Feather dust-up: Energy institutions fall out over wind’s role in S.A. blackout

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Major differences emerge between AEMO and the industry regulator and rule-makers over role of wind farm “feathering” in S.A. blackout and what to do about it.

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A huge disagreement has emerged between Australia’s major energy institutions over the role of wind energy in the lead up to the South Australia blackout, and over the measures that should be introduced to protect against a repeat event.

In what is emerging as a major flash-point, and one sure to be exploited by the anti-renewables brigade in the government and the media, the Australian Energy market Commission has urged new mechanisms to be introduced, and supported a push by the regulator to have the variability of wind and “feathering” in high wind speeds classified as a “contingency event.”

Such a classification could have a serious impact on the way the grid is managed as the share of wind and solar grows. And the Australian Energy Market Operator is fighting back, arguing that the variability of wind and solar can be managed within the normal dispatch operations, and with better forecasting.

The trigger point for this disagreement is the lead up to the state-wide South Australian blackout, and it appears that AEMO has a completely different view of what happened then than the AEMC and the Australian Energy Regulator, which last week shocked the industry by issuing legal proceedings against four wind farm operators.

In its latest review published on Thursday, the AEMC backs the AER view that “feathering” of wind farms in South Australia contributed to a significant fall in output ahead of the blackout and the tornadoes that tore down the transmission lines, leaving the inter-connector with flows above its limits, and the system potentially not in a secure operating state.

But the industry is saying that economists at the AEMC and the lawyers at the AER have got this completely wrong, and they misunderstand the operating systems.

They appear to assume that once above 90km/h, wind farms automatically feather and that it happens in unison, and significant amounts were lost.

But AEMO data shows that the feathering in the lead up to the South Australian blackout was minimal, and up to 40MW at worst – much less than that assumed by the AER and the AEMC. Feathering is usually used to ensure that wind farms can maintain maximum rated output.

Others point to the fact that Torrens Insland gas generators also wound back their output at the same time – an event that gets no mention by the AEMC.

Despite this, and ahead of a major meeting between the leading institutions and stakeholders on Friday, the AEMC has issued a discussion paper – written by staff – that highlights the differences between AEMO and the AER about how to handle the variability of wind.

“Through its investigation of AEMO’s compliance during the pre-black system event period, the AER uncovered a fundamental disagreement with AEMO as to what kinds of events on the power system can be identified as contingency events,” the report says.

The AEMC appears to have come down on the side of the AER, and wants the possibility of “fast-ramps” of wind and solar – and their potential variability – to be declared a “contingency” event.

AEMO favours treating it as a normal part of its dispatch arrangements, and said in its submission to this latest inquiry that imposing contingencies on such events is unworkable. It notes they cannot be done without rule changes, and “more fundamentally, reclassification is unlikely to be an efficient means of mitigating these risks.”

Industry insiders have pointed out that no energy market in the world treats the variability of wind and solar, or “feathering” as a contingency. The very idea of it is bizarre, they said.

“Basically there is a fundamental flaw in how they interpret ‘contingency’ and ‘credible contingency’,” one industry insider said. “They are creating more and more layers of legality so that AEMO ‘can do stuff’ to back off the inter-connectors when they need to …. but they have the power to do it now, they just have created procedures which limit themselves.”

Another insider noted: “It looks like (the AEMC staff) have already made up their minds.”

Others say this is symptomatic of the fundamental differences in views about the energy system and how it should operate. The polemic over the clean energy transition is just as hot inside the energy institutions themselves as it is outside and in the media.

AEMO’s submission argues against the classification of wind feathering as a contingency, saying it would not be helpful, and there are many other variables that it needs to worry about, such as the unpredictable actions of semi-scheduled generators, sudden changes in load, the passing of clouds, etc.

Feathering, at least, is largely predictable. But imposing a contingency risks causing a large volume of “generation runback schemes” to operate, creating more problems.

But even after considering all this, the AER and the AEMC staff appear to have dug in.

Partly, this controversy is sparked over AEMO’s actions on the day of the blackout. It has been criticised, including by the regulator, for not taking certain actions, including dialling back the amount that was being carried on the main interconnector, or signalling a potential contingency event (the approaching storms) to other generators.

“Through its investigation of AEMO’s compliance during the pre-black system event period, the AER uncovered a fundamental disagreement with AEMO as to what kinds of events on the power system can be identified as contingency events,” the report says.

In its compliance report, the AER considered that this situation represented a risk to power system security, as the actual metered flows on the Heywood interconnector were sufficiently high to raise the possibility of separation between South Australia and Victoria.

It said that feathering of the multiple wind turbines pushed Heywood flows to a point where, had the identified credible contingency (loss of Lake Bonney wind farm, the largest generator operating at the time) occurred; there was a real risk of excessive flows tripping the Heywood interconnector.

(AEMO, it should be noted, disagrees with this). “Despite identifying these risks, AEMO did not take operational action as they did not consider wind farm feathering to represent a contingency event as defined in the rules,” the AEMC paper says.

Exactly where this lands is going to be interesting. AEMO has already implemented numerous new measures since the blackout, including constraints on interconnector flows when storm systems approach, and keeping a minimum amount of synchronous generation on line. This could cause it to go further.

Among other measures proposed by the AEMC is the fast-tracking of network investments identified by AEMO as necessary to accommodate the big increase in renewables. This includes the new interconnector from South Australia to NSW, which the regulator has been sitting on for some time, and upgraded connections elsewhere.

This will be welcomed by many in the industry who point to the lack of progress on transmission investment and the apparent hold-ups on new investment that have emerged. ITK analyst, Energy Insiders podcast co-host and RenewEconomy contributor David Leitch has been particularly critical of this.

Connection issues, often due to a lack of capacity, but also strict new generator performance standards, are now cited as the biggest hurdle for new wind and solar developments.

The South Australia government welcomed the move to speed up the regulatory process. “The interconnector will help us make use of our renewable energy to deliver lower prices and more secure power to consumers,” Treasurer Rob Lucas said in a statement.

“The AEMC report shows that resilience must be embedded into the rules of the power system to deal with a renewables’ dominated power system …. we’re also excited about the projects that are lining up to be built on the back of the interconnector, turning South Australia into an export powerhouse.”

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