The Australian Energy Market Operator has relaxed limits on wind generation in South Australia, as it continues to review the system strength needs of the grid with the highest penetration of wind and solar in the world.
In the wake of the state’s system black last year and subsequent reviews, AEMO imposed new rules that came into force in July that required a minimum amount of “synchronous” generation, and would impose constraints on wind output if those minimum requirements could not be met.
The rule was seen as heavy handed by some in the industry, but AEMO is gradually relaxing the limits and constraints as it conducts further studies into how the system can be managed with a high and growing share of variable renewables.
In a market notice published last Friday, AEMO said the limit for higher levels of non-synchronous generation (essentially wind at the moment) when only a minimum strength requirement is met had been increased from 1200MW to 1295MW.
It has also increased the trigger point for higher levels of synchronous generation from 1700MW of non-synchronous generation to 1870MW. It has also added to the “variations” of gas generators required at any point in time.
AEMO says it plans a further update in January, and it is expected that it will gradually loosen the controls as it becomes more comfortable with the new technology.
When those limits are passed, AEMO will instruct certain wind farms to “spill” excess capacity if not enough gas generators are switched on at the time.
In an interview with RenewEconomy’s weekly Energy Insiders podcast this week, AEMO chief executive Audrey Zibelman admitted there was still a lot of work to do to fully understand how a high penetration renewable energy system works.
“It will take time for us to develop the capabilities to manage that,” Zibelman said. “We need to make sure that our lack of understanding does not become a barrier (to new technologies).”
South Australia currently sources more than 50 per cent of its electricity demand from large-scale wind and rooftop solar, with about 1,800MW of wind and 740MW of rooftop solar in place.
Another 650MW of large-scale wind and solar are under construction, another 1GW in the pipeline, and households and businesses are still adding 100MW of rooftop solar a year.
Rainer Korte, the head of asset management at Electranet, the operator of the state’s transmission infrastructure, said late last month that there had been “a lot of wind spill” over the last 4-5 months because of the AEMO cap.
But he said that ElectraNet was not expecting those limits to be in place in the long term, because the market operator would learn to use new technologies and new investments in network infrastructure and storage.
Korte pointed to a recent ElectraNet study on a proposal for an upgraded transmission line on the Eyre Peninsula – the very end of Australia’s elongated network – to help address issues that arose from the system black last year and ongoing unreliability.
That study says an upgraded line would deliver more savings to consumers over the long term because it would allow more wind generation in the region – Macquarie’s green grid proposal outlined 4,000MW of wind resources in the area – and encourage new loads from mining opportunities.
But the transmission proposal is facing competition from other ideas: SA Power Networks, which operates the local grid, favours distributed generation, while battery storage manufacturers support more storage that they say will reduce the need for major new transmission lines.