First blackout of the wind power heavy system

GreatApe

https://www.drax.com/energy-policy/need-whole-country-frequency/

Written two years ago but explans the problem well

1. Coal and gas power stations have inertia which dampen frequency changes

2. They can respond within about 1 second (drax says their coal units within half a second) to increase or decrease output

3. Wind and solar don't have inertia not useable inertia

4. As wind and solar go up the need for more synthetic inertia and frequency control gets more important

JKenH

Martyn1981 wrote: »

Just for fun, before the government decided to kill off domestic PV subsidies of 4p/kWh this year, they had originally expected them to be 20.7p/kWh, and there's more, that's in 2011 monies, and we don't want to sell you just that, let's throw in the fact they were then 25 not 20 yrs, so roughly 4p v's an expected 32p (not exact, but I think a close guess).

Nobody, certainly not me, expected RE costs to fall so fast.

How much have domestic PV prices fallen since 2011, assuming they are about £1000 per kwp now? Not as fast as the FiT?

mmmmikey

GreatApe wrote: »

https://www.drax.com/energy-policy/need-whole-country-frequency/

Written two years ago but explans the problem well

Yes, well worth a read, and also worth following the various embeded links. This article explains what they've done in Quebec to mitigate the issue, I wonder if we'll end up doing much the same in the UK?

https://spectrum.ieee.org/energywise/energy/renewables/can-synthetic-inertia-stabilize-power-grids

zeupater

mmmmikey wrote: »

Yes, well worth a read, and also worth following the various embeded links. This article explains what they've done in Quebec to mitigate the issue, I wonder if we'll end up doing much the same in the UK?

https://spectrum.ieee.org/energywise/energy/renewables/can-synthetic-inertia-stabilize-power-grids

Hi

... but doesn't that effectively say that the IEEE would deem that a collection of large wind turbines acting together actually has a level of rotational inertia which would collectively equate to that of a conventional power station and that this inertia can be tapped to help maintain frequency when there's an outage elsewhere, the effect of which had already been established after analysing an example of this happening?! ...

... maybe, after reading that, the future doesn't seem quite as bleak as we're sometimes led to believe ... Kinetic energy, momentum and rotational inertia in spinning mass, who'd have thought it, isn't science wonderful! ....

HTH
Z

Martyn1981

JKenH wrote: »

How much have domestic PV prices fallen since 2011, assuming they are about £1000 per kwp now? Not as fast as the FiT?

No not as fast as you say, but 4p(ish) was at least helpful, I'd suggest 7p would have kept install rates high*. But we shouldn't compare prices directly to the FiT as there are also other income streams, the leccy savings and the export payments. For simplicity if they provided 50% of the income, then a 50% drop in PV install costs would warrant a 100% drop in the FiT IYSWIM.

*When the government cut the FiT right down to about 5p, they also set maximum quarterly install limits, which were very low.

The difficulty is in deciding what level of subsidy (for anything) is fair and reasonable. To promote a product, no subsidy is really needed, but to promote a desired change such as a shift to RE, and away from FF's and to meet targets, even international fines, then it all gets a bit more complicated.

Also, where does the money go. Should we pay subsidies to households and small businesses, out of levies on households and small businesses, or give it all to China and France as the principal investors in HPC? What about jobs, such as the UK's solar industry, etc etc.. It all gets too complex.

mmmmikey

zeupater wrote: »

Hi

... but doesn't that effectively say that the IEEE would deem that a collection of large wind turbines acting together actually has a level of rotational inertia which would collectively equate to that of a conventional power station and that this inertia can be tapped to help maintain frequency when there's an outage elsewhere, the effect of which had already been established after analysing an example of this happening?! ...

... maybe, after reading that, the future doesn't seem quite as bleak as we're sometimes led to believe ... Kinetic energy, momentum and rotational inertia in spinning mass, who'd have thought it, isn't science wonderful! ....

HTH
Z

I don't think that's quite what it says. My understanding is that the inertia described here is synthetic - i.e. additonal software, controls and other engineering are making the wind turbines generate power in a manner in which they exhibit an inertia like effect and seem to behave like conventional gas / coal turbines. The point being that the industry regulator had to legislate to ensure that the wind installations are designed like this, because otherwise there is a potential problem (which may or may not be part of the issue we had last week).

