Network Causality–Based Decision Support for Power Grid Resilience Considering Braess’s Paradox

Worldwide large-scale power outages caused by earthquakes and associated damage to nearby facilities have prompted the need for proactive measures to improve the seismic resilience of power grids. It is noted that Braess’s paradox, e.g., strengthening individual components of a grid, may inadvertently degrade overall performance, and may arise due to the high interdependence between components and cascading failures resulting from the sequential redistributions of power flow. To investigate the underlying cause of the paradox, this paper proposes a novel framework for seismic resilience analysis of power grids. The framework analyzes the reliability index (β) and the redundancy index (π) at the component and system levels, respectively, to understand system reliability aspects of resilience, which is referred to as the β-π analysis. The causal effects of line component upgrades on system-level performance are quantified based on the results of the β-π analysis and the causal model describing the network’s behavior in response to hazards. Proposed causality-based measures of component importance show that performance maintenance of specific lines ignoring the paradox may obscure overall system resilience. A numerical example demonstrates the practicality of the framework for assessing the seismic resilience of power grids and supporting operational decisions to improve seismic resilience.