AEMO conducts investigations of 'unusual power system events' within the NEM. These events are known as “reviewable operating incidents” and are generally not considered as “credible contingency events”. As such, these events are not normally taken into account in the operation of the NEM.
The full scope of such events is set out in National Electricity Rules Clause 4.8.15 and the guidelines established by the Reliability Panel.
AEMO conducts these investigations to assess the adequacy of the provision and response of facilities or services, and the subsequent appropriateness of actions taken to restore or maintain power system security. AEMO then publishes a report on each incident.
AEMO has classified each incident on the basis of impact in relation to the level of load or generation loss
|| No loss of load or generation
| Not Significant
|| Loss of load or generation less than 50MW
|| Loss of load or generation exceeding 50MW but less than 250MW
| Very Significant
|| Loss of load or generation exceeding 250MW
AEMO maintains statistics of these reviewable operating incidents in order to identify any trends in performance.
AEMO maintains a list of Critical Transmission Elements for the purpose of identifying Reviewable Operating Incidents.
A number of reviewable incidents may result from or result in AEMO reclassifying a non-credible contingency as a credible contingency. In accordance with Clause 4.2.3A(i) of the NER AEMO is required to report on the reasons for all decisions to reclassify contingencies.
Archived reports are available from AEMO’s Information & Support Hub.