Properties Of Transmission Lines Research Articles

Experimental studies of anodized Al surface with composite nanopore structures to enhance the anti-icing properties of transmission lines

Experimental studies of anodized Al surface with composite nanopore structures to enhance the anti-icing properties of transmission lines

Built-In Coil Current Sensing for 7-Tesla 1H/23Na and 1H/31P Magnetic Resonance Imaging

This article introduces two designs for dual-tuned built-in radio-frequency coil current sensing in 7-Tesla magnetic resonance imaging based on the current forcing property of the quarter-wave transmission line. The first design offers dual-tuned built-in coil current sensing at <sup>1</sup>H/<sup>23</sup>Na resonant frequencies to probe the coil current consecutively at 298 MHz and 78.8 MHz, without the need for any integrated sensor on the coil. The second design enables dual-tuned built-in coil current sensing at <sup>1</sup>H/<sup>31</sup>P resonant frequencies to probe the coil current at 298 MHz and 120 MHz consecutively. The first design achieved good matching (<-40 dB) and low insertion loss (<0.5 dB) for <sup>1</sup>H and <sup>23</sup>Na magnetic resonance signals. The <sup>1</sup>H/<sup>31</sup>P design also exhibited good matching (<-30 dB) and low insertion loss (<0.67 dB). Therefore, both designs show promising potential for monitoring current flows in dual-tuned coils at the Larmor frequencies of different atomic nuclei.

Machine learning-based single-phase ground fault identification strategy for AC-DC transmission lines

In this paper, an improved single-phase grounding fault (SPGF) nature identification strategy based on machine learning is proposed. To solve the problem of conventional single-phase automatic reclosure cannot distinguishing the nature of SPGF in AC-DC hybrid lines, the fault phase voltage characteristics of AC lines with DC feed are analyzed, and the voltage harmonic energy feature vector is extracted. The whale optimization algorithm (WOA) designed by orthogonal experiment design (OED) is used to select the model parameters of the least square support vector machine (LSSVM), and a discriminative model for the fault properties of the hybrid transmission line is obtained. The simulation experiments based on PSCAD/EMTDC 4.5.0 platform are conducted for model training and fault identification performance testing, and the results verifies the effectiveness and feasibility of the proposed method. Compared with LSSVM, the fault identification strategy based on OED-WOA-LSSVM has a higher accuracy in fault identification. In addition, the accuracy of the model identification strategy under different fault locations, parallel compensation degree, transition resistance, and power system noise effects is also verified.

The Use of Coplanar Transmission Lines for Protecting Receiving Antenna Systems from Powerful Electromagnetic Radiation in a Wide Frequency Range

The goal of the work is to expand the frequency range of operation of coplanar waveguide transmission lines as broadband high-speed superconducting protection devices against powerful ultrashort electromagnetic radiation, and to apply them in antenna devices of radio electronic systems designed to ensure the reliable operation of critical infrastructure facilities. The aim is achieved by solving the following tasks: investigating the electrophysical properties of coplanar transmission lines, in particular, capacitance, surface and wave resistance in different phase states that arise under the influence of powerful electromagnetic radiation, and determining the main factors for effective protection in a wide frequency range, designing protective devices. The most important result is the establishment of the possibility of using coplanar transmission lines as protection devices in a wide frequency range up to 100 GHz, as well as the establishment of the dependence of their main characteristics on the design parameters of the superconducting protection device. The significance of the obtained results consists of solving a complex problem of providing protection of antenna systems against powerful ultrashort radiation by establishing an analytical relationship between the electrophysical parameters of coplanar waveguide transmission lines, which are in different phase states determined by the influence of powerful electromagnetic radiation, and their design parameters. The peculiarity of the obtained results is in the clarification of the dependence of the wave resistance of the coplanar waveguide transmission lines in superconducting, mixed, and normal phase states on the change of their active component of surface resistance, determined in turn by the design characteristics of the protective device. The difference from the known works lies in obtaining relationships for determining the wave resistance of protective devices in different phase states.

