What Happens to Unused Electricity in Distribution Transformers?

[anorlunda]

The system has a vast 'smoothing capacity' hanging on it, in the form of all the other consumers.

You can monitor the net effects of smoothing (including voltage effects) and if the ability of power plants to respond in your own home. Just sample and display frequency.

If you don't want to do it at home, there are Web sites that let you do it. I'll bet that Jim could find such a site for us.

I'll give you a magic number 1/8. Take the instantaneous unbalance between grid generation and load (including any effects of voltage), multiply by 1/8 and you get rate of change of frequency. Express power as percent of the total capacity (not current load but rated capacity) of all generators on the grid. Expressed frequency as percent.

Suppose we had a grid with 100GW of capacity online and a base frequency of 50 hertz, then an unbalance of 1GW will cause 1/8 %/second or 1/16 hertz /second rate of change of frequency.

Working backward, watching frequency in real time, differentiate and multiply by 8 and you can observe the real time unbalance in the grid. You should see that typical unbalance is on the order of .005% on a big grid.

On small grids, such as on a self sufficient island, it is much worse. I vacationed once on Grand Canary, and I could hear the refrigerator motor speed changing up and down.

Sophie, is the UK synchronized to Europe?

Watch frequency long enough an you will see a major event like a 1GW plant tripping. Correlate that with news reports, and you can learn which plant tripped.

p.s. The magic number 8 has to do with the inertia of turbine-generators.

 

[sophiecentaur]

Sophie, is the UK synchronized to Europe?

I can answer that one. No. We have a HV DC link with France. I think, in UK, we import more than we export, but I could be wrong.
UK doesn't count as a "self sufficient island" with those sorts of problems. haha

 

[Jeff Rosenbury]

Who's who in European grids.

The UK is connected to Ireland. Parts of North Africa are connected to Europe.

 

[jim hardy]

I'll bet that Jim could find such a site for us.

Here's one, it's part of that fnet link from post #26
i have never watched it before , at first glance it looks a little crude.
http://powerit.utk.edu/worldmap/

The US one i enjoy and watch often.
http://fnetpublic.utk.edu/anglecontour.html

here's their homepage i'll look tonight for more links..
http://powerit.utk.edu/fnet.html

Surely some European universities are doing the same thing.

 

[anorlunda]

Thanks Jim.

I found this video on one of the links you gave. It animates a mega frequency event. Cool.

 

[sophiecentaur]

This made me think. The KE of the rotors can be expressed as a source of instantaneous power, to deal with the changes in load. That could tell you what sort of frequency change to expect before the fuel supply adjustment has time to chase the load change. Or you could work backwards, perhaps.
About 50 years ago, I remember, at a steam rally (traction engines and static ), the commentator referred to the 'instantaneous power' available from the flywheel of a steam ploughing engine. It struck me, at the time as a bit 'vague' but he reckoned he knew what he meant.

 

[jim hardy]

The KE of the rotors can be expressed as a source of instantaneous power, to deal with the changes in load. That could tell you w

That number is a basic machine constant , it enters into Anorlunda's system stability calculations..
Recall from Anorlunda that angular displacement down a wire determines power flow
so we have rotating inertia of a machine coupled by the electrical analogy of a torsional spring to an electrically immovable object(called infinite bus)via the grid...
That rotating inertia through the torsional spring against the grid is a spring-mass system capable of harmonic motion .
A typical natural frequency for it is 1 hz. It's fairly well damped by amortisseur windings on the generator.

The motors in your airconditioner and fridge also have rotating inertia.
So the grid looks stationary, its wires and poles don't move but to me it is a very dynamic living thing. Every wire is transmitting energy in some direction just as if it were a spinning driveshaft on bearings.

Power side of EE is far from boring .

 

[jim hardy]

I found this video on one of the links you gave. It animates a mega frequency event. Cool.

Wow i didnt know about those.

My friends told me about this one. A line near Miami got switched out by accidental relay actuation during maintenance

you can see the adjacent regions speed up when Miami quit accepting power from them
and the transient went clear up to the Great Lakes.We had no such instrumentation in my day - somebody from each plant took our charts to the main office where system guys compared them by hand and magnifying glass.

Cool !

 

[johnbbahm]

There are some economic activities that thrive on cheap power. Making aluminum is an example. I could easily foresee industrial plants designed to take up the slack.

Another option is energy storage. There are several competing technologies being developed, plus some old fashioned hydo projects. Pump the water uphill when power is cheap and generate peaking power when it's expensive. Still, none of these solutions are inexpensive or likely to get that way soon.

I was thinking about refineries using the surplus to make fuel from water, and atmospheric CO2.
Once the energy is stored as fuel, it has a long and very practicable shelve life.

 

[sophiecentaur]

I was thinking about refineries using the surplus to make fuel from water, and atmospheric CO2.
Once the energy is stored as fuel, it has a long and very practicable shelve life.

On the face of it, it sounds like a good idea. What is the conversion efficiency, I wonder?

 

[johnbbahm]

From what I can tell, Audi say about 70%,
http://news.nationalgeographic.com/energy/2015/04/150428-audi-ediesel-made-from-water-air/
"Audi says the efficiency of the overall process is “very high”—about 70 percent"
I think the best and the brightest petroleum engineers might be able to make additional improvements.
From what i have read, the process is very similar Olefin processing.

 

[anorlunda]

From what I can tell, Audi say about 70%,
http://news.nationalgeographic.com/energy/2015/04/150428-audi-ediesel-made-from-water-air/
"Audi says the efficiency of the overall process is “very high”—about 70 percent"
I think the best and the brightest petroleum engineers might be able to make additional improvements.
From what i have read, the process is very similar Olefin processing.

That is what they claim, but color me skeptical. If that was true then they have the solution to climate change. Just run that process with non carbon electricity and remove all excess CO2 from the atmosphere. I don't believe it.

 

[johnbbahm]

The Naval research labs are looking at the same process to make jet fuel for aircraft carriers.
http://www.nrl.navy.mil/media/news-releases/2012/fueling-the-fleet-navy-looks-to-the-seas
I think they hit a snag about the fuel was not flight certified.
Then they were saying 60%.
I think it would be a good way to store surplus alternative energy.

 

[sophiecentaur]

I think it would be a good way to store surplus alternative energy.

If it could be done on a small scale (shoebox size) then it could be an addition to the Hybrid Vehicle.
[Edit - actually that's a bit daft, isn't it? Except for regen braking. Change that to 'in the home' and it could make sense.]

 

[johnbbahm]

One of the first articles I saw on this, was from Germany,
they were thinking of an outdoor air conditioner size unit,
to convert summer surplus photovoltaic electricity to natural gas, for winter heating.
The gas would be stored in the
natural gas grid. The is not really a price performer at the current price of natural gas.
At roughly 55 Kwh per gallon of gasoline, I am thinking it is something that needs a bigger scale.