September 28, 2016 | South Australia (entire state)
People affected (entire state)
Wind generation lost in 7 seconds
Interconnector overload (650 MW rated)
Transmission towers destroyed
What Happened
A once-in-50-year storm swept across South Australia with twin tornadoes packing winds up to 260 km/h. The tornadoes ripped through transmission corridors, destroying 22 high-voltage towers and severing the lines connecting the state's northern wind farms to Adelaide. (continue below)
As transmission lines fell, voltage dips rippled through the grid. Wind turbines are designed to ride through brief voltage drops, but each turbine has a safety limit on how many dips it can handle in quick succession. Nine wind farms hit that limit almost simultaneously, dropping 456 MW of generation in under 7 seconds.
The single interconnector to Victoria tried to compensate, surging to 850 MW against its 650 MW capacity. It tripped on overload protection, isolating the entire state. Within seconds, every remaining generator shut down. Total cascading failure.
Timeline
16:16:49
First fault: 66 kV line near Adelaide trips
A distribution line trips from storm damage but automatically resets. The cascade sequence has begun.
16:17:36
First major 275 kV line destroyed
The Brinkworth-Templers West line faults as tornado damage near Blyth takes out transmission towers. Power flow begins redistributing.
16:17:55
Wind farms begin mass disconnection
Repeated voltage dips exceed the ride-through limits on wind turbine protection systems. Multiple farms start shedding output simultaneously.
16:18:09
456 MW lost in 7 seconds
Hallett drops 123 MW, Hornsdale drops 86 MW, Snowtown drops 106 MW. Nine wind farms lose output almost simultaneously. The grid cannot absorb this.
16:18:14
Heywood interconnector overloads
The sole link to Victoria surges to 850 MW trying to compensate, far exceeding its 650 MW capacity. Both circuits trip on overload protection.
16:18:16
System Black
South Australia is completely isolated from the National Electricity Market. Remaining generators trip on under-frequency protection. The entire state goes dark.
19:00
First customers restored
After a complex black-start process requiring power from Victoria, first Adelaide metro customers get power back. Full restoration takes 13 days.
Root Cause
The Hidden Vulnerability
Wind turbines have a safety feature called "repeat-LVRT protection" that disconnects them after too many voltage dips in a short window. The critical finding: these protection settings were invisible to the grid operator. AEMO had no idea nine wind farms would disconnect simultaneously.
The OEM default settings on the turbines created a systemic risk that no one could see in the grid models. When the storm caused rapid voltage dips, the protection triggered across multiple farms at once, removing 456 MW in seconds.
Could This Have Been Prevented?
VPP Prevention Case
This blackout directly led to the construction of the Hornsdale Power Reserve (Tesla Big Battery). A fleet of distributed batteries could have absorbed the 456 MW shortfall in milliseconds, buying time for operators to manage the interconnector load.
At the time, South Australia had zero utility-scale battery storage. Eighteen months later, the Hornsdale battery would prove that 100 MW of fast-acting storage could prevent exactly this type of cascade.
Related Incidents
Sources (6)
<a href="https://www.aemo.com.au/-/media/Files/Electricity/NEM/Market_Notices_and_Events/Power_System_Incident_Reports/2017/Integrated-Final-Report-SA-Black-System-28-September-2016.pdf" target="_blank" rel="noopener">AEMO — Black System South Australia 28 September 2016: Final Report (March 2017)</a>
<a href="https://www.aemo.com.au/-/media/files/electricity/nem/market_notices_and_events/power_system_incident_reports/2018/aemo-compliance-report--sa-black-system-event.pdf" target="_blank" rel="noopener">AEMO — Black System Event Compliance Report (2018)</a>
ElectraNet — Transmission line damage assessment (2016)
Business SA — Economic impact estimate: AUD $367 million
Bureau of Meteorology — Severe weather warning and tornado confirmation (Sep 2016)
<a href="https://en.wikipedia.org/wiki/2016_South_Australian_blackout" target="_blank" rel="noopener">Wikipedia — 2016 South Australian blackout</a>