1600KVA power transformer connection problem

The best way is to ask your provider. he can give you a difinite answer.

On principle, if you use this transformer independently, I think certainly no problem, the primary nd second winding is relative. only change D and Y to comply with your voltage requirement.

I declare I hvnt ever used this kind of large transformer. only speak from principle.

You will loose the capability to ground the secondary at the center of the Wye. This is likely a big problem unless you want to float the secondary or have some other exotic mean of grounding. In most country, floating the secondary can only be done using special protections and considerations.

I would probably return the transformer and insist to get it fixed. They simply have to re-wind the coils.