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In this paper, a novel architecture of hybrid PON for smart grid is proposed by introducing a wavelength-routing module (WRM). By using conventional optical passive components, a WRM with M ports is designed. The symmetry and passivity of the WRM makes it be easily integrated and very cheap in practice. Via the WRM, two types of network based on different ONU-interconnected manner can realize online access. Depending on optical switches and interconnecting fibers, full-fiber-fault protection and dynamic bandwidth allocation are realized in these networks. With the help of amplitude modulation, DPSK modulation and RSOA technology, wavelength triple-reuse is achieved. By means of injecting signals into left and right branches in access ring simultaneously, the transmission delay is decreased. Finally, the performance analysis and simulation of the network verifies the feasibility of the proposed architecture. [ABSTRACT FROM AUTHOR]

A novel concatenated coding system for both narrowband and broadband power line communications (NB-PLC and BB-PLC) is proposed. The order of the inner and the outer codes switches from the G3-PLC standard and the interleaver is eliminated. The Error-and-erasure decoder (EED) is selected as the Reed-Solomon inner code is because the impulsive noises clearly mark the erasure positions with a threshold-based algorithm. The nonbinary convolutional outer code with vector symbol decoding (VSD) can correct longer burst errors. The results show that for BB-PLC, the bit error rate (BER) of RS (63,51) error-only (ED) with VSD is 1.5×10-5 and of EED-VSD is 9.0×10-9 at Eb/No 26 dB. For NB-PLC, the BER of ED-VSD is 7.9×10-5 and of EED-VSD is 2.2×10-8 at Eb/No 16 dB. Therefore, BER of EED-VSD is three to four orders of magnitude lower than ED-VSD. Moreover, NB-PLC reaches the desired BER around 10-7 at about 10 dB lower Eb/No than BB-PLC. [ABSTRACT FROM AUTHOR]

Microgrid has one of the essential spots in research on distributed energy system. Different electric loads can be problematic for power quality in microgrids, also micro grid can offer more options for power quality management. The distributed generation offers a feasible alternative to traditional sources of electric power for residential, commercial, and industrial application. Recent interest in the DG infrastructure is increasing globally because of its cost effectiveness. In modernized civilization, the problem of increased load demand makes necessary development in smarter infrastructure, it holds a federalized method, named smart grid. It is the combination of renewable energy sources or dispersed system with digitalized controlling elements. Dispersed system forms the distributer energy resources. In modern power systems, the power quality monitoring is a common practice for utilities. The immersion of embedded controllers decreases the risk of fault analyzing time and enhances the overall system performance. This paper presents a novel approach in dynamic estimators for islanding detection in IEEE-9 bus system with wireless communication technology. [ABSTRACT FROM AUTHOR]

In this paper, a decision tree regression (DTR)-based fault distance estimation scheme for double-circuit transmission lines is presented. Fault location is estimated using the information obtained from fault events data. The DTR was chosen because it requires less training time, offers greater accuracy with a large data set, and robustness than all other techniques like artificial neural networks, support vector machines, adaptive neurofuzzy inference systems, etc. Hitherto, DT has been used for fault detection/classification, but it has not been used for fault location. Three-phase current and voltage signals measured at one end of the line are used as inputs to a fault-location network. The proposed method does not require a communication link as it uses only one-end measurements. Signals are processed with two signal-processing techniques—discrete Fourier transforms and discrete wavelet transform. A comparative study of both techniques has been carried out to observe the effect of signal processing on the fault-location estimation method. The proposed method is tested on three test systems, namely: 1) the 2-bus; 2) the WSCC-9-bus; and 3) the IEEE 14-bus test systems. The test results confirm that the proposed DTR-based algorithm is not affected by the variation in fault type, fault location, fault inception angle, fault resistance, prefault load angle, SCC, load variation, and line parameters. The proposed scheme is relatively simple and easy in comparison with complex equation-based fault-location estimation methods. [ABSTRACT FROM AUTHOR]

There are many techniques that have been developed to reduce peak to average power ratio (PAPR) in communication systems, but very few that can be implemented without any increase in the hardware complexity of a given system. This paper presents a method of PAPR that does not require any increase in hardware complexity as it achieves its effect through modification of the already existing transmit and receive pulse shaping filters. Furthermore, this paper presents the effect that this PAPR method has on the communications system as a whole by presenting the results on linear power increase and channel capacity with and without the PAPR method. [ABSTRACT FROM PUBLISHER]

