A Model-Based Fault Accommodation System

Abstract

Fault accommodation, the task of using the results from fault diagnosis to accommodate faults, is often performed by an operator through table-look-up strategies, which are often incomplete, time-consuming, and prone to errors. In this paper, we proposed an analytical model-based control redesign for fault accommodation. The whole fault accommodation system includes a dynamic process model, fault detection and isolation, fault identification and state estimation, and a dynamic optimization module for control redesign. One of the advantages of this method lies in its ability to simultaneously achieve economic optimality and operation safety because of its capability to handle both hard equipment constraints and operational constraints. Strategies for accommodating various types of abnormal situations are proposed. The details of each module are discussed, followed by a case study in which the methodology is applied to the Amoco model IV fluid catalytic cracking unit.