Transmission line compaction using high phase order transmission

Bortnik, Jacob
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This report discusses high phase order (HPO) technology, i.e. the use of more than the conventional 3 phases for transmission of electric power, its use in the compaction of lines, and power density maximization over existing servitudes. It is structured in four parts. The first part introduces the concepts, establishes the need, and lists the advantages ofHPO. The second part deals with the technology itself and shows that it is possible to analyze HPO systems using symmetrical component analysis, lists common transformer configurations, covers protection, and so on. The third part analyses 5 case studies, the first 3 being analytical, and the last 2 being the first experimental test line, and the world's :first utility application ofHPO lines. The fmal section is a South African case study and compares an HPO line to an existing 400 kV 3-phase line and shows that the former is 87.5% more expensive to implement than the latter. Comparing the 3-phase and 6-phase lines on a more even basis, yielded a breakeven distance of225.86 km, above which the 6-phase option becomes more economical. These results are then explained and discussed in the conclusions section.
A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering Degree awarded with distinction on 8 December I998 Johannesburg, 1998