Approximate Magnetic Flux Density Model of Overhead Power Lines for Conductor Sag Estimation

Abstract

Monitoring and supervision of overhead power lines have become essential actions in Electrical Power Systems since the
introduction of the Smart Grid concept. In order to monitor overhead power lines, simple non-invasive devices are mounted on support
poles, which detect line abnormalities and faults by measuring magnetic field originating from power line conductors. Measured signals
are also used to determine various electrical and non-electrical line parameters. In this paper a new approximate model for magnetic
flux density vector components of the overhead power lines suitable for real-time conductor sag estimation is presented. In the proposed
model, catenary-shaped power line conductors are approximated with tilted straight line conductors, and the approximate model is
calibrated by tuning model coefficients to match flux density vector components as in the case of real catenary-shaped conductors. The
accuracy of the proposed model is verified by measurements on three-phase overhead power line model scaled to laboratory conditions.
As a conclusion, an adaptive method for possible practical implementation based on the approximate model is considered.