Traveling-wave Technique Research Articles

A Study on Fault Localization Method of Three-Terminal Multi-Section Overhead Line–Cable Hybrid Line Using MEEMD Combined with Teager Energy Operator Algorithm

An improved fault localization method combining total aggregate empirical modal decomposition (MEEMD) and Teager energy operator (TEO) is proposed to address the fault localization issue of three-terminal multi-segment overhead line–cable hybrid transmission lines. This method solves the fault localization problem caused by wave impedance discontinuity in hybrid lines. First, the MEEMD algorithm, which improves modal aliasing, and the Teager energy operator, which reflects transient energy changes, are combined for the accurate detection of faulty traveling wave heads. The fault line section determination condition within the fault branch is used to determine the overhead line section or cable section where the fault is located after determining the faulty branch line. This condition is based on the time difference between the initial traveling wave of the fault arriving at each end measurement point and the T-node. Ultimately, the fault distance is determined using the double-ended traveling wave technique. By combining PSCAD and MATLAB for simulation verification, the accuracy of the ranging method is compared and analyzed, and the results show that the method is able to ensure the accuracy of ranging at different fault locations and transition resistances. Additionally, the localization error is basically kept within 30 m, which significantly improves the accuracy of fault localization.

Regularity and solutions for flame modelling in porous medium

The presented article deals with a model of flame propagation in porous medium. We depart from previously reported models in flame propagation, and we propose a new modelling conception based on a p-Laplacian operator. Such an operator is intended to extend the conceptions for reproducing the diffusion given in porous media. In addition, we introduce a nonlinear reaction term that generalizes the classical KPP-Fisher model of typical use in combustion. Our analysis shows first the boundedness and uniqueness of weak solutions. Afterward, we reformulate the driving equations using the travelling wave technique; and we introduce a density and flux ansatz to analyse the stability of a critical point. We obtain asymptotic profiles of travelling wave solutions, by making use of the Geometric Perturbation Theory. Eventually, we obtain upper solutions under selfsimilar forms for finite support propagating flames. This is particularly applicable for flames departing from compactly supported initial pressure–temperature distributions.

Location of Fault on Transmission Line using Traveling Wave Technique

When a fault on a transmission line manifests itself, the reliability of the power system is often compromised. It is advantageous to be able to stop certain faults from happening or to identify their causes when they do. The system may be quickly returned to its regular functioning condition by knowing the location of any possible line faults. This study proposes a method for fault localization based on travelling waves. This technique makes use of the currents and voltages coming from the line, as well as the speed of propagation, capacitance, inductance, the length of the transmission line, and the change in time that the fault occurs, in order to locate the specific site of the problem. The Onitsha to New/Haven 96 km transmission line was employed as a case study, and Matlab/Simulink was used to model, simulate, and apply the travelling wave fault detection equation. After simulating several fault sequences, the locations of the single line to ground fault, double line to ground fault, line to line fault, and three phase fault were found to be 48.539625306645 km, 48.539625261133 km, 48.539624540792 km, and 48.539625285965 km, respectively.

Fault Detection Using Backward Propagating Traveling Waves for Bipolar LCC-HVDC Lines

The line commutated converter (LCC)-high voltage direct current (HVDC) transmission lines may have various complementary protection algorithms based on derivatives of line parameters or differential line currents. The DC line fault detection based on distance relaying, traveling wave (TW), artificial neural network, fuzzy logic, and wavelet are a few of the popular schemes. However, the TW-based technique has been reported as one of the fastest techniques to detect and locate faults. The conventional TW techniques face limitations in detecting high resistance DC line faults. Therefore, this paper introduces an improved fault detection, classification, and location algorithm based on backward propagating TWs and fault classifier indices. The proposed algorithm is tested to detect, classify, and locate the faults under different system conditions such as pole-to-ground, pole-to-pole, and rectifier and inverter sides’ external faults. A bipolar LCC-HVDC transmission system of 900 km length is utilized to simulate the various fault conditions. The simulation results indicate fast, accurate, and reliable detection of faults. This scheme uses only single-end data measurement. The simulation study was performed for various fault locations (0–900 km) and transition resistances (0–150 Ω).

