Characterization and Design of a PLC Coupling System Based on Capacitive Divider Embedded in MV Cable Head

Power line communication (PLC) technology is exploited worldwide for automatic meter reading on low-voltage networks. On the contrary, it is not used at medium voltage (MV) level, where it requires dedicated and costly PLC couplers. To face this issue, in previous works the authors investigated the possibility of reducing costs by coupling the signal by means of elements already installed in MV networks. A patented solution was based on the exploitation of capacitive dividers of voltage detective systems (VDSs) normally installed in MV switchgears of distribution network's substations. This paper investigates the use of capacitive dividers embedded in commercial separable connector of MV cables heads, instead. In comparison with VDSs, cable heads voltage dividers have different characteristics; thus an ad-hoc characterization and design of PLC coupling system is presented and discussed. Firstly, impedance measurements are performed to characterize cable heads behavior in the frequency range of interest. An equivalent circuit model is obtained and used to design an electronic interface card for signal coupling. Simulations and experimental tests are performed in FCC above CENELEC frequency band, to analyze channel frequency response and transmission performances, in terms of success rate and SNR. The results testify the proposed coupling solution feasibility.