IEEE Power & Energy Magazine - January/February 2022 - 35

The first feeder installations were selected on circuit
sections that are more economically and technically viable.
these feeder installations carry light loads (typically from
1 MVA to 1.5 MVA), have a length of 10 mi, and predominantly
consist of overhead conductors. Also, SCE recently
commissioned a GFN, which is a commercially available
equipment package, installed in a substation for achieving
resonant ground substation (Figure 8) and more economic in
protecting multiple distribution circuit feeders.
Microgrid for Added Resilience
Beyond covered conductors and protection technology
explorations, advances in a variety of nontraditional electrical
energy resources have paved viable paths for microgrids
to play an important role in increasing the broader resiliency
of the electric power grid.
Given the potentially devastating outcome of wildfires,
utility companies in California are doing everything
they can to reduce the risk of ignitions. These measures
include unpopular mitigation of last resort called Public
Safety Power Shutoff (PSPS), where power is preemptively
turned off when conditions are ripe for the rapid
spread of catastrophic wildfires. PSPS implementation
brings tremendous complications in all aspects of utility
operations, not to mention the extensive communications
required with SCE's customers, community, and emergency
response stakeholders.
While the complexity of the PSPS operational protocols
is not the focus of this article, it is worth noting that tremendous
effort and resources have been devoted to ensuring PSPS
implementation is not only exercised as a measure of last resort,
but that its impact is reduced in SCE's service territory. Given
that so much of our modern-day
life depends on a reliable source
of electricity, resiliency considerations
are also paramount. With
the advent of energy storage and
various forms of nontraditional
energy resources, a microgrid
is a great example of application
to increase grid resiliency
against potential power outages
due to a variety of impacts
(including PSPS). SCE also sees
energy storage and microgrids as
an absolute necessary enabling
technology for decarbonizing the
electric grid.
One hurdle in the deployment
of the microgrid technology is the
economic justification of these
microgrid assets at current costs
compared to the value derived
from other alternatives (e.g.,
nonclean generators). To get over
Point of
Connection to
Switchrack
Fuses
2,000:5 CTs to
Remove From Bus
Differential
12 kV Cables to
GFN
figure 8. A GFN REFCL installed at an SCE substation.
january/february 2022
ieee power & energy magazine
35
this hurdle, SCE has to get past evaluating each microgrid
in isolation as a discrete asset and value them at a broader
system level. The integration and control of these discrete
installations in aggregate will provide significant benefits
that are otherwise not visible when being evaluated as
stand-alone assets. This is unlocking the value of ubiquitous
grid-edge considerations in that these inverted-based
resources can work collectively to provide greater system
value. A case in point is that these resources are, through
effective integration and controls, capable of shaping system
voltage and frequency so there is not a simultaneous
boosting and bucking of the adjacent units working against
each other.
Other Ways to Improve
Wildfire Resilience
In addition to system-hardening measures such as covered
conductors and special protection technologies such as
REFCL, a variety of newer technologies are being progressively
piloted to improve the inspection, asset condition
assessment, and situational awareness of the grid. These
emerging technologies help to detect prefailure conditions
of equipment or material so that SCE would make the correction
before a failure and possibly ignition occurs. For
example, detecting broken conductor strands, intermittent
tree branch contact with the electrical line trigger crew
to respond to the sites for further investigation and repair
the problems. Inspection technology, such as infrared and
corona detection, are supplementing SCE's traditional
visual asset inspection program to proactively identify and
remediate asset defects that may not be visible to the human
eye (e.g., hotspot on a wire).
Load Break Switch
600:5 Bank CTs
1,200:5 Neutral CT
50:5 Neutral CT
IEEE Power & Energy Magazine - January/February 2022

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