LINE IMPEDANCE MEASUREMENT FOR PLC CHANNEL CHARACTERIZATION WITH COMMERCIAL SMART METERING PLATFORMS

Power line communication (PLC) is widely used in power systems, for automatic meter reading and its use has been also investigate for other smart grid applications, such a secondary substation automation, remote control of distributed generator, and so on. To fully exploit the technology and face the problems related to disturbances and signal attenuations, it is important to characterize the communication channel, in the used PLC range, in terms of frequency response and line impedance, in the PLC frequency range of interest. This can allow individuating the best frequency bands for signal transmission, avoiding using those with higher levels of attenuation and/or noise. PLC line impedance depends on network topology, cables and loads and it can be time-varying; moreover, its measurement can be strongly affected by noise. Furthermore, the measurements are carried out in the absence of mains voltage, and they entail the use of and high-cost instrumentation (network analyzers or dedicated measurement systems based on data recording and processing software) and the grid topology knowledge. This paper investigates the feasibility of an alternative approach, which allows to measure the lie impedance by means of the typical electronic boards, equipped with a PLC modem, which are currently used for smart metering purposes; the proposed solution exploits the PLC signal itself as test signal for the impedance measurement. In this way, no dedicated measurement equipment is needed and the impedance measurement can be theoretically obtained for each signal transmission.