IEEE PES T&D Conference & Exposition 2022 - 119

Other than those notable developments, most advancements
in reliability metrics have focused on improving
the process for gathering data and computing the metrics.
Today, most reliability metrics are calculated automatically
with computerized outage-management systems to reduce
the risk of manual errors common when these metrics were
calculated by hand from paper outage tickets. Current outage-management
systems also provide reliability calculations
for mid-line devices to give utilities a more detailed
view of their performance. Before this methodology, most
reliability metrics focused on substation reliability performance.
As important as these improvements in performance
measurement have been, they have produced relatively few
changes to the key metrics themselves. They continue to
appear dated in the face of the significant advancements the
rest of the utility system has seen in recent decades.
The Changing Energy Landscape
In contrast to the few changes that have shaped common
distribution reliability metrics, the broader energy landOutage
Tracking
Early 1970s
1969
1947
Late 1970s
Mid 1980s
Late 1980s
1998
1989
1988
Survey on distribution failure causes and failure rates by Edison Electrical Institute (EEl) and American
Institute of Electrical Engineers (AlEE now IEEE).
Paper on designing distribution networks to specified levels of reliability using a metric similar to SAIFI.
Utilities begin to compute indices from paper outage tickets. Most common metrics: SAIFI, SAlDl, and
Customer Average Interruption Duration Index (CAIDI), although others were also defined.
Some large utilities develop their own individual outage-management systems (OMS) to calculate
the outage metrics.
U.S. and some international regulators start to take increased interest in distribution reliability.
Formation of IEEE Working group focusing on Distribution Reliability.
First commercial Outage Management System (OMS) starts to be developed. First textbook on reliability
metrics published defining SAIFI, SAlDl, and CAIDI.
IEEE defines commonly used reliability metrics.
IEEE 1366 first published, including definitions of key metrics and benchmark data. There were still wide
variations in OMS usage.
Customer-Focused
2001
2012
2000s
2003
IEEE 1366 becomes an IEEE standard.
scape has seen dramatic and rapid changes over recent
decades. It is widely acknowledged that evolving human
activities have caused climate change, and policymakers
are taking aggressive steps to address high-emission
energy resources by setting net-zero emissions targets and
mandates for reliability portfolio standards. These standards
would require minimum proportions of renewable
generation by set target dates.
These policy changes are creating increased requirements
for more advanced, flexible, and reliable electricity
grids that integrate considerably greater amounts of distributed
energy resources including rooftop solar photovoltaics,
distributed battery systems, electric vehicles, and more.
Advancements in manufacturing and technology in the areas
of information technology, renewable energy, energy storage,
consumer electronics, and electric vehicles are also
leading to rapid changes in both the way we use and produce
energy. These advancements are driving a more decentralized
energy system where customer-sited energy resources
are more relevant and prevalent.
Introduction of a method for classifying Major Event Days - 2.5 Beta Method.
Mass adoption of PC-based OMS. Reporting on CEMI becomes much more common.
IEEE 1366-2012 sees introduction of new CELlD-s and CELlD-t metrics for customers experiencing
long interruption durations (both individually and cumulatively).
figure 1. Reliability Metrics Timeline.
April 2022 Show Issue
ieee power & energy magazine
119

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