Hybrid Fault Diagnosis: Application to a Gas Turbine Engine

Abstract

This paper presents a hybrid framework for fault diagnosis of complex systems that are modeled by hybrid automata. A bank of residual generators is constructed based on the continuous models of the system. Each residual generator is modeled by a discrete-event system (DES). Next, the DES models of the residual generators and the DES model of the hybrid plant are combined to build an “extended DES” model. A hybrid diagnoser is constructed based on the extended DES model. The hybrid diagnoser effectively combines the readings of discrete sensors and the information supplied by the residual generators (which is based on continuous sensors) to determine the health status of the hybrid plant. The hybrid diagnosis approach is employed to investigate faults in the fuel supply system and the nozzle actuator of a single-spool turbojet engine with an afterburner.

Diagnosis of hybrid systems: Part 1- diagnosability

“…Here, we briefly describe the system. The details of modeling and fault diagnosis in the gas turbine engine is provided in [7]. The air is taken to the engine through the intake duct and compressed with the compressor.…”

“…In [7], we developed a hybrid automaton model for a gas turbine engine and studied fault diagnosis in the engine. We showed that there are cases in which some faults are not diagnosable either by using DES model (information provided by discrete sensors) alone or by using the continuous methods This work is supported in part by a Strategic Projects grant from the Natural Sciences and Engineering Research Council of Canada (NSERC).…”

“…However, these faults can be diagnosed if the information provided by the residual generators are integrated with the output of the discrete sensors. In [7], we developed a systematic method for constructing an extended DES model containing the information at the DES level of the engine as well as the diagnosis information provided by the residual generators. Based on the extended DES model, we constructed a hybrid diagnoser for the engine.…”

Diagnosis of hybrid systems: Part 2- residual generator selection and diagnosis in the presence of unreliable residual generators

“…In [5], we developed a hybrid automaton model for a gas turbine engine and studied fault diagnosis in the engine. We showed that there are cases that some faults are not diagnosable by using DES model (information provided by discrete sensors) alone or by using the continuous methods based on residual generation (using continuous sensors) alone.…”

“…In [5], we developed a systematic method for constructing an extended DES model containing the information at the DES level of the system as well as the diagnosis information provided by the residual generators. Based on the extended DES model, we construct a hybrid diagnoser for hybrid automata.…”