Characteristics Of Power Lines Research Articles

Synthesis of the Spatial Arrangement of Magnetic Field Sensors for Active Magnetic Field Shielding Systems of Overhead Power Lines

The purpose of the work is to develop a synthesis method for the spatial and angular arrangement of magnetic field sensors in order to ensure maximum efficiency of a robust system for active shielding of the magnetic field generated by overhead power lines, and to reduce the sensitivity of the synthesized system to initial uncertainties in changes in the level of the initial magnetic field, as well as system parameters while working. To achieve this goal, the spatial location coordinates and angular position of all magnetic field sensors, controller parameters, and gain vector for the compensating windings are determined. A synthesis of the spatial location and angular position of magnetic field sensors is created to solve a minimax vector optimization problem in which the vector objective function is calculated based on the Biot-Savart’s law. Solution of the minimax vector optimization problem, calculated on the basis of optimization algorithms for a multi-swarm of particles from Pareto-optimal solutions, taking into account the parameters of binary relations. Significant results obtained on the basis of the developed synthesis method are the effectiveness of a robust active shielding system for magnetic fields generated, as a consequence, by power lines with a synthesized spatial arrangement and angular position of magnetic field sensors obtained in the process of theoretical and experimental research. The significance of the results lies in the fact that practical recommendations are given for the reasonable choice of spatial location and angular position of magnetic field sensors, the spatial arrangement of shielding windings of a robust magnetic field shielding system for various characteristics of power lines.

Novel Rotated Virtual Synchronous Generator Control for Power-Sharing in Microgrids with Complex Line Impedance

Virtual synchronous generator (VSG) control is based on the fact that the line impedance in a microgrid is highly inductive. This assumption was made due to the emulation of the stator winding of an electrical machine. This concept can affect the controllability of a microgrid with complex line impedance, generating deviations in the chosen operation point. To overcome this issue, additional techniques must be implemented. This paper describes a novel mathematical approach that uses the power line characteristics in a microgrid to rotate the power control reference frame and proposes a new control method called a “Rotated Virtual Synchronous Generator” (RVSG). This RVSG control approach integrates the effect of complex impedance on the microgrid’s operation and adjusts the reference frame accordingly to improve the system’s stability and performance. The use of this proposed mathematical approach in microgrids allows the further emulation of virtual inertia in microgrids that lack inertia. Finally, a comparison between RVSG control and the classical virtual synchronous generator method is carried out to show that it allows the improvement of the transient power response, power quality, stability, and performance, mainly in microgrids with complex line impedance.

Autonomous Point Cloud Segmentation for Power Lines Inspection in Smart Grid

LiDAR is currently one of the most utilized sensors to effectively monitor the status of power lines and facilitate the inspection of remote power distribution networks and related infrastructures. To ensure the safe operation of the smart grid, various remote data acquisition strategies, such as Airborne Laser Scanning (ALS), Mobile Laser Scanning (MLS), and Terrestrial Laser Scanning (TSL) have been leveraged to allow continuous monitoring of regional power networks, which are typically surrounded by dense vegetation. In this article, an unsupervised Machine Learning (ML) framework is proposed, to detect, extract and analyze the characteristics of power lines of both high and low voltage, as well as the surrounding vegetation in a Power Line Corridor (PLC) solely from LiDAR data. Initially, the proposed approach eliminates the ground points from higher elevation points based on statistical analysis that applies density criteria and histogram thresholding. After denoising and transforming of the remaining candidate points by applying Principle Component Analysis (PCA) and Kd-tree, power line segmentation is achieved by utilizing a two-stage DBSCAN clustering to identify each power line individually. Finally, all high elevation points in the PLC are identified based on their distance to the newly segmented power lines. Conducted experiments illustrate that the proposed framework is an agnostic method that can efficiently detect the power lines and perform PLC-based hazard analysis.

Hybrid Power Line/Wireless Systems: Power Allocation for Minimizing the Average Bit Error Probability

This paper investigates power allocation for minimizing the average bit error probability (BEP) in hybrid communication systems, more specifically hybrid power line/wireless systems (HPWSs). In this regard, a brief discussion of HPWSs is presented in order to point out the complementary characteristics of power line and wireless media. By considering orthogonal frequency-division multiplexing and maximal-ratio combining, optimization problems associated with the minimization of the average BEP in hybrid communication systems are formulated under two distinct transmission power constraints, called sum power and sum power-channel constraints. For both constraints, it is demonstrated that at most one medium should be used for data transmission over subchannels with the same index in order to minimize the average BEP in hybrid communication systems. Based on this finding, power allocation algorithms are derived for this purpose in HPWSs. Numerical analyses are then used to validate the proposed algorithms by comparing them with interior-point-based power allocation algorithms. In addition, performance comparisons show the advantage of the proposals over alternative algorithms from the literature, including previous algorithms proposed for maximizing the achievable data rate.

