There isn't an 'easy way' as such, or not if you want the curve to be meaningful. I have a copy of what is without doubt the best document I've ever read on generator capability curves. It was written over thirty years ago by the CEGB and contains a remarkable level of detail that is rarely if ever discussed in modern texts. Does anyone know of a free file host which will accept a 12MB file? engineering.com seems limited to about 5MB or so.
  

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If we learn from our mistakes I'm getting a great education!
 

Scotty,

Can you post the name or title of the document so we could do a search for it?

rmw

I'm thinking of rapidshare.

Or just zip it into two parts. I wouldn't mind having a copy as well Scotty.

Maj

rmw,

It's a scan of a paper copy I was given by an old friend. It simply ain't out there on the net - I've looked long and hard for the CEGB archives. There are probably hundreds of top quality technical documents lurking in desk drawers and files belonging to retired CEGB engineers throughout the UK which one day will be lost forever because they are only in paper form.

OK, it's on rapidsahre for a while...

http://rapidshare.com/files/285572113/CEGB_Generator_Performance_Chart.pdf.html

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If we learn from our mistakes I'm getting a great education!
 

I could not get it.Can it be sent through e-mail

I got it, took an age to download - perahps try again?

Fantasic document, i will have to dig my old design notes out, our system was a lot simpler (but perhaps not as accurate.  As the documant says, if your concern is the lagging (overexcited) area, then it is quite simple, the leading area is a lot more complex.

Scotty,
I too couldn't download the CEGB document.
'Rapidshare' has restrictions for free upload/downloads. 'Mediafire' is better I think.

jan63:

The CEGB document is very detailed but the contents quite difficult to handle. Fortunately there is a far simpler but still very accurate version for the design of generator performance charts available. This is illustrated on page 20 in "Betriebsverhalten der Synchronmaschine" by Kurt Bonfert, published in 1962 by Springer-Verlag/Germany.

We have to consider two different versions of generator performance charts, one is valid for turbo generators (with cylindrical rotors) and one for salient pole machines (hydro generators). The difference lies in the values of the synchronous reactance. For hydro generators we have a direct axis synchronous reactance xd and a quadrature axis synchronous reactance xq (the xq value is about 60% to 70% of the xd value) whereas for turbo generators both values are about the same (xq = xd).

Let me know in case you have no access to the book mentioned above. I'll then try to draw up for you the two types of charts.

Scotty: Thanks for sharing with us a valuable part of your archive.

Regards

Wolf
WWW.HYDROPOWER-CONSULT.COM  

Tried to download it and got

Quote (RapidShare):

This file is neither allocated to a Premium Account, or a Collector's Account, and can therefore only be downloaded 10 times.

This limit is reached.

To download this file, the uploader either needs to transfer this file into his/her Collector's Account, or upload the file again. The file can later be moved to a Collector's Account. The uploader just needs to click the delete link of the file to get further information.

.
Scotty, I believe you have an email address for me, could you email it?

Wolf - no problem at all. Documents like that deserve to be shared, otherwise what is the point in me saving them from the bin?


David,

On it's way.


Everyone else - I'll try to find a better file host. My ADSL line has very poor uplink speed so I'd appreciate it if any can identify a decent file host as Rapidshare seems to have a few problems. Took forever to upload this morning!
  

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If we learn from our mistakes I'm getting a great education!
 

My home internet connection sucks. Stuggling to email this out to you David but will try again later. Might have another option when I get to work - will find out tomorrow.
  

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If we learn from our mistakes I'm getting a great education!
 

Scotty,
If you can't get it to work let me know. I can put in on our company's FTP server for a while.

Alan
----
"It's always fun to do the impossible." - Walt Disney

To do some heavy lifting for Scotty (thx Scotty), I have uploaded the CEGB file in two parts of about 6 GB each here. You may need to sign up for a free a/c. Lemme know if it worked.

http://www.scribd.com/doc/20296458/CEGB-Generator-Performance-Chart-Pages-1-to-31

http://www.scribd.com/doc/20296596/CEGB-Generator-Performance-Chart-Pages-32-to-63

Muthu
www.edison.co.in

Wolf, any chance you can UPLOAD that Kurt Bonfert's book and post a linky here ? ...

with translation, of course ....

Muthu
www.edison.co.in

Sorry about that all caps. I blame it entirely on the keyboard genie.

Muthu
www.edison.co.in

Edison,

Please tell me you meant 6MB each and you haven't increased the size by 10³.

Thanks to you and to Alan for the offer.
  

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If we learn from our mistakes I'm getting a great education!
 

Scotty, What's a few MB (or GB) between friends ?   

Muthu
www.edison.co.in

I'm hesitant to upload the book (or parts of it) because of copyright reasons. Also, a translation from German to English may be a bit time consuming. If there is enough interest, however, I'll design two example charts (one for hydro, one for turbo) and attach them to a post.

