Hi,

i think Generating Transformer are YNd1 for neutralizing the load angle two trafos going to be used in Parallel.

YNd1 means– High Voltage winding is Y connected with neutral terminal and Low Voltage winding is Delta connected. The phase angle of the LV winding lags the HV by 30 degrees.

Vector group is important when you run the transformers in parallel. One of the criteria for parallel run of transformers is that the transformers to be run in parallel have to be of same vector group. If you do not have the intension to run it parallel with any other transformer, it should be ok to go for YNyn0.

Why mostly GT(Generating Transformer)has only Ynd1 Vector Group?

hi friend

in short we can say that in ynd1 vector Group is used so that we can easily parallel the transformer or synchronize a generator step up transformer to Grid.

The Ynd11 has an HV to LV phase angle displacement of plus 30°, while that of the Ynd1 is minus 30°. Synchronization could be done if the HV and LV configurations were reversed, i.e., Yd11 and Dy1 in parallel. But, it is not possible if the Ynd1 were to be paralleled with a Ynd11 if the primary of both transformers were supplied from the same source.

regards

aakash