Field Trials for the Empirical Characterization of the Low Voltage Grid Access Impedance From 35 kHz to 500 kHz

The access impedance of low-voltage (LV) power networks is a major factor related to the performance of the narrow-band power line communications (NB-PLCs) and, in a wider sense, to electromagnetic compatibility (EMC) performance. Up to date, there is still a lack of knowledge about the frequency-dependent access impedance for frequencies above 9 kHz and up to 500 kHz, which is the band where the NB-PLC operates. The access impedance affects the transmission of the NB-PLC signal, and it determines the propagation of the non-intentional emissions that may disturb other electrical devices, including malfunctioning or reduced lifetime of equipment. This paper presents the results of field measurements of the LV access impedance up to 500 kHz in different scenarios, with measurement locations close to end users and near transformers. The results provide useful information to analyze the characteristics of the LV access impedance, including variation with frequency, ranges of values for different frequency bands, and analysis of specific phenomena. Moreover, the results reveal a diverse frequency-dependent behavior of the access impedance in different scenarios, depending on the grid topology, the number of end users (that is, number and type of connected loads), and the type of transformation center. Overall, the results of this paper offer a better understanding of the transmission of NB-PLC signals and EMC-related phenomena.The authors would like to thank Iberdrola for the availability and the collaboration of authorized staff for carrying out the field trials

A new voltage probe with improved performance at the 10 kHz–500 kHz frequency range for field measurements in LV networks

[EN] Voltage measurements in the frequency range from 10 kHz to 500 kHz are used to quantify the level of the Narrow Band Power Line Communication transmitted signals, the noise and the non-intentional conducted emissions generated by the devices connected to the Low Voltage grid. Considering that the voltage levels within this frequency range are very small if compared to measurements below 2 kHz, measuring equipment of higher precision is needed, but existing standards do not currently cover this frequency band. In this paper, a voltage adapter with improved performance at the 10 kHz–500 kHz frequency range for field measurements in LV networks is presented. Moreover, a measurement setup and methodology for the frequency-dependent characterization of this type of voltage adapters is described, which is used to demonstrate the outperformance of the designed probe with respect to four commercial devices.This work has been financially supported in part by the Basque Government (Elkartek program and IT-683-13)

Field Trials for the Characterization of Non-Intentional Emissions at Low-Voltage Grid in the Frequency Range Assigned to NB-PLC Technologies

The paper describes the results of a measurement campaign to characterize the non-intentional emissions (NIE) that are present in the low voltage section of the electrical grid, within the frequency range assigned to narrowband power line communications (NB-PLC), from 20 kHz to 500 kHz. These NIE may severely degrade the quality of the communications and, in some cases, even isolate the transmission devices. For this reason, the identification and characterization of these perturbations are important aspects for the proper performance of the smart grid services based on PLC. The proper characterization of NIE in this frequency range is a key aspect for the selection of efficient configurations to find the best trade-off between data throughput and robustness, or even for the definition of new improved error detection and correction methods. The huge number of types of NIE, together with the wide variety of grid topologies and loads distribution (density and location of homes and industrial facilities) are great challenges that complicate the thorough characterization of NIE. This work contributes with results from field trials in different scenarios, the identification of different types of NIE and the characterization both in time and frequency domains of all the registered disturbances. This contribution will be helpful for a better knowledge of the electrical grid as a transmission medium for PLC and, therefore, for evaluating the appropriateness of different robustness techniques to be applied in the next generation of smart grid services.This work was funded in part by the Basque Government under the grants IT1234-19 and Elkartek KK-2018/00037 and the Spanish Government under the grant RTI2018-099162-B-I00 (MCIU/AEI/FEDER-UE)

PLC for the smart grid: state-of-the-art and challenges

This paper aims to review systems and applications for power line communications (PLC) in the context of the smart grid. We discuss the main applications and summarise state-of-the-art PLC systems and standards. We report efforts and challenges in channel and noise modelling, as well as in state-of-the-art transmission technology approaches

