scholarly journals Regulating the Coordinates of the Electromechanical System of the Rolling Mill Based on the Elastic Torque Observer

2021 ◽  
Vol 21 (2) ◽  
pp. 115-129
Keyword(s):  
Automatic Control ◽  
Control Systems ◽  
Electric Drive ◽  
Rolling Mill ◽  
Experimental Studies ◽  
Speed Control ◽  
Electromechanical System ◽  
Transient Processes ◽  
Roll Speed ◽  
Elastic Shaft

The paper considers the electromechanical system of the reversing stand of the plate rolling mill 5000 of PJSC “Magnitogorsk Metallurgical Plant” (PJSC “MMK”). The performed experimental studies of transient processes in the mode of gripping metal by rolls allowed establishing unacceptable dynamic loads of an oscillatory nature and a loss of controllability of the electric drive. This confirms the need for the development of control methods that limit the motor and spindle torques. It is noted that the known control systems for the speed modes of an electric drive, which decrease the elastic moment due to the preliminary closing of the angular gaps, are, in essence, open-loop speed control systems. This does not provide for the controlled regulation of coordinates in dynamic modes. The paper proposes the development of a closed system for automatic control of coordinates of a two-mass electromechanical system with an observer of the moment of the elastic shaft and the speed of the second mass. An observer of the unmeasurable parameters of a two-mass rolling mill system has been developed. It provides an indirect determination (recovery) of the roll speed and the spindle torque in on-line mode. It is based on a system of equations in the state space. By comparing the reconstructed and experimentally obtained transient processes, the satisfactory accuracy of the results has been confirmed. Based on the proposed observer, the authors developed an automatic control system (ACS) of the roll speed with subordinate contours of the elastic shaft moment, speed and engine torque. The setting of closed-loop regulators has been substantiated. Transient processes of moments and velocities are considered at impact application of a load with increased speed of the second mass speed control loop. The analysis of the LAFC and LPFC confirmed the stability of the developed system in the frequency range. The analysis of experimental data substantiated a conclusion about the influence of the angular gap on the accuracy of the elastic moment recovery in the mode of metal capture by rolls. Prospects for the introduction of developments at mill 5000 and other rolling mills operating with shock load are noted.

scholarly journals Development of an Automatic Elastic Torque Control System Based on a Two-Mass Electric Drive Coordinate Observer

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 305
Author(s):  
Andrey A. Radionov ◽  
Alexandr S. Karandaev ◽  
Vadim R. Gasiyarov ◽  
Boris M. Loginov ◽  
Ekaterina A. Gartlib
Keyword(s):  
Control System ◽  
Literature Review ◽  
Control Systems ◽  
Electric Drive ◽  
Rolling Mill ◽  
A Priori ◽  
Torque Control ◽  
Mass System ◽  
Loop Control ◽  
Plate Rolling

Development of control system based on digital twins of physical processes is a promising area of research in the rolling industry. Closed-loop control systems are developed to control the coordinates of two-mass electromechanical systems in order to limit the dynamic loads on the equipment of main rolling lines. These control systems are based on observers (digital shadows) that indirectly detect (reconstruct) the roll speed and the elastic torque of the shaft (spindle) in real time. Notably, observers are required to work fast in order to reconstruct transients attributable to shock (impact) loads. Literature review shows that the known observers, which use complex algorithms to compute coordinates, do not respond fast enough. The paper analyzes the kinematic diagram of Mill 5000, a plate rolling mill. It presents oscillograms that prove that the elastic torque does oscillate as the rolls grip the strip dynamically. The authors hereof have developed an observer that reconstructs the coordinates of the uncontrolled mass (the shaft) and the spindle torque from the parameters of the controlled mass, namely the torque and speed of the motor. The paper further rationalizes an approach that consists of simulating the processes on a model to further directly configure them on the object. The authors analyze the transients of the reconstructed two-mass system coordinates, which are associated with the rolls gripping the strip. The paper compares data against oscillograms recorded on the mill itself. The accuracy is satisfactory. The proposed observer has been used to developed a three-loop automatic speed control system for the uncontrolled mass. Controller configurations are substantiated. The paper shows coordinates obtained by simulation modeling as functions of time. It further presents experiments run on Mill 5000; the conclusions are that the amplitude and oscillations of the elastic torque drop significantly. The paper concludes with recommendations on industrial adoption of the observer and the novel electric drive coordinate control system. Study presented herein substantiates and implements a concept of developing algorithms that solve specific problems and are readily implementable on the existing equipment without need for additional computing devices. The contribution of the paper consists of stating and solving the problem of developing and testing an automatic elastic torque control system for the shaft of a heavy-duty rolling mill. This system has been implemented in the form of algorithms that run in the software of the existing industrial controllers (PLCs). It is simple and performs well. It does not need additional sensors or computers to be implemented, nor does it rely on complex computational algorithms. Such algorithms are based on computational tables that require a priori data on numerous process parameters. In our literature review, we have not come across any industrial implementation of such algorithms on hot-rolling mills.

