realize automatic identification and self-adaptive optimization, so that the second flow AGC can obtain good control performance in the steel rolling process.
Description
Technical Field
The invention relates to the technical field of steel rolling control, in particular to a cold rolling mill second flow thickness control method and system based on system identification and parameter self-adaptation.
Background
The thickness Control system of the single-stand reversible cold rolling mill generally comprises three thickness Control (Automatic Gauge Control) modes of feedforward, second flow and monitoring. The second flow AGC is a main mode of feedback control, the second flow AGC is based on a deformation area second flow constant rule, the rule means that the mass flow of metal before and after a rack is constant, and the speed and the thickness of the strip steel before and after the rack keep strict proportional relation due to the fact that the widths of the strip steel before and after the rack are basically consistent, namely:
Ven×hen＝Vex×hex
in the formula Ven-strip inlet speed; vex-strip exit speed; h isen-strip entrance thickness; h isex-strip exit thickness.
The laser velocimeter can obtain the speed of the inlet and the outlet of the deformation area with high precision, and the thickness of the outlet of the strip steel can be calculated without delay by adding the front thickness gauge and then feedback control is carried out, so that the second flow AGC can obtain quite high thickness precision.
Because the outlet thickness gauge is at a distance from the roll seam of the rolling mill, the thickness of the outlet measured by the outlet thickness gauge is delayed, and the outlet thickness measured by the outlet thickness gauge is not suitable for being directly used for feedback control, but the precision of the thickness gauge is very high (the general measurement precision can reach 1 mu m), and the second flow pre-calculated outlet thickness can be corrected by using the outlet thickness measured by the outlet thickness gauge, so that the precision of calculating the outlet thickness by the second flow is further improved.
Currently, the second flow AGC method which is industrially practical generally calculates the adjustment amount of the roll gap through a Proportional Integral (PI) controller, and it is known that the selection of a PI parameter has a great influence on the control performance of the PI controller, and the working condition of the PI controller is constantly changed during the rolling process, so that the use of a fixed PI parameter is not suitable.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method and the system for controlling the second flow thickness of the cold rolling mill based on system identification and parameter self-adaptation are provided, so that the second flow thickness of the cold rolling mill can still obtain good control performance under the condition that the working condition is constantly changed.
The technical scheme adopted by the invention for solving the technical problems is as follows: a cold rolling mill second flow rate thickness control method based on system identification and parameter self-adaptation is characterized in that strip steel is started from an inlet coiling machine in each pass, passes through an inlet steering roller and then is rolled in a six-roller rolling mill, a hydraulic cylinder provides rolling force, then passes through an outlet steering roller and finally is coiled on an outlet coiling machine; the unit is provided with an inlet thickness gauge and an outlet thickness gauge which are respectively used for measuring the thickness of the inlet strip steel and the outlet strip steel, an inlet laser velocimeter and an outlet laser velocimeter which are respectively used for measuring the speed of the inlet strip steel and the outlet strip steel, all rolling process control functions are completed by programming in a PLC controller, and the unit is characterized in that: the method comprises the following steps:
s1, pre-calculating the theoretical value of the thickness of the strip steel outlet according to the second flow equation;
s2, measuring the actual value of the strip steel outlet thickness by using an outlet thickness gauge to correct the pre-calculated theoretical value of the strip steel outlet thickness;
s3, feeding second flow AGC, sampling AGC control quantity and strip steel outlet thickness, and then identifying parameters of a controlled object by using a least square method;
and S4, calculating the initial value of the PI parameter according to the parameter of the controlled object by experience, and continuously adjusting the PI parameter by using a self-adaptive method.
According to the above method, the S1 specifically includes:
delaying the thickness of the strip steel inlet measured by the inlet thickness gauge to the roll gap of a six-roll mill;
and pre-calculating the theoretical value of the thickness of the strip steel outlet according to the second flow equation.
