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South Australia statewide electricity blackout. 10

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"With synthetic inertia, I guess it pulls power from the system to motor the turbine if the system is accelerating?" Yup, regen as it is known in the electric car game.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
With the recent decision by one of the US grids to no longer keep the grid speed to keep clocks accurate, the exact average speed is no longer true. If you want an accurate clock you need to purchase an atomic clock.
So what we will have in the US is a ball park speed.

I can't speak as to what the other two grids are doing for speed stability.

Machine inertia can provide close to fault current levels of energy into the grid, where inverters are self limited to some level the semiconductors can handle. The issue is the machines are braced for the higher levels of energy for a short duration. But inverter inertia could potentially provide energy for a longer time into a larger system event, but only if there is a source behind it.
 
GregLocock said:
No, the issue is that the output of the inverters is locked (in ways I do not know) to the clock frequency of the transmission line, and, obviously, its voltage is greater. So for example my on-grid inverter tracks the clock frequency of the local line, but does not attempt to drive it. It pumps electricity in by delivering a higher voltage than the transmission line.
Click to expand...
This only works for a DC transmission line. And with a DC line, clock frequency is meaningless.
Inverters imply AC.
Raising the voltage will cause a reactive current to circulate but will not transfer power.
To transfer power, the inverter frequency must be a fraction of a cycle ahead of the grid frequency. That is why a grid reference is needed.
Consider a diesel generator. When the generator is synchronised, the output wave will be in step or almost in step with the grid and little or no power is transferred to the grid. As the throttle is opened the sine wave of the generator pulls a little ahead of the grid sine wave. Still the same frequency but a few degrees out of sync.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
I see what you are saying but on sunny days my neighboring suburb sees 270V on a 240v service because every man and his dog has on-grid pvs.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
On the inertia via electronics thing, I've just read that in the USA generators that can provide grid frequency stabilization are paid extra (good), and that 38% of that capacity is from batteries. So despite what some people above have claimed there is no problem with using electronically commutated supplies for grid stabilisation, at least up to 38%.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
That 38% from batteries makes no sense at all. There's no large scale battery storage systems on that scale. We're pondering systems that might get to 2 or 3% but nothing firm. I'm not aware of other utilities doing so either.
 
If one were to look at the ringing on a power system event recovery, the batteries would help in the longer term stability. But I have my doubts in the shorter term stability. I think you need some ratating mass for that. And maybe that's the point of having both, to shorten the ringing time.

I also agree that 38% battery sounds high.
38% of 1.5 TW= 570 MW (Hr) battery?

I don't know about being paid extra, but each company is required to have some amount of spinning reserve, and hot standby. Wind and solar can't do that. But energy storage can if it is big enough.

The key is more likely the ramp rates of each unit, or combined ramp rates of several units.
 
cranky,

Over here the CCGT generators are paid for 'ancillary services' other than simple generation. Gas turbines can respond more rapidly to changing system conditions than steam turbine stations which need time to increase boiler firing rate, and one of the ancillary services provided by the GT's is frequency correction, whereby the turbine governor becomes more aggressive in response and the firing limit of the engine is raised above the normal operating limit, thus allowing the engine to be over-fired in a bid to prop up a falling grid. It eats up hot parts life at a disturbing rate and understandably the machine owners want to be financially compensated for the loss of engine life before the machine has to be rebuilt.
 
No 38% of the frequency stabilisation is provided by batteries. Not 38% of capacity. Ah, found it, I was wrong, it says 38% of PJM(the largest comptitive electricity market in the world)'s frequency regulation is from non traditional capacity (flywheels batteries etc). Not the USA as a whole.

Here's a company that is doing what i proposed


and here's why




Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
from the BBC,

"An Australian state will install the world's largest lithium ion battery in a "historic" deal with electric car firm Tesla and energy company Neoen.

The battery will protect South Australia from the kind of energy crisis which famously blacked out the state, Premier Jay Weatherill said.

Tesla boss Elon Musk confirmed a much-publicised promise to build it within 100 days, or do it for free.

The 100-megawatt (129 megawatt hour) battery should be ready this year.

"There is certainly some risk, because this will be largest battery installation in the world by a significant margin," Mr Musk said in Adelaide on Friday."

Link:
 
Typical predicted shortfall in supply is 300 MW. here for example is what the energy overseer predicts for the next couple of years. You do the maths with a 100 MWh battery

aemo_lzezxd.jpg






Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
Greg... looks like you need three or four of them...

Dik
 
I /think/ that graph is the average power draw over a 24 h period, in which case a 100 MWh battery is not even going to make a dent in the shortfall.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
Isn't the point of the battery just to carry things long enough to get some big generators up and online or as carry thru cuz a cloud passed over a large solar array? In that case you can suck 500MW out of a 100MWhr battery for a short while. The size of the battery just offers the dispatchers more options ranging from do-nothing ride-throughs to crank up a coal plant.

Keith Cress
kcress -
 
That'd be OK if they just had an intermittent power problem, but they actually have a baseload problem, if the wind doesn't blow. Well, as it happens the Dear Leader is renting several truckloads of diesel generators.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
Yes, think of it as a big 'UPS system' which may allow the grid operators to manage a more graceful shutdown and/or isolation of critical infrastructure.

It could also limit the impact of 'brownouts', which those of us living here in SoCal can vividly remember from 2000/2001, when our state's power grid was being manipulated by the illegal actions of Enron, in an attempt to boost the 'cost' of electricity so as to unfairly cash-n on a 'crisis' that they had created:


John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without
 
JohnRBaker:

Funny, that's the way I considered it... Their problem is systemic and I think of this as a tiny bandaid.
 
I think it actually does deal with one specific systemic problem; when generators go down, the latency for the network to compensate for the step change can often lead to even worse cascade failure problems. A battery system could possibly allow the system to transition less abruptly, thereby reducing the risk of catastrophic cascade failures. The US has experienced a few instances where a single failure caused ripple effects over an area 10x the size of the area of the original failure.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
But Al Gore says the lithium ion battery will solve it. She'll be right, mate.
 
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