Waveguide Analysis of Radiofrequency Transmission in Well Tubulars for Electromagnetic Heating of Heavy Oil

This paper presents the numerical modelling and simulation of a 2D vertical well tubular model excited by a coaxial radiofrequency transmission line placed in its annular space for the purpose of downhole RF energy transmission. The study identifies the mechanism of energy losses due to coupling between the transmission line and steel tubing and casing using resonance mode analysis. The design of a left-handed artificial power line is proposed to minimize the losses due to the right-handed properties of the coaxial transmission line. The design utilizes ideal lumped element method to determine the left-handedness of the right-handed coaxial transmission line over the industrial heating radio-frequency band. The model is developed and simulated using COMSOL multi-physics commercial simulation software. The effect of transmission line position within the annular space on the tangential magnetic field and resulting power losses along the tubing is discussed. It is observed that the resulting artificial power line improves RF power transmission over 60 m depths of the vertical oil well within the industrial heating radiofrequency band.

A New Reconstruction Algorithm for Geometric Shape of Static Overhead Transmission Lines

This paper proposes a reconstruction algorithm for the geometric shapes of static overhead transmission lines that is based on the spatial coordinate data (obtained by field mapping) and the corresponding inclination data (obtained by attitude sensors). The algorithm takes the piecewise cubic Hermite interpolation function as the basic framework and corrects the aforementioned two types of data based on the “minimum energy principle” of the transmission line system. The introduction of a new energy function in modified energy method (MEM) overcame the shortcomings of conventional energy method (CEM) in fairing strategy, and the new Fairing Criterion made result curves more consistent with the mechanical properties of transmission lines. In the numerical simulation tests, the two energy methods were compared in terms of load type, horizontal span, elevation difference, and anti-disturbance ability, which showed that MEM has a higher reconstruction accuracy (average Euclidean distance is less than 1 cm) and better robustness than CEM. Meanwhile, the key parameters involved in the algorithm were discussed to guide the application in practical engineering. In addition, measurement tests under non-uniform icing were carried out in the field test station, and the results showed that the maximum relative error is less than 0.1%.

Researching a Simulation of Real-Time Nonlinear Dynamical Systems for Digital Power Grids in Massive IoT

“Digital real-time simulation” refers to the replication of output waveforms with the required accuracy, which duplicates the behavior of a real power system that is being simulated. A variety of problems relating to the functioning of power systems can be effectively solved using real-time simulators. Fortunately, modern state-of-the-art technological advancements have solved the energy problems. When used as a real-time application of electromagnetic transient-type simulation, the real-time digital simulator takes advantage of the traveling wave properties of cables and transmission lines in conjunction with a parallel processing platform. Power Control (PC), Hardware Under Test (HUT), Time Scale of Events (TSE), and Control Action (CA) are used as independent variables and the Real-Time Dynamic Simulation (RTDS) has been used as dependent variables. The objective of study improves the energy production in Digital Power Grids using Real-time Dynamic Nonlinear System Simulation System. The data was collected by using questionnaires based on 5-Likert Scale. The data has been analyzed using smart PLS 3. The questionnaire were filled from 50 technicians of power grids. The results are that Real-Time Dynamic Simulation improves the energy production in Digital Power Grids.

Crosstalk prediction and statistical properties of transmission line

In this paper, for the crosstalk error problem of multi-core stranded wires caused by non-uniform pitch, the Monte Carlo method is used to establish the probability distribution model of non-uniform pitch of stranded wires. For stranded wire crosstalk prediction, a transmission line pa-rameter prediction model is constructed using the BSO-BP neural network algorithm, and the effec-tiveness of the algorithm in this paper is verified by simulation. The final calculation gives the statis-tical characteristics of crosstalk on multicore stranded wires.

