Harmonics effects on wye-wye transformers

[GunnarDH]

What effect do harmonics have on wye-wye transformers with neutral grounded? What about not grounded? Also, in a wye-delta, why is there less distortion in the delta side voltage if neutral in the wye side is not connected to ground?
I understand why the Y transformers have distortion and the delta do not. But I don't understand why have a ground would effect either situation.

 

[cabraham]

https://www.physicsforums.com/threads/circulating-currents-in-delta-winding.884491/#post-5568453

Claude