Narrowband Power Line Communication Systems Research Articles

Enhancing safety in narrow-band transformerless PLC couplers with a passive symmetrical filter

As the demand for efficient data transmission over existing power infrastructure grows, power-line communication (PLC) systems have become increasingly vital. However, integrating communication signals with high-voltage power lines poses significant safety challenges, emphasizing the need for reliable, safe, and high-performance components. To address cost and safety concerns, this article introduces a symmetrical third-order band-pass filter design that employs a transformerless coupler, avoiding the expense and bulk of traditional transformers while enhancing both equipment and human safety in narrow-band PLC systems. The design, functionality, and safety considerations are discussed, with a focus on implementing a passive analog Butterworth filter, chosen for its flat frequency response in the passband. Additionally, we address the safety aspects of transformerless couplers in PLC applications, emphasizing their reliability and efficiency in maintaining signal integrity while minimizing the risks associated with high-voltage environments. Simulations validated the proposed design, confirming its effectiveness in achieving the desired frequency response. The design is cost-effective due to the elimination of the transformer and ensures safety through the strategic rearrangement of the coupler components, which isolates the power line from the communication side.

Performance Analysis of Orthogonal Multiplexing Techniques for PLC Systems with Low Cyclic Prefix Length and Symbol Timing Offset.

This paper investigates the degradation caused by interference resulting from cyclic prefix violation and symbol timing offset in narrowband power line communication systems. In this sense, it presents a unified formulation from which Hermitian symmetric orthogonal frequency division multiplexing (HS-OFDM), orthogonal chirp division multiplexing (OCDM), single-carrier cyclic prefix (SCCP), and orthogonal time-frequency division multiplexing (OTFDM) can be easily derived. The paper then provides closed-form expressions for quantifying the aforementioned interference in the presence of a frequency domain equalizer. The numerical analyses exhibit the performances of these schemes under various data communication conditions, such as the availability of channel state information, the presence or absence of interference, modeling of additive noise as a white or colored Gaussian random process, frequency domain equalizer type, and the use of bit and power allocation techniques. The closed-form expressions and performance analyses regarding achievable data rate and bit error probability provide guidance for dealing with distinct constraints in narrowband power line communication (PLC) systems using the HS-OFDM, OCDM, SCCP, or OTFDM scheme. Lastly, the unified formulation and results obtained motivate the design of multi-scheme transceivers.

A Notch Filter-Based Coupling Circuit for UNB and NB PLC Systems

This paper introduces an analog notch filtering-based coupling circuit for receivers in ultra-narrowband and narrowband power line communication systems, which are connected to low-voltage electric power grids. It is composed of a twin-T notch analog filter, which is responsible for imposing a significant attenuation on the main frequency (i.e., f0∈{50,60} Hz) in cascade with an elliptic low-pass analog filter, designed with a 3 dB cut-off frequency of fc≫f0. For f0=60 Hz and fc=2 MHz, the prototype of the analog notch filtering-based coupling circuit attains attenuation values of 22 dB and less than 2 dB at the main frequency and in the rest of the frequency bandwidth, respectively, when practical scenarios are considered. Lastly, it shows that the analog notch filtering-based coupling circuit is more effective than a typical capacitive coupling circuit when frequencies lower than 3 kHz are considered for data communication and sensing purposes.

Inductive coupling-based narrowband PLC systems for overhead MV power distribution networks: New insights

This paper advances the investigation of the adequacy of inductive coupling-based narrowband power line communication (PLC) systems in overhead medium voltage power distribution networks (MV-PDNs). Relying on raw data obtained from a measurement campaign which was carried out in urban and rural feeders in the south region of Brazil, it shows that overhead MV-PDNs may be a challenging data communication media when considering inductive coupling devices since the level of insertion losses associated with the coupling process is relevant. Also, the presence of significant loads between the source and destination nodes can severely degrade loops of currents, which are necessary to perform data communication in an inductive coupling-base PLC system, resulting in an erasure data communication media. For the reliable links (i.e., without erasure), the performance analysis shows that PLC channel impulse responses and additive noises can be respectively modeled as time-invariant systems with a quasi-flat channel frequency magnitude and white Gaussian random processes in urban and rural areas. Last but not least, an attenuation model and achievable data rates are discussed for the reliable links.

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

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.

