Application of simple cascade GPC with robust behaviour to a sugar refinery

This paper presents the application of a Generalized Predictive Controller (gpc) to sludge density control in a sugar factory. The loop is controlled by a cascade strategy, where both the master and the slave controllers are predictive ones. The control law is extremely simple to compute and the tuning is straightforward since a method to implement GPC previously developed by the authors which is very simple to implement and tune has been used. The controllers are embedded in the existing control system, needing the same computational requirements as PID routines. The original GPC algorithm is improved by the use of the so-called T polynomial, which increases the stability robustness by filtering the predictions in order to cope with model uncertainties and different process dynamics caused by changes in the process operating points.