Continuous Casting Mold Level Control System Based On Non-linear PID Controller

The realization of liquid level control during the continuous casting process improves the quality of slab and the efficiency of the casting machine. With the study on control system to realize the steady control of the liquid, a new control method was summaried in this thesis, and the research and development for the control of mold level has were carried out emphatically.The mold level control is an important part of continuous casting process. The mold level control system can stabilize level of mold, and enhance efficiency of the primary cooling, thus it will increase casting output and improve quality, will reduce labor intensity and accident. Mold level control system involves uncertainty model and time-variation model, such as, erosion of the tundish stopper, change of casting speed, mold oscillation, the bad working environment and so on. So it is difficult to stabilize mold level with traditional PID controller.In this thesis, a liquid level control system for mold has been made based on its level characteristics, and one non-linear PID controller with dead zone tache and saturation tache has been developed, which is modified by using the integral separated method. The controller has been applied to imitate the true with Simulimk model in the Matlab, and the result manifests that this mold level control system has the following characteristics:small overshoot, short transient and small stabilizing error. The result shows the mold level control method is effective and feasible.Finally, the software of the mold level control system has been designed. The software is analyzed and designed by object-oriented method, including user login systems, interface display, and interface switch and so on. The system can realize the display of the real-time liquid level curve and historical data display, alarm display, printing statements and other major functions, in order to achieve the aim of system supervision.