Distributed generation interconnection transformer and grounding selection

The interconnection of distributed generation (DG) into the power distribution system creates many challenges for utilities. Many of these challenges are related to the type of interconnection transformer (or lack thereof) and consequently the grounding used for the DG interconnection. There remains confusion about the various transformer types for DG interfacing. This is a critical point because the selection of the correct interface with the local utility will simplify feasibility studies; therefore, decreasing the overall cost of the DG interconnect investigation to benefit all. This paper discusses the advantages and disadvantages of different interconnecting transformers. Neutral reactor sizing for grounding transformer connections is discussed.