SU1569802A1 - Automatic control system - Google Patents

Abstract

The invention relates to the field of automatic control and regulation and can be used in the construction of control systems for technical objects containing significant delays. The object is also subject to the influence of uncontrolled disturbances such as pulses. An example of such objects is the domain oven. The aim of the invention is to improve the accuracy of the system. The goal is achieved by introducing two scale blocks 8 and 10 and block 7 of delay elements. The results of simulation modeling showed sufficient effectiveness of the proposed automatic control system when used for objects with significant delays, such as a blast furnace. 1 il.

Description

The invention relates to automatic control and regulation and can be used in the construction of a system of technical objects containing significant delays.

Object dynamics is described by a view model.

wffi "l

where L (P) and M (P) are polynomials in P, and the degree of the polynomial L (P) does not exceed the degree of the polynomial M (P);

Ј - lag.

The object is subject to the influence of uncontrolled impulses of the pulse type. The main control task is to track changes in the task y (t) to the unregulated output variable y (t), changing the regulating effect U (t).

The purpose of the invention is to improve the accuracy of regulation. The drawing shows a block diagram of an automatic regulation system.

The system contains the executive unit 1, the control object 2, the first 3 and second 4 sensors, the first 5 and second 6 low-frequency filters, the block 7 delay elements with the first 7-, second 7-2, ..., j-m 7-j , ..., nth 7-p delay elements, first scaling unit 8, block 9 scaling elements, containing the first 9-1, second 9-2 ,, .., j-th, ..., nth 9-n scaling elements, second scaling unit 10, adder 11, proportional-integral controller 12, unit 13 of comparison and setting unit S4,

The system diagram indicates: y (t) is the controlled output of the control object; y (t) is the reference signal for the value of the controlled output of the object; U (t) - regulating effect on the input

control object; m (t) is the signal of the regulating action, supplied by the input of the executive unit; V (t) is the uncontrolled perturbation brought to the control input of the object; Y (t +) and yn (t + Ј) are the object output values predicted at the time point (t +), respectively, in the proposed and known systems;

0

-

0

0

35 40 45

Jq

„

y (t + b) are the actual changes in the output of the object, presented with an emphasis on the delay time; CA (O and yj- (t) are the components of changes in the output of the object, due to the effect, respectively, of changes in the regulating effect U (t) and uncontrolled disturbance V (t);

The control object 2 is, for example, a blast furnace. The regulated output variable y (t) in this case is, for example, an indicator of the thermal state of the furnace. Regulatory input impact U (t) is, for example, the consumption of natural gas in the blast. The pulsed nature of the uncontrolled perturbations V (t), here is due, in particular, to the corresponding changes in the quality indicators of charge materials.

The executive unit 1 is, for example, an automatic control system for the flow of natural gas in the blast of a blast furnace, to the input of which a regulating influence jlt (t) is given, which is a task for the absolute value of the flow of natural gas or for its fraction in the volume blow fed into the oven.

The first sensor 3 is, for example, a membraneless differential pressure gauge with an electrical output, and the second sensor 4 is a system for monitoring the thermal state of a blast furnace according to the temperature of the tuyere zones.

The control system works as follows.

The signal about the predicted output value of the object y (t + Ј), coming from the output of the adder 11, in block 13 of the comparison is subtracted from the signal y (t) about the current task for the adjustable output of the object coming from the output

setting device 14. A signal about the error received is fed to the input of the proportional-integral controller 12. At the controller output, a signal iu (t) is formed, which is converted by the executive unit to the control action U (t) of the control object. If the transfer function of the executive unit is close to unity, then U (t) -x ji / (t). The signal y (t) about the current value of the object output comes from the output of the second sensor 4 through the second low-pass filter 6 connected in series, designed to suppress

51

high-frequency measuring interference and the second scaling unit 10 to one of the inputs of the adder 11.

