The Analysis And Design Of Control Parameter To Mill Feedback AGC System Considering Detection Lag

Steel is not only a main industrial materials,but also is the foundation and pillar of the national economy,the strip products is about half of the total yield of steel,The control precision of plate thickness is one of the most important quality flagging of strip products.In the mill AGC system the thickness gauge position is away from the roll gap,which cause the disadvantage of time delay.The mill AGC system structure is complicated and has the problem that non-linear and parameter change with time,those factors make it is hard to further improve the thickness precision of cold strip products.The detection lag always restrict the improvement of the rolling accuracy,so the analysis and design of control parameter to mill feedback AGC system with time delay is important.To solve the limitation of choosing the sampling control cycle which base on the experience,this paper analyses the control effect corresponded different sampling cycle with the root locus methods basing on the mathematical model built,the relationship between the performance of system and the parameter is obtained and the optimal regulator period control strategy is raised for the mill AGC system.Firstly,to solve the problem that the accurate mathematical model of gauge is difficult to build,the actual complicated model was simplified considering the impact of time delay.The discrete time model of the system is transformed into its continuous counterpart by the principle of equivalent step response between discrete and continuous system,then the transcendental expression is algebraic simplified with covariant properties of coordinate,Replacing the te-which in the model with the approximation method.The algebraic mathematical model described by transfer function is obtained finally.Secondly,The algebra transfer function model with real-coefficients is analyzed with Root locus method,the relationship between the performance of the system and the adjustment period is obtained by using date fitting algorithm.Finally,built the simulation and experimental system,the simulation and experimental results demonstrates the effectiveness of conclusion in regard to the relationship between the performance of the system and the adjustment period,the results show that basing the performance indicators of ITAE the strategy can effectively reduce the impact of time delay and improve the rolling accuracy.