Propagação de Comportamento Anormal em Sistemas Híbridos Dinâmicos

Abstract

The majorities of industrial systems may be considered as dynamic hybrid systems, that is, described by variables in the continuous and discrete domains. Therefore, due to the need to obtain high quality products with losses minimization, to have safer and environmental friendly process operation, is what justies the development of tools for evaluating fault propagation eects. In this work, some tools for the representation of dynamic hybrid systems were studied in order to address the abnormal behavior propagation. The rst tools are Petri nets that allow a qualitative mathematical representation, the analysis of the models and supply useful information on the structure and the dynamic behavior of the system. Another tool is the signed directed graph - SDG that includes the mechanisms of fault propagation and the development of a theory of modeling based on the knowledge of complicated systems. In this context, it was presented the qualitative modeling of dynamic systems by using Petri nets and SDG, with the occurrence of faults and the evaluation of their propagation during process operation. These techniques were applied to Chemical Engineering problems such as mixing tanks and batch reactors for Petri nets, tank systems and faulty continuous reactors with the use of SDG. In those processes, simulations were performed and the faults eects were evaluated for several operational scenarios. SDGs were also used to determine the fault propagation path, with the evaluation of each aected process variable of interest both in open and closed-loop operation.