Looper Controller Design And Implementation For Hot Strip Finishing Mill

In modern Hot Strip finishing production, with the growth of strip varieties, specifications, quality and yield, requirement for the quality of control system throughout the rolling process ,has becoming stricter and stricter. The loop control has become one of key technologies which decide the quality and stability of the strip. The development of the technology has been active at home and abroad. In this paper, the control strategy and controller parameters are optimized ,based on the PI+ILQ(Inverse linear Quadratic) theory and a hot rolling steel finishing mill, which greatly improved the stability of the finishing line and the quality of the production.First the paper reviews looper control technologies, and conducts analysis of the advantages and disadvantages of these methods. Then details the ILQ theory ,deducts the looper linear model of one hot strip finishing mill, designs ILQ controller on the basis of above.Then the implementation of the PI+ILQ method is mastered through the digestive of PLC program, including how to determine the parameters, the options of compensation, the beginning and end time of the PI/ILQ controller, and the switching method of PI/ILQ control.Finally, in the hands of the theory and realization principles of the PI+ILQ control ,few improvements are as following on the basis of the analysis of live ODQ data:(1)Improving the PI/ILQ switch way to deal with the over-current problem of F6 when rolling steel A;(2)Optimizing controller parameters to resolve the problem of tension lost in the head of the strip when rolling steel B;(3)Increasing the dad zone to deal with the instability of strip tension.