A Wavenumber Domain Reflectometry Approach to Locate and Image Line-Like Soft Faults in Cables

Soft fault detection for cables is of great significance to secure modern power system since the soft fault will gradually develop into a hard fault or electrical fire. The existing detection methods often apply to localize point-like faults, while most soft faults are line-like faults with a certain length. Considering that soft faults will change the signal propagation speed, this article establishes a transmission line model with respect to speed distribution. Then, a wavenumber domain reflectometry (WDR) is developed to obtain the speed distribution using the Volterra inverse scattering series (VISS). By dealing with zero wavenumber compensation and Gibbs ringing artifact suppression issues of VISS in the wavenumber domain, WDR achieves not only localization but also dielectric permittivity imagination for line-like faults without the need for time synchronization and the knowledge of line topology. Both simulations and experiments are carried out to study the localization and imagination of WDR. The results show that WDR locates the range of line-like faults more precisely than the existing fault detection methods, and achieves dielectric permittivity imagination with an accuracy larger than 97%.