A successful black box design : digital regulation of depositedzinc in hot-dip galvanizing at Sollac Florange

摘要

The paper is focused on the design and implementation of the mainncontrol loops : regulation of the deposited zinc, at the new hot-dipngalvanizing line of Sollac Florange. The main difficulties fornimplementing a high-performance feedback control come from the presencenof a large and variable time-delay (depending on the steel strip speed)nand from the nonlinear character of the plant model. The regulationnscheme is implemented on a PC connected to the process through annindustrial network. It uses a digital controller designed on the basisnof an identified discrete-time black box model. The scheme is open-loopnadaptive in the sense that the sampling frequency is related to thensteel strip speed, and that the parameters of the controllers fornvarious regions of operation are stored on a table. The results obtainednon the site conclude the paper. An improvement of the product qualitynand a reduction of the zinc consumption have been achieved