Fault Pinpointing in Underground Cables of Low-Voltage Distribution Networks with Inductive Wireless Power Transfer

This paper aims to propose inductive wireless power transfer (IWPT) technology for pinpointing fault locations in LV distribution underground cables following the use of other pre-location methods. The proposed device is portable, hence battery-powered, and operates by scanning for faults above ground via inductive coupling with the de-energized cable. This primarily relies on impedance changes in the cable due to permanent faults as the device scans the length of the cable. A detailed frequency domain mathematical model for the system is deduced and circuit design/parameters affecting the inductive coupling are investigated. An optimal design strategy for the portable device is demonstrated to achieve high fault-locating sensitivity with a minimum device VA rating. The device is tested under multiple fault scenarios (including shunt and open-circuit (cable break) faults) using a MATLAB/Simulink circuit model, and the results are validated against the mathematical model. The device's performance with single-core and multi-core cables is examined. Finally, a critical comparative evaluation of the IWPT method with existing fault pinpointing techniques is conducted that highlights both the advantages and limitations of the proposed technique. The research shows that the proposed technology provides a promising new solution for LV network operators to minimize excavations for underground cable faults by pinpointing locations where a considerable deflection in induced cable current occurs when passing a fault point.