According to the method, the S2 specifically comprises the following steps:
delaying the pre-calculated theoretical value of the thickness of the strip steel outlet to an outlet thickness gauge;
measuring the actual thickness value of the strip steel outlet by using an outlet thickness gauge, calculating and pre-calculating the outlet thickness difference and performing smoothing treatment to obtain the corrected value of the strip steel outlet thickness;
and calculating the corrected second flow outlet thickness according to the corrected strip steel outlet thickness value.
According to the method, the S3 specifically comprises the following steps:
performing time delay operation on the second flow AGC control quantity by using the result of S2;
sampling delayed control quantity after second flow AGC is put into and actual thickness value of a strip steel outlet;
the least squares identify the time constant and gain parameters of the controlled system.
According to the method, the S4 specifically comprises the following steps:
according to the identified time constant and gain parameter of the controlled system, calculating the initial parameter value of the PI controller according to experience;
putting the calculated initial parameter values into use, and adaptively correcting the PI parameters according to working conditions;
calculating the second flow thickness control quantity by using a PI controller with optimized parameters;
and finally, the second flow thickness control quantity obtained by calculation is led to a hydraulic roll gap control link, and the hydraulic roll gap control link controls the pressing stroke of the hydraulic cylinder.
The utility model provides a cold rolling mill second flow thickness control system based on system identification and parameter self-adaptation which characterized in that: the method comprises a memory, wherein a PLC program is stored in the memory and is used for being called by a PLC controller to complete the cold rolling mill second flow thickness control method based on system identification and parameter self-adaptation.
The invention has the beneficial effects that: according to the method, firstly, a theoretical value of the thickness of a strip steel outlet is pre-calculated according to a second flow equation, then, a thickness correction value is calculated according to an actual value of the thickness of the strip steel outlet measured by an outlet thickness gauge and is used for further correcting the pre-calculated thickness of the second flow, then, a PI parameter preliminary value calculated in the previous pass is used for carrying out second flow AGC control, and sampling is stopped when the initial sampling control quantity and the outlet thickness are put in until the actual value of the thickness of the strip steel outlet is close to a set value. And identifying model parameters of the controlled system according to the sampling data, calculating an initial value of the PI parameter according to experience, using the parameter in the subsequent rolling process, adaptively optimizing and adjusting the PI parameter along with the change of working conditions, and finally calculating the second flow thickness control quantity by using a PI controller for optimizing the parameter. The automatic identification and self-adaptive optimization second flow thickness control method is finally realized through the steps, so that the second flow AGC can obtain good control performance in the steel rolling process.
Drawings
FIG. 1 is a schematic view of a thickness control system of a single stand reversible mill and its main instrumentation.
FIG. 2 is a flowchart of a method according to an embodiment of the present invention.
In the figure: 1-inlet coiling machine, 2-inlet turning roll, 3-inlet thickness gauge, 4-hydraulic cylinder, 5-inlet laser velocimeter, 6-strip steel, 7-six-roll mill, 8-outlet laser velocimeter, 9-PLC controller, 10-outlet thickness gauge, 11-outlet turning roll and 12-outlet coiling machine.
Detailed Description
The invention is further illustrated by the following specific examples and figures.
Fig. 1 is a schematic view of a thickness control system of a single-stand reversible rolling mill and its main instrumentation, where the current rolling direction is from left to right, the next pass will be from right to left, and then the rolling is repeated in the reverse direction. In the present pass, the strip 6 is started from the entry coiler 1, rolled through the entry deflection roll 2 and then in a six-high rolling mill 7, the rolling force provided by the hydraulic cylinders 4, through the exit deflection roll 11 and finally coiled on the exit coiler 12. The unit is provided with an inlet thickness gauge 3 and an outlet thickness gauge 10 which respectively measure the thickness of the inlet strip steel and the outlet strip steel, and is also provided with an inlet laser velocimeter 5 and an outlet laser velocimeter 8 which can respectively measure the speed of the inlet strip steel and the speed of the outlet strip steel with high precision in order to realize second flow thickness control. All rolling process control functions are completed by programming in the PLC 9, and the specific control functions mainly comprise thickness control, hydraulic roll gap control, tension control, transmission control, roll bending and roll shifting control, plate shape control and the like. The thickness control system calculates the adjustment quantity of the roll gap of the rolling mill, and the adjustment is realized by adjusting the pressing stroke of the hydraulic cylinder through the hydraulic roll gap control system.
