INTEGRATED STRUCTURE DESIGN OF A PROCESS AND ITS CONTROL-SYSTEM

A graph-theoretic method for integration of process and control system (IPCS) syntheses with different controllability notions has been prop osed in the present paper. The foundation of this integration is a wel l-established, graph-theoretic approach to process synthesis in conjun ction with the analysis of structural controllability based on digraph -type process models. Unambiguous structural representation of the res ultant integrated process and control systems, IPXS structures in brie f, has been introduced for unambiguous representation of a process str ucture, it is rendered possible as an extension of the directed bipart ite graph, the P-graph. Different set of axioms are proposed for descr ibing the case of disturbance-rejective regulable and the combinatoria lly feasible and controllable structures in the special cases consider ed: the case of structural controllability and the case of fault-toler ant controllability. These axioms make the synthesis computationally m ore effective by considering very simple engineering knowledge. The ma ximal controllable structure of an IPXS synthesis problem has been def ined as the union of combinatorially feasible and controllable IPXS st ructures. Thus, the mathematical programming model, e.g. MINLP model, of an IPXS synthesis problem can be and should be derived from the max imal controllable structure. Different versions of a fundamental polyn omial time, combinatorial algorithm are presented for identifying the maximal controllable structure. The resultant IPXS structures are comp ared with the structures synthesized without considering their control systems. (C) 1998 Elsevier Science Ltd. All rights reserved.