Power line communications networks (PLCNs) facilitate efficient power management, data access, and monitoring services over a home area network by using a network implementation taking advantage of the built-in power cable infrastructure. A control station with which attached user stations communicate over the power line is used to coordinate the communications process. As serious distortion and losses are incurred by signals that are transmitted across the power line, it is highly desirable to employ relay stations to support the transmission of such data flows. Yet, to date, only limited research results are available for the cross-layer synthesis and management of such a relay-aided power line communications system. In this paper, we develop and study a relay backbone synthesis algorithm (RBSA) that is used to configure the PLC network topology, allowing active source stations to efficiently transport their message flows to the control station. We also present a relay backbone synthesis algorithm under fixed-topology (RBSAF) that enables the system management mechanism to jointly activate selective relay stations and schedule their sharing of the PLC medium, when considering nonadjustable PLC network topologies. Our new computationally efficient RBSA and RBSAF schemes are proven numerically to achieve throughput rates close to the optimal solution. [ABSTRACT FROM AUTHOR]

ITU-T G.9904 standard, also known as PoweRline Intelligent Metering Evolution (PRIME), is a Power Line Communications standard for advanced metering, grid control and asset monitoring defined by the International Telecommunication Union (ITU). In this paper, an analysis about how different characteristics of the communication channel and types of noise might affect the system performance is carried out. This study is based on simulations of the PRIME physical layer using different channel characteristics and transmission parameters. The conclusions obtained are very valuable for better understanding the behavior of the ITU-T G.9904 (PRIME) standard in the field, allowing future improvements in deployment strategies and equipment design. [ABSTRACT FROM AUTHOR]

Traditionally, jamming to the wireless system is a fatal threat to the security of home area networks (HANs), which impedes the two-way data transmission between electric devices and the smart meter, and thus deteriorates the reliability of the in-home communication of Smart Grid. On the basis of this consideration, this paper incorporates the power line system into the HAN and proposes a hybrid architecture of orthogonal frequency-division multiplexing-based wireless communication and power line communication for the Smart Grid security application. With this new solution, the channel diversity of the HAN is realized, and the communication reliability is still guaranteed even when the wireless channel suffers from jamming. Simulation results validate the feasibility of the proposed hybrid architecture, and furthermore, as a receiver diversity scheme, selection combining is preferred to maximum ratio combining. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The ideal mapping technology for transmission line inspection is the airborne LiDAR executed from helicopter platforms. It allows for full 3D geometry extraction in highly automated manner. Large scale aerial images can be also used for this purpose, however, automation is possible only for finding transmission line positions (2D geometry), and the sag needs to be estimated manually. For longer lines, these techniques are less expensive than ground surveys, yet they are still expensive. UAS technology has the potential to reduce these costs, especially if using inexpensive platforms with consumer grade cameras. This study investigates the potential of using high resolution UAS imagery for automatic modeling of transmission line 3D geometry. The key point of this experiment was to employ dense matching algorithms to appropriately acquired UAS images to have points created also on wires. This allowed to model the 3D geometry of transmission lines similarly to LiDAR acquired point clouds. Results showed that the transmission line modeling is possible with a high internal accuracy for both, horizontal and vertical directions, even when wires were represented by a partial (sparse) point cloud. [ABSTRACT FROM AUTHOR]

State estimation (SE) plays an essential role in the monitoring and supervision of power systems. In today's power systems, SE is typically done in a centralized or in a hierarchical way, but as power systems will be increasingly interconnected in the future smart grid, distributed SE will become an important alternative to centralized and hierarchical solutions. As the future smart grid may rely on distributed SE, it is essential to understand the potential vulnerabilities that distributed SE may have. In this paper, we show that an attacker that compromises the communication infrastructure of a single control center in an interconnected power system can successfully perform a denial-of-service attack against state-of-the-art distributed SE, and consequently, it can blind the system operators of every region. As a solution to mitigate such a denial-of-service attack, we propose a fully distributed algorithm for attack detection. Furthermore, we propose a fully distributed algorithm that identifies the most likely attack location based on the individual regions' beliefs about the attack location, isolates the identified region, and then reruns the distributed SE. We validate the proposed algorithms on the IEEE 118 bus benchmark power system. [ABSTRACT FROM PUBLISHER]

The effectiveness of various functions in a smart distribution grid relies on a reliable communication system. These functions are normally developed based on specific automation schemes. The majority of automated fault-management schemes (AFMSs) requires a dependable communication system to accomplish their intended functions. In a smart distribution grid, the AFMSs are responsible for automatic fault detection, location, isolation, and service restoration activities. Failure to communicate among various communicating devices involved in the AFMS may have a considerable impact on the reliability of electricity service delivered to the customers. This paper aims to quantitatively evaluate the reliability impact of failure to communicate in the AFMS. A highly loaded urban distribution network equipped with AFMS is utilized for directing the quantitative reliability case studies. The study results show that the service reliability can be significantly affected if the communication system fails to operate successfully. [ABSTRACT FROM AUTHOR]

In this paper, we present the measurement methodology and results for a low voltage Power line Communications (PLC) network under different configurations. Based on the measurements, a correlation of the channel transfer characteristics to the network topology is established and a deterministic model based on two-wire transmission line theory for transverse electromagnetic (TEM) wave propagation is proposed. The channel frequency response in frequency range of 1-30MHz is determined, where the model results agree well with the measurements. [ABSTRACT FROM AUTHOR]

