AEMO NEM Event – Gordon-Chapel Street Reclassification Scheduling Error - 16 December 2014
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At 07:46 hrs on 16 December 2014, there was a simultaneous trip of the Basslink interconnector and trip and auto reclose of the Gordon – Chapel Street No.1 and No.2 220 kV transmission lines in Tasmania.
AEMO declared the Gordon – Chapel Street lines as “vulnerable due to lightning” at 09:38 hrs, and reclassified their loss as a credible contingency due to lightning at 11:35 hrs.
At 13:00 hrs, TasNetworks advised AEMO that the Gordon – Chapel Street trip and auto reclose at 07:46 hrs was single pole only on both lines.
With this information, AEMO should have immediately withdrawn the declaration of those lines as “vulnerable” and the reclassification of its loss as a credible contingency event. AEMO did not do this until 13:40 hrs.
AEMO declares a scheduling error occurred for the period when the reclassification should not have been applied, that is from dispatch interval ending 1305 to 1345.
AEMO estimates the NEM impact of the error to be $1,673
Under NER clause 3.16.2 (a), Market Participants affected by a scheduling error may apply to the dispute resolution panel established under NER clause 8.2.6A for a determination on compensation.
For further information on this document, please contact: Ross Gillett, Markets department.