Study On Coordinate Optimization And Control Of Secondary Cooling And Ems Of Continuous Casting

The process of Continuous casting cooling is a nonlinear,strong coupling,multi-input multi-output(MIMO)system.In the existing control system of continuous casting,secondary cooling control and final electromagnetic stirring control are two independent control system.The optimization of control parameter often use the independent model without considering the coupling effect between them,which lead to the billet quality fluctuation with the changes of process parameter or steel.To further improve the quality of continuous casting technology and steel,it has theoretical significance and practical value to coordinate of the two parameters of control system.In this paper,main work is as follows:1.Study on square billet continuous casting solidification heat transfer model.Based on the characteristics of continuous casting solidification heat transfer,the control volume method is adopted to build the two-dimensional variable grid process of continuous casting slab solidification heat transfer model,the source term method is used to the phase change phenomena in the process of solidification heat transfer.2.Qualitative and quantitative research on secondary cooling and final electromagnetic stirring on the solidification process.Combined with the optimum mixing conditions and requirements of final electromagnetic stirring,through simulating and analyzing the coupling nature and change law of some target control parameters,such as temperature field,final shell thickness,temperature drop and down,which is caused by the speed,degree of superheat and water changes of four different cooling section.Providing theoretical basis and data support for the further coordination optimization of secondary cooling and end electromagnetic stirring.3.Research on the Pareto multi-objective particle swarm optimization algorithm.The coordination optimization process of secondary cooling and end electromagnetic stirring belongs to multi-objective optimization problem(MOP)in essence.Multi-objective optimization problems often exist several contradictory goals.In this paper,according to the MOP and the features of the PSO algorithm,that is prone to the consistency of the optimal solution set is not high,distribution uniformity is poor.Through to the weakening treatment of particles beyond the search space,using the adaptive grid to trim solution set distribution.A multi-dimensional vector weight processed to obtain final Pareto optimal solution weight parameters.To form the improved multi-objective particle swarm optimization algorithm based on the Pareto.The simulation shows that this algorithm can effectively improve the consistency of solution set,improve the Pareto front distribution,make the decision of optimal solution scheme more rich.4.To optimize and to solve the problem of Pareto multi-objective coordinate optimization with secondary cooling and electromagnetic stirring.Building multi-objective optimization algorithm based on the secondary cooling zone temperature field and temperature going up and down,and liquid core radius which satisfy the best electromagnetic stirring condition.The improved multi-objective particle swarm optimization algorithm based on the Pareto is introduced in the multi-objective optimization problem of continuous casting secondary cooling and electromagnetic stirring,the simulation results shows that this algorithm can improve the coupling effect of two independent control system,expand the selection space of optimal solution set,optimize the distribution of the Pareto front,improve the disturbance resistance caused by process variable fluctuations,reduce slab quality fluctuation caused by the change of process parameters or steel.