Effects of segmented shield wires on signal attenuation of power-line carrier channels on overhead transmission lines.

摘要

Shield wire segmentation has been used for quite some time as an effective method for reducing transmission line power losses, with most segmented shield wire applications on extra high voltage lines utilizing phase-to-phase power-line carrier (PLC) coupling. However, as transmission system efficiency becomes more of a priority, some utilities may consider applying segmented shield wires to lower voltage lines, such as 115-kV and 230-kV lines, which most often utilize single phase-to-ground PLC coupling. Thus, knowledge of the effects of segmented shield wires on PLC signal attenuation for various coupling methods would be useful to relay engineers.;Previous work in this area made recommendations regarding the application of PLC systems to overhead lines with segmented shield wires based on a very limited analysis of PLC signal attenuation on transmission lines with segmented shield wires. This work expands and makes recommendations based on a much more in-depth analysis of this problem. The contribution of this work includes generalized modeling of overhead transmission lines for calculation of signal attenuation and the analysis of effects from segmented shield wires to PLC signal transmission. The generalized modeling is validated by computer simulation and field measurement results. The effects of coupling methods, terminating impedance, shield wire connections and ground resistivity, line taps and phase wire transposition are all considered in the generalized modeling.