Analysis of typical PLC pulses for sensing high-impedance faults based on time-domain reflectometry

Abstract

This paper focuses on a comprehensive analysis of typical power line communication (PLC) pulses for sensing high impedance faults in power distribution networks (PDNs) when the pulse compression time-domain reflectometry (TDR) system applies. In this sense, closed-form expressions for the PLC pulses, namely Hermitian symmetric orthogonal frequency-division multiplexing (HS-OFDM), impulsive ultra-wideband (UWB), and chirp spread spectrum (CSS), and their corresponding autocorrelation functions are presented. Also, parameters based on radar theory (e.g., range resolution, pulse compression ratio, reflectogram distortion, and maximum unambiguous range) are introduced to evaluate the usefulness of these PLC pulses for providing proper TDR measurements (reflectograms). A comparative numerical analysis considering frequency bands that comprise narrowband and broadband PLC systems, with a highlight on well-established regulatory constraints, is discussed. Numerical results show that the use of UWB pulses yields a larger number of reflectograms in a given time interval, while HS-OFDM and CSS pulses provide higher reflectogram quality and better resolution, under the same conditions. Also, narrowband PLC systems are suitable for the majority of PDNs, with the use of broadband PLC ones left for attaining high resolutions at short distances.