Comparative severity of prolonged and repeated outages

Determine whether a prolonged outage is more harmful than multiple shorter outages having the same total duration, and characterize how the temporal pattern of outages affects their reliability risk.

Background

The paper proposes reliability standards formed by combining a state transformation, a time-dependent functional, and a risk measure. Among the candidate metrics is the mean frequency of outages, which captures how often the USE process exceeds the outage threshold but does not directly encode the full duration or temporal arrangement of those outages.

The authors identify an unresolved interpretive and modelling issue concerning customer impact: equal aggregate outage duration may produce different consequences depending on whether it occurs as one prolonged outage or as several shorter outages, and the placement of outages in time may also affect severity. Resolving this issue would help determine how outage frequency, duration, and temporal pattern should be incorporated into reliability standards.

References

It is unclear whether a prolonged outage is worse than multiple shorter outages with an equal total duration. Additionally, the impact of the time pattern in which these outages occur remains unclear.

— Measures of Reliability Risk for the Australian Energy Sector  (2609.36751 - Boland et al., 29 Sep 2026) in Section 2, Subsection “Constructing the Reliability Standard,” Table “Metrics ρ as Superpositions of R, τ and σ,” entry “Mean frequency of outages”