Methods to ascertain the resistance of stranded conductors in the frequency range of 40 Hz–150 kHz

Abstract

Although a few years have passed since the first electromagnetic compatibility problem occurred in the supraharmonic frequency range (2–150 kHz), a lot of questions are still to be answered before the completion of appropriate electromagnetic compatibility (EMC) standards. An exciting question is how supraharmonic disturbances spread and aggregate on the network. To get a better picture of this, the frequency dependent characteristics of the network elements must be examined. This paper deals with the resistance of three stranded conductors with different cross section areas typically used in the low voltage (LV) and medium voltage (MV) distribution lines. From the methodology point of view, the problem was approached by laboratory measurements, numerical simulations with Filament technique, which was realized in MATLAB. In addition the results are compared with a few other analytical calculation methods (e.g. series expansion of Bessel functions, skin factor method, Hankel method, K. Simonyi’s approximation) found in the literature. These were performed, assessed and compared. Besides that, a new method combining two analytical methods is proposed to approximate the internal impedance of conductors. It must be noted that our intention was to cover not only the supraharmonics area, but also the power harmonics range; therefore, investigations start from 40 Hz instead of 2 kHz.