Small vulnerable sets determine large network cascades in power grids

TL;DR

This paper identifies a small, central subset of power grid components that are critical in triggering large cascading failures, providing insights for improving grid resilience and vulnerability analysis methods.

Contribution

It introduces a method to identify a small vulnerable set in power grids that significantly influences cascade size, advancing understanding of failure origins.

Findings

Vulnerable set is small and topologically central.

Large cascades are often triggered near this vulnerable set.

Vulnerability analysis methods are applicable to other networks.

Abstract

The understanding of cascading failures in complex systems has been hindered by the lack of realistic large-scale modeling and analysis that can account for variable system conditions. Here, using the North American power grid, we identify, quantify, and analyze the set of network components that are vulnerable to cascading failures under any out of multiple conditions. We show that the vulnerable set consists of a small but topologically central portion of the network and that large cascades are disproportionately more likely to be triggered by initial failures close to this set. These results elucidate aspects of the origins and causes of cascading failures relevant for grid design and operation, and demonstrate vulnerability analysis methods that are applicable to a wider class of cascade-prone networks.