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

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.