Plantwide control - A review and a new design procedure

Most (if not all) available control theories assume that a control structure is given at the outset. They therefore fail to answer some basic questions that a control engineer regularly meets in practice (Foss 1973): 'Which variables should be controlled, which variables should be measured, which inputs should be manipulated, and which links should be made between them?' These are the questions that plantwide control tries to answer. There are two main approaches to the problem, a mathematically oriented approach (control structure design) and a process oriented approach. Both approaches are reviewed in the paper. We also provide some definitions of terms used within the area of plantwide control.