Abstract
The idea of unbalanced power flow calculation was proposed many years ago. At that time, however, the needs for such techniques was not an argent issue. But modern power system networks are comprised of long untransposed transmission lines. Therefore, for some kind of analysis, it is now almost impossible to treat a system as though it were a symmetrical network. The aims of most previous studies were oriented to solve voltage/current imbalance in local or small system because local imbalance was a serious concern. This is still an important issue, but more recently our needs have become concentrated on practical bulk power systems, since principal EHV lines are entirely untransposed.
Following such a background, we have developed a practical unbalanced load flow program. This program was developed for steady state analysis of large scale of practical networks under many possible unbalanced conditions.