Adaptive thresholding algorithm for detection of coded signals in narrowband powerline communication systems

ABSTRACT werline Communication (PLC) signals are affected by a combination of different sources of noise. Among them, impulse noise represents the most harmful component, making the use of encoding algorithms an essential requirement. Algorithms based on Complementary Sequences (CS) are an attractive option for signal detection in conditions of low signal-to-noise ratios (SNR). One of the main characteristics of CS is the high SNR gain by computing the sum of their autocorrelation functions, which, in a noiseless scenario, results in a Kronecker delta. In the presence of noise, the amplitude of main deltas is no longer proportional to the length of the sequences, and a variable number of random amplitude sidelobes emerge around it. This work analyses some of the algorithms present in the bibliography and proposes a novel dynamic algorithm to detect the correlation deltas immersed in the PLC impulse noise. The proposal is based on the estimation of the noise variance and the correlation peaks in order to compute a near-optimal validation threshold. The proposal is simulated and evaluated in a PLC environment with a Middleton Class A noise model, and the algorithm performance is compared in a real communication test over the electrical network of the university building.

Channel Coding Based on Power Line Communication

This paper focuses on the forward error correction (FEC), the basic parameters determination of the RS convolution code, Turbo code and the LDPC code, and the corresponding encoding and decoding algorithm in power line communication (PLC) standard. Simulation experiment which is designed for narrow-band power line communication system based on OFDM is done. The coding using RS convolution code, Turbo code and LDPC code are compared, and further it is determined that which encoding method is more suitable for power line communication in China.

Cyclostationary Impulsive Noise Mitigation in the Presence of Cyclic Frequency Offset for Narrowband Powerline Communication Systems

Cyclostationary impulsive noise (CSIN) is the dominant source of additive noise in narrowband powerline communication (NB-PLC) systems. Frequency-shift (FRESH) filters have been applied to NB-PLC systems based on orthogonal frequency division multiplexing (OFDM) to mitigate CSIN and enhance the OFDM signals by leveraging the difference in cyclic frequency associated with CSIN and OFDM data symbols. Note that under the effects of frequency fluctuation in the mains voltage, the cyclic frequency offset associated with CSIN can degrade the performance of FRESH-filter receivers. To alleviate such an impact on the FRESH-filter receivers, this paper presents a method for the estimation of the cyclic frequency offset by observing phase variations in the coefficients of the FRESH filter. Computer simulations based on IEEE 1901.2 specifications demonstrate the effectiveness of the proposed scheme in suppressing the cyclic frequency relative error by at least 15.45 dB. Following compensation for the cyclic frequency offset, the proposed scheme achieved a bit error rate of 10 − 4 with an E b / N 0 loss of only 0.7 dB, compared with the ideal case. Compared to the case without the cyclic frequency offset compensation, the proposed scheme achieved an E b / N 0 gain of 2.7 dB.

Cyclostationary impulsive noise mitigation algorithm for narrowband powerline communications

The dominant noise in narrowband powerline communication (NB-PLC) systems is cyclostationary impulsive noise (IN), which severely degrades communication performance. Conventionally, a frequency shift (FRESH) filtering approach exploits the cyclostationary effect to extract the IN component in the received signal. In this paper, we propose a three-stage adaptive FRESH-based cyclostationary noise estimator to make a reliable IN estimation. Inspired by the active noise cancellation method, we firstly employ a FRESH filter to generate a reference IN signal. In addition, considering the cyclostationarity of the IN, we exploit the time-averaged objective function to adjust the coefficients of the FRESH filter. Then, this reference IN signal is fed into an adaptive estimator to further refine the estimation of IN. Lastly, the refined IN estimations are rectified by a hard thresholding device such that significant and reliable IN estimations can be leached out. By subtracting the reliable IN estimations from the received signal, we mitigate the impact of IN on the data transmission for NB-PLC systems. Computer simulation is conducted based on the IEEE 1901.2 specification and we use real measured IN data to verify the effectiveness of our proposed method. The results have shown that the improvement in terms of the normalized mean squared error can be up to 7.57 dB.

