Power line communications (PLC) have been an active research area for many years and it is still the case, mainly because they present economic and technical natural advantages for a wide range of applications using the existing electrical grid as transmission medium. In this paper, the authors provide an update on PLC technologies and their applications in Smart Grids, the main challenges they are currently facing, how they can be addressed, and the current research initiatives.

Distributed Energy Resources might have a severe influence on Power Line Communications, as they can generate interfering signals and high frequency emissions or supraharmonics that may cause loss of metering and control data. In this paper, the influence of various energy resources on Narrowband Power Line Communications is described and analyzed through several test measurements performed in a real microgrid. Accordingly, the paper describes the effects on smart metering communications through the Medium Access Control (MAC) layer analysis. Results show that the switching frequency of inverters and the presence of battery chargers are remarkable sources of disturbance in low voltage distribution networks. In this sense, the results presented can contribute to efforts towards standardization and normative of emissions at higher frequencies higher, such as CENELEC EN 50160 and IEC/TS 62749.

In DVB-T2, the single frequency network (SFN) mode is an attractive planning alternative to the well-known multiple frequency network (MFN) mode. SFN networks provide augmented spectrum efficiency as well as a quality of service improvement due to a more homogeneous distribution of the received signal strength over the coverage area. Nevertheless, some areas will also show degradation in practice. In order to improve the performance of the SFN operation, the second generation broadcast system DVB-T2 standard incorporates multiple input single output (MISO) antenna diversity mechanisms. Based on empirical analyses and system level simulations, this paper analyzes the key factors affecting the SFN operation. This paper analyzes SFN effects as well as the corresponding MISO gain margins for commercial and custom software defined radio (SDR) receiver implementations. The results show that the MISO gain is restricted only to the overlapping areas of an SFN where a small power imbalance between MISO groups, is present being the achievable MISO gain higher with high modulation code rates. The results also address that degradation arises in the non-overlapping regions of an SFN. This paper provides also updated C/N thresholds for DVB-T2 network planning.

This work presents a novel measurement method to characterize long-term and short-term variations of the LV grid impedance from 20 kHz to 10 MHz with configurable time, frequency and amplitude resolutions. The characterization of the grid access impedance in this frequency range is vital for the design and development of NB-PLC and BB-PLC technologies. The measurement system is valid for in-home, indoor cable networks and for the harsh conditions of the LV distribution grid, where a large input dynamic range and strong protection mechanisms against high-amplitude impulsive noises are required. Its accuracy is evaluated by comparison to a precision impedance meter for a wide set of impedance values, obtaining a maximum deviation within ±8%. First trials of the grid impedance sub-cycle variations caused by commercial appliances and for frequencies assigned to BB-PLC are also presented in this paper. The results demonstrate that the grid impedance is highly time-varying within the mains cycle, both in amplitude and phase. These first outcomes point at the need to evaluate the accumulative effects of sub-cycle variations in the LV distribution grid, so that equalization algorithms in the next BB-PLC technologies could be developed to overcome the impact of these fast variations.