Grid "balanced on a knife edge": AEMO flags more solar delays in Victoria | RenewEconomy

Grid “balanced on a knife edge”: AEMO flags more solar delays in Victoria

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AEMO warns solar project owners that constraints and delays may be long lasting as it seeks a solution to issues “unprecedented in any power system.”

Kiamal solar farm. Waiting in a connections queue.
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The Australian Energy Market Operator has told owners of solar projects in western Victoria that the local grid is “balanced on a knife edge” and has warned of further delays in connection of new solar farms in the region.

Five operating solar farms – four in Victoria and one in NSW – have had their output curtailed by half since mid September after modelling revealed “system strength issues”, and the risk of severe “oscillation” in the event of a major network fault or outage.

The decision to curtail the solar farms has reduced available capacity by around 170MW, costing their owners a combined $1 million a day in lost revenue and depriving the state of a potentially valuable resource as the summer heat sets in.

But the spillover effects have extended elsewhere, with delays to the connection and commissioning of other new solar projects, including the 106MW Yatpool solar project, situated right next door to the Karadoc solar farm, one of the existing solar farms that has been heavily curtailed, and the bigger (256MW  DC) Kiamal solar farm.

In a letter sent last week to solar farm owners and projects developers, and seen by RenewEconomy, AEMO’s head of energy system engineering Christian Schaefer warns that the issues being faced in the region are highly complex and “unique in the world” and he cannot predict when they will be resolved.

One near-term solution resides in changing the tuning of inverters in the solar farms – who all happen to use SMA inverters – but the complexity and the lack of suitable high-speed monitoring equipment in that part of the network, and the difficulty in aligning test windows, is causing delays

“At the time of writing, AEMO is unable to commit to a firm time for forming the tuning solution with the NSP’s (network service providers) and the five solar farms,” Schaefer wrote.

He said further checks and analysis would lead to further investigation and then to possible options for quantifying and “reducing the overall impact of current and future” stability constraints.

“To AEMO’s knowledge, the nature and extent of the issues seen in the West Murray zone and unprecedented in any power system, and we have some of the foremost experts in the world investigating them,” Shaefer wrote. He said the system is “balanced on a knife-edge.”

Finding a solution is likely to be a long, exhausting and costly process.

Moreover, any new projects will have to go through exhaustive “wide area” modelling before connection, and comprehensive guidelines will be published shortly. He said there are about 1,200MW of committed inverter-based projects in the zone, and about 3,000MW in the application phase, plus a growing amount of small-scale solar.

“This means that both higher connection standards and restricted operation are inevitable.”

In AEMO’s Electricity Statement of Opportunities published in August, Yatpool had been expected to be commissioned in November, but that was before the system strength issues were identified in early September. Its owners Bay-Wa could not be reached for comment.

Shaefer’s letter was sent on the same day as AEMO published proposals for a long-term solutions to the problems, a potential new link from NSW and Victoria, and a few days before it declared a “fault shortfall” which could lead to another medium-term solution, the installation of synchronous condensers at various points in the network.

One project that has already installed a large synchronous condenser, Kiamal, was due to be completed this year and would be the state’s largest, but it is not clear exactly what stage the solar project is at, nor if its syncon can assist the other existing solar projects, which include the Karadoc, Bannerton, Wemen and Gannawarra solar farms in Victoria, and the Broken Hill solar farm in NSW.

But Schaefer warned in his letter: “There are physical limits on the amount of system strength remediation that can be achieved by installing more synchronous condensers in the current network.” This means “deeper” connection works will be necessary, and these must be funded by connecting parties.

Even then, there were likely to be thermal constraints and decreasing marginal loss factors as more projects became committed, Schaefer warned. This will be the case until a new link, or upgrade, is approved and delivered – but that could be a decade away, with 2028/29 seen as the earliest possible deliver of a new link.

Solar project developers that RenewEconomy has spoken to say they understand the complexity and the depth of the problem, and appreciate AEMO’s efforts to resolve the issue.

But they do wonder how it came to this; how the system strength issues were only identified many months after most of the solar farms had begun generating. They are also seeking clarity about the future options, particularly in regard to the potential need to re-negotiate or adjust existing generating performance standards (GPS) crucial to their operation.

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  1. Glenn 7 months ago

    Seems like a good place for some big batteries, it should be able to increase there their revenue by more than the ‘$1m a day’ they are losing right now, as they can sell at peak prices.

  2. MrMauricio 7 months ago

    All that poles and wires regulator-approved gold plating!!!What was actually done/prepared for???

    • Peter Farley 7 months ago

      Almost all the poles and wires gold plating was either in the distribution grid or in NSW and Queensland transmission but not interstate connections.

    • Joe 7 months ago

      To improve the bottom line?

  3. Andrew Roydhouse 7 months ago


    More like asleep at the wheel.

    The PV projects did not just appear overnight.

    ‘Foremost experts in the world’ = something straight out of “Yes, Minister”.

    Experts in what Sir Humphrey?

    Well, Minister, in confusing the situation so that the Government does not appear nearly as incompetent as we were Minister.

    I suppose they’re also foremost experts in billing as well?

    “Yes, Minister!”

  4. Malcolm McCaskill 7 months ago

    The wind farms are wilting in the heat. I live near the Macarthur wind farm and there’s been a strong hot northerley wind all day, but it’s only been at a 20-45% capacity factor. The issue has affected all the Vic wind farms, and some have had periods of no output despite good winds and high power prices (40 to 45 degrees, blowing a gale and half-hourly prices up to up to $2500/MWh). Perhaps low-spec wind turbines that turn off beyond a temperature threshold are as much an issue as the ride-through settings found in the South Australian system black. We certainly don’t want more wind farms that switch off at 40 degrees.

  5. Honest Mike 7 months ago

    “balanced on a knife edge”??? blind hope that synchronous condensers, power connection to NSW and inverter tuning will solve the problem???? sounds like the message is not getting through…. energy storage enables renewables. there is a thresh hold at which the percentage of renewable to total power generated becomes counter productive until energy storage is addressed. additional transmission link is only attempting to export SA’s grid instability problems and it sounds like Victoria is attempting to do the same

  6. Peter Farley 7 months ago

    Part of the solution will probably be significant local storage and more storage/demand response at the load end, the cost of the storage etc will mean that these plants will be at a competitive disadvantage.
    A bigger part of the solution will be to build slightly less productive generation near the load and/or near the existing eastern transmission grid. That probably means that not much more capacity will be built in this region no matter how good the sunlight is. When you are planning a mine, one of the first questions you ask is how do we get the product to market, it seems that that question was not investigated thoroughly enough.
    The current situation probably means that someone who could build an energy intensive business in the Mallee could get very cheap power, perhaps another Sundrop Farms or Nectar or perhaps a processing plant for mineral sands

  7. Alexander Hromas 7 months ago

    Unbelievable the guys who run this organisation are paid heaps to be situation aware and yet they could not see this slow train wreck coming its only taken 7 or so years to arrive. Were they asleep at the wheel? Perhaps we should sack the lot and start again.

  8. Glenn 7 months ago

    In other news;

    “Federal government has announced it will underwrite two new gas-fired power stations.
    132-megawatt gas plant in Gatton, in Queensland’s south-east, with another 220-megawatt gas generator project in Dandenong, Victoria”

    theguardian com australia-news/2019/dec/23/morrison-government-to-underwrite-two-new-gas-power-stations

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