US Grid Resistance/ Inductances

Hi

To evaluate a challenge of a new design we need to know the US grid resistance and inductance, highs and lows for both, for 3 phase systems

Where I live in Denmark, I can call up the power company and get the information (not always the inductance), but where can I find the information for the US grid system?

Regards

Klaus

Reply to
Klaus Kragelund
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Hey Klaus:

I don't know where to look specifically, but if you don't get a better answer here then Google on standards for off-grid solar power inverters.

If you don't get a good answer at all in a few days then send me an email (tim at Wescott design dot com) -- I have done consulting in the past with a startup that was doing solar power inverters, and I can probably hook you up with at least one of the guys who were responsible for hooking things up. I don't know your answer, but they probably do.

The latest IEEE Spectrum magazine has an interesting article on using individual "consumer" inverters to help regulate the grid -- apparently it's already happening over on your side of the pond, and California is starting to formulate regulations for it over here.

--
Tim Wescott 
Wescott Design Services 
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Reply to
Tim Wescott

Probably also via the power companies, the departments that handle interconnect requests.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Thank you for the hints and the offer, I appreciate it

Will return if nothing pops up

Cheers

Klaus

Reply to
Klaus Kragelund

"The grid" in the US is managed by ten regional organizations - there is a list here:

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They might be able to tell you, or tell you who to ask.

Also, "the grid" in the continental US has three interconnected areas - eastern, western, and Texas. There are DC links between these three areas. I don't *know*, but it wouldn't surprise me if the values are a bit different for those three areas. There is a map and more information at

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.

Matt Roberds

Reply to
mroberds

For what kind / scale of connection? What I'm familiar with is, for 480V

3ph systems, you have impedance in terms of short circuit current, so that your facility and equipment must use fuses capable of clearing 100kA or less, or 200kA, or even more. The impedance is largely determined by how big a transformer you have at the "drop", and somewhat by the HV wiring to the site. HV should usually be a small part, as there will be other customers on a given run (usually) and the resistance must be low enough to supply them as well.

I think inductive reactance is something like 10% of the resistance, pretty low at line frequency.

For low voltages, my experience is that 240V (semi- to non-industrial) is rarely over 10kA fault (again, depends on transformers, wiring and facilities), and residential 120V, under 2kA.

As for specifics, you'd have to ask someone else... as others have said, power co. is probably as good as any..?

Tim

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Seven Transistor Labs 
Electrical Engineering Consultation 
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Reply to
Tim Williams

Do you want to know the Thevenin source impedance at the customer interface?

Reply to
Ralph Barone

** That is definitely going to be highly variable from place to place.

While the permitted voltage drop under rated load may be only a few percent, it may also be much less in some cases - hence the massive ratings required for HRC fuses.

... Phil

Reply to
Phil Allison

It's for 3 phase. Often the short circuit current will reveal the resistance and is somewhat easy to find. What we need specifically is the span of the inductance

Thanks for the numbers

I will ask them, they probably have the answers right at hand

Cheers

Klaus

Reply to
Klaus Kragelund

Well, there's no need for thevenin, it's just a resistance and an inductance we need

Cheers

Klaus

Reply to
Klaus Kragelund

In the mean time, over in Holland, this has been proposed already more than 10 years ago, to let a 'swarm' of grid connected solar inverters collectively stabilise grid voltage under fluctuating loads/insolation.

At a small Netherlands Energy Research Foundation.

joe

Reply to
joe hey

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