DEVELOPMENT OF AN OPTIMAL TECHNIQUE FOR RELIABILITY ANALYSIS OF POWER LINE COMMUNICATION SYSTEM FOR SMART GRID REALIZATION

Power Line Communication (PLC) is a communication technology that enables transmission of data on a conductor which is also used for electric power transmission. The development of a PLC system presents a significant challenge for the communication engineer due to the unusual channel characteristics that affect high-speed signal transmission since the electric power grid is designed to operate at 50/60 Hz. In addition, the topology of electric power grid network is often very irregular resulting in significant dispersion of the transmitted message signals as it is susceptible to noise and attenuation due to power lines being primarily used for transmission of electricity as a result of its viability for smart grid realization. This study therefore investigates the reliability analysis of PLC for Smart Grid (SG) realization using clipping and Turbo equalizer techniques to reduce the effects of noise and attenuation in narrowband (9-490 kHz) PLC system respectively. This optimal technique is based on the minimum Bit Error Rate (BER) search. The results show that the technique used improves the BER performance of the narrowband PLC system for smart grid realization. The result of this study provides a reliable communication and control for cost efficiency of existing power line infrastructure for Smart Grid. Keywords: PLC, Smart Grid, Attenuation, Clipping, Equalizer, Electric Power Transmission, Bit Error Rate. DOI : 10.7176/MTM/9-8-01 Publication date : August 31st 2019

Multihop DF Relaying in NB-PLC System Over Rayleigh Fading and Bernoulli–Laplacian Noise

In this paper, we consider a decode-and-forward relay-assisted multihop power-line communication (PLC) system. The statistics of the end-to-end signal-to-noise ratio (SNR) in the destination are studied considering the Gaussian-distributed background and Laplacian-distributed impulsive noises. Using the statistics of the instantaneous SNR, the performance of the considered narrowband (NB) PLC system is analyzed. Particularly, new expressions are derived for the outage probability and end-to-end average bit-error-rate. Moreover, the average channel capacity is also obtained. The analytical results are corroborated through Monte Carlo simulations.

First and Second-Order Semi-Hidden Fritchman Markov models for a multi-carrier based indoor narrowband power line communication system

The realization of a Semi-Hidden Fritchman Markov models (SHFMMs) for power line communication (PLC) channel is only practicable if combined with efficient algorithms for learning and inference. This article thus reports First and Second-Order SHFMMs for the bit error pattern at the output of an Orthogonal Frequency Division Multiplexing based system for in-home narrowband PLC applications. Accurate SHFMMs have been derived for a residential and laboratory environment using the efficient iterative Baum–Welch algorithm. The log-likelihood ratio plots, the error-free run distribution plots, the mean square error and Chi-Square (χ2) test validates the accuracy of the derived models. The reliability and accuracy of resulting models are confirmed by a close match between the measured bit error sequences and the model generated bit error sequences. The estimated Second-Order SHFMMs have been validated to be superior to the First-Order models, although at the expense of more computational complexity. Resulting models assist designers to speed up and facilitate the process of designing and evaluating novelties for PLC systems.

Coupling for Power Line Communications: A Survey

The advent of power line communication (PLC) for smart grids, vehicular communications, and data network access, has recently gained ample interest among the researchers and industries. Couplers - devices used to inject data communication signals into (Alternating Current or Direct Current) power lines are very important components of a PLC system. There is, however, an obvious gap in literature for a detailed review of existing PLC couplers. In this paper, we present a comprehensive review of couplers, which are required in narrowband and broadband PLC transceivers. We provide, also, a novel classification of PLC couplers based on the type of physical coupling, voltage levels, frequency bandwidth, propagation mode, and number of connections. Prevailing issues that protract the design of couplers and consequently subtended the invention of different types of couplers are clearly described. This survey will guide researchers, and designers alike, into a quicker resourcing when studying coupling in narrowband and broadband PLC systems.

Statistical modeling of mains zero crossing variation in powerline communication

In this paper, authors investigate statistical modeling of measured mains Zero Crossing (ZC) non idealities in narrowband powerline communication systems (PLC) using time series approach based on autoregressive moving average model (ARMA). For this purpose, Box Jenkins analysis steps are deployed for detected ZC impulsive variations. Estimated models exhibit a good fit based on R-square metric reaching 90%. This modeling approach is extended to three measurement environment: in home, in lab and rural locations. Obtained models are useful for NB-PLC channel emulator implementation.

Simulation of a Narrowband Power Line Communications System over Medium Voltage

Narrowband Power Line Communications (NB-PLCs) are investigated as an alternative option for transferring low rate smart grid (SG) data via Medium Voltage (MV) power lines. In this framework, two variants of orthogonal frequency division multiplexing are examined, namely Filtered-OFDM (F-OFDM) and Wavelet-OFDM (W-OFDM), in an attempt to determine which of them is capable of transmitting low rate SG data to greater distances over non-branched MV power lines. The reach of NB-PLC signals via MV power lines is estimated, taking into account the transfer function of the relevant PLC channels and noise mechanisms as well as the specific features of the two modulation options under consideration. Simulations show that NB-PLC transmission constitutes a technically feasible and economically affordable option for exchanging low rate data with remote SG nodes dispersed over the MV grid. Moreover, simulations show that F-OFDM allows low rate data transmission to considerably greater distances compared to W-OFDM.

