Petersen coil injection at 11kv transformer

[mbrooke]

I am interested in the electrical theory behind this. I came across several Norwegian technical papers where utility transformers (11kv-230/400Y) are Y grounded, delta, Y grounded with the primary H0 grounded through a reactor. ? :huh: The 11kv network is Petersen coil earthed at the 132-11kv substation.


So my question is this, what are they trying to accomplish? Why not use a delta-wye (Dyn01) transformer like all other utilities outside North America? Isn't the Petersen reactor at the 132kv-11kv substation enough? Why go through all the extra cost?


Here is an example, the diagrams are self explanatory:

http://vestfold-trafo.no/wp-content/uploads/2013/10/Kunde-powerpoint-TOTEM-NY.pdf


My apologies for the paper not being in English, I could not find anything in the IEEE or IEC of such a practice and it only seems to be contained to Norway. I am open to all theories and ideas, including how wye-delta-wye trafo works in the first place.

 

[Tony S]

http://www.swedishneutral.se/main.php?name=neutral_asc

 

[mbrooke]

http://www.swedishneutral.se/main.php?name=neutral_asc

Yup- thats what they place on the neutral terminal of the 132-11kv transformer, which compensates the entire 11kv network or at least it should. The concept is so temporary faults auto self extinguish without having to open and reclose the feeder. However, I can't figure out why they are doing the same for the 11kv-230/400v pole transformers. Plenty POCOs use Petersen coils at the substation, but never seen it also at the pole.