Channel Impulse Response Multilevel Quantization for Power Line Communications

Physical layer security (PLS) has become a popular topic in the research community as a complement to traditional security schemes. Particularly, by taking advantage of the channel’s symmetry, a robust ecosystem of security applications has developed in wireless communications. However, in power line communications (PLC), the general lack of channel symmetry has limited and hampered the development of physical layer techniques. In this paper, we address the cited constraint, by deriving a symmetric virtual channel impulse response (CIR) from the corresponding asymmetric PLC channel state information (CSI). In view of this, we propose a low-complexity and, to the best of our knowledge, the first CIR multilevel quantization algorithm that can be used in various PLC applications. While we contextualize our solution within the PLS domain, it has a wide applicability. Specifically, we start by analyzing the PLC channel path delays reciprocity, its relationship with topology changes, and its independence from all other power line characteristics. Then, the quality and viability of the proposed scheme are quantified, by comparing the bit mismatch rate (BMR) with its one-level quantization counterpart. The simulation results, under different topologies, confirm the performance of the proposed approach that can reduce the BMR by at least three orders of magnitude with respect to the one-level quantization, for noise levels below 90 dBuV. Finally, we conclude the paper by showing a few applications of the proposed solution and highlighting some future research directions.

Impulsive Modelling of Noise for OFDM Systems in Power Line Communication: A Necessity or a Redundant Task?

In Power Line Communication, variations in the characteristics of power lines and additive noise reduce the efficiency of Orthogonal Frequency Division Multiplexing (OFDM), and that makes channel estimation essential. The earlier estimation techniques in the literature assume channel noise is Gaussian as in the wireless communication, whereas the recent ones model the corrupted noise more realistic, impulsive, which results in complicated receivers. This study judges the need of impulsive noise modelling and complex receivers. The performances of two Maximum A-Posteriori (MAP) channel estimators proposed for additive Gaussian noise and impulsive noise are compared under impulsive noise. The channel data used in the simulations is taken from the literature and impulsive noise is modelled by Middleton Class A distribution. The results show that the MAP estimator, which assumes Gaussian noise instead of impulsive, has better performance. The MAP estimator which assumes impulsive noise has a satisfactory performance under weak impulsive noise and low Signal to Noise Ratio (SNR) only, otherwise its performance is low, close to Maximum Likelihood estimator performance. The estimator designed for Gaussian noise has a better performance even under heavy impulsive noise and this distinction is clearer for low SNR cases.

Childhood leukemia risk in the California Power Line Study: Magnetic fields versus distance from power lines

Pooled analyses have suggested a small increased risk of childhood leukemia associated with distance and with exposure to high magnetic fields from power transmission lines. Because magnetic fields are correlated with distance from lines, the question of whether the risk is due to magnetic fields exposure or to some other factor associated with distance from lines is unresolved. We used data from a large records-based case-control study to examine several research questions formulated to disentangle the relationships among magnetic fields, distance from high voltage lines, and childhood leukemia risk. In models examining an interaction between distance and magnetic fields exposure, we found that neither close proximity to high voltage lines alone nor exposure to high calculated fields alone were associated with childhood leukemia risk. Rather, elevated risk was confined to the group that was both very close to high voltage lines (<50 m) and had high calculated fields (≥0.4 μT) (odds ratio 4.06, 95% CI 1.16, 14.3). Further, high calculated fields (≥0.4 μT) that were due solely to lower voltage lines (<200 kV) were not associated with elevated risk; rather, risk was confined to high fields attributable to high voltage lines. Whilst other explanations are possible, our findings argue against magnetic fields as a sole explanation for the association between distance and childhood leukemia and in favor of some other explanation linked to characteristics of power lines.

High-voltage overhead transmission lines and farmland value: Evidences from the real estate market in Apulia, southern Italy

The construction of high-voltage overhead transmission lines on farmland implies a permanent easement, involving expropriation of land and depreciation of the remaining farm area. The Italian system operator should pay compensation for both aspects, but recognizes only the former. Therefore, landowners often appeal to the law courts and claim compensation for the depreciation of the entire non-occupied area, often obliging the system operator to pay substantial amounts. This delays the provision of new power lines and increases their respective costs.In order to verify the correctness of the modus operandi by the system operator and landowners, a study was carried out into the impact of several characteristics of power lines on farmland value in northern Apulia, south Italy. The results highlighted that the area occupied by plinths and cabins, the height of towers and the type of intersection were the main sources of depreciation, which varies depending on the crop. Moreover, depreciation on the residual area exists, but only involves two narrow strips of land on either side of infrastructure. Finally, it is not constant, but tends to decrease rapidly as the distance from the infrastructure increases, and zeroes at 30–70 m from the power line.

