Renew Economy - Giles Parkinson
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| Image: ABC |
A preliminary report into last week's blackout in South Australia
from the Australian Energy Market Operator says it is clear that it was a
"weather event" that sparked 30 seconds of chaos and triggered the
collapse of three main transmission lines and ultimately the state-wide
blackout.
But the report, although reaching no conclusions, and based on
incomplete data, invites the media – and wind farm opponents in
Coalition and industry – to cite wind energy as a key factor by
inferring that some of the state's wind farms contributed to
the cascading impacts that caused the state-wide outage.
The report was released on Wednesday morning, just two days before a hastily convened COAG energy minister's meeting on Friday.
This is grist for the mill for that meeting – and it appears its
timing serves no other purpose. No doubt it will be seized upon by the
Coalition in its campaign against wind farms and its attempts to stop
the states from going forward with their own renewable energy programs.
In particular, the Coalition will point to the loss of 315MW of wind
power highlighted by AEMO in the press release after the collapse of the
last of the transmission lines that preceded the failure of the
inter-connector. At which point all the remaining gas and wind
generators tripped.
But there is a question about whether this loss of wind capacity really mattered. The data in the actual report suggests not.
Wind generators were producing a total of 883MW at the time (gas was
providing 330MW and 613MW was coming from Victoria) – and had ridden out
the loss of the first two transmission lines.
A small amount of wind capacity dropped out after the second
transmission line collapsed, possibly – the operators say – as the
result of lightning strikes and a software glitch that has since been
rectified.
But as this chart below shows, there was no impact on frequency. It
was only the failure of the third transmission line at 1615.18 that some
generation was lost, the frequency dropped the system went black 1.2
seconds later.
The loss of the third transmission line took away the delivery
mechanism for two other wind farms, which suggests it wouldn't have
mattered which power source was operating on that line. Within another
half a second, all remaining gas and wind plants had gone after the
interconnector tripped.
The report does not say why this happened, or why they stopped
generating. It could be because they had nowhere to send their output.
Or that, as mentioned earlier, some were hit by lightning, or tripped
after repeated voltage drops.
Nor does the report does not say if the total blackout would avoided
by having a brown coal generator on line, or if the outcome would have
been any different with no wind power.
The report also point to problems with conventional generation,
saying that contracted but un-named providers of "black start" services –
peaking gas fired and diesel power stations – failed to deliver and
could not be used to restart the main gas generator, meaning the
operator had to wait until a new link was established with Victoria.
They are paid millions of dollars to provide this essential service,
but failed when needed. The report does not say why, possibly because it
won't even say who.
Indeed, the report is also likely to trigger discussions about the
role of AEMO itself, and the actions that it took, or didn't take, in
the lead up to the blackout.
It says, for instance, that it was on a "heightened state of readiness" with "emergency procedures in place".
But market players are wondering why it saw no reason to allocate
more back-up power, or adjust the flow on the interconnector so that
they could respond to any unforeseen events, particularly for the
lightning that is frequent in that part of the world.
If it had "reclassified" the potential loss of the interconnector,
this would have invoked the provision of 35MW of local FCAS constraint
and constrained the interconnector, leaving enough headroom to manage
this power flow increase.
Already, the question is being asked: how serious does a storm have
to be, and who made the call that this was not serious enough? Many in
the market are also expecting a review of the fault
ride-through equipment and systems that are rarely tested in real-time.
AEMO has already taken some preventative measures in the interim,
placing constraints on wind farms and taking control of the wholesale
market – essentially running it as a centrally controlled system rather
than an open energy market.
The reason for this is the continued absence of the three main
transmission lines, and some smaller lines, which are unprecedented and
beyond the system design. It has also reclassified 10 wind farms that it
says "did not operate" normally during the weather events.
It effectively means their combined output cannot exceed 600MW, or
that of the interconnector. It says this will remain in place until more
is known about the issues. AEMO wants to see high speed data from all
wind farms in the region in order to confirm that each generator
performed in line with their respective agreements.
The preliminary report explains how severe weather moved through
South Australia on the afternoon of Wednesday, September 28, with high
winds, thunderstorms, 80,000 lightning strikes, hail, and heavy rainfall
and even two tornadoes.
The weather, it said, resulted in multiple transmission system faults
including, and in the space of 12 seconds, the loss of three major 275
kV transmission lines north of Adelaide.
The sequence of events as described by AEMO went something like this:
– At 1618 (network time): One line faulted: No change to generation or load. … but 1 transmission line out of service
– Another line faulted (and successful re-connected within 1 second).
Then it re-faulted and 2 transmission lines out of service.
– 1 second later, there was about 123MW reduction in wind output.
– 4 seconds later – another transmission fault …. and now 3 transmission lines were out of service
– About 2 seconds later another about 192MW reduction in wind output
occurred. This caused the flow across Heywood Interconnector to increase
to over 850MW, causing it to trip. In less than half a second the whole
state went to "system black".
The cause of wind farm disconnection is still not clear and is not
dealt with by AEMO. There is some suggestion that some wind farms could
have been lost because of multiple lightning strikes, or because of
protection measures.
Strikes at some turbines may have triggered an automatic shutdown
after three successive faults – although these faults could have been
caused by lightning or falls in frequency. There are concerns that these
turbines should have been configured to ride through more such events.
It wouldn't be the first time lightning has caused havoc in South
Australia. In 2005, a lightning strike forced the Northern brown coal
generator to drop from nearly full output to zero, causing the
inter-connector to trip and the loss of a number of other conventional
power plants.
Still, these are troubling times for the wind industry, and for the
solar industry as well, which could also find itself impacted should the
states find themselves beaten into submission by the federal government
and a baying media crowd.
South Australia premier Jay Weatherill says the report shows that it was a weather event and was not a "renewable energy" event.
"Now, armed with that information, we need to attend the national
energy ministers meeting on Friday to take steps to ensure that we have a
secure, clean and affordable electricity system," he was quoted as
saying by the ABC.
Prime minister Malcolm Turnbull, however, said the state had failed
to keep the lights on. "SA has the highest wholesale energy costs in
Australia. That is not good for business. It's not good for a state
which needs to get more jobs, [and has] a higher unemployment rate than
any other."
The Clean Energy Council says it was clear that the blackout was
caused by the storm that took out the huge electricity pylons
and triggered a sequence of "extraordinary events", and it wouldn't have
mattered if the state was running on coal, gas, nuclear or renewable
energy.
"This was a once-in-50-year storm which placed extraordinary stress
on the power system, and the cascading events that followed the damage
to the transmission system have never been experienced before," CEO Kane
Thornton said.
"Australia's power network is highly sophisticated with a range of
advanced protection and fault ride-through equipment and systems that
are rarely tested in real-time. These were put under unprecedented
pressure due to the extreme weather events in South Australia.
"No doubt there will be much we can learn to improve the resilience
of the electricity system in light of the evolving energy mix and the
probability of increased storm events in the future.
"There is no evidence to suggest that maintaining Northern Power
Station in operation or the increased role of wind power changed the
outcome in these extraordinary events."
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