Design modification and layout of utility substations for six phase transmission

Evaluations performed on the New York State Electric and Gas Corporation´s 115-kV Goudey-Oakdale line and Goudey and Oakdale substations to assess the capability of the existing equipment operate as part of a six-phase demonstration project are described. The design modifications that will be made to meet the goals of the commercial demonstration and to allow integration into the existing three phase operating grid are also described. Reconfiguration of an existing double-circuit line to a single-circuit six-phase line requires installation of phase configuration transformers at the end of the line terminals and the associated switching, metering, and protection equipment. In addition, the phase conductors from the terminals of the transformers must be transposed for connection to the transmission line to achieve the desired 60° vectorial separation angle between adjacent phase conductors. Concepts of substation compaction that have been pursued when attempting substation modifications for six-phase reconfiguration are discussed