A REVIEW ON PLC MODELING TECHNIQUES FOR RESIDENTIAL NETWORKS

This paper discuss about the recent developments in the field of power line communication for residential networks. In the recent past, various techniques have been developed to model the power line channel. However, none of these techniques could realize a power line channel accurately. Measurement campaigns were also undertaken across the world to understand the dynamic behavior and statistically analyze the power line channel. The major complexity in PLC is the difference in the power line characteristics across the world.

AUTOMATIC RAILWAY POWER LINE EXTRACTION USING MOBILE LASER SCANNING DATA

Research on power line extraction technology using mobile laser point clouds has important practical significance on railway power lines patrol work. In this paper, we presents a new method for automatic extracting railway power line from MLS (Mobile Laser Scanning) data. Firstly, according to the spatial structure characteristics of power-line and trajectory, the significant data is segmented piecewise. Then, use the self-adaptive space region growing method to extract power lines parallel with rails. Finally use PCA (Principal Components Analysis) combine with information entropy theory method to judge a section of the power line whether is junction or not and which type of junction it belongs to. The least squares fitting algorithm is introduced to model the power line. An evaluation of the proposed method over a complicated railway point clouds acquired by a RIEGL VMX450 MLS system shows that the proposed method is promising.

AUTOMATIC RAILWAY POWER LINE EXTRACTION USING MOBILE LASER SCANNING DATA

Abstract. Research on power line extraction technology using mobile laser point clouds has important practical significance on railway power lines patrol work. In this paper, we presents a new method for automatic extracting railway power line from MLS (Mobile Laser Scanning) data. Firstly, according to the spatial structure characteristics of power-line and trajectory, the significant data is segmented piecewise. Then, use the self-adaptive space region growing method to extract power lines parallel with rails. Finally use PCA (Principal Components Analysis) combine with information entropy theory method to judge a section of the power line whether is junction or not and which type of junction it belongs to. The least squares fitting algorithm is introduced to model the power line. An evaluation of the proposed method over a complicated railway point clouds acquired by a RIEGL VMX450 MLS system shows that the proposed method is promising.

Robust Fuzzy Control for De-icing Robot Manipulator based on Sliding Mode Technique

Flexible mechanical characteristics of power lines and poor conditions induce difficulties for the precise trajectory tracking control of a de-icing robot with an n-link robot manipulator. A robust fuzzy control based on adaptive sliding mode technique for precise trajectory tracking of a deicing robot is presented in this paper. The global controller is composed of three terms. The fuzzy inference system is utilized to approximate the unknown system structure and parameters, and the adaptive sliding mode control term is adopted to counteract the perturbations of the de-icing robot system. Meanwhile, a compensation term is designed to compensate the modeling errors, the approximation errors and others. The online adaptive laws of the controller parameters are derived via Lyapunov function method to guarantee the system stability. Finally, the experimental apparatus is provided to verify the correctness and effectiveness of the proposed scheme. Experimental results show that this scheme has more fast dynamic response and higher tracking precision than traditional feedback linearization control, and removes the control chattering phenomenon which is a main disadvantage of conventional sliding mode control in terms of robustness. Keywords: De-icing robot, fuzzy control, sliding mode control, uncertain nonlinear system.

Broadband over Power Line (BPL): An Emerging Technology for Bangladesh

Broadband over Power Line (BPL) is an alternative means of providing high-speed Internet access, Voice over Internet Protocol (VoIP), and other broadband services to homes and businesses by using the existing medium voltage (MV) and low voltage (LV) power lines. This paper provides a comprehensive understanding about BPL with its implementation prospects. In this context, the existing power grid infrastructures are discussed elaborately. BPL system functionality with its components and its benefits over other access technologies is also pointed out. Implementation scenarios for various deployment options are illustrated here. The different implementation challenges for BPL system, such as the characteristics of power lines, attenuation problem, noise, potential interference with the other radio frequencies are also presented with their remedies. Comparative analysis between several broadband access technologies shows the feasibility of BPL deployments all over the world.

Triple-Network Convergence of Power Lines as a Transmission

By analyzing the transmission characteristics of power line and the orthogonal frequency division multiplexing (OFDM) communication system, the concrete scheme of triple-network convergence based on the transmission medium of power line was given out. The Methods of constructing the intelligent triple-network convergence based on the OFDM technology, the system model and the hardware realization methods of power line communication system based on the DSP chip were given. Combining the latest OFDM technology, the channel coding technology and the modulation and demodulation technology in the power line communication system were researched, and new technology to high-speed data transmission on the radio channel was achived. And the simulation results of system design was given.

