Development and application of a comprehensive model-based methodology for fault mitigation of fuel cell powered systems

The present paper describes an innovative and generalizable approach to apply fault mitigation strategies to fuel cell powered systems, upon information on system State of Health and Remaining Useful Life. Model-based approach is proposed to derive useful performance-related indicators for each system component. The model comprises two main parts: a nominal part, providing the key variables behavior in nominal conditions, and a faulty part that can be used for fault identification purposes. The framework of the algorithm firstly addresses a monitoring phase, through which residuals are computed, and if one or more residuals overcome defined thresholds, a fault detection is triggered. Afterwards, fault isolation is performed by means of a Fault Signature Matrix and the fault identification (i.e., its magnitude and time-behavior definition) is performed thanks to the faulty sub-models. Once characterized the fault, several strategies (according to different fault magnitudes) are considered, and the most suitable one can be chosen and applied. A case study is then presented to validate the methodology on a fuel starvation fault caused in a 6-cells solid oxide fuel cell stack by a fuel leakage in the anode pipeline. Once applied the mitigation strategy, it has been verified that the power output of the system safely bounds within 20% of its nominal value, whereas stack efficiency variation is negligible. The methodology herein proposed could substantially help the commercial success of solid oxide fuel cell technology, allowing increasing lifetime, with a much focused control of the main variable for diagnostic and maintenance-oriented applications. Indeed, if used in real applications, the proposed approach will speed up maintenance actions even setting the system in a soft condition to be properly prepared for replacement as well.