Missed amongst other news last week, I see that the AEMO has released it’s preliminary incident report into the trip that forced SA to be electrically islanded from the rest of the NEM for one week in mid-November.
The report states that two trips occurred at approximately 04:39PM NEM Time (UTC +10) on the 12th of November:
- Both South East – Tailem Bend 275 kV lines (No. 1 and No. 2 lines) – Caused by a double circuit transmission tower failure.
- The Keith – Tailem Bend 132 kV line tripped at the Tailem Bend end only – Due to operation of an automated inter–tripping scheme.
Wind gusts concurrent to the associated thunderstorms were measured as high as 115 km/h in the state. The closest reading to Tailem Bend was at Murray Bridge which measured a 61km/h wind gust at 4:43PM local time.
Frequency and Voltage Performance
Three days after the incident, I published an article and chart that showed the separation of SA and VIC frequency using 5-second data. The AEMO preliminary report includes a zoomed-in high speed trace of frequency, and states that SA frequency peaked at approximately 50.53 Hz shortly after the trip.
Source: AEMO Prelimary Report pg.9
Additionally, several voltage dips at the Para 275kV substation were recorded in the seconds directly after the trip.
A final report is expected in due course.