scholarly journals MODELING OF A SYSTEM FOR AUTOMATIC REGULATION OF THE TENSION MODE IN THE ROUGHING GROUP OF STANDS OF A CONTINUOUS SECTION MIL

2021 ◽  
pp. 67-73
Author(s):  
Ivan Marynych ◽  
Olga Serdiuk
Keyword(s):  
Control System ◽  
Automatic Control ◽  
Control Systems ◽  
Automatic Control System ◽  
Rolling Mill ◽  
Rolling Speed ◽  
Automatic Regulation ◽  
Automatic Control Systems ◽  
Rolling Mode ◽  
Uneven Heating

The subject of the research is automatic control system modeling features for tensioning of stands roughing group, which takes into account changes in the rolling speed at exit of the previous stand and entrance to the next stand. Control systems for high-speed rolling on section mills are the most critical systems, since the trouble-free operation of rolling mill largely depends on their work. Rolling speed control is understood to mean tension regulation in the roughing group of stands and stabilization of the rolling loop in the finishing groups. The influence of such technological factors as uneven heating of blanks, change in the crimping mode in stands, etc. leads to the appearance of tension or back-up forces, deviation of rolled loop from the specified values. Tension rolling, in contrast to loop rolling, is a stable rolling mode. However, (at significant values of tension in the rolled products) such a rolling mode leads to different thicknesses of the finished product. The loop rolling mode is an unstable mode and is impossible without automatic control systems. Both in the tension rolling mode and in the free rolling mode with a loop, it is necessary to study automatic control systems in order to determine the possibilities of compensating for disturbing influences and obtaining rolled products of the given accuracy. Therefore, the main task of the automatic control system is to maintain the rolling mode with the lowest possible tension. To achieve this goal, direct control of the tension of the rolled strip with modern technical means is rather difficult, and the operation of tension control systems is based on indirect methods of measuring it, and the study of the system efficiency is reduced to modeling the process itself. The developed model consists of three stands and two inter-stand spaces, since it takes into account changes in rolling speed at the exit of previous stand and the entrance to the next stand. It is due to this that adequate simulation results are obtained that are close to the real rolling process. Keywords: automation, rolls, stand, inter-stand spacing, modeling, loop tension, rolling mill, roughing group.

Experimental Parametrization of the Dual-Mass Electromechanical System of a Rolling Mill

2021 ◽  
Vol 64 (3) ◽  
pp. 24-35
Author(s):  
Alexander Karandaev ◽  
◽  
Andrey Radionov ◽  
Boris Loginov ◽  
Olga Gasiyarova ◽  
...  
Keyword(s):  
Electric Drive ◽  
Rolling Mill ◽  
Torque Control ◽  
Electromechanical System ◽  
Model Parameters ◽  
Mass Model ◽  
Mass System ◽  
Iron And Steel ◽  
Electric Drives ◽  
Drive Control

