Search

The electrical properties and defects behavior in Si-based laterally diffused metal oxide semiconductor (LDMOS) chips under repetitive gate transmission line pulse stress were investigated. The results show that the threshold voltage increased by 22.4%, the output saturation current reduced by 12.5%, and the gate leakage current increased with the increasing gate voltage by 4.3 mA/V after the stress. An intrinsic trap H1 at 300 K was observed in the fresh Si-based LDMOS chip by using deep-level transient spectroscopy, where the activation energy did not change obviously, but the interface state density increased after the stress, resulting in the increase of threshold voltage. In addition, a new trap E1 appeared at 75 K in the stressed Si-based LDMOS chip, which may capture electrons, decreasing the effective electron concentration, leading to the decrease of the saturation current. High-resolution transmission electron microscopy results show that there are some cracks at the grain boundaries in poly-silicon, which may be the main path for the gate leakage current. Our study lays a foundation to further understand defects and their evolution in the Si-based LDMOS chips during the operation. [ABSTRACT FROM AUTHOR]

Rapid switching of transmission line parameters has emerged as a way to manipulate signals and as a testbed for various electromagnetic processes in time-varying media, including metamaterials. In general, the switching results in wave reflection and transmission similar to that for a spatial interface but at new frequencies. Here, various realizations of parameter switching are studied: connection and disconnection of reactive elements (capacitors and inductors) in series and in parallel. The temporal boundary conditions for the current and voltage distributions are derived rigorously based on the telegrapher's equations that explicitly model additional elements, instead of taking the equivalent values. It is shown that the temporal boundary conditions depend not only on the parameter values before and after switching but on its specific realization. Connecting or disconnecting reactive elements always involves energy losses. When new elements are added, two types of losses are identified. The first type is related to the creation of static magnetic and electric fields in the elements after switching. The second type is related to a very rapid energy dissipation during switching even for a vanishingly small resistivity in the line. When elements are removed, their energy is also removed from the waves. The effects of finite switching times are discussed. This study defines some serious constraints in using switchable transmission lines for the realization of photonic time crystals and efficient wave manipulation without externally added energy. The results are also applicable to wave propagation phenomena in other media with time-varying parameters. [ABSTRACT FROM AUTHOR]

Generating wavelength-tunable picosecond laser pulses from an ultrafast laser source is essential for femtosecond stimulated Raman scattering (FSRS) measurements. Etalon filters produce narrowband (picosecond) pulses with an asymmetric temporal profile that is ideal for stimulated resonance Raman excitation. However, direct spectral filtering of femtosecond laser pulses is typically limited to the laser's fundamental and harmonic frequencies due to very low transmission of broad bandwidth pulses through an etalon. Here, we show that a single etalon filter (15 cm−1 bandwidth; 172 cm−1 free spectral range) provides an efficient and tunable option for generating Raman pump pulses over a wide range of wavelengths when used in combination with an optical parametric amplifier and a second harmonic generation (SHG) crystal that has an appropriate phase-matching bandwidth for partial spectral compression before the etalon. Tuning the SHG wavelength to match individual transmission lines of the etalon filter gives asymmetric picosecond pump pulses over a range of 460–650 nm. Importantly, the SHG crystal length determines the temporal rise time of the filtered pulse, which is an important property for reducing background and increasing Raman signals compared with symmetric pulses having the same total energy. We examine the wavelength-dependent trade-off between spectral narrowing via SHG and the asymmetric pulse shape after transmission through the etalon. This approach provides a relatively simple and efficient method to generate tunable pump pulses with the optimum temporal profile for resonance-enhanced FSRS measurements across the visible region of the spectrum. [ABSTRACT FROM AUTHOR]

We demonstrate the integration of vanadium dioxide single-crystal nanobeams fabricated by modified vapor–liquid–solid method as electrical switching elements into a radio-frequency transmission line and evaluate the performances of the overall device in modulating the transmission of the conveyed RF electromagnetic waves. The switching capability of the RF device is based on the metal–insulator transition of VO2 nanobeams, with an on/off electrical switching ratio of 10 4 , i.e., resistance modulation from more than 10 6 Ω when the wires are in the insulating state to only ≈ 20 Ω when they are in the metal-like state. The thermal and electrical activation of the VO2 wires between the two dissimilar states is resulting in RF switching performances characterized by more than 15 dB change in the transmission coefficient of the device over the 100 MHz–24 GHz frequency domain. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of volume traps intentionally introduced into a silicon-on-insulator (SOI) substrate by inserting a layer of polysilicon beneath buried oxide. In radio frequency applications, this type of substrate, referred to as trap-rich, is known to considerably reduce the generation of harmonics resulting from the parasitic non-linear charge dynamics introduced by the substrate handler under the buried oxide. This analysis focuses on a test vehicle in the form of an integrated coplanar waveguide on two types of substrates, namely, high-resistivity SOI substrates with and without a trap-rich layer. From a modeling point of view, a simulation methodology is implemented in order to convert the 3D simulation of the coplanar waveguide into a 2D treatment that takes into account the wave propagation effect associated with the distributed nature of the transmission line. As a first step, this modeling strategy is implemented to reproduce the effect of increasing substrate resistivity on 2nd and 3rd harmonic reductions, leading to an excellent agreement with experimental data. Building on this validation of the simulation method, we have opted to simulate the non-linear response of the transmission line on the SOI trap-rich substrate by simplifying the trap distribution model. To avoid the adoption of unverified and strongly process-dependent trap distributions across the bandgap, a midgap monovalent trap density has been introduced, either acceptor or donor density. A monovalent density of acceptor traps with a concentration of 1016 cm−3 and a carrier lifetime of 0.1 ns has been shown to reproduce the experimental data very accurately with a substantial reduction in 2nd and 3rd harmonics. A detailed analysis of the displacement current waveforms explains the beneficial role of acceptor traps compared with donor traps. [ABSTRACT FROM AUTHOR]

