Insulation coordination, environmental and system analysis of existing double circuit line reconfigured to six-phase operation

Conversion of an existing double-circuit 115 kV overhead transmission line near Binghamton, New York to six-phase operation will provide a commercial demonstration of feasibility of high phase order power transmission. Analyses of insulation performance, corona and field effects, and a load flow and system stability have been performed as part of the preliminary engineering for this project. It is shown that conversion of the Goudey-Oakdale double-circuit 115 kV line to 93 kV six-phase is possible if insulator strings are lengthened to 8 units/string. This results in a 40% increase in thermal loading capacity and a doubling of surge impedance loading, while meeting all applicable electrical environmental requirements