A single-input multiple-output-based architecture is considered to support co-channel interference (CCI) suppression processing at the receiver, where narrowband (NB) outdoor power-line communications (PLC) in the 42–89 kHz frequency band are assumed. The phantom mode (PM) in a multiconductor power transmission cable is employed for transmission, and both the PM and the differential mode (DM) are used at the receiver. Transfer functions for the PM–PM and the PM–DM modes are modeled for short-range and long-range outdoor NB PLC topologies incorporating three-path propagation using a deterministic transmission-line modeling approach. An orthogonal frequency-division multiplexing (OFDM) waveform based on the PRIME standard is used for the desired and CCI signals. Interference suppression is achieved through a zero-forcing algorithm that leverages multichannel reception and requires channel state estimates for the interference signal. Stochastic network structures are further discussed to demonstrate the average interference suppression performance. Bit-error-rate performance is estimated in the presence of interference with and without zero-forcing suppression. Results indicate that the suppression algorithm leads to a more robust interference-tolerant receiver, particularly when the relative channel responses between modes for the desired signal and the interference signal are sufficiently different. [ABSTRACT FROM AUTHOR]

Channel response and noise in the in-home power-line channel are time varying, and show periodic patterns since electric devices, which are major noise sources, synchronously run with the ac-line cycle. Using the relatively stable channel characteristic of the power line, orthogonal frequency-division multiple access (OFDMA) schemes in power-line communications (PLCs) can achieve multiuser diversity gain even in random access. In this paper, we propose a carrier-sense multiple access with a collision-avoidance (CSMA/CA) protocol for OFDMA-based broadband PLC. To achieve the maximum diversity gain, we formulate a utility maximization problem for our considered framework. Then, we solve this problem by dividing it into two subproblems. The first one divides the whole bandwidth into a certain number of subchannels appropriately, and then the second one allocates a subchannel to each node according to the channel condition. To solve each subproblem, we first consider optimal algorithms and then heuristic algorithms to overcome the complexity. Through extensive simulations, we show that our proposal greatly improves the overall system utility compared to the single-channel CSMA/CA scheme. The performance improvement of our proposal over the single channel scheme is mainly achieved by lowering collision probability and exploiting multiuser diversity. [ABSTRACT FROM AUTHOR]

The implementation of power-line communication systems requires detailed knowledge of the channel properties, such as transfer function, noise levels, and channel capacity in order to assess the services that can be provided. In this paper, the interference scenario on overhead medium-voltage power distribution lines caused by external electromagnetic (EM) fields is examined by focusing on the noise induced. The external EM fields are considered to be the main source of occurring noise and a novel method capable to calculate the corresponding noise levels is presented. The proposed method is compared to other existing models and its strengths are highlighted. The effect of the induced noise to the overall data capacity of the power-line communication channel is examined. Eventually, the influence of several parameters, such as the magnitude and direction of propagation of the external EM field, network topology, earth's EM properties, and different levels of emissions suggested by various organizations are investigated. [ABSTRACT FROM AUTHOR]

We investigate to find an efficient resource allocation algorithm among three proposed algorithms to improve the outage probability for multiple users in an indoor power-line communications system. The bit-error rate for users requiring different quality of service is considered to see whether the outage probability has improved. The suggested algorithms are shown to find the distribution of subchannels that improve the average outage probability when all users experience multipath fading time-varying channel characteristics. We compare the performance of the proposed algorithms with a conventional resource allocation algorithm and demonstrate its efficiency. Simulation results demonstrate that the performance of the greedy-algorithm-based algorithm is superior to that of the conventional algorithm in almost outage threshold ranges. [ABSTRACT FROM AUTHOR]

The paper deals with creating an indoor power line model based on random parameters. This model approximates the real parameters of the power line communication with sufficient precision. A detailed analysis of earlier and current research in power line communication modelling, especially for power line models, is described. Measurement of transmission line parameters and power line model verification follows. Based on model analysis and load impedance measurement, a mathematical description of the model is designed. A reference model for different scenarios is realized too. The last part gives the analysis of this model and simulation results. [ABSTRACT FROM AUTHOR]

Enhanced and directional transmission through a slit surrounded with grooves in a conducting plane is investigated. A boundary-value problem of electromagnetic wave scattering from a slit surrounded with a finite number of rectangular grooves on both surfaces in a conducting plane is rigorously solved based on the eigenfunction expansion, Fourier transform and mode matching method. The radiated power density and the transmission coefficient are represented in a series. Computation is performed to illustrate the transmission behaviours in terms of the groove geometry. [ABSTRACT FROM AUTHOR]

Power line communication, that is, using the electricity infrastructure for data transmission, is experiencing a renaissance in the context of Smart Grid. Smart Grid objectives include the integration of intermittent renewable energy sources into the electricity supply chain, securing reliable electricity delivery, and using the existing electrical infrastructure more efficiently. This paper surveys power line communications (PLCs) in the context of Smart Grid. The specifications G3-PLC, PRIME, HomePlug Green PHY, and HomePlug AV2, and the standards IEEE 1901/1901.2 and ITU-T G.hn/G.hnem are discussed. [ABSTRACT FROM AUTHOR]

