Multi-phase (6-phase & 12-phase) power transmission systems with thyristor controlled series capacitor

Multi-phase (employing phases more than three) power transmission systems have been investigated as a potential alternative to conventional three-phase systems for bulk power transmission at EHV and UHV levels in the past. The technology has been found to be effective to remove some of the limitations of three-phase system arising out of the use of extremely high voltages to increase power capability of lines, excessive rights-of-way (ROW) requirement and several environmental problems. A recently conducted survey reveals that the integration of flexible A.C. transmission system (FACTS) devices into conventional three-phase transmission system for enhancement and control of power flow is well established, however, this aspect has not been investigated for multi-phase power transmission systems. This paper therefore attempts to study: a FACTS device i.e. thyristor controlled series capacitor (TCSC), its model and effect on power flow and load ability of multi-phase EHV transmission lines. Sample systems are employed to study quantitative benefits of six-phase and twelve-phase lines over their three-phase counter parts.