AEMO declares system strength shortfall in Queensland after wind, solar curtailed

The Australian Energy Market Operator (AEMO) has declared parts of the North Queensland grid have unacceptably high fault levels, recognising an issue that has hampered the operation of renewables projects in the region.

AEMO has made a formal declaration of a “system strength shortfall” in North Queensland, that applies to the 275kV node at the Ross substation, and further explains why three wind and solar projects in the region were hit with directions to cut output.

The declaration of a fault level shortfall now places an obligation on the transmission network service provider Powerlink to ensure the fault is addressed. A similar declaration was made in the West Murray region of Victoria/NSW after five solar farms in the area had their output cut in half.

Under the new declaration, AEMO has issued a deadline of 31 August 2021 for Powerlink to “ensure that the necessary system strength services to address the fault level shortfall are available.”

“System strength” relates to the electricity system’s ability to respond to disturbances in the supply-demand balance within the system, as well as managing fluctuations in voltage and frequency.

These fluctuations can have a significant impact on generators connecting to the network through inverters, which generally includes all solar generators, as they can impact the operation of control systems, and therefore exacerbate system instabilities.

As reported by RenewEconomy in March, two Queensland solar farms, and one wind farm, have all been impacted by the system strength issues in Queensland.

The Haughton and Sun Metals solar farms near Townsville, and the Mt Emerald wind farm, face having their output curtailed as much as 100 per cent, depending on the conditions and demands on the network.

AEMO expects that if action is not taken, that a system strength shortfall of 90MVA will continue at the Ross substation through to at least 2024-25.

The Clean Energy Council welcomed AEMO’s declaration of the “strength gap”, saying that it was now an opportunity for the issue to be addressed and restrictions on renewable energy generators in the region lifted.

“These renewable generators have been constrained through no fault of their own. As a result, the commercial returns of these projects are seriously impacted,” Clean Energy Council Chief Executive Kane Thornton said.

“It is critical that this issue is addressed quickly to ensure they can generate at full capacity to bring more low-cost generation to market.”

“While renewable resources, particularly solar, have a strong future in North Queensland, these types of uncertainties render planning and investment in the region harder and less likely. Addressing system strength is vital to ensuring North Queensland remains an attractive location for future renewable energy generation.”

The Queensland energy minister Anthony Lynham was confident that the supply strength issue could be resolved, without any impact on Queensland consumers.

“This system strength challenge is being experienced across the National Electricity Market as renewable generation increases,” Lynham said. “The Australian Energy Market Operator has previously declared system strength shortfalls in South Australia, Tasmania and Victoria.”

“Powerlink and CleanCo are working together to have Far North Queensland hydro power station, Kareeya, running in synchronous condenser mode, while its sister hydro station Barron Gorge is generating to assist”.

“Powerlink is also exploring options to increase the synchronous capacity in North Queensland to support the development of more renewable projects going forward. We can do this relatively simply because Queenslanders own all of these energy assets.”

“This behind-the-scenes technical work is having no impact on power supply to households or businesses in North Queensland. Queensland continues to have the energy trifecta: lowest average retail prices on the eastern seaboard, reliable supply and a planned transition to a renewable future,” Lynham added.

It is the fourth such shortfall identified by AEMO, and follows the declaration of a system strength shortfall at Red Cliffs in Victoria in December last year, which AEMO has noted faces more significant stability challenges.

Five Victorian solar farms have been ordered to cut their output by 50 per cent, with other projects in the region facing commissioning delays, due to the system strength issues in the region.

Such grid connection issues have emerged as one of the most significant barriers to new investment in wind and solar projects in some parts of Australia.

A survey of clean energy business leaders undertaken by the Clean Energy Council found that difficulties in connecting projects to the grid, causing delays and curtailments to projects, was one of the biggest concerns facing project developers.

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