Open AccessSeries impedance of distribution cables with sector‐shaped conductors
Author(s) -
Urquhart Andrew J.,
Thomson Murray
Publication year - 2015
Publication title -
iet generation, transmission and distribution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 110
eISSN - 1751-8695
pISSN - 1751-8687
DOI - 10.1049/iet-gtd.2015.0546
Subject(s) - electrical impedance , eddy current , harmonic , solver , power (physics) , mechanics , electrical engineering , acoustics , computer science , physics , engineering , mathematics , mathematical optimization , quantum mechanics
Models of power distribution networks require accurate cable impedance data. For unbalanced networks, both the self‐impedances and the mutual impedances are needed. However, published studies use differing approaches to determine cable impedances, leaving uncertainty over the level of detail required. This study compares impedances provided by the manufacturer with those from several analytical methods, showing the impact of modelling the non‐circular geometry and of including corrections allowing for the AC resistance. The analysis is compared to results from a freely available finite element (FE) solver where the current distribution is modelled in detail, taking account of eddy currents and the rotation of the cores relative to the neutral due to the cable lay. At 50 Hz, the analytical methods provide a good approximation, but the FE results show that eddy currents affect the impedance at harmonic frequencies. The results also show the impact of including the ground path in the impedance calculation. The current distribution in the ground has a wide cross‐sectional area, suggesting that the assumption of a perfect multi‐grounded neutral is inappropriate for low voltage networks with short cable lengths.