  Modern grid monitoring equipment enables utilities to collect detailed
records of power interruptions. These data are aggregated to compute publicly
reported metrics describing high-level characteristics of grid performance. The
current work explores the depth of insights that can be gained from public
data, and the implications of losing visibility into heterogeneity in grid
performance through aggregation. We present an exploratory analysis examining
three years of high-resolution power interruption data collected by archiving
information posted in real-time on the public-facing website of a utility in
the Western United States. We report on the size, frequency and duration of
individual power interruptions, and on spatio-temporal variability in aggregate
reliability metrics. Our results show that metrics of grid performance can vary
spatially and temporally by orders of magnitude, revealing heterogeneity that
is not evidenced in publicly reported metrics. We show that limited access to
granular information presents a substantive barrier to conducting detailed
policy analysis, and discuss how more widespread data access could help to
answer questions that remain unanswered in the literature to date. Given open
questions about whether grid performance is adequate to support societal needs,
we recommend establishing pathways to make high-resolution power interruption
data available to support policy research.