Temperature and Electric Field Distribution Characteristics of a DC-GIL Basin-Type Spacer with 3D Modelling and Simulation

The temperature properties of real-type direct-current gas-insulated transmission lines (DC-GIL) with a basin-type spacer were investigated by the finite element method in this paper. A horizontally installed model was established and the temperature distribution was obtained with a 3D model. The specific heat capacity and thermal conductivity of the spacer were measured and applied in the simulation. The results show that the temperature of the convex surface was slightly higher than that of the concave surface. With an increase in the SF6 pressure, the temperature of the spacer decreased, which can be attributed to the improvement of convection due to increases in the heat capacity per unit volume. With an increase in the ambient temperature, the temperature of the spacer increased linearly. The temperature difference between the inner and outer parts of the spacer increased with increases in the load current. Besides, an obvious increase in the surface electric field strength appeared under the influence of the thermal gradient compared to the results without the thermal gradient. Thus, special attention should be paid to the insulation properties of the spacer considering the influence of temperature distribution. This study evaluates both the thermal and insulation characteristics of the GIL along with the spacer under various conditions.

Effect of Cyclical Bending and Rubbing on the Characteristic Impedance of Textile Signal Lines.

This article presents the results of tests on the resistance of new textile signal lines to bending and abrasion. The textile signal lines are one of the most important parts of the electronic system incorporated into modern smart garments. The main application of the lines presented in this article is the transmission of digital signals or high-frequency analogue signals. The tested lines were made of fabrics with sewn paths made of electro-conductive fabric. The construction of a measuring stand for testing the electric properties of textile transmission lines is shown. This article presents the effects of bending and abrasion on the resistance of electro-conductive strips, which are one of the elements of textile signal lines. The article also presents the effects of bending and abrasion on the characteristic impedance of constructed textile signal lines. Statistical analysis of the obtained results is also presented.

A Compact Dual-Band Triple-Mode Antenna With Pattern and Polarization Diversities Enabled by Shielded Mushroom Structures

In this article, a compact triple-port dual-band triple-mode antenna enabled by a shielded mushroom structure with operational bands centered at 2.4 and 5.8 GHz is proposed possessing both pattern and polarization diversities. By tailoring the dispersive properties of the artificial transmission line (ATL) cells and structuring them into a multilayer architecture, the integrated antenna is capable of generating vertically polarized, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> -horizontally polarized, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> -horizontally polarized radiation patterns simultaneously at two predefined bands with good port isolations and field orthogonality. The design concept and the analysis of the ATL cells in the form of shielded mushrooms are described, illustrating the dual-band operating principle of the antenna. A proof-of-concept antenna is designed with a footprint of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.48\lambda _{0}^{2}$ </tex-math></inline-formula> and a profile of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.07\lambda _{0}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free space wavelength at 2.4 GHz. The proposed antenna was fabricated and characterized, achieving measured <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{11} &lt; - 10$ </tex-math></inline-formula> dB bandwidths of 35 and 85 MHz in the two targeted bands, respectively, with mutual coupling smaller than −15 dB and envelope correlation coefficients below 0.01 for all three ports. Moreover, it is shown that the two operational bands of the antenna can be independently controlled, which reveals the unprecedented degrees-of-freedom in its design. The demonstrated dual-band triple-mode antenna is highly useful for dual-band multimode wireless devices and dual-band multiple-input multiple-out communication systems.

Dual-band substrate integrate waveguide slot antenna for 5G applications

The current fifth generation (5G) and millimeterwave technologies are urgently needed to provide huge bandwidth, dual-bands, multi bands, high gain and high directivity radiation pattern beams antennas. However, antennas at millimeterwave suffer from radiation loss and component loss with narrow bandwidth, especially when it is implemented using microstrip structures. Different transmission lines such as waveguide and substrate integrated waveguide (SIW) are studied and introduced for realizing antennas at millimeterwave bands. SIW structures are good candidate for implementation of antenna due to its property of low loss transmission line comprises the properties of microstrip and waveguide technology. However, SIW antennas and structures at millimeterwave have unwanted radiation losses comes from the vias holes. In addition, the vias separation distance is depended on waveguide size, which leads to a bigger size for massive antenna array network at proposed 26 GHz and 28 GHz. Hence, this paper proposed a dual band, compact size, and optimal SIW antenna structure to reduce the vias losses and provides higher bandwidth and gain at 26 GHz and 28 GHz. The proposed design is implemented using three slots to achieve the dual band property and increases the return loss. The proposed design is simulated and studied using CST software. The outcomes of dual-band response at 26 GHz and 28 GHz with a return loss more than 10 dB and a fractional bandwidth of 15% are achieved. A good gain around 8 dB is achieved. These results give a promising solution for realizing a full antenna array based on SIW technology at millimeterwave and 5G technology.