"In 2005 the utility amended its grid code, requiring wind farms to pull their weight: it mandated that new wind turbines be capable of delivering a power boost equal to 6 percent of their rated capacity during low-frequency events. Manufacturers responded with synthetic inertia designs, and the first were installed in 2011."

I definitely agree that the future is rosy as far as wind power is concerned, but only if we avoid complacency and make sure that as we scale up we recognise the additional challenges that creates and reflect those challenges in the design.

zeupater

mmmmikey wrote: »

I don't think that's quite what it says. My understanding is that the inertia described here is synthetic - i.e. additonal software, controls and other engineering are making the wind turbines generate power in a manner in which they exhibit an inertia like effect and seem to behave like conventional gas / coal turbines. The point being that the industry regulator had to legislate to ensure that the wind installations are designed like this, because otherwise there is a potential problem (which may or may not be part of the issue we had last week).

"In 2005 the utility amended its grid code, requiring wind farms to pull their weight: it mandated that new wind turbines be capable of delivering a power boost equal to 6 percent of their rated capacity during low-frequency events. Manufacturers responded with synthetic inertia designs, and the first were installed in 2011."

I definitely agree that the future is rosy as far as wind power is concerned, but only if we avoid complacency and make sure that as we scale up we recognise the additional challenges that creates and reflect those challenges in the design.

Hi

What I read in the article which seemed to address the issue was ...

To emulate the inertial behavior of massive rotating equipment, a renewable generator must somehow find extra power quick. Qu!bec's wind turbines do so through a collaboration between the turbines' solid-state power electronics and their moving parts. "When the wind turbines see an imbalance between load and generation that causes a frequency deviation on the system they’re able to … extract some kinetic energy that is stored in the rotating masses of the wind turbines,”

... looks pretty relevant, but then again, those turbines may be old & the latest ones being installed nowadays may be less advanced ... ... in which case lessons will be learned!

HTH
Z

mmmmikey

zeupater wrote: »

... looks pretty relevant, but then again, those turbines may be old & the latest ones being installed nowadays may be less advanced ...

Whoops, thanks, yes, I've realised that the inference that we have the "older non-syntehtic inertia" type in the UK was in another article, not the one I linked to, my mistake. It will be interesting to see what the Ofgem report has to say.

I know from the news that National Grid are submitting their initial report to Ofgem today - do you know if that report will hit the public domain or will we have to wait for the Ofgem report?


Thanks, Mike

Martyn1981

mmmmikey wrote: »

"In 2005 the utility amended its grid code, requiring wind farms to pull their weight: it mandated that new wind turbines be capable of delivering a power boost equal to 6 percent of their rated capacity during low-frequency events. Manufacturers responded with synthetic inertia designs, and the first were installed in 2011."

Only pondering out loud, but the 2005-2011 WT's will be much smaller than the monsters we now have, so I assume greater rotational inertia per WT, though of course less WT's.

Also, I think (and by I think, I mean scratching the bottom of my memory) but WT's performance can be altered by choosing the size of the generator. So a smaller unit, will give a higher capacity factor*, at the price perhaps of a bit less annual generation, but would (here's the guess part) also improve rotational inertia for that generator, though again with the caveat that it will be a slightly smaller generator.

*Same base design, only the rating changes, say from 9MW to 8.5MW, perhaps for that higher cf, or because the location has more variable winds, and there's a need to 'mine' the lower wind speeds etc etc..

mmmmikey

Martyn1981 wrote: »

Only pondering out loud, but the 2005-2011 WT's will be much smaller than the monsters we now have, so I assume greater rotational inertia per WT, though of course less WT's.

Again, scratching my head and remebering back to O-Level physics ( which was some time ago now ) then I think the speed of rotation is more siginificant than the mass here - i.e. gas generators spin at 3000 rpm whereas wind turbines turn at a fraction of that speed.


Edit: so shouldn't we be discussing momentum as well as inertia? One for the scientists.....