02-04-2010, 03:15 PM
ABSTRACT
The concept of six phase transmission lines was introduced by Barns & Barthold during 1972. Six phase power system is a part of multiphase power system. Due to harmonics effect and various other reasons Six phase systems and six phase machines are not popular but six phase transmission lines are more popular due to its increased power transfer capability by times, maintaining the same conductor configuration, rights of way, better efficiency, better voltage regulation, greater stability and greater reliability
High Phase Order(HPO) transmission is the use of more than the conventional three phases to transmit power over a given transmission corridor. Table I illustrates the increased power that can be potentially be transmitted if an existing double circuit line is converted to a 6-phase line
This increase in power may be coupled with a decrease in electric and magnetic field strengths for certain configurations and reduction in radio and audible noise levels. For the HPO Demonstration Project, a 6-phase system was selected since it represents an optimum between the proportional increase in loading and the proportional increase in surge impedance obtained by increasing the number of phases with the increase in power transfer capability.
In 1978 the U.S. Department of energy sponsored a project for the construction and testing of experimental 6 and 12 phase lines. As a part of this project, new high phase order tower, insulators and insulator spacer designs were developed. Test lines have successfully shown practical and simple constructions for 6-phase transmission and proved all advantages predicted before.
