Multiterminal Three Phase Transformer Model With Balanced or Unbalanced Loading

A terminal model of a transformer is developed which permits balanced or unbalanced loading. After the terminal-loading problem is solved, currents within and voltages across the individual windings can be obtained. The method is general and allows for standard and complicated winding interconnections such as deltas and extended deltas, Y´s and ungrounded Y´s, series connections, zig-zag, phase shifters, etc. In addition, these connections can be performed successively to get an even greater variety of winding connections. Unbalanced loading includes a single or double line-to-ground fault. The method then enables the winding currents to be obtained for subsequent force and stress analysis. The method can also be used to obtain regulation effects and terminal to terminal impedances.