Study On Torsional Vibration Modeling And Suppression Strategies Of Rolling Mill’s Main Drive System

The torsional vibration of the main drive system of the rolling mill causes chatter marks on the surface of the rolling stock and rolls,which seriously affects the quality of the rolled product.When torsional vibration occurs frequently,it can cause production accidents and result in irreversible situations.For this reason,how to suppress torsional vibration is of great significance for rolling steel production.The main drive system of the rolling mill is a large-scale complex system that combines electrical and mechanical coupling.It has characteristics such as strong coupling,nonlinearity,and difficult to measure parameters.Therefore,there are many factors affecting the torsional vibration of the rolling mill in the main drive system of the rolling mill.In this paper,the controller of the electromechanical coupling model of the main drive system of the rolling mill is designed to suppress the torsional vibration.The main contents include the following aspects:The main drive system of the rolling mill is simplified as a “mass-spring” system.Based on the kinetic energy theorem and the Lagrange equation,an electromechanical coupling dynamics model is established.Furthermore,considering that the rotor eccentricity is one of the causes of motor speed vibration in the main drive system,the torsional vibration of the rolling mill can be induced indirectly.For this purpose,based on the eccentricity of the rotor,an electromechanical coupling model of the main transmission of the rolling mill based on rotor eccentricity is established on the basis of the electromechanical coupling model of the main drive system of the rolling mill.According to this model,the simulation analysis is performed to analyze the influence of rotor eccentricity on the state of the motor.Based on these two models,the controller is designed to suppress the torsional vibration of the rolling mill and bring the control system to a stable state.With the electromechanical coupling torsional vibration model as the control object,it is considered that the elastic connection shaft can cause the torsional vibration of the main drive system of the rolling mill and the difficult measurement of the system parameters.Using the ADALINE(Adaptive Linear Neuron)algorithm to improve the state observer,the weight coefficient can be updated online to improve the observation precision,so as to avoid real-time measurement and reduce the cost.The integral state is introduced and additional feedback is added to reduce the influence of the disturbance torque.At the same time,the synchronization controller is designed at the acceleration level to reduce the adjustment time.At last,the simulation results show that the control amplitude and the time of adjusting time have good effect.Considering the influence of rotor eccentricity,the electromechanical coupling model of the main drive system of the rolling mill based on the rotor eccentricity of the asynchronous motor is used as the control object,and the influence of rotor eccentricity on the motor and torsional vibration is analyzed.The rotor eccentricity can be regarded as system internal disturbance and a controller can be set.Firstly,the state observer is combined with the disturbance observer,and the observer parameters are adjusted according to the stability margin when the system is stable,so as to realize the observation and compensation of the inner ring of the system.At the same time,taking into account the characteristics of complex system and difficult to measure parameters,the neural network speed controller updates the weight coefficient on-line and realizes speed control.Finally,the effectiveness of the proposed control structure in suppressing the torsional vibration of the rolling mill is verified by comparing the simulation experiments.