Process control structure selection based on economics

In process systems, selecting suitable sets of manipulated and controlled v ariables and the design of their interconnection known as the control struc ture selection problem, is an important structural optimization problem. Th e operating performance of a plant depends on the control structure selecte d, as well as the characteristics of the disturbances acting on the plant. The economic penalty associated with the variability of main process variab les close to active constraints was used ira this work to develop a quantit ative measure for the ranking of alternative control structures. The proble m is formulated as a mixed integer nonlinear optimization problem of specia l structure, which was used for an algorithm to solve this problem to globa l optimality. The final formulation is a mixed integer linear problem for w hich effective solution methods are currently available. The validity and u sefulness of the method are demonstrated through a number of case studies.