IEEE Power & Energy Magazine - September/October 2021 - 75

Therefore, a new operational mechanism that has been discussed
is the so-called N−(X+) operation. The " + " indicates
augmentation of the classical N−X criterion with the " size "
of the indistinct contingency considered. This theoretical
approach would likely involve data-driven analysis to determine
what indistinct events might be considered reasonably
possible in the surrounding circumstances. A similar approach
has already been adopted by National Grid in Great Britain.
While at present the N−(X+) security criterion is not
being explicitly considered as a potential amendment to
the NEM regulatory frameworks, at least in the context of
resilience and indistinct events, AEMO is already adopting
data-driven probabilistic approaches to deal with operating
reserves to guarantee reliability.
Extending Protected
Events Arrangements
The focus of AEMC's current work is to consider noncredible
indistinct risks, which may include HILP-type events. These
events can take several forms, including those dependent on
external abnormal conditions (condition-dependent) and those
independent of external conditions (condition-independent).
Noncondition-dependent indistinct risks that can be considered
are " standing " risks since the risk does not change by
reference to external abnormal conditions. An example could
include a cyberattack. This type of risk is indistinct in that it
may affect multiple undefinable assets on the system, and it
is described as " standing " since the threat is not necessarily
dependent on identifiable external conditions. However, it is
noted that, in the case of an attack warning, the risk might
be considered " condition-dependent, " and other approaches
could be used. This type of indistinct risk is being investigated
by AEMC. It may be that the standing nature means the
protected event framework could form the basis of a regulatory
approach for managing standing indistinct risks, too.
Implementing New
Operational Measures
Condition-dependent indistinct risks are the other area of
focus in AEMC's work program. These are indistinct noncredible
risks, the magnitude of which changes depending
on external abnormal conditions. Examples of such conditions
could include a large storm crossing a region of the
power system. AEMC is considering new frameworks to
allow AEMO to take necessary operational actions to manage
these kinds of risks. Steps may include restricting power
flows on interconnectors, procuring additional ancillary
services, and directing additional synchronous generating
units to be online to increase system inertia, fault levels, and
dynamic active and reactive power capability.
The framework being considered by AEMC through the
" indistinct events rule change " aims to establish processes
that would provide the system operator with the flexibility to
effectively manage the power system's rapidly changing risk
profile. In devising such a framework, it will be important to
september/october 2021
consider how the risks can be managed given the associated
extreme uncertainty. It will also be necessary to consider
how governance frameworks can ensure the full suite of
costs is identified. For example, transparency and openness
will likely be important to allow all affected parties to have
a say and that all learnings from past events are captured and
inform the operational frameworks.
Acknowledgment
The authors appreciate the support of AEMC while acknowledging
that the views expressed in this article are those of
the authors only.
For Further Reading
" Mechanisms to enhance resilience in the power system:
Review of the South Australian black system event, " Australian
Energy Market Commission, Sydney, Final Rep., Dec. 12, 2019.
[Online]. Available: https://www.aemc.gov.au/markets-reviews
-advice/review-of-the-system-black-event-in-south-australi
" National electricity amendment (enhancing operational
resilience in relation to indistinct events) rule 2021, " Australian
Energy Market Commission, Sydney, Consultation
Paper, Dec. 17, 2020. [Online]. Available: https://www.aemc
.gov.au/rule-changes/enhancing-operational-resilience
-relation-indistinct-events
" Black system in South Australia 28 September 2016, " Australian
Energy Market Operator, Melbourne, Final Rep., Mar. 28,
2017. [Online]. Available: https://protect-au.mimecast.com/s/
K9mqC3Q8MvCp56v7Etpl5Vr?domain=aemo.com.au
P. Mancarella and F. Billimoria, " The fragile grid: The
physics and economics of security services in low-carbon
power systems, " IEEE Power Energy Mag., vol. 19, no. 2, pp.
79-88, Mar.-Apr. 2021. doi: 10.1109/MPE.2020.3043570.
R. Moreno et al., " From reliability to resilience: Planning
the grid against the extremes, " IEEE Power Energy
Mag., vol. 18, no. 4, pp. 41-53, July-Aug. 2020. doi: 10.1109/
MPE.2020.2985439.
M. Panteli and P. Mancarella, " The grid: Stronger, bigger,
smarter: presenting a conceptual framework of power system
resilience, " IEEE Power Energy Mag., vol. 13, no. 3, pp.
58-66, May-June 2015. doi: 10.1109/MPE.2015.2397334.
" Technical report on the events of 9 August 2019, " National
Grid ESO, London, Sept. 6, 2019. [Online]. Available:
https://www.ofgem.gov.uk/system/files/docs/2019/09/eso
_technical_report_-_final.pdf
Biographies
Julian Eggleston is with the Australian Energy Market
Commission, Sydney, 2000, Australia.
Christiaan Zuur is with the Australian Energy Market
Commission, Sydney, 2000, Australia.
Pierluigi Mancarella is with the University of Melbourne,
Melbourne, 3010, Australia, and the University of
Manchester, Manchester, M13 9PL, United Kingdom.
p&e
ieee power & energy magazine
75

https://www.aemc.gov.au/markets-reviews-advice/review-of-the-system-black-event-in-south-australi https://www.aemc.gov.au/markets-reviews-advice/review-of-the-system-black-event-in-south-australi https://www.aemc.gov.au/rule-changes/enhancing-operational-resilience-relation-indistinct-events https://www.aemc.gov.au/rule-changes/enhancing-operational-resilience-relation-indistinct-events https://www.aemc.gov.au/rule-changes/enhancing-operational-resilience-relation-indistinct-events https://protect-au.mimecast.com/s/K9mqC3Q8MvCp56v7Etpl5Vr?domain=aemo.com.au https://protect-au.mimecast.com/s/K9mqC3Q8MvCp56v7Etpl5Vr?domain=aemo.com.au https://www.ofgem.gov.uk/sites/default/files/docs/2019/09/eso_technical_report_-_final.pdf https://www.ofgem.gov.uk/sites/default/files/docs/2019/09/eso_technical_report_-_final.pdf

IEEE Power & Energy Magazine - September/October 2021

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - September/October 2021