Power Line Communication (PLC) is the response for nowadays high demand of multimedia services in domestic environment, not only for its fast and reliable transfer characteristics but also for its flexible low cost implementation, since the PLC technology uses the existing electrical network infrastructure and the omnipresent outlets throughout the home. The transfer of such a high bit rate through the mains network generates acceptable radiated emission regulated by international standards, but the increment in speed for new generation PLC may cause higher levels of emissions. This paper explains the use of the Time Reversal (TR) technique to mitigate radiated emissions from PLC systems. This method was probed experimentally in real electrical networks with excellent results: in 40% of the observations, the Electromagnetic Interference (EMI) generated by PLC transmission could be reduced by more than 3 dB, and this EMI mitigation factor could increase to more than 10 dB in particular configurations. [ABSTRACT FROM AUTHOR]

A new lower bound below the information rate transferred through the Additive White Gaussian Noise (AWGN) channel affected by discrete-time multiplicative phase noise is proposed in the paper. The proposed lower bound is based on the Kalman approach to data-aided carrier phase recovery, and is less computationally demanding than known methods based on phase quantization and trellis representation of phase memory or on particle filtering. Simulation results show that the lower bound is close to the actual channel capacity, especially at low-to-intermediate signal-to-noise ratio. [ABSTRACT FROM AUTHOR]

This paper focuses on efforts to build what policymakers call the 'smart grid,' involving 1) improved remote monitoring and automatic and remote control of facilities in high-voltage electricity transmission networks; 2) improved remote monitoring, two-way communications, and automatic and remote control of local distribution networks; and 3) installation of 'smart' metering and associated communications capabilities on customer premises so that customers can receive real-time price information and/or take advantage of opportunities to contract with their retail supplier to manage the consumer's electricity demands remotely in response to wholesale prices and network congestion. I examine the opportunities, challenges, and uncertainties associated with investments in 'smart grid' technologies. I discuss some basic electricity supply and demand, pricing, and physical network attributes that are critical for understanding the opportunities and challenges associated with expanding deployment of smart grid technologies. Then I cover issues associated with the deployment of these technologies at the high voltage transmission, local distribution, and end-use metering levels. [ABSTRACT FROM AUTHOR]

Abstract: The accelerated evolution of power systems and the associated new trends, such as Smart Grids, has stimulated the development of various approaches in handling the problems of increased electricity demands, power market (de)regulation and power systems reliability. One of the new key concepts is the virtual power plant (VPP), which represents a controllable portfolio of distributed energy resources (DERs). Such a portfolio can be operated in various modes, each with a set of unique control requirements. An open framework providing robust solution for large scale DERs integration and control is one of the key issues in Smart Grid development. This paper proposes an approach for solving this problem by utilizing standards-based power system communications, application modeling based on event-driven information services and algorithms for optimized VPP control. The applicability of the proposed technical solution is demonstrated and analyzed via simulation of the developed economic dispatch algorithm. [Copyright &y& Elsevier]

As an inherent characteristic of any distributed system, the execution and performance of distributed virtual simulations totally rely on underlay communication infrastructure and resources. The performance of such simulations is directly restricted by the communication latencies between interdependent simulation components. The high level architecture (HLA) is a framework designed with the objective of organizing these simulations through management services. However, the framework is unaware of the communication delays caused by the network distances between communicating simulation parts. These delays can result from nonplanned initial deployment or dynamic simulation changes, requiring constant load balancing. Due to the importance of balancing distributed simulations, many approaches have been designed. In order to provide a balancing system aware of the dynamic communication changes, a delay-based redistribution scheme has been designed. The scheme successfully arranges the load, but it lacks precision due to communication delay oscillations. Therefore, extensions are proposed to modify the balancing algorithm in order to avoid unnecessary, mistaken load rearrangements. In the experimental results, the delay-based scheme has been able to reduce the simulation execution time when compared with the distributed balancing scheme, and the proposed extension has been capable of increasing the precision of the balancing. [ABSTRACT FROM AUTHOR]

Electromagnetic interference, man-made noise, and multipath effects are the main causes of bit errors in power-line communication. In this paper, it is experimentally demonstrated that the power-line noise distribution is non-Gaussian below 12 MHz, and close to Gaussian in the 12–50 MHz range. The noise-amplitude distribution of each individual frequency in the spectrum is analyzed and the generalized Gaussian distribution (GGD) is introduced as a suitable noise model across the spectrum. Orthogonal frequency-division multiplexing (OFDM) with convolutional coding and soft-Viterbi decoding is adopted to design a GGD-optimal communication system. Simulations demonstrate the performance improvement offered over the Gaussian-optimal receiver. The channel simulations are verified through measurements. [ABSTRACT FROM AUTHOR]

