IEEE standard for protective relaying for generators 5

[supraskate13]

I tried searching the IEEE website but I could not browse it as it is acting funky. I do have a user name and password but still....the site isn't working for me.

Anyway I have a bunch of standards filled away but they are not labled by title they are labled by standard number...I.E. C37.91-2000

Could anyone give me the standard number for the standard I am looking for? I believe it will be titled "IEEE Guide for Protective Relay Applications to Generators"

Thanks!

 

[RalphChristie]

ANSI/IEEE C37.91-2000: Guide for Protective Relay applications to Power Transformers.

ANSI/IEEE C37.102-1996: Guide for AC Generator Protection.

 

[supraskate13]

I have looked at both. The AC protection for Generators does not provide me with a curve for Volts per Hertz protection. the only curve I could see is one that shows how different relays will react to under frequency condidtions.

I am looking for curve that shows %Volts/Hz vs Operate time(minutes) simmilar to that shown on Page 37 of the relay applications to Transformers.

thank you for your propt response though

perhaps there is a reference out there somewhere that lists the standars by title instead of number?

 

[stevenal]

Here is the link to the online standards:

http://standards.ieee.org/reading/ieee/std/index.html

If your password is valid, you should be able to open the protective relaying standards page where they are listed by number and name.
Both standards say to consult the manufacturer. You might want to consult the manufacturer.

 

[RalphChristie]

Supraskate13:

I did not realise you were looking for a certain curve. (I suppose this question refer to thread238-146506?)

Try ANSI/IEEE C37.106-2003: IEEE Guide for Abnormal Frequency Protection for Power Generating Plants. Unfortunately I do only have a copy of the 1987-edition, but it seems as if it contains the curve you are looking for.

Regards

 

[davidbeach]

ANSI/IEEE C37.106-2003 does have some curves, but even those curves show the importance of getting detailed information from the manufacturer. There are example curves in the standard, labeled MFR 1, MFR 2, etc., and they are all different enough that using any of them could be a misapplication.

 

[supraskate13]

I looked over the standard and I do agree that I need to get the manufacturer limits to accuratley set the relay. I know for sure now that the generator protection relay is set wrong for V/Hz protection because it is set to trip on an inverse time curve at a time of 139 seconds at 115% V/Hz, this is bad considering it is the only relay that has any V/HZ protection enabled.

 

[dpc]

You also need to consider the voltage regulator. It may have its own V/Hz protection with the relay serving as a backup. You don't want the relay to get ahead of the voltage regulator.

 

[supraskate13]

I thought about that, but looking at the one-line it appears that the voltage regulator looks at a different set of generator PT's, Making the V/Hz voltage input and the Regulator inputs seperate.

 

[ScottyUK]

dpc raises a good point.

The VTs you mention are presumably on the same bus? It is common to use two sets of VTs, one for the AVR and one for protection - there is frequently also some means of allowing the AVR to use the protection VTs in the event of losing its own set.

Regardless of the VTs used, the AVR limiters should have the ability to act to control a V/Hz excursion before the V/Hz relay causes a trip. Depending on the AVR this could be relatively slow if it uses a multi-stage system of PMG / pilot exciter / exciter / rotor. There are a lot of lags in such a system, making it sluggish to respond when compared with a directly excited design.

You should check your connection agreement with your grid operator. Most specify that generating units shall maintain output down to, say, 47Hz on a 50Hz system. Your V/Hz relay should not operate within the time peiod which your grid operator expects your set to be available. This sort of detail should have been made available to the generator OEM at the time of design.

In many cases the GSU transformer will get in to trouble with overfluxing long before the generator itself starts to approach saturation. You should consider whether the transformer has a lower V/Hz capability than the generator and protect it accordingly. On a close-coupled generator and GSU transformer, one relay can protect both.


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I don't suffer from insanity. I enjoy it...

 

[dpc]

But the V/Hz should be basically the same regardless of what set of PTs are being referenced.

If you set the V/Hz, OV and UV on the relaying to be more sensitive than the VR settings, you may get unnecessary relay operations. So you should verify what is set up in the voltage regulator control.