Topological models and critical slowing down: Two approaches to power system blackout risk analysis

This paper describes results from the analysis of two approaches to blackout risk analysis in electric power systems. In the first analysis, we compare two topological (graph-theoretic) methods for finding vulnerable locations in a power grid, to a simple model of cascading outage. This comparison indicates that topological models can lead to misleading conclusions about vulnerability. In the second analysis, we describe preliminary results indicating that both a simple dynamic power system model and frequency data from the August 10, 1996 disturbance in North America show evidence of critical slowing down as the system approaches a failure point. In both examples, autocorrelation in the time-domain signals (frequency and phase angle), significantly increases before reaching the critical point. These results indicate that critical slowing down could be a useful indicator of increased blackout risk.