In the scaling unit 10, this signal is multiplied by a constant coefficient С „, the value of which shows the extent to which the output value at the moment of time (t + Ј) is determined by its current value y (t), i.e. Prediction of the free component of output changes is made:

y, (t

cЈy (t).

The magnitude of the coefficient C2 is determined by the dynamic characteristics of the object. In particular, if the control object can be represented by a model in the form of a serially connected delay link and aperiodic link with a transfer function of the form:

W (P). k e-rf} TR + 1

where k and T are respectively the gain and constant inertia time,

that

69802

U (t) passes successively all n delay elements of the block 7 delay elements, spending in each of

5 elements per time interval AЈ.

Thus, at the output of any j-ro delay element 7-j, a signal U (t − ji) t is applied to the next delay element and to co10, the corresponding scaling element 9-j. From the output of the delay element 7-n, the signal is fed only to the input of the scaling element 9-n. In the first scaling unit 8, the signal U (t

15 is multiplied by the scaling factor g. H. C., and in the scaling elements i max 9-1, 9-2.,., 9-j, ..., 9-n the corresponding signals U (t - & amp ), U (t - 2 & t), ..., U (t - jiЈ), ..., U (t - n &)

20 are multiplied, respectively, by weights C, C 4 ,. .., GIJ,. .., С The values of the coefficients С, Сю, ..., C (i, ..., С1г, are determined in accordance with the weight control function, in

25 in particular for an object in the form of serially connected aperiodic and delayed links:

thirty

p - A V

C, - T1H;

Cr

-t | t

The signal U (t) on the actually implemented control action is fed from the output of the first sensor 3 through the first low-frequency filter 5, where it is averaged over the time interval, to the input of the first scaling unit 8 and to the input of the first delay element 7-1 of the delay unit 7 . The constant time T of the inertia of this link can be chosen from the condition At.

In the first delay element 7-1, the signal is delayed by time dЈ. The signal U (t-At) from the output of the delay element 7-1 is fed to the input of the first scaling element 9-1 of the scaling element block 9 and to the input of the second delaying element 7-2, where it is delayed by an additional time interval. The signal U (t - 2Ј) from the output of the second delay element 7-2 is fed to the input of the second scaling element 9-2 and to the input of the third delay element 7-3, and so on. Those. signal

g - 1lЈ- / T

 (j - Y ut e

As a result of summing the signals 5 from the outputs of the first scaling unit 8 and the scaling elements 9-1, 9-2, ..., 9-p, performed in the adder 11, the predicted value of the forced component of the changes yB (t t) is formed under the influence of the use of regulatory actions implemented in the delayed interval:

45

y (t + fr) C, U (t) u: t-jdf).

The value of the interval fcЈ. The choice of the number n of discrete intervals in the approximation of the delay interval (can be carried out according to recommendations.

Claims (1)

Invention Formula An automatic control system comprising first and second sensors, first and second low-pass filters connected in series reference block, comparison unit, proportional-integral controller, ispol-. the control unit and the control object, the adder, the inputs of the first and second sensors are connected respectively to the input and output of the control object, and the outputs of the first and second sensors are connected to the inputs of the first and second low-j filters, respectively, the output of the adder is connected to the input block, comparison, about t., and that with the purpose of increasing the accuracy of the system, the first and second scaling blocks were introduced into it, n connected in series. Compiler A. Laschev Editor I. Derbak Tehred M. DidykKorrektor L. Beskid Order 1449 Circulation 667 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab., D. 4/5  i-p- TP i-m Шг-L- --- - i I л - ITU - г --- - «- д --- ш --- - - - - - - - - .-. “H. Production and publishing plant Patent, Uzhgorod, st. Gagarin, 101 Delay elements and n-scaling elements, each input of KS scaling elements connected to the output of the corresponding. Delay element number, the input of the first of which is connected to the input of the first scaling unit and connected to the output of the first low-frequency filter, the input of the second scaling unit connected to the output of the second low-pass filter, the outputs of the first and second scaling units, as well as the outputs of the scaling elements are connected to the corresponding inputs of the adder. Subscription