Are Stabilizing Windings Necessary in All Y-Connected Transformers?

For many years it has been common practice to include a delta-connected stabilizing winding in Y-Y-connected transformers and Y-connected autotransformers. This applies to 3-phase units of all types of core construction, as well as to 3-phase banks of single-phase units. The practice has been followed so closely for so many years that it is generally taken for granted that the stabilizing winding is a necessary part of such transformers. In many cases it is; but is it necessary or even desirable to include a stabilizing winding in all cases, regardless of system characteristics and conditions? It is the purpose of this paper to present a comprehensive examination of the elements which determine the answer or answers to this question, in the light of modern power system operating conditions and operating practice.