Australia’s most powerful battery still seeking answers for transformer failure, to be offline for maintenance

The owners of the Waratah Super Battery say they are still seeking answers for the dramatic failure of its transformers last month, and have announced that the country’s most powerful battery will be offline for scheduled maintenance from late November.

The scheduled maintenance from November 20 to December 2 means that the battery will not be able to provide its contracted service as a giant “shock absorber” to the grid, which it is currently providing on an interim basis at half capacity.

It had hoped to reach full capacity in late October, but experienced what it described internally as a “catastrophic failure” in one of its transformers just four hours away from the completion of hold point 5 testing – the last hurdle before full commissioning.

The 850 MW, 1680 MWh Waratah battery is the most powerful battery in Australia, and likely the world, and is the biggest machine to be connected to the Australian grid.

Its primary role, under a 5.5 year contract, is to act as a “shock absorber” to the grid, essentially staying on standby to allow the big transmission lines feeding the state’s biggest cities and load centres to operate at greater capacity. This was deemed essential to support the closure of the state’s ageing coal fired power stations.

But early on Saturday, October 18, Akaysha says one of its three High Voltage Transformers (HVT3) failed, and a second was de-energised as a precaution for safety assessments.

“Throughout the incident and since, despite the loss of one transformer (HVT3) and the de-energising of another transformer (HVT2), the Waratah Super Battery has maintained its System Integrity Protection Scheme (SIPS) service requirements of 350MW, the interim commercial operating capacity, securely with its first transformer (HVT1),” it said in its latest statement.

“The battery continues to operate with available capacity of 350MW, and there has been no impact to the NSW electricity grid.”

It says the two affected transformers are undergoing detailed engineering assessments and investigations as part of the Root Cause Analysis. It says this is a complex, multi-stage process involving physical inspection, testing and analysis, which could take weeks or months before an answer is found.

• AEMO’s market forecasts currently register the Waratah battery as having “zero” capacity, a source of curiousity for market watchers in the days before the transformer failure was finally revealed through the leak of internal memos.

Akaysha says this reflects the fact that Waratah’s current operating capacity is fully committed to the interim “shock absorber” contract, officially known as the System Integrity Protection Scheme (SIPS).

Under its original plan, Akaysha supersized its battery beyond the parameters of the SIPS contract to allow more capacity to trade the market. That part of its revenue stream will have to wait until it reaches full capacity.

Akaysha says the upcoming shutdown is part of routine maintenance and has been coordinated with AEMO and Transgrid for several months. “During this time, the SIPS service will be unavailable, which was always anticipated by Transgrid, AEMO and EnergyCo,” it said in a statement.

Akaysha is expected to suffer from lost revenues because of the delay in reaching full capacity. An earlier advice of delays – mostly due to bad weather – was flagged in March, and the latest delay will push the final completion back at least six months.

Transgrid, which is responsible for the delivery of the service, has already asked for adjustments to the revenues paid for the service. The scale of these payments – indeed of any payments related to the battery itself – have not been revealed because they are deemed commercially sensitive.

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