Wind Farm output in SA constrained, again, by AEMO’s “System Strength” constraint

A quick note today to record the 15:45 dispatch interval in the NEM (so 15:15 Adelaide time) where we see a number of wind farms across South Australia constrained down as a result of the “System Strength” constraint that was imposed during the high wind conditions in winter storms across the state this afternoon.

Here’s a screenshot from ez2viewAustralia v7.3.0 at the time:


Constraint Equations like these arose in the aftermath of the state-wide blackout of 28th September 2016.

About the Author

Paul McArdle
One of three founders of Global-Roam back in 2000, Paul has been CEO of the company since that time. As an author on WattClarity, Paul's focus has been to help make the electricity market more understandable.

7 Comments on "Wind Farm output in SA constrained, again, by AEMO’s “System Strength” constraint"

  1. As I understand it, 4 gas generators are required to be online for Wind to be allowed greater than 1200MW but I believe Osborne is not “counted” as it is only connected to te 66kV network. But it does seem surprising PPCCGT is only classed as one unit for this purpose? I cant find the actual exact requirements for Wind to be allowed greater than 1200MW. Is it documented somewhere?

  2. The next question is what AEMO are doing to update this constraint, given that there are another 3 large wind farms under development. They are supposed to follow processes that involve contestibility, but this appears to be an emergency procedure. Can the new big battery gain accreditation to be part of the “3 generators” rule ? Does it have enough synthetic inertia to count as 2 generators ? Can batteries in the new Riverland Solar Farm be included based on their synthetic inertia as measured at the 275 kV network ?

    AEMO have also been developing plans for a new 275V AC “Horsham link”, but again there doesn’t appear to have been any contestibility of approaches. The existing AC link via Heywood is limited to well below its 1150 MW thermal rating because of frequency issues, so would a better investment be to upgrade it to DC between Tungkillo and Heywood, which could give a capacity of ~1500 MW with wire return or 3000 MW with earth return ?

    • There are currently 440 MW of new wind capacity underway – Hornsdale 3 (109 MW), Lincoln Gap (212 MW) and Willogolecha (119 MW). Perhaps one saving grace of these new ones is they are more exposed to easterlies than many of the older wind farms, so while they will produce during the westerlies of low pressure cells, they will also produce during the easterlies of highs, provided the high pressure cell is centred far enough south (as it normally is during summer).

      • How on earth can thermal possibly plan and predict their costs facing a wind sector varying between 3-85% of installed capacity we typically see here-

        Feast or famine and like Pelican Point they’re supposed to be able to enter into cheaper long term contracts for gas. When they couldn’t possibly offer that to the new gas field developers to defray their investment risk, there were plenty of Asian buyers only too happy to fill the void and leave the locals to the vicissitudes of the spot market. Laughing all the way to the bank now with global gas price rises.

        As if that’s not hard enough, now we have the SA Govt throwing taxpayer funds at a Tesla battery and diesel generators that will ostensibly be creaming the top off any power price peaks further compounding their planning and contractual input dilemma. Never have I seen so much folly with lack of comprehension of the big picture here and the impending disaster.

        There are parallels here with the NBN thought bubble. Utter Groupthink bedazzled by the chimera of ultimate speed and totally oblivious to the elephant in the room with bandwidth/congestion costs and now they’re doing the same again with power despatchability as they’re mesmerised by the lure of ‘free’ power from Gaia. The Devil’s all in the despatchability and he’s about to claim his dues.

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