Research On The Control Methods For Continuous Casting Mold Level

Today modern continuous casting technology has developed fast and has been applied to steel production as one of important process.It is important step for achievement of optimization for country's steel industry structure to accelerate the development of continuous casting technology.As industrial automation advances,we have shifted our attention away from the production of casting billet to the quality of it.As one of the important part of continuous casting production,how the mold level control system works will greatly affect the quality of casting billet.Generally,according to technical standards,the accuracy of mold level control must fall within ±3mm.If the mold level changes greatly it will lead to quality defects such as slag inclusion and cracks,even steel overflow and bleed-out accidents from casting,so it is imperative to improve the accuracy of mold level control.While the mold level system is characterized by time variety and nonlinearity and is disturbed by external circumstances and noise arising from measurement,it is impossible for us to build system model accurately and is also impossible for traditional control methods to meet the needs that arise from manufacturers for quality.To address this problem,a mold level control method based on ADRC is proposed in this thesis.First,the composition of mold level control-system is analyzed and the model consisting of each component of control system is also built.Second,in terms of the characteristic of each component of the system,cascade control strategy is adopted and the control of mold level is achieved through the control of the position of stopper(also called mold inlet flow).Third,ADRC is selected as the main controller of mold level control system,further make an assessment of system uncertainty and make up for its deficiency.Finally,with many adjustable parameters it is hard for ADRC to be set,PSO is used in this thesis to optimize these parameters.By comparing PID control method with Matlab simulation,we can find that mold level control system as above said has short responsive time,has small workload of overshoot and has excellent strengths in strong robustness.Through mold level control system,the accuracy of its control is improved so that the needs for quality are met.