Time-Frequency Modulation Diversity to Combat Periodic Impulsive Noise in Narrowband Powerline Communications

Non-Gaussian noise/interference severely limits communication performance of narrowband powerline communication (PLC) systems. Such noise/interference is dominated by periodic impulsive noise whose statistics varies with the AC cycle. The periodic impulsive noise statistics deviates significantly from that of additive white Gaussian noise, thereby causing dramatic performance degradation in conventional narrowband PLC systems. In this paper, we propose a robust transmission scheme and corresponding receiver methods to combat periodic impulsive noise in OFDM-based narrowband PLC. Towards that end, we propose (1) a time-frequency modulation diversity scheme at the transmitter and a diversity demodulator at the receiver to improve communication reliability without decreasing data rates; and (2) a semi-online algorithm that exploits the sparsity of the noise in the frequency domain to estimate the noise power spectrum for reliable decoding at the diversity demodulator. In the simulations, compared with a narrowband PLC system using Reed-Solomon and convolutional coding, whole-packet interleaving and DBPSK/BPSK modulation, our proposed transceiver methods achieve up to 8 dB gains in E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> with convolutional coding and a smaller-sized interleaver/deinterleaver.

Local Utility Power Line Communications in the 3–500 kHz Band: Channel Impairments, Noise, and Standards

Future smart grid systems will intelligently monitor and control energy flows to improve the efficiency and reliability of power delivery. This monitoring and control requires low-delay, highly reliable communication between customers, local utilities, and regional utilities. A vital part of future smart grids is the two way communication links between smart meters at the customer sites and a (decentralized) command and control center operated by the local utility. To enable these two-way communication links, narrowband power line communication (PLC) systems operating in the 3-500 kHz band are attractive because they can be deployed over existing outdoor power lines. Power lines, however, have traditionally been designed for one-directional power delivery and remain hostile environments for communication signal propagation. In this article, we review signal processing approaches to model channel impairments and impulsive noise and mitigate their effects in narrowband PLC systems. We examine ways to improve the communication performance based on current and emerging standards.

Channel characterization and system verification for narrowband power line communication in smart grid applications

Narrowband power line communication systems in the frequency range below 500 kHz may play an important role in building up a smart grid. In the last few years, many efforts have been made to characterize power line networks. However, there are few guidelines for translating these results into real-life applications, such as performance comparison of different NB-PLC systems with realistic channel conditions or investigation of PLC systems considering critical transmission channels. In this article we propose a topology-independent approach that covers the channel characterization, channel emulation, and performance evaluation of PLC systems with realistic channel conditions in the laboratory. A comparison of the modem performance measured under real channel conditions with the performance obtained with the emulated channel conditions verifies the accuracy of the channel emulation and the correctness of the proposed approach.

Performance evaluation of a narrowband power line communication for smart grid with noise reduction technique

Performance of the narrowband power line communication (PLC) is significantly degraded by the impulsive noise with very large amplitudes and short durations. In practical applications, the simple memoryless nonlinearity techniques (Clipping, Blanking, and Clipping/Blanking) are often used in order to mitigate the effect of the impulsive noise. In this paper, we propose an optimal Clipping/Blanking technique for impulsive noise reduction in narrowband (9-490 kHz) PLC system. This optimal technique is based on the minimum bit error rate (BER) search. To this end, we have derived the transfer function of a typical low voltage (LV) PLC network using the common bottom-up approach and scattering matrix method. Our simulation results, in terms of BER versus signal to noise ratio (SNR), show that the proposed technique slightly improves the BER performance of the narrowband PLC system for smart grid applications and two-way communication between smart meters and utilities <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> .

A mathematical model of noise in narrowband power line communication systems

This manuscript introduces a mathematically tractable and accurate model of narrowband power line noise based on experimental measurements. In this paper, the noise is expressed as a Gaussian process whose instantaneous variance is a periodic time function. With this assumption and representation, the cyclostationary features of power line noise can be described in close form. The periodic function that represents the variance is then approximated with a small number of parameters. The noise waveform generated with this model shows good agreement with that of actually measured noise. Noise waveforms generated by different models are also compared with that of the proposed model.