A fault diagnosis concept for a high-pressure-preheater line

This contribution describes a combined analytical/fuzzy model-based fault diagnosis concept which has been applied to the high-pressure-preheater line of a power plant. The key idea is to divide the whole system under supervision into several subsystems and to employ all available analytical knowledge to generate residuals for each subsystem seperately. Thereby the necessary observers for fault detection are of a handable size. For fault isolation, the residual evaluation is done by applying qualitative knowledge about the fault effects on the residuals and about the interaction of the different subsystems. Here a rule base is evaluated using fuzzy logic. With this method a complex system can be supervised without the need for a complex analytical model of the whole system. Furthermore, the presentation of the fault isolation results leaves the final decision about a fault alarm to the human operator. Results from a power plant prove the successful application of the proposed supervision concept