EXPERIMENTAL ACTIVITY AND ANALYSIS OF PLC TECHNOLOGY IN VARIOUS SCENARIOS

Power line communications (PLCs) have become a key technology in the telecommunication world, both in terms of stand-alone technology or a technology that can complement other systems, e.g., radio communications. Since PLCs exploit the existing power delivery grid to convey data signals, the application scenarios are multiple. Historically, PLCs have been deployed in outdoor low voltage (< 1 kV) power distribution networks for the automatic metering and the management of the loads. Today, the evolution of the electrical grid toward an intelligent and smart grid that dynamically manages the generation, the distribution and the consumption of the power makes this technology still relevant in this scenario. Therefore, PLCs have raised significant interest in recent years for the possibility of delivering broadband Internet access and high speed services to homes and within the home. The increase in demand for such services has inspired the research activity in the in-home scenario, both toward the direction of the development of independent or integrated solutions, with respect to already existing technologies. Another application scenario that has not been deeply investigated yet is the in-vehicle one, which includes the in-car, in-plane and in-ship scenario. Since the power grid has not been designed for data communications, the transmission medium is hostile and exhibits high attenuation, multipath propagation and frequency selectivity, due to the presence of branches, discontinuities and unmatched loads. For the proper design of a power line communication (PLC) system, good knowledge of the grid characteristics in terms of propagation channel and disturbances is required. In this respect, we have performed experimental measurement campaigns in all the aforementioned scenarios. We aimed to investigate the grid characteristics from a telecommunication point of view. In this thesis, we present the results of our experimental activity. Firstly, we analyze the outdoor low voltage and industrial scenario. We have carried out a measurement campaign in an artificial network that can resemble either an outdoor low voltage power distribution network or an industrial or marine power system. We have focused on the channel frequency response, the line impedance and the background PLC noise, within the narrow band and the broad band frequency ranges. Then, we focus on the in-home scenario. In this context, we have studied the impact of the electrical devices (loads) connected to the power grid on the PLC medium characteristics and on the quality of the data communication. Their behavior has been investigated both in the time and frequency domain, in terms of load impedance and impulsive noise components that they inject into the network. Finally, we consider in-vehicle PLC, in particular the in-ship and in-car environment. Firstly, we summarize the results of a channel measurement campaign that we have carried out in a large cruise ship focusing on the low voltage power distribution network in the band 0-50 MHz. Thus, we present the results of an entire PLC noise and channel measurement campaign that we have performed in a compact electrical car

A new coupling solution for G3-PLC employment in MV smart grids

This paper proposes a new coupling solution for transmitting narrowband multicarrier power line communication (PLC) signals over medium voltage (MV) power lines. The proposed system is based on an innovative PLC coupling principle, patented by the authors, which exploits the capacitive divider embedded in voltage detecting systems (VDS) already installed inside the MV switchboard. Thus, no dedicated couplers have to be installed and no switchboard modifications or energy interruptions are needed. This allows a significant cost reduction of MV PLC implementation. A first prototype of the proposed coupling system was presented in previous papers: it had a 15 kHz bandwidth useful to couple single carrier PSK modulated PLC signals with a center frequency from 50–200 kHz. In this paper, a new prototype is developed with a larger bandwidth, up to 164 kHz, thus allowing to couple multicarrier G3-PLC signals using orthogonal frequency division multiplexing (OFDM) digital modulation. This modulation ensures a more robust communication even in harsh power line channels. In the paper, the new coupling system design is described in detail. A new procedure is presented for tuning the coupling system parameters at first installation in a generic MV switchboard. Finally, laboratory and in-field experimental test results are reported and discussed. The coupling performances are evaluated measuring the throughput and success rate in the case of both 18 and 36 subcarriers, in one of the different tone masks standardized for the FCC-above CENELEC band (that is, from 154.6875–487.5 kHz). The experimental results show an efficient behavior of the proposed coupler allowing a two-way communication of G3-PLC OFDM signals on MV networks

Characterization and Emulation of Low-Voltage Power Line Channels for Narrowband and Broadband Communication

The demand for smart grid and smart home applications has raised the recent interest in power line communication (PLC) technologies, and has driven a broad set of deep surveys in low-voltage (LV) power line channels. This book proposes a set of novel approaches, to characterize and to emulate LV power line channels in the frequency range from0.15to 10 MHz, which closes gaps between the traditional narrowband (up to 500 kHz) and broadband (above1.8 MHz) ranges

Characterization and Emulation of Low-Voltage Power Line Channels for Narrowband and Broadband Communication

The demand for smart grid and smart home applications has raised the recent interest in power line communication (PLC) technologies, and has driven a broad set of deep surveys in low-voltage (LV) power line channels. This book proposes a set of novel approaches, to characterize and to emulate LV power line channels in the frequency range from0.15to 10 MHz, which closes gaps between the traditional narrowband (up to 500 kHz) and broadband (above1.8 MHz) ranges

Impact Assessment of the Power Line Channel Characteristics in Real Topology

This paper investigates the effect of different parameters of power line topology on PLC system. Information about real radial power distribution network is used to define a PLC channel model in NS-3 simulator. The overhead LV distribution network was modelled in the extended bandwidth. Results of real measurements are linked with simulation results in order to see which parameters influence the communication significantly