Choosing Vector Group of Generator between YNd11 & YNd1

The power plant project is 163MW CCPP and the owner want to select Generator Converter vector group between YNd11 & YNd1. Which vector group should be chosen?

The following will tell you the suggestions with reasons.

Basically this vector group arrangement will define the physical displacement of the generator shaft and the electrical phase of the network. Both solutions can work, the decision depends on the environment in which the generator and the converte will work. I suggest you should consult those who will provide the rest of the systems around, like protection etc.If this is a stand alone generator than from a bird's view looks identical.

As mentioned above it is important to consider the other converter which will need to be in sync. If you are using a Station Auxiliary Converter for start-up and then when transferring the load to Generator Auxiliary transformer you must pick the vectors such that the secondary's of each are in phase and the primary of the Generator Step-up and the Station Auxiliary are in phase. From a reliability stand point if you are in the United States with the YNd1 it is more likely you can find a replacement in the event of a failure. If you are in Europe then a YNd11 is more prevalent. Either transformer will do the job.


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