IEEE PES T&D Conference & Exposition 2022 - 122

For individual customer-level reliability performance,
some utilities and regulators depend on CAIDI. However,
CAIDI is not a good customer-centric metric as it may
falsely indicate that reliability is deteriorating even when
reliability-improvement initiatives are undertaken and reliability
has improved. Therefore, we have chosen to exclude
CAIDI from the charts.
However, IEEE 1366-2012 contains an alternative, though
underused, metric capturing worst-served individual performance:
CEMSMI. It covers the number of customers that
experience more than a certain number of interruptions in a
year, including both momentary and sustained interruptions.
Therefore, it gives a more rounded view of performance vs.
the system average. As the distinction between momentary
and sustained outages loses importance over time-in the
digital and connected world, all outages matter regardless of
State
California
Connecticut
Delaware
DC
Florida
Maryland
Michigan
New Jersey
North Dakota
Washington
table 1. CEMI Reporting in the U.S.
CEMI Reporting
Requirement to report CEMI-12
Requirement to report CEMI-3 to 10
Requirement to report CEMI-8
Requirement to report CEMI-8
Requirement to report CEMI-5 for utilities
> 50,000 customers
Requirement to report CEMI-2, 4, 6, and 8
DTE Energy Reporting CEMI-1 to 10
Atlantic City Electric reporting CEMI on a
company and district basis
Northern States Power reporting on
CEMI-4 to 6
Avista reporting on CEMI-0 to 6
duration-CEMSMI may emerge as a key index for measuring
the individual electricity user experience (Figure 5). The information
contained within CEMSMI reporting can help utilities
target their investments where it matters most. To date,
we have identified two utilities that are reporting CEMSMI
metrics: Rocky Mountain Power (Pacificorp) in Idaho and
Avista in Washington.
Performance for Different Customer
Types Matters
As discussed, most utilities use average systemwide indices
to report their reliability. But, as mentioned, these typical
metrics do not reveal much about reliability for commercial
and industrial (C&I) customers, because these customers are
greatly outnumbered by residential customers. However,
C&I customers consume more power than their residential
counterparts and experience greater financial losses when
outages do occur.
Improving grid reliability is a key focus for many
utilities, but large C&I customers in the United States are
becoming increasingly frustrated with the performance
of their power utilities. S&C Electric Company has studied
the state of C&I reliability over the last five years and
found that these companies have seen little to no improvement
in overall power reliability despite increased expectations
of their utility.
Systemwide
Feeder-Level
MAIFI
SAIDI and
SAIFI
Major
Event
Days
C&I companies are not the only customer type unaccounted
for in commonly used reliability metrics. New categories
of customers, such as distributed generation and energy
storage operators, are also not captured in traditional metrics.
This is increasingly concerning as these customers are
increasing their share of power. These emerging customers
depend on distribution grid reliability to export their energy
and provide services to the grid or other users on a peer-topeer
basis. New metrics could be
adopted that capture the impact of
unplanned interruptions on these
customer types, such as measuring
the average interruption frequency
or average interruption duration
for distributed generation, similar
to the SAIFI and SAIDI metrics
for traditional utility customers.
Additionally,
Commentary:
Evolution toward
better customercentric
metrics.
Electricity
Customer
CEMM
Momentary
Interruptions
CEMI
Duration of Outages
Typical
Outages 5 min
to Several Hours
CELID
Long
Interruptions
> 12 Hours
Size of Circle = Relative Level of Utility Use of This Metric
figure 4. Where key utility reliability metrics need to move.
122
ieee power & energy magazine
reporting on
new metrics, such as CELID and
CEMSMI, could create benefits
for other categories of customers,
including residential, C&I,
and distributed generation.
What Will Come Next?
As energy systems integrate even
greater amounts of distributed
generation and electrified transportation,
distribution system
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