Design of Station Supply System in Hydroelectric Plants

"help is expected"

It may be but I doubt it will be. You have been warned about your attitude before.

BTW I can't see the United States Bureau of Reclamation being interest in your hydro power plant until you've wrecked it!

Have you looked at the "single line diagrams" for this plant?

Usually, stations have two sources of auxiliary supply, one off site (Often, to build, commission and start it up in the first place) and a local supply taken off the generators.

This is just good planning, since a plant may be shut down for servicing at some time and you do not want it to depend on remote supplies to keep running when it is a major hydro facility.

These two supplies will never be in phase, so transformers should not be paralleled on low voltage[ LV ] side.

It is common practice to split the load into two equal halves, say main and standby auxiliaries or genset A and genset B, with their own transfo - which stops a single failure putting the whole site off. So each half of load would have a local and remote source transfo, making 4 transfo in total.

So, a transformer rated for 50% total site load does not seem unacceptable to me.

And in any case, you write that each transfo is supplying 50% of station load - which is not the same as "rated for 50% station load.

Two transfo with an LV bus coupler breaker between their individual LV distribution buses is a standard arrangement, with the load split normally but on one transfo when necessary e.g. to service one transfo. Each transfo is rated for 100% load but normally supplies only 50% load.

I would like to see your plant SLD before answering

You have 2 designs.

One with redundancy one without.

What do you expect help with?

I am about to take the trash out.

Help is expected......

yeah, i mean UAT rated for 100% of load, but supplying only 50% of load means two tranasformers working in parallel......... so transformers should not be paralleled on low voltage[ LV ] side .....!!!?? (as per 67model comments)

regards,

sks

If the primary sides of the two trafos are connected to the same (or synchronised) supply then the load sides can be paralleled. Naturally the trafos' windings should be closely phase matched.

The reticulation can be designed for full parallel loading or segregated loading. Of course the designs will be different. Not right or wrong just correct for purpose.

sauravbabu,

Your original posting ends with, I quote, "And to supply 100% of total load - parallel operation is needed."

Let us be clear, this is not a wrong statement if it is LV busbars/distribution boards which are being paralleled (being normally separated, each connected to their own transformer, but paralleled onto one transformer when the other transformer is disconnected by fault/maintenance). In that LV distribution arrangement, each bus is connected to 50% of load - each transfo carries 50% of load while bus-coupler is open (normal) and 100% when coupler is closed. Interlocking stops LV bus-coupler being closed while both transfo are connected to their LV buses.

And because that quote was a new sentence, not following on in sentence where you refer to "document", one cannot know if it is a quotation from the document or your comment.

It is not possible to tell if the words you wrote are from the document or your own summation - if you put words from the document within "" (quotation marks), your problem would be more evident - especially since your point seems to be that you feel you have a specification document containing a technical error.

67model