The improvement in transmission resilience metrics from reduced outages or faster restoration can be calculated by rerunning historical outage data

TL;DR

The paper tackles the challenge of quantifying transmission resilience benefits without relying on uncertain future event models. It proposes a historical rerun approach that replays past outage events with simulated upgrades (reduced outages and faster restorations) to compute changes in resilience metrics such as $D_{95\%}$ and MVA-days out. Case studies on Hurricane Ida and the Midwest derecho, plus region-wide analyses for the Midwest, show that modest upgrades (e.g., 10% hardening or 10% faster restorations) yield measurable resilience gains, with hardening primarily reducing event size and nadir, while faster restorations more effectively reduce restoration-duration metrics. This data-driven method provides tangible, stakeholder-relevant estimates of resilience benefits and can be adapted to specific events, regions, or event types to inform investment decisions.

Abstract

Transmission utilities routinely collect detailed outage data, including resilience events in which outages bunch up due to weather. The resilience events and their resilience metrics can readily be extracted from this historical outage data. Improvements such as grid hardening or investments in restoration lead to reduced outages or faster restoration. We show how to rerun this history with the effects of the reduced outages or faster restoration included to find the resulting improvement in resilience metrics, thus quantifying the benefits of these investments. This is demonstrated with case studies for specific events (a derecho and a hurricane), and all large events or large thunderstorms in the Midwest USA. Instead of predicting future extreme events with models, which is very challenging, the historical rerun readily quantifies the benefits that a resilience investment would have had if it had been made in the past. The historical rerun is particularly vivid in making the case for resilience investments to stakeholders because it quantifies the benefits for events actually experienced by those stakeholders, rather than for future events predicted with uncertainty.

Figures (2)

• Figure 1: Outage & restore processes, and performance curve of Hurricane Ida
• Figure 2: Outage & restore processes, & performance curve of Midwest Derecho