wind power

[don_resqcapt19]

Here is a link to some HVDC systems that were made by Siemens. They range in capacity from 55 MW to 3100MW. Some are used to match the frequency between two girds, and other are used for long distance high power transmission circuits.

 

[gadfly56]

What's the % loss/mile on the grid?

I can't answer that directly, but I understand that overall transmission losses are about 50%. Sorry, can't remember where I picked that up.

 

[petersonra]

I can't answer that directly, but I understand that overall transmission losses are about 50%. Sorry, can't remember where I picked that up.

I have seen a number like that as well. supposedly a "smart grid" will somehow reduce the losses.

 

[don_resqcapt19]

This document estimates the US transmission and distribution losses at 7.2%.

 

[ohm]

This document estimates the US transmission and distribution losses at 7.2%.

Great article Don.

The composite core low sag lines seem likea good way to double or even tripple their effectiveness without having to beef up the towers. 3M may be a company to watch.

Does DC transmission lines offer a storage (capacitive) effect and get away from the skin effect we see w/ AC?

How important is a "Smart Grid" i.e. GPS, Sat. clocks etc. ?

Is there anything in the works to improve transformer losses and how good are inverters (thyristors).

I think I was misled by the 50% T/D losses number we all heard but couldn't pin down. But it seems that was the split between T & D of the 7.2% total loss, which seems much more reasonable.

 

[charlie]

. . . I know Charlie E another Mod can if he picks up on this. . .

I have intentionally stayed out of this discussion. I am not an engineer, have never worked in relaying, substation design, or transmission line design. My expertise is in distribution and codes and standards. I am familiar with some of the things you guys have talked about but don't have the basic knowledge to enter the conversation. This is an interesting conversation though, especially about the Texas interconnection. It is interesting to me that Texas has a treaty with the US that permits it to secede from the union and it may also divide itself into either 3 or 5 states with all of the rights of a state. :smile:

 

[Cold Fusion]

It really doesn't matter. There are 3 interconnect grids in the US and any load or generation change within a grid has an effect on the grid frequency. As you get a larger distance away from the point of the frequency disturbance, the magnitude of the disturbance is dampened.

don -
Would "phase" or "phase differential" be a better description than "frequency"?

I'm thinking that if the the phase angle is off far enough to be a frequency disturbance, then one of the generators is exceeding a 90deg power angle and is slipping a pole.

Maybe it is just a semantics issue. But the idea of a frequency "disturbance" for two gens tied together - brings to mind the poles of one gen going by the poles of other --- ouch!

cf

 

[Cold Fusion]

---A converter to get from AC to DC then an inverter, possibly mains commutated, to get it back to AC.
Not quite sure I see the point for the sort powers at grid interconnector level though, unless you are going to take advantage HVDC transmission. ---

As I recall (400 level class in transmission - 23 years ago - recollection could be a bit fuzzy) short DC links are put in for stability reasons. The two examples we worked were James Bay Hydro AC transmission to a back to back, DC link at Niagra Falls; and a 30 mile (kilometer?) under water, DC link to Goat Island, Norway. These two DC links were put in to prevent stability problems associated with AC links.

carl

 

[don_resqcapt19]

don -
Would "phase" or "phase differential" be a better description than "frequency"?

I'm thinking that if the the phase angle is off far enough to be a frequency disturbance, then one of the generators is exceeding a 90deg power angle and is slipping a pole.

Maybe it is just a semantics issue. But the idea of a frequency "disturbance" for two gens tied together - brings to mind the poles of one gen going by the poles of other --- ouch!

cf

The amount of frequency deviation is small. I think that the protective relaying starts tripping generators and circuits off line with a deviation of 0.2 hertz or so. When there is a large load change or generation change, the frequency of the grid in that area changes. As that change ripples across the grid it is dampened. It is my understanding that even though everything in a grid is physically connected together the frequency is not exactly the same across the whole interconnect. Not really sure how this works.
I guess we need a transmission engineer to help us out with this. My information is only from things I have read. It is a subject that I am interested in, but I am not an engineer and don't really understand all I have read about how the grid works.
There are not too many people that really do. A EE with a PhD that has worked on the US grid for the last 40 years stated the following on another forum..."there are less than 100 people that really understand how the power grid functions, and I am not one of those people. It has been said that the power transmission and distribution sytem is the most complicated machine that has ever been built.

 

[dereckbc]

Texas has a treaty with the US that permits it to secede from the union and it may also divide itself into either 3 or 5 states with all of the rights of a state. :smile:

Not entirely true.
http://www.texassecede.com/faq.htm
However there is nothing to prevent Texas from secedeing, all it takes is a vote of the people of TX. There are several organazations in th estate pushing hard since the new administration took office and it is gaining traction.

 

[McGowdog]

as a "little brother" myself, I would like to say that is a term I think all of us "younger brother's" resent.


I prefer "the more handsome brother".

or "the taller brother".

or "the one who didn't have to endure the first-born overprotectiveness of mommy and daddy, and by the time I reached 16, curfews were a thing of the past".

That's it! One of my "older" and "bigger" brothers calls me his "little" brother. Now he goes about 305 and he DID have the lap-band proceedure, but he stands about 5'10". I'm the only one in the family (youngest of 4 bros) who is 6'0". I thought my dad was taller, but either he shrunk or I got taller. I like that. I'm the taller brother; and I concur with the curfew thing.

What about a tower, like I saw on the History Channel, that captures the collected sun rays from mirrors... and a wind tower? Both, but with a nuclear energy backup? The wind and solar novelties could be good visual for the Greenies, and the nuclear could do the grunt work!

 

[Besoeker]

Here is a link to some HVDC systems that were made by Siemens. They range in capacity from 55 MW to 3100MW. Some are used to match the frequency between two girds, and other are used for long distance high power transmission circuits.

Interesting link. I didn't know that asynchronous gereration existed for major power generation in USA, or anywhere for that matter.
I can now see why back to back ac-dc-ac systems would be required for applications other than long distance transmission.

And it maybe explains why there is such a long delivery on LASCR's.....