Robust control of plantwide chemical processes based on parameter dependent dissipativity

Abstract

We propose a dissipativity based robust stability analysis and control design for plantwide chemical processes. A plantwide process is represented as a network of process units (subsystems) interconnected via mass and energy flows (e.g., material recycle and energy integration) and controlled by a network of controllers. In this analysis, the dynamical properties of process units are captured by their dissipativity. The plantwide stability is determined based on the dissipativity of each process unit and the network topology. To perform robust stability analysis, the process units are represented using LPV models which accommodate their uncertainties and a method is developed to determine the dissipativity (the storage function and the supply rate) of process units as a function of the scheduling variable. By polytopic LPV modelling, a dynamical system can be represented as the linear combination of the models at convex vertices. This allows the proposed dissipativity to be determined based on the dissipativity of each model at vertices. This plantwide analysis is based on the dissipativity of the LPV models of process units rather than the model for the entire plant and as such it very scalable. In this work, the results include: (1) determining dissipativity for LPV systems (2) robust analysis on the effects of uncertainties in process units on the stability of the plantwide system (3) robust control design for plantwide systems.