Modelling and experimental validation of EM wave propagation due to PDs in XLPE cables

Abstract

Monitoring of electromagnetic (EM) waves due to partial discharge (PD) is a promising tool for condition monitoring of cables. This study presents the development of a modelling scheme for simulation of EM wave propagation due to PDs occurring at cavities in the cross-linked polyethylene (XLPE) insulation. Simulation models for generation and propagation of PD pulses through the cable geometry are developed. A finite element method (FEM)-based model is developed to simulate the PD current along cylindrical voids in the cable insulation. The initial fields due to the PD currents in the voids are simulated by an FEM model. The propagated EM fields inside and outside the cable surface due to PD's occurring inside the voids are analysed by a finite-difference time-domain model. The analysis of propagated EM fields due to a Gaussian-shaped PD pulse identifies the dominant components of propagated electric and magnetic fields along the cable geometry. Furthermore, the propagated EM fields at the cable sheath due to different void dimensions are simulated and experimental validation of the propagated magnetic field is conducted with measurement by an high-frequency current transformer sensor installed around an earth wire from the sheath of an 11 kV XLPE cable.