IEEE Power & Energy Magazine - January/February 2022 - 53

Impacts and Mitigation Strategies
for Australian Electricity Grids
When a fault occurs because
of bushfires, the affected line
can be re-energized manually or
with an autorecloser, restoring
power transfer. In more extreme
cases, however, heat from the
fire can damage the towers,
conductors, or insulators, and power transfer cannot be restored until the damaged lines can be repaired.
What is worse, in the presence of prolonged and widespread fires, crew interventions to repair the
affected asset may become extremely difficult and dangerous, leading to areas experiencing days and
even weeks of outages. Such outages may also cause serious issues to system operation, particularly
because the usual redundancy in power flow routes, which can ensure that system security may not be
available due to line disconnections.
Distribution networks are subject to the same kind of issues as transmission networks, particularly the
most isolated rural regions, which are typically linked by long overhead lines. Furthermore, distribution
networks are often closer to bush areas and conductors are closer to the ground, so they are exposed to
greater risks from bushfires. The main disruptions due to bushfires are often related to distribution rather
than transmission networks.
Climate change has led to more dangerous weather conditions for bushfires in Australia, with this
trend projected to continue. Given the huge distances where long power lines cross forests and heavily
vegetated regions, ongoing developments are needed to reduce bushfire risk and increase power
system resilience.
This article examines bushfire impacts and mitigation strategies for Australian electricity networks and
power systems. It looks into system operation, T&D networks, climate change risk, and the future role of
distributed energy resources (DERs). Illustrative case studies support this examination.
Bushfires and System Operation
Bushfires and System Security
The effect of bushfires on transmission lines creates vulnerabilities that threaten the integrity of the grid
and its secure operation. In the NEM, system security is managed using the N-1 criterion (no power loss
after any outage of a single element such as generators, lines, and so on) for a predetermined set of " credible "
contingencies. The trip of a single transmission line due to a bushfire
would normally be a credible contingency. Therefore, the loss of a single
line would not be expected to interrupt the operation of the power system.
It would not be expected to lead to the interruption of supply to customers,
except in the (inevitable) case of a radial line or where the load is shed postfault
to prevent an overload of the remaining lines.
The tripping of both circuits of a double circuit line is normally not
regarded as a credible contingency in the NEM. The situation is similar
for multiple circuits in the same corridor. However, in the presence of an
approaching bushfire, the probability of multiple circuits tripping concurrently
is significantly increased. Therefore, in the NEM, the Australian Energy
Market Operator (AEMO) could reclassify the tripping of multiple circuits as a credible
contingency. This would lead to the system operator constraining flows in the network and
potentially procuring more ancillary services to manage the credible loss of multiple circuits.
As this could incur additional production costs, the system operator would need to 1) have transparent
criteria for reclassifying the contingency as credible, including the proximity of the fire and the wind speed
and direction and 2) notify market participants when reclassification occurs. Although this may be a routine
exercise in the presence of a single bushfire, the issue is that in extreme bushfire conditions and with the size
of the Australian networks, it is common to have multiple fires threatening multiple transmission corridors.
This occurred in Australia in the summer of 2019-2020, for example. Therefore, the system operator may
need to concurrently reclassify the tripping of multiple lines in different locations as credible contingencies.
Keeping track of multiple bushfires, and hence multiple contingency reclassifications, is a complex task that
requires constant updating. It also can become very challenging to determine which set of measures, including
january/february 2022
ieee power & energy magazine
53

IEEE Power & Energy Magazine - January/February 2022

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