Real time prelocalization of underground single-phase cable insulation failure by using the sheath behavior at fault point

This article presents a prelocalization approach of insulation faults affecting single-phase cables by using electrical measurements of voltage and current available in one substation. This approach is based on the theory of distributed parameters for modeling the faults to the ground. The specificity of this approach is the introduction of a resistance modeling the sheath-ground insulation allowing us to study the various types of faults to the ground (frankly and resistive). The fault distance and resistances are determined by two methods numerical and analytical. Many fault scenarios applied to the 150 kV underground cable connecting HTB sub-stations of Tyna–Taparoura–Sidimansour in Sfax, show a good agreement between the two methods. A simulation of the global system using the software Simulink-SimPowerSystems of Matlab is carried out giving us the voltages and currents on the source side necessary to the execution of the developed methods and the validation of the obtained results.

► We model the insulation faults affecting single-phase cables based on the distributed parameters theory.
► The fault analysis considers only electrical measurements available in source-substation.
► We introduce two resistances ‘core-sheath and sheath-ground’ to model frank and resistive fault.
► The developed approach shows the robustness according to fault localization and load variation.
► The error estimated on the fault distance does not exceed 3%.