On the Transient Response and the Frequency Analysis of Transmission Line Towers

This paper proposes an approach to the study of the transient response and the frequency characteristics of power lines' towers, when subjected to lightening strikes. It starts with dividing the nonuniform line representing the tower into a number of sections. From the usually known dependence of the tower's characteristic impedance on the vertical coordinate and the application of a recursive circuit reduction technique, an s-domain expression for the tower input impedance can be obtained. This expression, followed by the numerical Laplace inversion, is utilized for the determination of the tower's transient response. The impedance expression can be also used to determine the tower's resonance frequencies. This was used to demonstrate some potentially critical situations in which the tower is hit by lightning strikes comprising multiple current pulses. The validity of the proposed technique is demonstrated by comparing the achieved results with those already available in the literature for the same case studies.

KNN–Q(λ) algorithm-based line-grasping control of a de-icing robot

Flexible mechanical characteristics of power lines and the complex environment induce difficulties for line-grasping control of a de-icing robot when crossing obstacles. An online learning supported line-grasping control method for a de-icing robot based on the KNN– Q( λ) algorithm is presented in this paper. The proposed KNN– Q( λ) algorithm combines reinforcement learning with the k-nearest neighbor algorithm to perceive continuous states and uses a collective decision making mechanism in the action selection process to output continuous actions. Benefiting from the ability of online learning, the KNN– Q( λ)-based line-grasping control method may tolerate possible robot model errors, robot arm attitude errors and environment interferences to line-grasping control. Simulation experiment results show that as a continuous-states-continuous-actions reinforcement learning algorithm, the KNN– Q( λ) algorithm outperforms traditional reinforcement learning algorithms for the application of line-grasping control in terms of leaning rate and robustness.

Review of Channel Characterization for Power Line Communications

The power line communication (PLC) channel has been a transmission medium that enables to transfer high-speed digital data through the classical electrical wires. Channel characteristics of power lines are very important for communications systems design. In order to get the suitable model for power line communications analysis and improve the PLC communication quality, researchers do lots of study about the PLC channel characterizations based on actual measurement and theoretical analysis. This paper reviews the conclusions of recent studies, summaries the characteristics of PLC channel for medium voltage power lines and low voltage power lines. The further research is also put forward.

Transmission characteristics simulation on power line communications

AbstractIn power line communications (PLC) systems, medium‐ and low‐voltage power lines are used as a communication network. Reflections caused by impedance mismatches degrade the transmission characteristics in the frequency range for PLC systems. If transmission characteristics of power lines can be estimated by simulation, the design and operation of PLC networks will be efficient. This paper proposes a method of simulating the transmission characteristics of a channel model between a transmitter and a receiver installed on a distribution network. The propagation characteristics of PLC signals of each distribution facility are described using two‐port networks. A channel model is automatically generated from the combination of component models along the topology of the distribution network and the transmitter and receiver locations. The proposed method was validated using field data and was proved to be effective. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(3): 46–55, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10233

Characteristic Evaluation of Power Line with Lamp Switch Branch for Power Line Communication

In this paper, we calculated balance-unbalance conversion factor, common mode current and leaked electric field in the power line with branch in high frequency by using the method of moments. A power line in general domestic has diverged variously. Especially, we paid attention to the lamp switch branch, in which only one line of the pair line is lengthened to make an ON/OFF switch. Furthermore, in order to improve the calculation accuracy, we measured lamp switch equivalent circuit for MHz band by the impedance analyzer. In order to confirm the validity of the calculation, we measured these characteristics of the same model beforehand, and compared the measurement value with the calculation value. As the result, the calculation and measurement values are approximated well in these characteristics. And the characteristics of power line with lamp switch branch in the condition of switch on and off are cleared up by these calculation and measurement.

Approximate computation of high-frequency characteristics for power line with horizontal disposition and middle-phase to ground coupling

Paper presents an approximate computation of high-frequency high-voltage power-line characteristics: amplitude, phase and group delay characteristic. Analytical approximate formulae are derived for the power line with three conductors in horizontal disposition and middle-phase to ground coupling. Expressions derived from modal analysis and detailed computation methods allow analysis of power-line high-frequency characteristics, like oscillations in high-frequency characteristics due to reflection on the power line. Such formulae are available in the literature for modal propagation functions and power-line amplitude characteristic. However, this paper also treats power-line phase characteristic and group delay important for digital communication systems design that are not thoroughly investigated in analog communications. The paper shows that nonlinearities in the phase characteristic due to reflection are determined with Hilbert transform of the amplitude characteristic.