The invention provides a cold rolling mill second flow thickness control method based on system identification and parameter self-adaptation, as shown in figure 2, comprising the following steps:
and S1, pre-calculating the theoretical value of the thickness of the strip steel outlet according to the second flow equation.
S1 specifically includes:
s101, delaying the thickness of the strip steel inlet measured by the inlet thickness gauge to a roll gap of a six-roll mill.
The thickness of the strip steel inlet measured by the inlet thickness gauge is delayed to the roll gap of the rolling mill, and the delay time is changed along with the change of the strip steel inlet speed, so that a synchronous transmission model TPM is adopted to complete the delay function, the model can still accurately delay the tracked strip steel from the inlet thickness gauge to the roll gap of the rolling mill under the condition that the inlet speed is changed at will, and the inlet thickness obtained after delay is set as Hen,del. The relevant contents of the synchronous transmission model can be found in chinese patent CN 102380515B.
And S102, pre-calculating the theoretical value of the thickness of the strip steel outlet according to the second flow equation.
Calculating the thickness of the strip steel outlet according to the speed of the strip steel inlet and outlet and the thickness of the delayed strip steel inlet in the second flow direction:
in the formula, hMF,calcThe thickness of the strip steel outlet is pre-calculated for the second flow range; venIs the actual value of the strip inlet speed, VexThe actual values of the strip steel outlet speed are respectively passed throughMeasured by a mouth laser velocimeter.
And S2, measuring the actual thickness value of the strip steel outlet by using an outlet thickness gauge to correct the pre-calculated theoretical value of the strip steel outlet thickness.
S2 specifically includes:
s201, delaying the pre-calculated theoretical value of the thickness of the strip steel outlet to an outlet thickness gauge.
Delaying the pre-calculated thickness of the strip steel outlet to an outlet thickness gauge, adopting a synchronous transmission model TPM, and setting the outlet thickness obtained after delaying as hex,del。
S202, measuring the actual value of the thickness of the strip steel outlet by using an outlet thickness gauge, calculating and pre-calculating the outlet thickness difference, and smoothing to obtain the corrected value of the strip steel outlet thickness.
Calculating the error between the thickness measured by the outlet thickness gauge and the outlet thickness pre-calculated, and then smoothing by using a first-order hysteresis link PT1 to obtain an outlet thickness correction value, namely:
Δhthg＝PT1(hthg-hex,del)
in the formula, hthgIs the outlet thickness measurement value h of the outlet thickness gauge at the current momentex,delFor the pre-calculated outlet thickness value after the delay, PT1 is a first-order lag link, and the discrete PT1 link algorithm is as follows:
in the formula, Ypt1(n) is an output value of the PT1 link at the current moment; y ispt1(n-1) is the output value of PT1 at the last moment of the link; t isSSampling time of a PLC controller; t isPT1The PT1 link time constant is obtained by the following values:
Lexthe distance between the roll gap of the rolling mill and the outlet thickness gauge; xnThe input value at the current moment is the difference between the thickness measured by the thickness gauge at the current moment and the thickness of the pre-calculated outlet after time delay; xn-1Is the difference valueThe value of the last time instant.
And S203, calculating the corrected second flow outlet thickness according to the corrected strip steel outlet thickness correction value.
Calculating the second flow outlet thickness after correction according to the outlet thickness correction value as follows:
hMF＝hMF,calc+Δhthg。
and S3, throwing second flow AGC, sampling AGC control quantity and strip steel outlet thickness, and identifying the parameters of the controlled object by using a least square method.
S3 specifically includes:
s301, using the result of S2, performs a delay operation on the second flow AGC control amount.