Regards

Wolf
WWW.HYDROPOWER-CONSULT.COM

Hi Wolf,

Yes, I'd be interested in seeing them, especially if you can show the steps in producing them. I know a former colleague who would also be very interested although he's not a member here.
  

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If we learn from our mistakes I'm getting a great education!
 

Thankyou.I have got it.

Operating performance of the synchronous machine and asynchronouse machine.

Betriebsverhalten der Synchronmaschine und Asynchronmaschine

http://www.et5.tu-harburg.de/Lehre/Praktikum/Grundlagen_Praktikum/PDFs/V19.pdf

Hi Scotty:

It will be my pleasure to give you this information. However, due to heavy work load, I've to ask for a little bit of patience.

Regards

Wolf
WWW.HYDROPOWER-CONSULT.COM

 

Hi folks:

Thanks for the patience.

Attached please find a method how to design a turbo generator (cylindrical rotor design) capability chart (Attachment I). It seems that it is not possible to place two attachments to one post. The second attachment will therefore be sent separately.

In case there is an interest, I can work out a capability chart design for a hydro generator (salient pole design) as well.

Best regards

Wolf
WWW.HYDROPOWER-CONSULT.COM

• http://files.engineering.com/getfile.aspx?folder=beb83bb9-1881-4450-b9d7-0c

Folks:

Here is my second attachment.

Regards

Wolf
WWW.HYDROPOWER-CONSULT.COM

• http://files.engineering.com/getfile.aspx?folder=f9551e27-1737-4d40-92f2-e0

Hi everybody, this thread is very interesting.

scotty, do you still have that CEGB document online? I tried the link but I guess the sharepoint is expired.

Wolf39, is the procedure your posted applicable to diesel generators and GTGs as well?

ThePunisher:

The procedure I issued is valid only for synchronous generators with cylindrical rotors. GTGs and fast running Diesel generators are falling into this category. Low speed Diesel generators with higher outputs, however, usually are equipped with salient poles, like hydro generators. To design a performance chart for this type of design is possible but more complicated. It seems that there is very little interest for such chart since there was no reaction expressed in the forum after I posted the other procedure last month.

Regards

Wolf
www.hydropower-consult.com    

So does it mean that I can use the same procedure for diesel generators 1000ekW and less? If you say slow speed, at what RPM are we talking about?

We have a large 3.74MW, 5.5MVA, 0.68 P.F. with a max kVAR = 4.45MVAR, 900RPM, Diesel generator. We have data for generator impendances and time constants. I am hoping you have something that couild help us at least construct this geenrator's capability curve since we are no longer able to contact the manufacturer for no apparent reason from the client.

ThePunisher:

If you read my posts carefully, you will find all the information you've asked for.

Regards

Wolf
www.hydropower-consult.com

Ok, it's back on Rapidshare for a while. Roughly 10MB compressed.

http://rapidshare.com/files/311035705/CEGB_Generator_Performance_Chart.rar.html
  

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If we learn from our mistakes I'm getting a great education!
 

Thanks scotty,

Sure this will be great info! Thanks wolf39 for the curve plot.

wolf39,
 I for one have slow salient pole generators. From what I remember the difference between the files you uploaded (which are great by the way) is that there would be a difference in the underexcitation limit, since it could be running for a while with no (or reverse) excitation. If you have any info I that I would be interested.
Thanks

Hi Wolf,

If I remember my machine theory correctly a salient pole machine typically has a much greater capability to absorb reactive power than a turbo machine. I'd be interested in seeing how you develop a capability chart for a hydro machine, I haven't done much with salient pole machines because of the relative lack of hydro machines in the UK and I'd be interested to learn. Sorry if silence came across as dis-interest.
  

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If we learn from our mistakes I'm getting a great education!
 

...the modern adopted method is there is no under-excited limit on the S-base circle for hydro-gen.  To form the underexcited lower region you set the UEL limits with a margin to coordinate around the LOE-40 relay.

The underexcited zone becomes a question of bus voltage stability during the cap-curve test.  The unit can run within a +/-5% variation of Vt for the given capability curve.  Larger changes rescales the curve by the ratio of Vt/Xd against the base vector (Vt+IsxjXd = Ef)

Generally during underexcitation the stray flux tends to exit more perpendicular to the core laminations at the end-arms, hence the step back design of the top 3 and bottom 3 stator lamination stacks.

I've ran fully underexcited with good terminal voltage and with infra-red on a hydro, there were no heating concerns.  In contrast, I have also ran another unit at ~ 70degrees rotor angle underexcited with a low bus voltage, and at that region a stability limit can exist.

UEL testing is the definitely the harder part of cap-curve testing.