Dynamically induced cascading failures in supply networks

Abstract

Reliable functioning of infrastructure networks is essential for our modern society since the disruption of any communication, transport or supply network poses serious risks to our normal life. Cascading failures, namely events in which the initial and local failure of a component triggers a sequence of multiple failures of other parts of the network, are the main cause of large-scale network outages. Although cascading failures often exhibit dynamical transients, i.e., momentary variations of the state of the system, the modelling of cascades has so far mainly focused on the analysis of sequences of steady states. In this article, we focus on electrical supply networks and introduce a general dynamical framework that takes into consideration both the event-based nature of cascades and the details of the network dynamics. In this way, we account for possible losses of transmission lines and for the dynamical transition from one steady state to the next, which can significantly increase the vulnerability of a network. We find that transients in the flows of a supply network play a crucial role in the emergence of collective behaviors and may cause cascades which cannot be predicted by a steady-state analysis approach. We illustrate our results on a series of network case studies, including the real topology of the national power grids of Spain, France and Great Britain. We finally propose a forecasting method that may help to better understanding the stability conditions of a network, and also to identify its critical lines and components in advance or during an exceptional situation. Overall, our work highlights the relevance of dynamically induced failures on the synchronization dynamics of national power grids of different European countries and it provides novel methods to predict and limit cascading failures.