Although the second flow AGC can calculate the thickness of the strip steel outlet in real time, the measurement link and the control implementation link inevitably have time delay, and in addition, the transmission time of the strip steel from the roll gap of the rolling mill to the outlet thickness gauge is also considered, so that the AGC control quantity and the measured thickness of the strip steel outlet are not synchronous in time, and therefore, the control quantity and the measured thickness of the outlet have to be synchronously delayed.
The time needing time delay comprises second flow control lag time and transmission time of the strip steel transmitted from a roll gap of the rolling mill to an outlet thickness gauge, the second flow control lag time specifically comprises measuring time of a laser velocimeter and the thickness gauge and hydraulic roll gap control time, the lag time change of the part is not large, and the part can be used as a time constant, namely:
Tdelay＝THGC+TS+Tlaser+TTHG
in the formula, THGCFor controlling the time of hydraulic roll gap, TSIs the sampling period, T, of the PLC controllerlaserMeasuring time, T, for a laser velocimeterTHGThe time was measured for the thickness gauge.
The transmission time of the strip steel from the roll gap of the rolling mill to the outlet thickness gauge is related to the outlet speed of the strip steel, and when the outlet speed changes, the transmission time also changes, so that a synchronous transmission functional block TPM is also adopted to carry out synchronous transmission of control quantity.
Overall, the second flow AGC control quantity SMFPerforming a delay operation, specifically including performing TdelayThe time delay and the transmission time delay of the strip steel from the roll gap of the rolling mill to the outlet thickness gauge are finally obtained, and the second flow AGC control quantity S after the time delay is finally obtainedMF,del。
And S302, sampling the delayed control quantity after the second flow AGC is put into use and the actual value of the thickness of the strip steel outlet.
A second flow AGC control quantity S after the sampling delay from the sampling time of the second flow AGCMF,delAnd the thickness value of the strip steel outlet until the actual value of the thickness of the strip steel outlet is close to the set value.
For example, in this embodiment, the second flow AGC is put in when the rolling speed exceeds 60m/min in a certain rolling pass, and the second flow AGC control amount S after the start of sampling delay is setMF,delAnd the thickness value of the strip steel outlet, wherein the thickness of the strip steel outlet is gradually close to the set value under the control of the second flow thickness, and when the actual value of the thickness of the strip steel outlet is (95 percent, 105 percent) of the set value]When the thickness of the outlet is within the range of (2), judging that the thickness of the outlet is close to a set value at the moment, and stopping sampling.
Due to the existence of the time delay, a part of data of the flow AGC control quantity in the second after the time delay of the sampling is 0 at the initial stage, the control quantity can be changed into a non-zero value only after the time delay is finished, the part of data which is zero is useless and is deleted, and the outlet thickness value of the sampling corresponding to the zero value also needs to be deleted. The non-zero data thus left constitute two data sets, each data set having n data, i.e., U ═ U1,U2,U3,……,Un]And Y ═ Y1,Y2,Y3,……,Yn]. Wherein U is the sampled second-time delay flow AGC control quantity, and Y is the sampled strip steel outlet thickness.
And S303, identifying the time constant and the gain parameter of the controlled system by least square.
The simplification of the controlled system is regarded as a first-order inertia element with hysteresis, i.e. with a transfer function of
Where the lag time τ is Tdelay，KCGain parameter, T, for first-order inertia elementCIs the time constant of the first-order inertia element. To find these two parameters, let
In the formula TSAnd (3) calculating the values of a and b by using a least square method for the sampling time of the PLC. The detailed algorithm is as follows:
YN＝[Y2Y3Y4……Yn]
further, the time constant and gain parameters can be found:
TC＝-TS/ln(a)
KC＝b/(1-a)。
and S4, calculating the initial value of the PI parameter according to the parameter of the controlled object by experience, and continuously adjusting the PI parameter by using a self-adaptive method.
S4 specifically includes:
s401, according to the identified time constant and gain parameter of the controlled system, calculating the preliminary parameter value of the PI controller according to experience.
