ROBUSTNESS ANALYSIS AND CONTROL OF A PILOT-SCALE DISTILLATION COLUMN

A pilot-scale distillation column has been connected to an industrial Distributed Control System (ABB MOD 300). The connection of this DCS t o a VAX-cluster through Ethernet Gateway facilitates data-collection f rom the column. This set-up has been used to investigate different con trol strategies as well as advanced operational techniques. This paper considers the preliminary study of the robustness analysis of this pi lot-scale distillation column. Using a combination of plant data and n on-linear simulations, both a nominal column model and an associated m odel uncertainty are identified. This information is used to carry out a complete analysis of robust stability and performance for the case where a (Ziegler-Nichols tuned) multiloop control scheme is employed. To perform robustness analysis of the control, both structured and hig hly structured uncertainty characterization approaches are used and it is shown that the latter case provides less conservative results. (C) 1997 Elsevier Science Ltd.