PNNL

Abstract

Promptly following any blackout, an investigation is conducted to determine the who, what, where, when, why, and how. For system operators, it is important to quickly grasp the scale and magnitude of the event and rapidly restore service. Then a broader set of stakeholders get involved to assess system performance, determine root causes, compile lessons learned, and develop recommendations. At the heart of the post-mortem investigation is the detailed sequence of events. As accurately as possible, investigators need to know what happened and when. Especially during a cascading failure where events occur rapidly, accurate timing is crucial to understanding how the event unfolded so that the root causes can be determined. The sequence of events is based on vast amounts of data collected from multiple points in the system from a myriad of data collection instruments, some devoted to the purpose of supporting system disturbance post mortem analysis, others providing useful additional context or filling in missing gaps. The more that the investigators know about their available sources of data, and the inherent limitations of each, the better (and quicker) will be the analysis. This is especially important when a large blackout has occurred; there is pressure to find answers quickly, but due to the size and complexity of the event, a deliberate and methodical investigation is necessary. This article discusses the role that system monitoring plays in supporting the investigation of large-scale system disruptions and blackouts.