IEEE Power & Energy Magazine - Grid Edge 2023 - 100

downstream of the outage point. On the other hand, MESS
can be relocated and reconnected at a proper utility service
line to supply customers' loads where required. The key
differentiator for MESS is the ability to relocate and select
a new interconnection point with minimum effort, considering
the impacted area.
MESS Use Cases and Examples
While portable diesel generators are mainly limited to an
emergency backup power supply for a permitted duration,
a MESS can operate and serve customers and the distribution
grid for different use cases indefinitely (while the
energy supply lasts). MESS use cases and stacking them for
seasonal and locational applications is the key in revealing
the true values of MESS technology.
Outage Management (Planned or
Unplanned)
The primary use case for MESS is supplying customers
during system planned/unplanned outages. The importance
of outage preparedness and management is significantly
growing due to the increased frequency of weather-related
outage occurrences globally and across North America.
Examples of natural disasters causing grid outages are:
✔ Wildfires affecting power lines and substations or
high-speed winds causing towers/poles and lines to
go down, forcing a power shutdown
✔ Flooding that impacts substations resulting in outages
for safety
✔ Hurricanes bringing down poles and power lines
✔ Storms, especially ice storms in cold climates, increasing
line/tower loading and causing breakage
✔ Drought and heatwave increasing electrical loading
resulting in protection system tripping due to overloads.
Figure
2 shows a map of major weather-related disasters
across the United States in 2021 that caused outages and
damages more than $1 billion. The number of outages tied
to severe weather has doubled over the last 20 years (more
than 100 cases annually on average over the past five years).
Example of an Outage Event: Public
Safety Power Shutoff (PSPS)
Public Safety Power Shutoff (PSPS) has been practiced
for several years in California to avoid catastrophic wildfires
due to extreme weather conditions (e.g., high winds in
the dry season). To protect high-risk communities' safety,
the utility de-energizes high-voltage lines in certain areas
before weather events occur. This, in turn, exposes several
customers to outages for a few hours up to multiple days.
Historically, severe weather conditions have been rare,
and the high fire-threat areas have been rural and less
inhabited. Thus, the impacts of PSPS outages were not significant
or visible. This has changed significantly during
the last five years, pushing California utilities to take measures
for efficient outage management to reduce the impact
on customers and communities. In response, however, a
shadow grid of dispersed diesel generators has emerged for
backup power during outages to maintain uptime, which
is contradictory to California's direction towards a 100%
clean energy future (Figure 3). In addition, it has raised
serious environmental and health concerns among communities,
especially those vulnerable communities exposed
to diesel-generated pollutants (particulate matter, volatile
organic compounds, nitrous oxides, and sulfur dioxide in
addition to carbon monoxide), which exacerbates respiratory
illnesses. The red and orange areas in Figure 3 serve
as indicators of the most environmentally burdened communities,
which are also among communities more exposed
to PSPS events.
Not Effective
Effective
figure 1. Effectiveness of MESS versus stationary ESS for customer outages.
100
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April 2023
IEEE Power & Energy Magazine - Grid Edge 2023

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