Analysis of Reversed Power Flow in an Open Wye-Open Delta Transformer Bank

摘要

This paper has explored the inherent characteristics of a distribution transformer with open wye-open delta connection. This connection requiring only two phases on the primary line and provding three-phase four-wire service for single-phase loads and three-phase loads simultaneously is therefore widely applied in the distribution systems of Taiwan Power Company. There are two single-phase transformers, named lighting-Usually the kilovoltampere ratings of these two transformers are different. The asymmetrical structure makes its operational characteristics complicated. Usually, these two single-phase transformers do not share the load kilovoltamperes equally. moreover, the real power is usually supplied by each of the two single-phase conditio, real power may be supplied to the load by oly one and part of the real power may feedback to the source from the other. This state is unfavorable and should be avoided. On the basis of a detailed mathematicla model of the open wye-open delta bank, this unfavorable situation is investigated in this paper.