Research On Adaptive Dynamic Control Algorithm For Second Cooling Of Continuous Casting

Secondary cooling control in continuous casting is the key technology in improving quality and quantity of continuous casting slab,casting speed is important factor that affecting secondary cooling water.Conventional model of secondary cooling control in continuous casting is built when casting speed is stable.Surface temperature of slab deviated from target value.Therefore,it is the key to realize the accurate control of continuous casting with dynamic secondary cooling control based on the feedback.In solidification process of continuous casting,because of no linear and large time delay,it would be lead to instability such as overshoot or oscillation with conventional PID algorithm in dynamic secondary cooling control.Therefore,it has actual meaning for improving control accuracy and speed of dynamic secondary cooling control to study self-adaption PID control algorithm.Based on the analysis of dynamic and static characteristics of solidification process of secondary cooling zone in continuous casting,this paper research on adaptive PID control algorithm for secondary cooling of continuous casting and dynamic optimization control system for secondary cooling water in continuous casting is developed and simulated.The main work as follows:1.Build secondary cooling process model and analyze dynamic and static characteristics of solidification process.Based on the online solidification heat transfer model,secondary cooling process model is built.On the basis of the process model,the relationship between casting speed and process parameters during the solidification process is analyzed.2.Research on adaptive dynamic control algorithm.PI controllers through dynamic set-point weighting is deeply studied based on the secondary cooling process model which is regarded as controlled plant.Parameter value of ? is improved and its parameters are optimized by particle swarm optimization algorithm.Compared control effect of PI controller through Dynamic Set-point Weighting and conventional PID controller based on the MATLAB simulation platform to validate the robustness of PI controller through Dynamic Set-point Weighting.3.Software development of secondary cooling dynamic control system.Software designed of dynamic control system based on vb.net programming environment.Program of PID control algorithm is realized.Prediction model of target temperature is built based on support vector machine and realized simulation operation of secondary cooling dynamic control system.Secondary cooling monitor and control system is designed by WINCC configuration software.4.Build hardware-in-the-loop simulation platform of secondary cooling dynamic control system.It is consists of five parts including touch screen,analog caster,secondary stage control system,PLC control system and monitor system.Touch screen is used to simulate casting speed and tundish temperature and send signal of operation of the system.There are interface actual temperatures of billets and parameters of solidification state when system starts.Monitor system is used to monitor change of cooling water and interface temperature.PLC control system is used to connect each part of system and control cooling water.Secondary stage control system is used for actual interface temperature of slabs to realize the effective tracking of target temperature through adaptive dynamic control algorithm.The results show that secondary cooling dynamic control system operation stably.Interface temperatures of slabs have small overshoot when casting speed change suddenly and system control accuracy and meet control requirements.