Transients in electromechanical systems need to be modeled adequately if the existing electric drive control algorithms are to be improved, or new ones are to be developed. This fully applies to the electric drives of roll-ing mill stands. When studying such drives, one often needs to find a tradeoff between the complexity of Park-Gorev equation-based mathematical description of processes in variable frequency drives, and the capabilities of simpler models that adequately describe the processes relevant for each specific case. The latter include the known dual-mass model of the electromechanical system of a rolling mill stand featuring a flexible shaft and gaps in transmissions. Research presented herein covers the parameters of this model, which need to be ob-tained experimentally. The most accurate way to find the model parameters is to derive them from the oscillo-grams sampled on the object when running in typical transient. This particular paper addresses the electrome-chanical system of the horizontal stand in Plate Mill 5000 deployed at Magnitogorsk Iron and Steel Works (MMK PJSC). The paper substantiates the methodology behind parametrizing the system and shows how to cal-culate the moments of inertia of rotating masses from oscillograms of unloaded drive acceleration. To showcase the method, the paper presents finding the stiffness factor of an elastic coupling from the transients recorded when halting the electric drive. Focus is made on finding the time constants of the internal torque control cir-cuit as approximated by first-order or second-order filters. By comparing the simulation output against the os-cillograms sampled on the mill itself, the model was proven to adequately compute the parameters of the object. The paper concludes with recommendations on how the developed methods could be used to find the parame-ters of a dual-mass system when modeling the electric drives in rolling mills. The conclusions outline possible further research.

scholarly journals Synthesis of a robust control system for two-mass electric drive by H∞-theory

2020 ◽  
pp. 44-48
Author(s):  
Є.С. Руднєв ◽  
O.O. Тимофєєва ◽  
Р.М. Брожко
Keyword(s):  
Control System ◽  
Robust Control ◽  
Control Systems ◽  
Electric Drive ◽  
Control Object ◽  
Transient Processes ◽  
Speed Controller ◽  
Wide Range ◽  
Robust Control Systems

The practice of designing and operating control systems for industrial facilities has shown that systems synthesized according to the criteria of modular and symmetric optima, as well as by quadratic quality criteria, are sensitive to changes in the parameters of the controlled object, incoming characteristics, disturbing influences, the structure and parameters of the object model changing, which used in control loops. Such systems can lose optimality as well as productivity, if information about the object and operating environment is known with some probability or uncertainty. For an industrial electric drive, changes in load torque, moment of inertia of rotating parts, supply voltage and environmental characteristics (temperature, vibration) are especially significant. These changes affect both the mechanical characteristics rigidity and the transients’ quality. Robust control systems provide a required quality of work when changing the characteristics of impacts and instability of the control object parameters in a wide range. In the presence of uncertainties, a robust controller provides robust stability and quality for all admissible uncertainties. The synthesis of robust control systems with an H∞-speed controller of a two-mass electric drive by methods of H∞-theory is presented in order to prove the possibility of using algorithms for a given stabilization and speed control, as well as providing the necessary degree of sensitivity to parametric and coordinate disturbances acting on the control object. Application of the method of robust controllers’ synthesis taking into account the requirements for the quality of a controlled coordinate transient processes in the control system. The analysis of the operation of a synthesized robust system with an H∞-speed controller using digital modeling on mathematical models in the MATLAB / Simulink environment is carried out. The possibility of the speed independent control, the steady-state error and the nature of the transient processes of the controlled coordinate in the synthesized electric drive control system is shown.

scholarly journals Dynamic Models Of An Electromechanical Electric Drive System Of An Asynchronous Motor

2021 ◽  
Vol 03 (04) ◽  
pp. 134-139
Author(s):  
Zaylobitdin Mamatovich Rejabov ◽  
Keyword(s):  
Automatic Control ◽  
Electric Drive ◽  
Dynamic Models ◽  
Equations Of Motion ◽  
Asynchronous Motor ◽  
Drive System ◽  
Transient Processes ◽  
Electric Drive System ◽  
Control Devices ◽  
Joint Consideration

Asynchronous motors require its study not only in stationary modes, but also in dynamic ones. At the same time, this makes it possible to formulate the corresponding requirements for automatic control devices of a regulated IM, the implementation of which will ensure the optimal course of transient processes in the electric drive system; it requires its study not only in stationary modes, but also in dynamic ones. This simultaneously makes it possible to formulate the corresponding requirements for automatic control devices of variable IM, the implementation of which will ensure the optimal course of transient processes in the electric drive system The study of electromechanical transient modes requires a joint consideration and solution of the equations of equilibrium of electrical quantities in the windings of the machine and the equations of motion of an electric drive.

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