Unusual Generator to GSU Transformer Configuration

[doehl1]

I've inherited a project with an existing standby generator, 2.5MW, 480V, wye connected which feeds an existing 480/11kV Wye-Delta GSU transformer. In this case the wye connected generator is connected to the wye windings on the primary of the transformer. Wye's are solidly grounded. Service is standby and been like this for a decade. I'm not used to seeing the wye to wye connection like this. Usually its wye (gen) to delta (GSU primary).

Now we're installing a new 1.5MW generator adjacent to the original as an expansion to the plant and we'll need a new GSU transformer as well. If we go with the same arrangement as the original setup, I'm concerned about circulating currents, and possibly ground fault sensitivity. But it doesn't seem to make sense to have two different set ups (one trafo D-W, and one W-D), and I'm not going to be able to get funds to replace the original trafo.

Would appreciate your thoughts or suggestions.

David

http://www.mavenpower.com

 

[Parchie]

I guess going for a D-Y GSU would be desirable. Your new 1.5MW wye generator will provide a ground reference for the delta side of the D-Y GSU. At the same time, the Wye side of the 1.5MW GSU can provide a ground reference fo the 11 kV bus!

 

[FreddyNurk]

What's being used for the ground fault protection scheme for the 11kV?