Research And Application On Dynamic Speed Drop Control Method In Hot Rolling Main Drive Systems

With the increasingly high demand of steel plate quality for modern rolling industrial, hot-rolling mill main drive systems are required more accurate and higher dynamic performance. The plant of this paper is the2160hot-rolling mill R1drive system, there is a serious impact downhill problem in the biting stage of hot rolling mill Rl, which leads to the head of slab difficult to adjust and severe shake problem for mill. This thesis analysis the causes of impact downhill problem,then improve the impact of hot rolling mill R1main drive downhill performance from two aspect of optimizing control system and improving rolling technology.The main drive of the hot rolling mill Rl uses high-power AC-AC Variable Frequency Drive synchronous motor with AC-AC variable frequency vector control mode and the classic DC motor speed-current double closed loop PI control method to control the synchronous motor, Which the speed control loop and current control loop are PI controller. Because of the speed closed-loop integral time constant longer than the current closed-loop many times, so when the motor withstand sudden load, the speed of main drive downhill quickly, the recover current torque component can not be timely to increase the speed and make the impact deceleration long time. For the hot strip mill of this type of higher transmission system, it is difficult to meet the requirements of the speed control system only by adjustting the speed regulator parameters. This article focuses on the study of advanced control theory-disturbance load observer theory, and then designs the disturbance load observer in the main drive control system of hot-rolling mill R1. The applications of disturbance load observer in practice prove the effectiveness in solving the impact of downhill problem.By analyzing the problem of impact downhill in the main drive of the2160mill, this article investigates three strategies to improve the impact downhill of the mill. The three strategies are:speed loop proportional integral coefficient switching strategy, disturbance load observer strategy, speed pre-compensation strategy. This article also analyses and contrasts the effects and characteristics of these three methods in the practical application.The conclusion of this study has been validated in the production sites, with all of the requirement types of assessment strip are exceeded than the required technical specifications, which provides a reliable technical foundation for the enterprise to achieve good economic benefits.