Qualitative Fault Diagnosis with System Decomposition: Application to a Large-Scale Boiler Plant

Abstract This study suggests a systematic method to decompose a large-scale process into sub-processes and then diagnose them. It is based on qualitative fault diagnosis of fault-effect tree model and for the minimization of knowledge base and flexible diagnosis. The new node, called a gate-variable, is introduced to connect the cause-effect relationships of each sub-process. Off-line analysis is performed to construct fault-effect trees of gate-variables. And, diagnosis strategy is modified to get the same result without system decomposition. The method is illustrated with a fault diagnosis system for a boiler plant.