This paper analyzes the strategies for injecting power-line communications (PLC) metering signals in secondary substations with multiple distribution transformers. The study is based on real measurements of PLC connectivity across the low-voltage sections of transformers in a representative set of secondary substations. The results show that there is not a general rule indicating the quality of the PLC channel among secondary windings of distribution transformers in a secondary substation and, consequently, there is no general solution based in pre-existing information. Following this conclusion, a strategy is defined to maximize the performance of the PLC system, based on the PRIME PLC specification. This strategy is based in the use of a base node connected to one of the low-voltage panels, together with auxiliary nodes connected to the remaining low-voltage panels, and interconnecting all of the elements (base node and auxiliary devices) by means of non-PLC technologies. [ABSTRACT FROM AUTHOR]

A complete model of a power-line communication (PLC) system on a medium-voltage (MV) network in the case of a line-shield configuration is presented in this paper. An MV cable model in a line-shield configuration is considered together with the power transformers, the signal coupling networks, and the receiving and transmitting line coupling interface of a ST7540 FSK power-line transceiver. Simulations of the complete model of the system under consideration have been carried out for different line lengths, with and without power transformers and derivation branches. The model is validated by experimental tests performed in the laboratory. The measured results confirm the reliability of the model. [ABSTRACT FROM AUTHOR]

Passband and baseband transmissions are two competing transmission schemes for power-line communication (PLC) orthogonal frequency-division multiplexing (OFDM) systems. The advantage of the former is that it is simpler to implement for digital circuits as it needs the half-size inverse fast Fourier transform/fast Fourier transform. As will be shown, there are synchronization errors, such as carrier frequency offset (CFO) and sampling frequency offset (SFO) that degrade the performance of passband transmission. On the other hand, baseband transmission is expected to be less complex in an analog circuit implementation and to be affected by only SFO, since it does not need up-down conversion. Both CFO and SFO are caused by the frequency errors of the reference clocks in the transmitter and receiver. In this paper, signal-to-interference-plus-noise ratios and capacities are considered in comparing the effects of synchronization errors in passband and baseband transmissions. The results indicate that the performance degradation of passband transmission is almost the same as that of baseband transmission in the presence of synchronization errors. [ABSTRACT FROM AUTHOR]

The popularity of orthogonal frequency-division multiplexing (OFDM), or more precisely cyclic prefix–OFDM (CP-OFDM), which is indeed totally justified by its intrinsic properties, makes the breakthrough of other modulation techniques difficult. In the case of power-line communication (PLC) networks, windowed OFDM was the retained modulation in the HPAV specification, the current standard implemented in most of the recent in-home PLC systems. But another modulation, called OFDM/OQAM, has been recently presented as a viable alternative to the classical OFDM. Now, the results of our comparisons between the two modulations schemes, done in terms of capacity and throughput, aim at showing that the baseband version of OFDM/OQAM, named in short Hermitian symmetric–OQAM (HS-OQAM), is a serious candidate to efficiently improve data rates in PLC networks. [ABSTRACT FROM AUTHOR]

A smart-metering system is a system that meters electricity, gas, and water consumption and manages their supply by controlling measuring devices remotely. Power-line communication (PLC) does not require a separate communication line and can be easily installed by utilizing power-line infrastructure. PLC also allows users to easily connect measuring devices to the PLC network by plugging the power cord into an electrical outlet. Therefore, a smart-metering system over PLC has been considered as one of the most appropriate technologies for meter reading and automatic control, which are essential in realization of a smart grid. We propose a secure smart-metering protocol including: 1) key materials generation and provisioning to devices without exposure; 2) initialization to authenticate devices in the network and share keys between devices before exchanging data, (3) secure transmission of meter-reading data, and 4) revocation management to handle discarded devices from the network. Especially, our protocol provides strong authentication of devices and data: It prevents a single point of failure by adopting secret sharing through multiple certificate authorities. It also reduces the risk of denial-of-service attacks on the server by hop-by-hop authentication for data transmitted from terminal nodes to the server. [ABSTRACT FROM AUTHOR]

Various principles and algorithms of the wide-area protection system (WAPS) have been developed so far. However, there are few discussions about the foundation in implementation of the WAPS (i.e., the corresponding communication system and its reliability). This paper presents a reliability evaluation method for the communication systems in wide-area protection (CSWAP). First, system structure and characteristics of the CSWAP are hierarchically analyzed from layers of substation communication, regional communication, and wide-area communication. The reliability model based on fault-tree analysis for each layer is then established. Second, three reliability indices are introduced. Third, an index calculation method based on sequential Monte Carlo simulation is proposed, which adopts the idea of static handling, takes into account faults and repairs of components, and overcomes several disadvantages of analytical methods, such as complicated calculation and weak adaptability. Finally, a case of the CSWAP in the IEEE 11-bus system is analyzed to summarize the effect factors of its reliability and demonstrate the validity of the proposed method. The results show that the models have definite physical significance, and the proposed method is helpful for quantitative reliability assessment, influencing factor analysis, and weakness identification. [ABSTRACT FROM AUTHOR]