Bifurcations and Dynamics of Traveling Wave Solutions for the Regularized Saint-Venant Equation

This paper studies the bifurcations of phase portraits for the regularized Saint-Venant equation (a two-component system), which appears in shallow water theory, by using the theory of dynamical systems and singular traveling wave techniques developed in [Li & Chen, 2007] under different parameter conditions in the two-parameter space. Some explicit exact parametric representations of the solitary wave solutions, smooth periodic wave solutions, periodic peakons, as well as peakon solutions, are obtained. More interestingly, it is found that the so-called [Formula: see text]-traveling wave system has a family of pseudo-peakon wave solutions, and their limiting solution is a peakon solution. In addition, it is found that the [Formula: see text]-traveling wave system has two families of uncountably infinitely many solitary wave solutions and compacton solutions.

A Two-End Traveling Wave Fault Location System for MV Cables

In this paper, a new low-cost device is proposed for fault location in power distribution system. The device is part of a system that should include several units installed in couples at the two ends of medium voltage (MV) cable lines. Their low cost justifies a widespread installation of these devices, moreover other functionalities could be considered so as to enrich the potential of the system for MV cables monitoring and asset management. The system exploits a two-end traveling wave technique, low complexity, and low-cost solutions both for the analog front end as well as for the communication infrastructure. A LoRa network is indeed considered as wireless modulation technique perfectly suited when communication links with three characteristics are needed: low power, low bit rate, and long range. This paper shows the device that has been set up in Prysmian Electronics with some experimental phases showing the effectiveness of the proposed solution and the further developments expected.

Experimental analysis of the transport and the separation of plastic and metal micronized particles using travelling waves conveyor

The movement of the powdery material occurs in a multi-phase non-uniform electrostatic field at determined values of the voltage and the frequency, using travelling wave technique. This technique was applied for very small particles such as bacteria and other similar particle size. The objective of this work is to analyze the movement of PVC micronized particles and the feasibility of the separation of PVC/copper granular mixture of average size 100 μm. Two-phase and three-phase conveyors, which are supplied by high voltage amplifiers controlled by digital function generators, have been the subject of a parametric experimental investigation. Several factors were analyzed such as the voltage level up to 1400 V, the frequency, the phase shift and the number of phases of the conveyor. The obtained results showed that depending on the values of the above factors: i) the micronized particles can move instantly right after switching the conveyor, ii) the particles move towards one direction or the other of the conveyor iii) the separation of a granular mixture of plastic and copper micronized particles is possible.

Spatial elongation of population receptive field profiles revealed by model-free fMRI back-projection.

Estimates of visual field topographies in human visual cortex obtained through fMRI traveling wave techniques usually provide the parameters of population receptive field (pRF) location (polar angle, eccentricity) and receptive field size. These parameters are obtained by fitting the recorded data to a standard model population receptive field. In this work, pRF profiles are measured directly by back-projecting preprocessed fMRI time-series to sweeps of a bar across the visual field in different angles. The current data suggest that the model-free pRF profiles contain information not only about receptive field location and size but also about the pRF shape characteristics. The elongation (ellipticity) of pRFs decreases along the early visual hierarchy to a different degree for the ventral and the dorsal stream. Furthermore, ellipticity changes as a function of eccentricity. pRF orientation shows a high degree of collinearity with its angular position within the visual field. Using model-free pRF measurements, the traveling wave technique provides additional characteristics of pRF topographies that are not restricted to size and provide robust measures within the single subject.

Quantification of Conductor Surface Roughness Profiles in Printed Circuit Boards

Conductor (copper) foil surface roughness in printed circuit boards (PCBs) is inevitable due to adhesion with laminate dielectrics. Surface roughness limits data rates and frequency range of application of copper interconnects and affects signal integrity (SI) in high-speed electronic designs. In measurements of dielectric properties of laminate dielectrics using traveling-wave techniques, conductor surface roughness may significantly affect accuracy of measuring dielectric constant (DK) and dissipation factor (DF), especially at frequencies above a few gigahertz, when copper roughness is comparable to skin depth of copper. This paper proposes an algorithm for characterization of copper foil surface roughness. This is done by analyzing the microsection images of copper foils obtained using optical or scanning electron microscopes. The statistics obtained from numerous copper foil roughness profiles allows for introducing a new metric for roughness characterization of PCB interconnects and developing “design curves,” which could be used by SI engineers in their designs.

Improved Experiment-Based Technique to Characterize Dielectric Properties of Printed Circuit Boards

Recently, an experiment-based traveling-wave technique to separate conductor loss from dielectric loss on printed circuit board (PCB) striplines, called the differential extrapolation roughness measurement (DERM), has been proposed. The further development of this procedure is presented in this paper. The new procedure is applied to both loss constant and phase constant, as opposed to the previous procedure, which is applied to only loss constant. A new roughness parameter QR to quantify conductor surface roughness has been proposed, and it is used in the improved procedure. This allows for more accurate extraction of dielectric constant and loss tangent over a wide frequency range. In this paper, the three sets of test vehicles are studied. Each set has three different types of copper surface roughness profiles; two of these sets are known to have the same dielectric, which is used for the validation of the proposed extraction procedure. The new corrected extracted dielectric parameters as functions of frequency for these sets of test vehicles are compared with those obtained using the previous DERM technique.