According to the identified controlled system parameters, the optimal value of the PI parameter is preliminarily calculated according to an empirical formula, and the specific algorithm is as follows:
TI,ini＝1.484×(Tdelay/TC)0.68
in the formula, KP,iniAnd TI,iniRespectively ratio of PI controllersThe coefficients and the integration time.
S402, putting the calculated initial parameter values into use, and adaptively correcting the PI parameters according to working conditions.
The second flow AGC of the current pass uses the primary value of the PI parameter calculated in the previous pass in the initial stage, after the system identification and PI parameter calculation process of the current pass are finished, the newly calculated primary value of the proportional coefficient and the integral time can be used, and then the PI parameter is corrected in a self-adaptive mode according to the actual outlet thickness difference and the strip steel outlet speed. The correction method of the proportionality coefficient comprises the following steps:
KP＝KP,ini×Ga
in the formula, GaThe self-adaptive factor is determined according to the size of the outlet thickness difference, and the larger the outlet thickness difference is, the larger the self-adaptive factor is.
Specifically, an upper limit value of the outlet thickness difference is set according to the required thickness of the product, for example, when the required thickness of the product of the rolling mill is 0.4mm, the upper limit value of the outlet thickness difference is set to be 5 μm, or when the required thickness of the product is 0.8mm, the upper limit value of the outlet thickness difference is set to be 6 μm, and so on, the upper limit values of the outlet thickness differences of all the products are respectively set according to the process requirements. When the actual outlet thickness difference is actually used, G is determined when the absolute value of the actual outlet thickness difference value is within the upper limit value rangea0.8; g when the absolute value of the actual value of the outlet thickness difference exceeds the upper limit value but is within 2 times of the upper limit valuea1.0; g is determined when the absolute value of the actual value of the outlet thickness difference exceeds 2 times of the upper limit value but is within 4 times of the upper limit valuea1.5; g when the absolute value of the actual value of the outlet thickness difference exceeds 4 times of the upper limit valuea＝10.0。
Then, the correction algorithm of the integration time is as follows:
in the formula, LthgIs the distance, V, between the front and rear thickness gauges of the millexIs the actual value of the strip outlet speed ViniThe strip steel outlet speed in the previous step of sampling the control quantity and the outlet speed is obtained.
And S403, calculating the second flow rate thickness control quantity by using the PI controller with optimized parameters.
And (3) calculating the roll gap regulating quantity of the second flow thickness control according to the outlet thickness difference by using a parameter optimized PI controller, namely:
in the formula, PI represents a proportional-integral controller, hsetIs an outlet thickness set point, CSIs the rigidity coefficient of the rolling mill and is obtained by testing during the test of the rolling mill, CMThe plastic coefficient of the strip steel.
The discrete PI controller algorithm is as follows:
in the formula, YnAnd Yn-1Respectively output values of the PI controller at the current moment and the last moment; xnIs the input value of the PI controller, here the current timeThe value of (c).
And finally, the second flow thickness control quantity obtained by calculation is led to a hydraulic roll gap control link, and the hydraulic roll gap control link controls the pressing stroke of the hydraulic cylinder to realize the optimized second flow thickness control method.
The second flow thickness control method of the cold rolling mill provided by the embodiment comprises the steps of firstly pre-calculating the thickness of a strip steel outlet according to a second flow direction, then calculating a thickness correction value according to the thickness measured by an outlet thickness gauge for further correcting the second flow pre-calculated thickness, then using the PI parameter preliminary value calculated in the previous pass to input second flow AGC control, and stopping sampling when the input initial sampling control amount and the outlet thickness are close to the set value until the actual value of the strip steel outlet thickness is close to the set value. And identifying model parameters of the controlled system according to the sampling data, calculating an initial value of the PI parameter according to experience, using the parameter in the subsequent rolling process, adaptively optimizing and adjusting the PI parameter along with the change of working conditions, and finally calculating the second flow thickness control quantity by using a PI controller for optimizing the parameter. The automatic identification and self-adaptive optimization second flow thickness control method is finally realized through the steps, so that the second flow AGC can obtain good control performance in the steel rolling process.
