Wind output curtailed again in South Australia | RenewEconomy

Wind output curtailed again in South Australia

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Wind output in South Australia was heavily constrained again over the weekend because not enough gas generators were online.

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Wind output in South Australia has been curtailed for the third time in a month due to new rules imposed by the Australian Energy Market Operator, which restricts wind output to a maximum 12000MW unless four gas units are operating in the state.

Over the weekend, strong winds in southern states pushed wind generation very near to full capacity, but the withdrawal of one gas fired generator early on Sunday morning meant that wind out had to scaled back by more than one fifth.

curtail graph copy

The new rules from the AEMO allow for wind to go up to 1200MW without restriction if three gas units are operating, and beyond 1200MW if four are offline.

According to Dylan McConnell, from the Climate and Energy College in Melbourne, even with this constraint,
wind power still managed to provide 72 per cent of South Australia’s grid-based electricity consumption on Saturday.

AEMO also invoked constraints on the interconnector between Victoria and South Australia on Friday night, limiting the export limit to 250MW as a precaution to deal with extreme wind conditions that had been forecast, and the impacts that could have had on local network infrastructure.

The constraints on wind were first invoked earlier in July, the first time it had been imposed since a rule change made with little fanfare in December.

The move is regarded as overly conservative, but given the controversy over recent blackouts and load-shedding, although not the fault of renewables, AEMO is keen to play safe.

Industry participants assume that the rule will be relaxed once AEMO becomes more comfortable with alternatives, such as battery storage, frequency control from wind farms, and demand management.

One of the biggest impacts of the rules is that electricity prices will not fall far as they usually do in high wind conditions because of the need to have three or four gas generators switched on. Gas generators, which are expensive to run, set the marginal price of electricity in the market.

On Saturday, despite wind power providing nearly three quarters of grid demand, the average price for the day was more than $90/MWh – the price set by gas generators.

The wind farms most impacted by the curtailment were once again Waterloo and North Brown Hill, but it also seems that units of Snowtown and Hornsdale wind farms were also affected.



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  1. Peter F 3 years ago

    Looks like more batteries are going to be ordered quite soon either that or a group owned pumped hydro system.

    Where can we find daily and weekly flows on the interconnectors

    • Chris Schneider 3 years ago

      1414Degrees is looking like the solution here! AEMO has the data but only live of interconnect.

    • eljeiffel 3 years ago

      Here is VIC1-SA1 (Heywood I/C) for the last week ..

      You can find all NEM I/C’s from there for various reporting periods.

      • Malcolm M 3 years ago

        That’s a huge temporal variation in the inter-connector limit, which has to be managed on both sides of the inter-connector. The case AEMO put prior to the upgrade was for 680 MW in both directions, but it seems there are other constraints that were not envisaged. Why didn’t experienced electrical engineers foresee these other constraints ? What further investments can remove these constraints ? AEMO’s report on the Victorian network development shows a shows a thermal limit on the inter-connector of 1150 MW. Would more batteries unlock more of this capacity at a lower cost than a new inter-connector?

        • solarguy 3 years ago

          I would guess yes.

  2. Jo 3 years ago

    Great news for the wind farm operators. They have a windfall! (pun intended)

  3. Rod 3 years ago

    And then at 13:00 SA time Monday the interconnector had a wobble and this happened.
    Sorry for the format but that is negative $1000 and $14000 for Raise and lower reg (which I assume is frequency control)
    The AEMO site says these prices may be adjusted!



    Raise Reg

    Lower Reg

  4. Ian Fordham 3 years ago

    Does anyone know what is the actual requirement, there was 3 TIPS ‘B” units online all weekend as well as at least one GT of Pelican Point…. That sounds like 4.

    • Rob 3 years ago

      Can anyone explain the reason for this strange rule regarding gas plants and wind generators?

      • Malcolm M 3 years ago

        How would these requirements change if the Heywood inter-connector were DC ? The DC link to Tasmania doesn’t seem to have these frequency stability problems. It seems to operate at its nominated capacity without all the transient constraints of the Heywood link.

  5. Tom 3 years ago

    I took this screenshot a week ago, in another period of high wind. (I hope it uploads properly).

    For a couple of hours overnight in the early hours of Sat 22nd July, and then for another hour in around noon that day, the wholesale price of electricity in SA dropped to minus $60/MWh.

    I don’t really understand how the wholesale price drops to the negatives (except for 5-minute periods when the first 5-minute period is priced at $14,000/MWh), but it seems that the wind generation plus the compulsory minimum gas generation overwhelmed the state demand plus the interconnector capacity, hence the price trough.

    No wonder the gas generators decide to make themselves unavailable rather than paying customers to take their power.

    But imagine if you were a battery owner trading energy. You would have charged your batteries for nothing (or even been paid to charge them), and then sold your stored energy for $100/MWh or so. If this could happen 4 or 5 times a week you would be very profitable, even at $250/KWh capital costs.

    The more wind power that is installed, and especially if the “Big Battery” forces relaxation of the “minimum 4 gas generators” rule, then the more frequently this ultra-low price pattern will occur, and hence the greater the business case for more and more battery installations will become.

    Critical mass is not far away. Exciting times ahead.

  6. Robert Comerford 3 years ago

    Running gas when wind is producing power; smells like more fossil fuel market protection b/s.

  7. Ken Fabian 3 years ago

    Does that mean the wind generation that was still supplying power got higher prices than otherwise? Overall, did they gain or lose income? It doesn’t seem clear.

    And which wind farms got to stay running and which didn’t – or was the restriction spread across them all?

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