In this paper a novel approach based on Radial Basis Function Network (RBFN) is proposed for fault identification and zone classification in extra high tension (EHT) lines for high speed protection using terminal line data. The proposed method utilizes the current and voltage signals measured online at the line terminals for generating the training patterns for training the RBFN and with this approach, the faulty phase identification and fault zone classification could be achieved very effectively. The effectiveness of the proposed relay model is established by comparing its performance with an existing practical numerical line protection relay. [ABSTRACT FROM AUTHOR]

The tapped lines are usually used to supply small communities or facilities in sparsely populated and isolated rural areas. Locating faults in such lines are difficult regarding the effect of infeed/outfeed current from tapped lines as well as reactance effect. To deal with mentioned problems a novel one ended fault location algorithm is presented in this paper, which applies generalized models of fault loop voltage and current to formulate the fault location algorithm. The derived algorithm has a very simple first-order formula and does not require knowledge of data from other ends. This feature becomes more significant in the case of isolated rural areas where it may not exist proper communicational link to exchange data with main ends. The methodology is based on calculating the current distribution factor and estimating the current from two other ends, so it measures the exact distance from fault locator to fault point. The result of simulation for three ended transmission line verifies the high accuracy of the method with regard to various equivalent source impedances, fault resistances and locations as well as fault types. Finally the algorithm expanded to multi-tapped lines and the results demonstrate the high accuracy and robustness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

We propose a bottom-up power-line communication (PLC) channel simulator for networks that deploy multiconductor cables and enable establishing a multiple-input multiple-output (MIMO) communication link between two nodes. We show that the fundamental multiconductor transmission-line (MTL) relations are a matrix form extension of the two-conductor transmission-line equations, and that they allow the application of the voltage ratio approach for the computation of the channel transfer function (CTF). Thus, any complex network can be remapped to obtain a simple representation in terms of MTL elementary units. Then, the MIMO CTF is computed as the product of the insertion loss of the units. We discuss the analytical computation of the per-unit-length (p.u.l.) parameters for two electrical cables, that we refer to as symmetric and ribbon. Further, we propose using an improved cable model for ribbon cables that accounts for the dielectric nonuniformity. We report the comparison between simulation and experimental measures for two test networks. The results are in good agreement. This validates the proposed MIMO PLC channel simulation approach. [ABSTRACT FROM AUTHOR]

Multipath phenomenon lies in the heart of power-line communication and leads to the reception of multiple replicas of the transmit signal at the receiver through various paths. Statistical knowledge of arriving paths is essential in order to evaluate performance of communication systems. First arriving path is distinguishable from the other paths in the sense that it experiences less reflection and less attenuation along its propagation path, giving it a favorable position regarding detectability. In this study, statistics of the first arriving path are initially investigated. It is shown that the first arriving path can be defined with log-Normal probability density function. It is seen that the mean of the approximating log-Normal variable decreases with an increasing number of branches between transmitter and receiver while its variance increases. The same finding is also observed when the maximum number of branches that extend out a branching node is increased. Although statistics of the first arriving path are emphasized more, statistical characterization of the other paths is discussed as well. Infinite bandwidth assumption in which all paths arriving at the receiver can be resolved is considered in the analysis. However, a brief discussion on the impact of finite bandwidth is given. [ABSTRACT FROM AUTHOR]

Bandwidth constraints could have an adverse impact on the flexible AC transmission system (FACTS) controllers relying on signals communicated from distant locations. An observer-driven system copy (OSC) architecture is adopted here to deal with low data rates caused by the limited bandwidth availability. The basic idea is to use the knowledge of the nominal system to approximate its actual behavior during the intervals when data from the remote phasor measurement units (PMUs) are not available. This is corrected whenever the most recent states are obtained from the reduced-order observer at the PMU location. The closed-loop behavior deteriorates as the operating condition drifts away from the nominal. Nonetheless, significantly better response is achieved under limited bandwidth availability compared to the conventional approach of communicating the measured outputs. The deterioration is quantified in terms of the difference between the nominal and the offnominal condition. [ABSTRACT FROM AUTHOR]

With the decision to construct the smart grids around China, the power line communications (PLC) on the low-voltage (LV) distribution networks have become one of the potential technologies to commute the information between the end users and the power provider. In order to provide communications services with different priorities under the smart grids environment, it is a must to design a completely new PLC system with variable information rate, which means understanding of the LV PLC channel characteristics become vital. This paper presents the measurement results of channel properties of LV PLC systems after giving a general overview of the topologies for the typical LV distribution networks in China. The testing results show that the main reason influencing the reliable communication of high-speed data of power line is the attenuation of the high-frequency signal, which exhibits more obviously in the branch of power line. It is almost impossible to use the frequency range from 10 to 20 MHz for the reliable communications from distribution transformer to end user, so it must be solved with the aid of such means as the repeater and the modulation schemes. Considering the signal's attenuation, the lower frequency range from 2 to 10 MHz is more suitable for the high-speed data access system. Based on the general topologies of the LV distribution networks, a new method with the help of the reflection matrix based on the multiconductor transmission line theory is proposed to model the channel transfer functions, taking into account of the source inner impedance matrix. The simulation results fit the measured data quite well and verify the feasibility of the proposed modeling scheme. [ABSTRACT FROM AUTHOR]

