High impedance fault evaluation using narrowband Power Line Communication techniques

Occurrence of High Impedance Faults in urban overhead power distribution networks can cause economical and safety issues for both the public and the utility. These faults may hardly be detected using conventional protection methods, so a sophisticated system has to be developed to deal with the problem. In this work the usage of high frequency ranges and specifically the Cenelec A Band frequency range is examined for the detection of such kind of faults by monitoring the input impedance of the system. High impedance faults can cause significant deviation to the overall impedance at specific frequencies. Several branched overhead Medium Voltage topologies are examined and significant conclusions are extracted. Furthermore, a parametric analysis is conducted with respect to the earth´s electromagnetic properties, i.e. ground resistivity and relative permittivity, regarding their impact on the efficacy of the method. Finally, the occurrence of fault at all possible locations of a transmission line is examined and also analyzed.