Component-Based Modelling of Thermofluid Systems for Sensor Placement and Fault Detection

Abstract

Modelling of thermofluid systems is complex because of the coupling of thermal and hydraulic energies. Bond graph language is a suitable tool for modelling such nonlinearmultienergy domain systems along with their control systems. Structural control properties of the system can be determined using the causal properties of bond graphs, without resorting to any formal computation. An ontology for classifying thermofluid process components is presented in this article, along with connection syntax and model validation algorithms. Then the theory for structural analysis is used to design sensor placements for observability and also for component fault detection and isolation. This study also deals with developing a bond graph–based model representation mechanism to perform structurallevel linking of submodels.The methodology developed is applied to two example systems. Simulation of process faults is used to validate the theoretically obtained fault signatures for a thermofluid system in the second example.