Approximation of Transmission Line Parameters of Single-Core XLPE Cables

An accurate model of the high frequency behavior of a power cable is required for the precise simulation of the propagation of partial discharges in such a system. A cable model consists of the transmission line parameters: characteristic impedance, attenuation coefficient and propagation velocity. The semi-conducting screens of an XLPE power cable have a significant influence on the pulse propagation along the cable. Unfortunately, the dielectric properties of these layers are usually unknown and can vary hugely between cable types. This paper shows how the characteristic impedance and propagation velocity can be estimated using the cable geometry and the dielectric properties of XLPE. Typical uncertainties in the input parameters result in an uncertainty of a few percent in the approximation of the characteristic impedance and propagation velocity.