Ultra-fast current differential protection with high-sensitivity for HVDC transmission lines

Protection of transmission lines is the most important defense against faults in multi-terminal HVDC system. Up until now, no single protection can balance the operation speed and sensitivity needed for all fault types. To solve this problem, a novel current differential protection for HVDC transmission line is proposed in this paper. The intrinsic properties of a HVDC transmission line are analyzed first. Then, essence of ideal current differential protection is revealed and fundamental relations between line models and performance degradation of existing differential protections are discussed. Based on this analysis, a novel current differential protection scheme, including fault detection and faulty pole selection, is developed, and Bergeron model is used to describe the electrical wave propagation process along line, resulting in only simple computations are needed in each calculation cycle. Finally, a simulation model of Wudongde ± 800 kV HVDC project in China is established in PSCAD/EMTDC for verification. By discussing diversified faults and transient processes, simulation results prove that regardless of fault type, distance and transition impedance, the proposed differential protection can respond correctly. Main contribution of this paper is reducing the operation time of differential protection from hundreds of milliseconds to several milliseconds.

Dispersion Analysis of Periodically Loaded Transmission Lines with Twist Symmetry Using the Mode-Matching Technique

A mode-matching formulation is presented and used to analyze the dispersion properties of twist-symmetric transmission lines. The structures are coaxial lines periodically loaded with infinitely thin screens, which are rotated with respect to each other to possess twist symmetry. The results obtained using the proposed formulation are in good agreement with those of commercial simulators. Furthermore, using the presented mode-matching formulation, it is demonstrated that the propagation characteristics in the twist-symmetric structures are linked to the scattering and coupling of the higher order modes. The physical insight offered by this analysis is valuable for the design of various electromagnetic devices, such as filters, antennas, and phase-shifters.

Suppressed-gap millimetre wave kinetic inductance detectors using DC-bias current

In this study, we evaluate the suitability of using DC-biased aluminium resonators as low-frequency kinetic inductance detectors capable of operating in the frequency range of 50–120 GHz. Our analysis routine for supercurrent-biased resonators is based on the Usadel equations and gives outputs including density of states, complex conductivities, transmission line properties, and quasiparticle lifetimes. Results from our analysis confirm previous experimental observations on resonant frequency tuneability and retention of high quality factor. Crucially, our analysis suggests that DC-biased resonators demonstrate significantly suppressed superconducting density of states gap. Consequently these resonators have lower frequency detection threshold and are suitable materials for low-frequency kinetic inductance detectors.

A Novel Scaling Process for the Computation of Multiconductor Transmission-Line Modal Properties Using the Basis Invariance of Total Current and Power

Some modal (or decoupled) transmission-line properties such as per-unit-length impedance, admittance, or characteristic impedance have long been held to be, in general, non-unique. This ambiguity arises from the nature of the similarity transformations used to relate the terminal and modal domains, for which the voltage transformation matrix has been shown to be only loosely related to the corresponding current transformation matrix. Modern methods have attempted to relate the two, but these relations typically rely on arbitrary normalizations, leading to strictly incorrect and/or non-unique results. This work introduces relations between the two transformations, derived from the physical equivalence of total power and currents between the two domains, by which the transformation matrices can be unambiguously related to each other, and the modal properties uniquely solved. This technique allows for the correct extraction of the modal transmission-line properties for any arbitrary system of conductors. Multiple examples are studied to validate the proposed solution process.