A novel discrete wavelet transform based on traveling wave technique for identifying the fault location for transmission network systems

AbstractThis paper proposes a technique to identify fault location on transmission systems using discrete wavelet transforms (DWTs). Fault conditions are simulated using alternative transients program/electromagnetic transients program (ATP/EMTP) in order to obtain the current signals. Various cases based on Thailand electricity transmission systems are studied to verify the validity of the proposed technique. The comparisons among the maximum coefficients in first scale of all buses that can detect fault are performed to detect the faulty bus. The first peak time of positive sequence current obtained from the faulty bus is used as input data for the traveling wave equation. It is shown that the proposed technique gives satisfactory accuracy and is suitable for all types of fault occurring in different sections of transmission lines. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Continuum cascade model of directed random graphs: traveling wave analysis

We study a class of directed random graphs. In these graphs, the interval [0, x] is the vertex set, and from each y ∈ [0, x], directed links are drawn to points in the interval (y, x] which are chosen uniformly with density 1. We analyze the length of the longest directed path starting from the origin. In the x → ∞ limit, we employ traveling wave techniques to extract the asymptotic behavior of this quantity. We also study the size of a cascade tree composed of vertices which can be reached via directed paths starting at the origin.

Thermal diffusivity study in supported epitaxial InN thin films by the traveling-wave technique

High-quality crystalline (c) InN thin films have been obtained via gas-source molecular beam epitaxy, using hydrazoic acid (HN3) precursor, on indium tin oxide/glass, c-sapphire, and c-GaN substrates at growth temperatures between 623 and 823 K. A systematic study of thermal diffusivity has been performed using the traveling-wave method. We report a high thermal diffusivity value of 0.55 cm2/s for a combined 1.7 μm thick InN film grown on GaN substrates not observed before. X-ray diffraction data of InN grown on GaN substrates indicated lattice shrinkage with increasing thickness of the film that supports efficient phonon propagation and resulting higher thermal diffusivity. The lattice vibrational modes expressed in the Raman spectroscopic data corroborate the diffraction results. The thickness dependence of the thermal diffusivity has been modeled to estimate a bulk value of the essential thermal property.

Similarity Reduction and similarity solutions of Zabolotskay–Khoklov equation with a dissipative term via symmetry method

Similarity reductions of the Zabolotskay–Khoklov equation with a dissipative term to one-dimensional partial differential equations including Burger's equation are investigated by the symmetry method. Some similarity solutions of the Z–K equation are obtained via the method of travelling wave technique due to Jeffery and Xu and the method of separation of variables.

Elastic, mechanical, and thermal properties of nanocrystalline diamond films

Nanocrystalline columnar-structured diamond films with column diameters less than 100 nm and thicknesses in the range of 1–5 μm were grown on silicon substrates by chemical vapor deposition (CVD) in a microwave plasma reactor with purified methane and hydrogen used as the reactants. Uniform conformal nucleation densities in excess of 1012 cm−2 were accomplished prior to growth by seeding with explosively formed nanodiamonds, which resulted in good optical quality films. The film thickness was measured in situ by the laser reflectometry method. The grain size and optical quality of the films were characterized by scanning electron microscopy and Raman measurements. Broadband surface acoustic wave pulses were used to measure the anomalous dispersion in the layered systems. The experimental dispersion curves were fitted by theory, assuming the diamond film as an isotropic layer on an anisotropic silicon substrate, to determine mean values of the density and Young’s modulus of the diamond films. The density was close to the density of single crystal diamond or polycrystalline diamond plates grown by the CVD technique, whereas the Young’s modulus varied strongly with the nucleation density between 517 and 1120 GPa. Young’s moduli close to the single crystal values were obtained for films grown with a nucleation density ⩾1012 cm−2. The thermal diffusivity in these films was measured by the traveling wave technique. The value for ∼3.5-μm-thick nanocrystalline diamond films with nucleation densities ⩾1012 cm−2 was ∼7.2 cm2/s, whereas those with lower nucleation densities showed a value of ∼5.5 cm2/s.

