The South Australian Black Out: A Grid On The Edge

  • Date: 30/09/16
  • Jo Nova

Australians are going to be talking about this for weeks. Indeed, the SA Blackout is the stuff of legend.

South Australia, Electricity, Wind Supplies,Graph.  Blackout Sept 29. 2016.

The Greens are blaming coal (what else?) for causing bad storms and blackouts. Forget that Queensland gets hit with cyclones all the time and the whole state grid doesn’t break. Some greenies are also raging against “the politicization” of the storms. Yes, Indeedy. Go tell that to Will Steffen.

We are not being told the whole story. We do know that South Australia has the highest emphasis on renewables in the world. It also has a fragile electricity network, and wild price spikes to boot. (Coincidence?) The death of a few transmission towers should not knock out a whole state, nor should it take so long to recover from. The storm struck worst north of Adelaide near Port Augusta but the juicy interconnector from Victoria runs in from the south, and goes right up past Adelaide and most of the population. Why couldn’t the broken parts of the system be isolated?

Digging around I find ominous warnings that while the lightning and winds probably caused the blackout, the state of the South Australian grid appeared to be teetering on the brink, without enough reserve, or without well planned protection mechanisms to cope with an inherently unstable system.  The excess of wind power made the system more fragile, and also made it harder to restore. There appear to be three reasons (at least) that excessive wind power is less fun, more costly, and golly, but if windmills don’t stop storms, why buy those expensive electrons?

1. Wind power adds instability of the system – not only does it ramp up and down frequently on an hourly scale, but it’s harder to mesh at the cycles per second scale too. This is about maintaining the “frequency” of the system (in Australia’s case thats 50Hz). Windpower is a type of energy that doesn’t easily synchronize with the 50Hz frequency (or any stable frequency). Other generators that have turbines that spin at regular speeds do (coal, gas, biomass, and hydro). They are easy to synchronize.

The frequency thing is critical — think of AC — Alternating Current — as being a push-pull of electrons 50 times a second. If any source of electricity joins the grid out of phase or at any other frequency, like say 49*, the waves of electrons are going to get out of synch fairly quickly. And we’d get horrible interference patterns of spikes and dips. This is a point where systems have to shut down (in seconds) to protect everything. This is an intrinsic design vulnerability in a system which prioritizes renewables over “thermal” energy.

*UPDATE: Thanks to Tomomason and Analytik and some great comments below, I now know that the frequency varies a little as load and supply ebb from 49.85 – 50.15 (See also the subthread by co2isnotevil at #5). These tiny variations are used as feedback for plant operators to adjust their operation. Read both subthreads for more information. This is why the whole grid is so much more stable with a dominant supply from synchronousturbines (ie thermal, biomass or hydro).

2. Wind power can’t be used to reboot the system and SA was getting warnings about that too.

Commenter Andrew W at WattClarity:

“ the ElectraNet boss on radio this morning mentioned that wind generated electricity cannot be used for ‘black start’ processes, that they need to get full control of load and frequency before introducing wind..

To do a Black Start (cranking up the whole grid from nothing) we need hydro, or thermal, but wind power is not much use. InDaily reports that not only is wind not much use, but that SA electricity wasn’t prepared with extra fuel at the gas generators. (It’s amazing they got things running again at all really!)

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