Monitoring and diagnosis of equipment faults

Plant equipment faults and grid upset events, including those that presently result in transients that challenge the protection system, might be better managed through the use of advanced operator aids. There are clear safety and economic advantages if the probability that an upset will lead to an unplanned shutdown can be reduced or if the plant response to an upset can be mitigated such that transient-induced thermal stresses are reduced. Presently an operator’s response to events is driven by paper-based procedures: a sensor sends a signal to an alarm panel in the main control room; after consulting written procedures operators adjust controls to rectify the fault. But a more informed operator working with procedures that are executed in a semi-automated manner, according to the process flow of (i) sensor fault identification to (ii) component fault identification to a (iii) realignment control action by control algorithms, has the potential to stabilize the plant in a more timely and precise manner and thereby avert a shutdown or temper transient-induced thermal fatigue. The Computer Operator Support System (COSS) is a concept that has been proposed for providing the operator with new capabilities to handle such events (see also ‘A Computerized Operator Support System Prototype,’ by K. Thomas, R. Boring, R. Lew et. al., INL/EXT13-29651, September 17, 2013). The COSS is envisioned as collection of technologies to assist operators in monitoring overall plant performance and making timely, informed decisions on appropriate control actions. The COSS does not replace the operator, but aids him or her by providing rapid assessments, computations, and recommendations to reduce workload and augment operator judgment and decision-making during fast-moving, complex events. The functions provided by a COSS require technologies for sensor validation and component fault diagnosis.