A cold rolling mill second flow thickness control system based on system identification and parameter self-adaptation comprises a memory, wherein a PLC program is stored in the memory and is used for being called by a PLC controller to complete the cold rolling mill second flow thickness control method based on system identification and parameter self-adaptation.
It is to be understood that the embodiments described herein may be implemented by hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the processing units may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, microprocessors, microcontrollers, other electronic units designed to perform the functions described herein, or a combination thereof. When the embodiments are implemented in software, firmware, middleware or microcode, program code or code segments, they can be stored in a machine-readable medium, such as a storage component.
The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.
Claims (4)
1. A cold rolling mill second flow rate thickness control method based on system identification and parameter self-adaptation is characterized in that strip steel is started from an inlet coiling machine in each pass, passes through an inlet steering roller and then is rolled in a six-roller rolling mill, a hydraulic cylinder provides rolling force, then passes through an outlet steering roller and finally is coiled on an outlet coiling machine; the unit is provided with an inlet thickness gauge and an outlet thickness gauge which are respectively used for measuring the thickness of the inlet strip steel and the outlet strip steel, an inlet laser velocimeter and an outlet laser velocimeter which are respectively used for measuring the speed of the inlet strip steel and the outlet strip steel, all rolling process control functions are completed by programming in a PLC controller, and the unit is characterized in that: the method comprises the following steps:
s1, pre-calculating the theoretical value of the thickness of the strip steel outlet according to the second flow equation;
s2, measuring the actual value of the strip steel outlet thickness by using an outlet thickness gauge to correct the pre-calculated theoretical value of the strip steel outlet thickness;
s3, feeding second flow AGC, sampling AGC control quantity and strip steel outlet thickness, and then identifying parameters of a controlled object by using a least square method;
s3 specifically includes:
s301, utilizing the result of S2 to carry out time delay operation on the second flow AGC control quantity;
the time needing time delay comprises second flow control lag time and transmission time of the strip steel from the roll gap of the rolling mill to the outlet thickness gauge, and the second flow control lag time TdelayThe method specifically comprises the following steps of measuring time by a laser velocimeter and a thickness gauge and controlling time of a hydraulic roll gap, wherein the lag time of the part is taken as a time constant, namely:
Tdelay＝THGC+TS+Tlaser+TTHG
in the formula, THGCFor controlling the time of hydraulic roll gap, TSIs the sampling period, T, of the PLC controllerlaserMeasuring time, T, for a laser velocimeterTHGMeasuring time for a thickness gauge;
the transmission time of the strip steel from the roll gap of the rolling mill to the outlet thickness gauge is related to the outlet speed of the strip steel, and when the outlet speed changes, the transmission time also changes, so that a synchronous transmission functional block TPM is also adopted to carry out synchronous transmission of control quantity;
overall, the second flow AGC control quantity SMFPerforming a delay operation, specifically including performing TdelayThe time delay and the transmission time delay of the strip steel from the roll gap of the rolling mill to the outlet thickness gauge are finally obtained, and the second flow AGC controlled variable after the time delay is finally obtainedSMF,del；
S302, sampling delayed control quantity after second flow AGC is put into and actual values of the thickness of the strip steel outlet;
a second flow AGC control quantity S after the sampling delay from the sampling time of the second flow AGCMF,delAnd the thickness value of the strip steel outlet until the actual value of the thickness of the strip steel outlet is close to the set value;
s303, identifying a time constant and a gain parameter of the controlled system by least square;
s4, calculating the preliminary value of the PI parameter according to the parameter of the controlled object by experience, and continuously adjusting the PI parameter by using a self-adaptive method;
s4 specifically includes:
s401, calculating a preliminary parameter value of the PI controller according to experience according to the identified time constant and the gain parameter of the controlled system;
according to the identified controlled system parameters, the optimal value of the PI parameter is preliminarily calculated according to an empirical formula, and the specific algorithm is as follows:
