IEEE Power & Energy Magazine - January/February 2022 - 84

relative humidity), the vegetation of the crossing area, terrain
slope, fuel bed conditions, and flame front properties.
Hence, weather forecasting tools and systems (e.g., satellite
observations) for acquiring knowledge of territory characteristics
are vital. Wildfire tracking is also important, as
collected data during wildfire progression can be used to
update propagation assessment and organize system emergency
responses. Satellites and unmanned aerial vehicles
can be used to monitor wildfire progression when approaching
the fire is unsafe.
There are a variety of tools available to estimate wildfire
propagation. PG&E uses a tool developed by Technosylva
to derive fire propagation and consequence outcomes, such
as impacted infrastructure. Additionally, the U.S. Forest
Service uses the FlamMap application, which includes the
FARSITE simulator to compute wildfire growth and behavior.
The tool considers detailed sequences of weather conditions.
Since propagation depends on weather forecasting and
terrain characteristics that cannot be quantified with great
accuracy, different scenarios can be explored by considering
the forecast error and quantification accuracy of terrain
characteristics. PG&E highlighted the need to use a probabilistic
fire spread model.
Once the timing and impact of wildfire on system components
are assessed, a preemptive operation strategy can
be determined. Customer interruptions may be mitigated
through the schedule and dispatch of the DER and network
reconfiguration, taking into account the stochastic generation
of renewables. Wildfires mainly affect overhead lines, poles,
and substations components. Concerning overhead lines, a
wildfire can damage them or erode their thermal rating due
to the increase of the conductor's surface temperature. Also,
the impact of wildfire on DER can be estimated to develop
a strategy based on the available generation units. DER can
be fully destroyed by the wildfire, or their operation can be
affected by its smoke. For instance, wildfire smoke contains
small particles that reduce the amount of sunlight reaching
solar panels, reducing the PV output.
To mitigate issues expected from a reduction in a conductor's
safe carrying capacity, the system can be reconfigured
with DER and other resources operated to avoid limit violation
and tripping. If line damage is expected, the system operator
needs to determine a system reconfiguration to maintain
the full connectivity of the system. If full connectivity is not
possible, appropriate schedule and dispatch of the DER may
minimize load shedding in the isolated parts of the system
and ensure uninterruptible system operation. If the wildfire
damages a substation, load shedding of downstream loads can
be mitigated by using the residential DER (including flexible
loads) connected to the LV distribution system.
Figure 5 shows damage provoked by the 2007 forest
fires in Greece. In the case of Greece wildfires, monitoring
the spatiotemporal impact of the wildfires via GIS
has assisted the distribution system operator in choosing
appropriate locations for the mobile generators to reduce
restoration times after the damage. GIS information also
enables the rapid development of restoration plans. The
timely estimation of the required number of repair crews
and necessary materials for system restoration significantly
shortens system restoration times. A tool for estimating
wildfire propagation was not available in Greece.
Such a tool could support faster decisions to identify which
figure 5. Damaged lines and poles from the 2007 forest fires in Greece. (Source: Courtesy of Public Power Corporation,
Greece.)
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IEEE Power & Energy Magazine - January/February 2022

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