To overcome the shortcomings in the process of electric power operators' communication by using the telephone, such as "being unable to save process of information", "tending to shield information" and "providing just single input method", an operators' multi-communication medium interaction platform based on internet is established on the IM and BBS principles. There are instant communication system and information issuing and query system in this platform aiming at scheduling characteristics of electric power system. The principles and realizations of the systems are discussed. The interaction platform has the following characteristics: supporting the text-input interaction, providing a variety of interaction tools, allowing the interaction with more operators, combining with Chinese scheduling model, reducing the burden of operators and so on. Compared with telephone, this platform can save process of information, avoid shielding information, serve multiple operators' communicating simultaneity and offer more communication methods, etc. [ABSTRACT FROM AUTHOR]

Abstract-In this paper, a new technique is proposed for blind estimation of carrier frequency offset (CFO) in wireless orthogonal frequency-division multiplexing (OFDM) systems with constant-modulus constellations. The proposed scheme is based on the assumption that the channel slowly changes in the time domain with respect to the OFDM symbol duration. As a consequence, the channel effect on a given subcarrier in two consecutive OFDM symbols is approximately the same. Based on this assumption, a cost function is derived such that the power difference between all subcarriers in two consecutive OFDM symbols is minimized. Using Monte Carlo simulation, we demonstrate that the proposed scheme has superior performance in both static and time-varying frequency-selective fading channels. The proposed system can rapidly and accurately estimate the CFO using only three trial values, given that the CFO is less than half of the subcarriers' frequency spacing. [ABSTRACT FROM AUTHOR]

Space-time block coded (STBC) single carrier (SC) transmission was extended in a distributed fashion for practical implementation of user cooperation. However, STBC was designed under the assumption that the channel is static over the duration of a space-time codeword. Thus, the distributed STBC SC system suffers from the time selectivity of wireless fading channels. To achieve a reliable performance over fast fading channels, we propose a distributed space-frequency block coded (D-SFBC) SC transmission. This paper analytically compares the performance of these two distributed SC transmissions over fast fading environment. For evaluation of mean square error (MSE) over fast fading channels, we present a channel model that captures the time-varying nature of wireless channels. It gives an insight into the characteristics of inter-carrier interference and simplifies the evaluation of MSE. Using this model, it is proven that the D-SFBC SC transmission outperforms the D-STBC SC transmission when there exists a severe Doppler spread. Simulation results are also provided to validate our analysis and to compare two distributed single carrier transmission schemes. [ABSTRACT FROM AUTHOR]

Control of power systems relies on the availability and quality of sensor measurements. However, measurements are inevitably subjected to faults caused by sensor failure, broken or bad connections, bad communication, or malfunction of some hardware or software. These faults, in turn, may cause the failure of power system controllers and consequently, severe contingencies in the power system. To avoid such contingencies, this paper presents a sensor evaluation and (missing sensor) restoration scheme (SERS) by using auto-associative neural networks (auto encoders) and particle swarm optimization. Based on the SERS, a missing-sensor-fault-tolerant control is developed for controlling a static synchronous series compensator (SSSC) connected to a power network. This missing-sensor fault-tolerant control (MSFTC) improves the reliability, maintainability, and survivability of the SSSC and the power network. The effectiveness of the MSFTC is demonstrated by a real-time implementation of an SSSC connected to the IEEE 10-machine 39-bus system on a Real Time Digital Simulator and TMS320C6701 digital signal processor platform. The proposed fault-tolerant control can be readily applied to many existing controllers in power systems. [ABSTRACT FROM AUTHOR]

A novel design idea for frequency-locked-loop (FLL) discriminator is proposed, under the premise of changing rate of frequency-rate in returned signal is rather small, the signal after quadrature-demodulation can be regarded as a linear frequency-modulated (LFM) signal, by using estimations of its initial frequency and frequency rate as error control quantities of FLL, FLL's toleration ability to high dynamic signals is greatly enhanced. FFT discriminator and dot-product cross-product discriminator are exploited by FLL discriminator at different phase of frequencytracking, thus wide discriminate range and high discriminate precision are acquired. An effective and simple abnormal value elimination method is presented especially for the abnormal discriminate value under extremely-low-SNR. Simulation results applying the discriminator to a FLL showed that FLL can tolerate rather high dynamics and tracking accuracy of frequency achieved 0.2 Hz even under a SNR as low as --40 dB, which verified the validity of above ideas. [ABSTRACT FROM AUTHOR]