Phase and thickness dependence of thermal diffusivity in a-SiC xN y and a-BC xN y

Thermal diffusivity (α) and bonding configuration of amorphous silicon carbon nitride (a-SiC x N y ) and boron carbon nitride (a-BC x N y ) films on silicon substrates were studied. Measurement of α by the traveling wave technique and bonding characterisation through X-ray photoelectron spectroscopy in a-SiC x N y and a-BC x N y films having different carbon concentrations revealed that lower coordinated bonds were detrimental to the thermal diffusivity of these films. Furthermore, α was found to depend on the thickness of these films deposited on silicon. This was attributed to the interface thermal resistance between two thermally different materials, the film and the substrate, although other factors such as film microstructure could also play a role. An empirical relation for the variation of thermal diffusivity with thickness is proposed.

Bonding characterization, density measurement, and thermal diffusivity studies of amorphous silicon carbon nitride and boron carbon nitride thin films

Thermal diffusivity (α) of amorphous silicon carbon nitride (a-SiCxNy) and boron carbon nitride (a-BCxNy) thin films on crystalline silicon has been studied as a function of the carbon content and thickness of the films using the traveling wave technique. The thermal diffusivity showed a steady fall from ∼0.35 to about 0.15 cm2/s for a-SiCxNy films as the carbon content increased from 30 to ∼70 at. %. This decrease in thermal diffusivity was also accompanied by a decrease in the film density from 3.35 to ∼2.3 g/cm3 as a function of the carbon content of the a-SiCxNy films. In case of a-BCxNy, a peak in thermal diffusivity (0.6 cm2/s) was detected at a carbon concentration of ∼25 at. % which reduced to 0.2 cm2/s for a carbon concentration of ∼60 at. % in the films. The value of the density also showed a peak (∼2 g/cm3) at a carbon concentration of 25 at. % before decreasing in the a-BCxNy films. A study of bonding characterization revealed a dominant lower coordinated C(sp)–N phase at higher carbon concentrations that played a detrimental role in the film properties observed. A critical issue of the thickness dependence of thermal diffusivity in a layered structure of a-SiCxNy and a-BCxNy on silicon is addressed with information extracted from aluminum thin films on different substrates. An empirical model is proposed which can explain the reported thickness and substrate dependence of the thermal diffusivity data.

Thermal diffusivity in diamond, SiCxNy and BCxNy

Thermal diffusivity (α) of free standing diamond, amorphous silicon carbon nitride (a-SiCxNy) and boron carbon nitride (a-BCxNy) thin films on crystalline silicon, has been studied using the travelling wave technique. Thermal diffusivity in all of them was found to depend on the microstructure. For a-SiCxNy and a-BCxNy thin films two distinct regimes of high and low carbon contents were observed in which the microstructure changed considerably and that has a profound effect on the thermal diffusivity. The defective C(sp)N phase plays a key role in determining the film properties.

Thermal diffusivity in amorphous silicon carbon nitride thin films by the traveling wave technique

Thermal diffusivity (α) of amorphous silicon carbon nitride (a-SiCxNy) thin films on crystalline silicon, prepared by ion beam sputtering, has been studied using the traveling wave technique. The variation of thermal diffusivity with carbon content in amorphous silicon carbon nitride samples are reported. Thermal diffusivity decreased from ∼0.35 cm2/s for samples with carbon contents of less than 30 at. %, to about 0.15 cm2/s for a-SiCxNy films with a carbon content of ∼70 at. %. A similar variation was found for the film density as measured by surface acoustic wave spectroscopy as a function of the carbon content. The results on a-SiCxNy, elucidate the relation between thermal diffusivity and the bonding configuration, density and microstructure of the network.

Pumping of water with ac electric fields applied to asymmetric pairs of microelectrodes.

Bulk fluid flow induced by an ac electric potential with a peak voltage below the ionization potential of water is described. The potential is applied to an ionic solution with a planar array of electrodes arranged in pairs so that one edge of a large electrode is close to an opposing narrow electrode. During half the cycle, the double layer on the surface of the electrodes charges as current flows between the electrodes. The electrodes charge in a nonuniform manner producing a gradient in potential parallel to the surface of the electrodes. This gradient drives the ions in the double layer across the surface of the electrode and this in turn drags the fluid across the electrode surface. The anisotropic nature of the pairs of electrodes is used to produce a net flow of fluid. The flow produced is approximately uniform at a distance from the electrodes that is greater than the periodicity of the electrode array. The potential and frequency dependence of this flow is reported and compared to a simple model. This method of producing fluid flow differs from electrical and thermal traveling-wave techniques as only a low voltage is required and the electrode construction is much simpler.