An electro-magnetic transient (EMT) analysis on a 132 kV rated Cu/XLPE/SCW/MDPE cable system and its related networks

Abstract

For the past few decades, underground cables have been extensively used to replace overhead line system which is prone to damages due to environmental phenomena. Given the wide range of advantages it offers, there is also a need to investigate whether or not lightning transient can cause underground cable insulation puncture or breakdown as it does to the overhead lines. This project was performed to investigate the likelihood of insulation failures on underground cables due to lightning currents and its induced voltages. Analysis and simulation were carried out using CDEGS software programming to determine whether or not electromagnetic transient induced by lightning can initiate overvoltages and overcurrent hence causing failure on the underground cables. A network system consisting of 132 kV Cu/XLPE/SCW/MDPE cable with a span of 150 meters was modeled into the HIFREQ module and a lightning surge was injected into the system. The significant and critical conditions of a 132 kV rated cable system that can cause insulation failure or breakdown was examined, taking into consideration the electric breakdown characteristics and some other important parameters of the system. The induced electromagnetic fields and voltages were obtained in time domain representation using Inverse Fast Fourier Transform method. The studies showed that for the varied parameters, there is no event severe enough to commence any insulation puncture in the underground cable system.