TI,ini＝1.484×(Tdelay/TC)0.68
in the formula, KP,iniAnd TI,iniRespectively are the preliminary calculated values of the proportional coefficient and the integral time of the PI controller; kCGain parameter, T, for first-order inertia elementCIs the time constant of the first-order inertia element;
s402, putting the calculated initial parameter values into use, and adaptively correcting the PI parameters according to working conditions;
the second flow AGC of the current pass uses the primary value of the PI parameter calculated in the previous pass at the initial stage, after the system identification and PI parameter calculation process of the current pass are finished, the newly calculated primary value of the proportional coefficient and the integral time can be used, and then the PI parameter is corrected in a self-adaptive manner according to the actual outlet thickness difference and the strip steel outlet speed; the correction method of the proportionality coefficient comprises the following steps:
KP＝KP,ini×Ga
in the formula, GaThe self-adaptive factor is determined according to the size of the outlet thickness difference, and the larger the outlet thickness difference is, the larger the self-adaptive factor is;
then, the correction algorithm of the integration time is as follows:
in the formula, LthgIs the distance, V, between the front and rear thickness gauges of the millexIs the actual value of the strip outlet speed ViniThe strip steel outlet speed in the previous step of sampling the control quantity and the outlet speed;
s403, calculating the second flow thickness control quantity by using the PI controller with optimized parameters;
and (3) calculating the roll gap regulating quantity of the second flow thickness control according to the outlet thickness difference by using a parameter optimized PI controller, namely:
in the formula, PI represents a proportional-integral controller, hsetIs an outlet thickness set point, CSIs the rigidity coefficient of the rolling mill and is obtained by testing during the test of the rolling mill, CMThe strip steel plasticity coefficient; h isMFThe corrected second flow outlet thickness;
the discrete PI controller algorithm is as follows:
in the formula, YnAnd Yn-1Respectively output values of the PI controller at the current moment and the last moment; xnIs the input value of the PI controller, here the current time
A value of (d); t isSThe sampling period of the PLC controller is set;
and finally, the second flow thickness control quantity obtained by calculation is led to a hydraulic roll gap control link, and the hydraulic roll gap control link controls the pressing stroke of the hydraulic cylinder.
2. The cold rolling mill second flow thickness control method based on system identification and parameter adaptation according to claim 1, characterized in that: the S1 specifically includes:
delaying the thickness of the strip steel inlet measured by the inlet thickness gauge to the roll gap of a six-roll mill;
and pre-calculating the theoretical value of the thickness of the strip steel outlet according to the second flow equation.
3. The cold rolling mill second flow thickness control method based on system identification and parameter adaptation according to claim 1, characterized in that: the S2 specifically includes:
delaying the pre-calculated theoretical value of the thickness of the strip steel outlet to an outlet thickness gauge;
measuring the actual thickness value of the strip steel outlet by using an outlet thickness gauge, calculating and pre-calculating the outlet thickness difference and performing smoothing treatment to obtain the corrected value of the strip steel outlet thickness;
and calculating the corrected second flow outlet thickness according to the corrected strip steel outlet thickness value.
4. The utility model provides a cold rolling mill second flow thickness control system based on system identification and parameter self-adaptation which characterized in that: the method comprises a memory, wherein a PLC program is stored in the memory and is used for being called by a PLC controller to complete the cold rolling mill second flow thickness control method based on system identification and parameter self-adaptation in any one of claims 1 to 3.
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| CN110355214B (en) * | 2019-06-24 | 2020-05-26 | 科芃智能科技（苏州）有限公司 | Mass flow inlet thickness storage calculation method based on minimum stack |
| CN110807029B (en) * | 2019-09-26 | 2023-04-25 | 乳源东阳光优艾希杰精箔有限公司 | Hash mapping storage method and system for second flow thickness |
| CN114749493B (en) * | 2022-06-13 | 2022-10-18 | 苏州翔楼新材料股份有限公司 | Self-adaptive adjustment method and system for production parameters of cold-rolled strip steel |
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| CN101844155B (en) * | 2009-12-29 | 2011-08-31 | 中冶南方（武汉）自动化有限公司 | Automatic gauge control (AGC) method for rolling mill |
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