To the Phenomenological theory of Avalanche-Like Effect in Dc-Biased Microwave Nonlinear HTS Transmission Line

A phenomenological model has been proposed to describe the avalanche-like transition of a microwave nonlinear HTSC-based transmission line into a dissipative state. This effect was observed by the authors in a dc-biased transmission line. The proposed model generalizes the well-known phenomenological model for the nonlinear HTSC-based transmission line under the action of a direct current. The character of the dependences obtained for microwave losses allows the jump-like changes in the properties of the nonlinear HTSC-based transmission line to be regarded as a fold-type catastrophe and the methodological and mathematical apparatus of the theory of catastrophes to be used in order to explain the results obtained and predict new ones.

Localization Properties of Non-Periodic Electrical Transmission Lines

The properties of localization of the I ω electric current function in non-periodic electrical transmission lines have been intensively studied in the last decade. The electric components have been distributed in several forms: (a) aperiodic, including self-similar sequences (Fibonacci and m-tuplingtupling Thue–Morse), (b) incommensurate sequences (Aubry–André and Soukoulis–Economou), and (c) long-range correlated sequences (binary discrete and continuous). The localization properties of the transmission lines were measured using typical diagnostic tools of quantum mechanics like normalized localization length, transmission coefficient, average overlap amplitude, etc. As a result, it has been shown that the localization properties of the classic electric transmission lines are similar to the one-dimensional tight-binding quantum model, but also features some differences. Hence, it is worthwhile to continue investigating disordered transmission lines. To explore new localization behaviors, we are now studying two different problems, namely the model of interacting hanging cells (consisting of a finite number of dual or direct cells hanging in random positions in the transmission line), and the parity-time symmetry problem ( PT -symmetry), where resistances R n are distributed according to gain-loss sequence ( R 2 n = + R , R 2 n − 1 = − R ). This review presents some of the most important results on the localization behavior of the I ω electric current function, in dual, direct, and mixed classic transmission lines, when the electrical components are distributed non-periodically.

Heterogeneities in electricity grids strongly enhance non-Gaussian features of frequency fluctuations under stochastic power input.

Stochastic feed-in of fluctuating renewable energies is steadily increasing in modern electricity grids, and this becomes an important risk factor for maintaining power grid stability. Here, we study the impact of wind power feed-in on the short-term frequency fluctuations in power grids based on an Institute of Electrical and Electronics Engineers test grid structure, the swing equation for the dynamics of voltage phase angles, and a series of measured wind speed data. External control measures are accounted for by adjusting the grid state to the average power feed-in on a time scale of 1 min. The wind power is injected at a single node by replacing one of the conventional generator nodes in the test grid by a wind farm. We determine histograms of local frequencies for a large number of 1-min wind speed sequences taken from the measured data and for different injection nodes. These histograms exhibit a common type of shape, which can be described by a Gaussian distribution for small frequencies and a nearly exponentially decaying tail part. Non-Gaussian features become particularly pronounced for wind power injection at locations, which are weakly connected to the main grid structure. This effect is only present when taking into account the heterogeneities in transmission line and node properties of the grid, while it disappears upon homogenizing of these features. The standard deviation of the frequency fluctuations increases linearly with the average injected wind power.

Characteristics of Coplanar Waveguide of Small Cross Section on BCB with Coplanar Ground to Conductor-Backed Plane Interconnection

Conductor-backed coplanar waveguide on 30-μm-thick BCB polymer is fabricated. In order to eliminate unwanted propagation modes for these lines designed for frequencies up to 1 THz, electroplated vias interconnect each coplanar ground to the backed conductor. Transmission line properties are extracted here up to 67 GHz, showing a characteristic impedance of about 50 Ω, but with high conduction losses for this frequency range due to the thin metal layer used. Thru-reflect-line correction and a de-embedding with electrical circuit of accesses are applied to extract line properties. The comparison with a coplanar waveguide model leads to a relative permittivity of 2.676 for the BCB in this low-frequency range.