MODEL-BASED CONTROL OF MOLD LEVEL IN A CONTINUOUS STEEL CASTER UNDER MODEL UNCERTAINTIES

In tackling the problem of liquid steel level regulation in the mold o f a continuous steel easter, the values of some system parameters, suc h as the clogging degree and the discharge coefficients of nozzles, ar e seldom precisely known. The discrete control laws developed in this work employ on-line estimated values of these parameters, to produce a stable regulation of mold and tundish levels for an industrial-type t wo-strand continuous slab easter. The estimation procedure is delayed by one time step (the sampling time) in order to become realizable; wh en the sampling time is small enough, the discrete control scheme give s stability and convergence properties that are analogous to those of an ideal control scheme with accurate knowledge of the parameter value s. (C) 1998 Elsevier Science Ltd. All rights reserved.