Plantwide control of uncertain plants
Plantwide control refers to the control of entire plants, consisting of many interconnected unit operations. Synthesizing a plantwide control system requires evaluating numerous alternatives involving controlled variables, control structures, controller designs and tunings, etc. A hierarchical procedure for systematically synthesizing a plantwide control has been proposed by Zheng et al. . In this procedure, the plantwide control problem is decomposed into six steps along which decisions are made based on economics. While many tools (e.g., a short-cut method for controlled variable selection, quantification of dynamic operability, etc.) have been developed by these authors to ease the implementation of the procedure on industrial processes, more tools need to be developed. For example, we need to develop systematic procedures for ensuring feasibility of the control structures, for selecting primary and secondary controlled variables and for designing controllers for systems with recycles. Furthermore, model uncertainty, which is important practically, needs to be taken into account to make these tools useful. The goal of this thesis is to accomplish these tasks. To this end, we address how model uncertainty affects the steady-state as well as the dynamic control structure.
0790: Systems design