138-kV, six-phase transmission system: Fault analysis

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In the past decade, transmission planners and researchers have been keenly investigating the feasibility of six-phase concept as a planning alternative. The concept, if proved feasible, would alleviate the problem of acquiring additional rights-of-way to meet the increase in electric power and energy demand. Allegheny Power System (APS) has been Investigating the conversion of some of their 138-kV three-phase double-circuit lines to 138-kV six-phase lines. The latter is an alternate option to 230-kV three-phase upgrading of the line. This paper addresses one aspect of the APS investigation, namely, fault analysis. It first discusses the greater variety of fault types that could arise on a six-phase line. It is then followed by the description of a technique for evaluating source impedances at the two ends of the line. The fault analysis by the phase coordinate method is delineated for one type of unfamiliar fault in the following section of the paper. The analytical results are presented for all types of significant faults that could occur on a six-phase line. Summary and results conclude the paper. The entire paper is developed by focusing the attention on a specific line in the APS territory. The contents of the paper should be of direct benefit to utility engineers. Copyright © 1982 by The Institute of Electrical and Electronics Engineers, Inc.

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IEEE Transactions on Power Apparatus and Systems