The paper presents an energy approach based on controllability and observability gramians for the optimal location of controllers/sensors in large-scale power systems. This approach consists of solving a stochastic optimization problem based on scenarios reflecting various operational situations (load changes, line tripping. . . ). This approach could be regarded as part of a structural optimization procedure aiming at defining some new control systems in the context of security improvements of large-scale power systems. Application to the "Two-area power system" gives very promising results. [ABSTRACT FROM AUTHOR]

This paper analyzes three types of interleavers: block, golden and golden relative to determine their performance in of low voltage power line channel. The model of noise given by Middleton is used for the simulation of the low voltage power line channel and the algorithm used to generate Gaussian noise is based on the Box-Muller method. The performance of interleavers block, golden and golden relative is compared in relationship to the length of the words versus the signal to noise ratio. The error bit by word versus signal to noise ratio is compared also. The codification of line used is no return to zero. It is concluded that the interleavers of golden has the best performance, thus it can be used in data transmission in low-voltage power line, reducing errors consecutive bits produced by impulse noise. [ABSTRACT FROM AUTHOR]

This paper presents a computational efficient distributed circuit model for broadband power-line communications (PLC) in the frequency range of 1 to 30 MHz. The model is derived based on the full wave approach and it takes into account the mutual coupling between the power lines, the effect of the ground plane and the discontinuity along the lines (e.g., PLC line bent with an arbitrary angle and the terminations). To derive the distributed circuit model, the PLC lines were divided into many small elements with each element treated as a dipole antenna. The electromagnetic fields along the power lines were considered as the summation of the field of these elements solved by the boundary conditions at the air-conductor and the air-ground interfaces from which the explicit expressions of the per-unit-length circuit parameters were obtained. To check the accuracy of our proposed model, the current distributions along PLC lines excited by an external source were determined using the chain matrix approach. Common-mode current is calculated with the transmission line equations. The agreement between our theoretical calculations with the experimental data as well as with full wave approach shows the validity and applicability of our proposed model for such PLC applications. [ABSTRACT FROM AUTHOR]

Ergodic chaotic parameter modulation (ECPM), based on a spreading chaotic dynamic system, has shown promise for, power-line communications (PLC) due to its simplicity in receiver design. Alternatively, direct sequence spread-spectrum modulation is known for its strengths in its resistance to multipath fading and some inherent narrowband interference suppression capability and thus is a logical choice for the difficult power-line environment. Previous work has evaluated the general analytical solution for the signal-to-noise ratio (SNR) for these techniques assuming an idealized implementation. This study provides a more detailed evaluation of the SNR as a function of gain factor, individual noise components and other issues that could reduce the overall effectiveness of the PLC technique. Improvements in symbol error probability with an increase in respective gain factors for various SNR conditions are shown. This study facilitates a direct SNR comparison of two modern PLC techniques in a noise-limited channel not previously performed. [ABSTRACT FROM AUTHOR]

Based on the empirical data obtained from two typical 10-kV power networks, the transmission properties of the 10-kV power line channel are investigated using the transmission line model. The frequency range is over 40 kHz-1.5 MHz. Our results show: 1) the power attenuation through the channel is about 20-25 dB/km when the channel does not have a branch and 2) the channel is time dispersed. In the frequency domain, the amplitude response is frequency selective while the phase response is linear. In the time domain, the impulse response shows a delay spread. The rms delay spread and the coherence bandwidth are in correlation with the network structure, and the corresponding values are on the order of 10 µs and 10 kHz. 3) The narrow fading of the channel follows Nakagami-m distribution. The channel is varying weakly with respect to time. When the data rate is up to kbps, the channel can be regarded as time invariant. [ABSTRACT FROM AUTHOR]

Low-voltage indoor triplex cables aimed primarily for residential power circuits are currently being used also for high-frequency applications. The propagation properties of such cables can only be established once cable natural parameters have been determined. However, due to the fact that cable conductors are very closely spaced, such parameters must necessarily be determined by numerical modeling. In this work, cable capacitances are evaluated by taking conductor proximity effects into account. Accurate results, obtained using a harmonic expansion method, are compared with approximations currently in use. Theoretical results are validated experimentally. [ABSTRACT FROM AUTHOR]

The impulsive noise and multipath effects are the main reasons to cause bit errors in power line communications. In this paper, the bit error rate (BER) performance of the orthogonal frequency division multiplexing (OFDM) system under the impulsive noise and multipath effects are theoretically analyzed in terms of closed form formulas. Through the analysis, it is shown that OFDM can mitigate the adverse effect of the impulsive noise and only the heavily disturbed impulsive noise will interfere the BER performance of the OFDM system. It is also shown that the adverse effect of multipath is more serious than that of impulsive noise. In this paper, the guard interval is used to improve the BER performance of the OFDM system. As the longer guard interval is inefficient in using the signal power, the optimum guard interval that can achieve the best BER performance is studied. [ABSTRACT FROM PUBLISHER]