An Integrated Tradeoff Design of Reduced-Order Diagnostic Observer for Event-Triggered Fault Detection

Reduced-order diagnostic observer (RODO) is more desirable in the monitoring of electrical systems due to the advantages of low computation consumption and flexible structure, while its tradeoff design remains a longstanding unsettled issue in model-based fault diagnosis research. In this paper, an integrated design scheme of RODO is developed for event-triggered systems, making, for the first time, a direct tradeoff between false alarm rate (FAR) and fault detection rate (FDR). Firstly, by considering the effects of disturbance, fault and event-triggered transmission error on the residual, along with the principle of residual evaluation, the event-triggered FAR and FDR are defined and their relationship is established. Then, by introducing the so-called quasi-Luenberger constraints, the Luenberger equality challenges in the optimization of performance tradeoff are removed and an iterative algorithm is developed for the tradeoff design of full-order or high-order diagnostic observer. Based on this, the deviations between the quasi-Luenberger and Luenberger equalities are further eliminated with the assistance of another iterative algorithm to achieve the tradeoff of RODO. Finally, a DC microgrid simulation is adopted to demonstrate the effectiveness of the proposed design scheme as well as its advantages over other schemes.