step-up transformer neutral grounding

[oluyomi]

3 nos of 400V generators synchronised and have common outgoing connected to the LV side of a 3500KVA 415V/11KV step-up transformer Dyn11 star 415V side and delta 11KV side. Should the neutral of the LV side of the transformer be connected to earth [grounded]?
Did your Utility recommend to use a Dyn11 instead of YNd11? or is it an in-house generation only

thanks all for your response it was an in-house generation only,
Dyn11 [is actually an 11KV/415V step-down transformer] and was used as 415V/11KV step-up transformer because it was available otherwise it would have been YNd11

presently no additional cost can be incured in the form of [zigzag transformer] as suggested

 

[odlanor]

Each utility has your own problem;- If they have 415V system, Dyn11 is better as a grounded system.
Acessant ,as an special case, should adequate yn winding for his own generation.