In this article, we present a polarization-insensitive terahertz metamaterial designed by stacking resonators capable of providing ultra-wideband terahertz transmissions. Our design includes a square ring resonator situated between two windmill-shaped resonators, separated by a polyimide spacer. We optimized the spacer thickness to achieve a broadband response in transmission. These optimized broadband metamaterial designs were fabricated through multiple steps of the photolithography process. Terahertz time-domain spectroscopy of the fabricated samples indicates broadband terahertz transmission, in agreement with both simulation findings and results calculated from the transmission line model for the multi-layered metamaterial geometry. Our research reveals a strong near-field coupling between resonators, leading to wideband transmission of terahertz waves. The stacking of these metamaterials is crucial in designing broadband bandpass filters and broadband modulators for terahertz photonics while keeping the resonance strength almost intact. [ABSTRACT FROM AUTHOR]

Recently, researchers have demonstrated, both theoretically and experimentally, that low-dimensional version of conventional leaky waves, known as "flatland leaky waves" (FLWs). FLWs can be supported by planar junctions of metasurfaces and are completely confined to a plane. Here, we design a structure that places an equivalent reactance surface near the transmission line to excite the FLWs. By properly designing the geometry of the unit cell, conditions can be created for faster surface waves (SWs) to excite slower SWs on the surface, resulting in the desired form of two-dimensional (2D) leaky-wave radiation. A sample was fabricated and measured, and both the simulation results and the experimental results yielded the desired results. Finally, we design the equivalent impedance surface model on which we can also observe the 2D FLWs. Our research not only deepens the understanding of the phenomenon of FLWs but also brings the application of equivalent reactance surfaces in the field of electromagnetic phenomena research to a higher level. [ABSTRACT FROM AUTHOR]

Many charged particle imaging techniques exist which directly measure, at a detector, the transverse position (x, y) and time-of-flight (t) of individual events in order to obtain a full set of 3D coordinates. Where curved velocity-mapping electric field lines are implemented, as in the case of 3D Velocity Map Imaging (3D VMI) and certain COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) instruments, the general transformation of (x, y, t)-data into initial 3D recoil momentum vectors (px, py, pz) is challenging and has not yet been fully addressed. Here we present a detailed and general method for this transformation, illustrated using our 3D VMI spectrometer and the well-known narrow-band photoionization of nitric oxide, for which we demonstrate quantitative agreement with reported values. We additionally show how to measure and correct (i) small errors in the laser polarization axis alignment at the interaction region of a 3D charged particle imaging spectrometer, and (ii) the spatial variation of gain on a microchannel plate (MCP) detector. Improvements to and characterization of our 3D VMI spectrometer yield an electron time-of-flight resolution of 72 ps across the full 40 mm MCP, in combination with pixel-level spatial resolution. [ABSTRACT FROM AUTHOR]

An intelligent protection scheme based on the single fuzzy inference system and discrete Fourier transform is proposed for the faulty phase detection and classification of faults on the mutually coupled double circuit transmission lines. This proposed protection technique uses the magnitude of the pre-processed current information of the sending end bus only. This is implemented in the MATLAB/Simulink environment on a 400 kV, 50 Hz, and 300 km double circuit power system model. The efficacy of the proposed scheme has been tested by performing a wide range of simulation studies concerning different types of faults (common short circuit faults, cross-country and evolving faults, and high impedance faults) and typical fault scenarios (current transformer saturation, noisy environment, and fault during power swing conditions) with variations in different fault parameters and operating conditions. The results presented confirm that the proposed method detects/classifies all the faults within one cycle time and is reliable with a detection/classification accuracy of 99.75%. It is immune to variations in fault parameters, and different operating conditions, and is not affected by the zero sequence mutual impedance. It does not require any training and communication link. Further, the performance is also appraised with other training-based protection schemes. [ABSTRACT FROM AUTHOR]

This paper mainly deals with the reliability modeling and optimal preventive replacement policies for a stochastically deteriorating system with random shocks. Specifically, the system is subject to stochastic performance deterioration, in which it is described with a Gamma process and degrades after a random degradation latency period. At the same time, a random shock process with a non-homogenous Poisson process is incorporated into system degradation modeling, where two kinds of shock effectiveness are formed upon arrival. The dependence between the degradation-induced failure and the shock-induced failure is bidirectional in this research. Based on system survival function, a periodic replacement policy and an inspection replacement policy are respectively investigated. The optimal solutions to the two preventive replacement policies are sought analytically and their resulting long-run average cost rates are compared to decide which one is more profitable. Finally, an illustrative example of the gas insulated transmission line is surveyed to validate the theoretical results, demonstrating that the random degradation onset time and two kinds of shocks are significant factors to system reliability evaluation and maintenance decisions. [ABSTRACT FROM AUTHOR]

This paper introduces an innovative antenna configuration that incorporates multiple quarter-wavelength transmission line segments. Additionally, it presents a mathematical framework for modeling the proposed antenna and deriving an expression for its input impedance, thereby investigating the effects of various parameters on its bandwidth. The design of the proposed antenna utilizes an asymmetric coplanar waveguide (ACPW) due to its ease of implementation without the need for vias. Furthermore, the implementation of ACPW results in parasitic coplanar capacitances, which are used to tune the resonance modes of the proposed antenna, thereby extending its bandwidth. Curved corners are incorporated into the proposed antenna, and characteristic mode analysis (CMA) is used to investigate the effect of these curved corners on the significant modes and radiation pattern. The proposed antenna has electrical dimensions of $ 0.3\lambda _{0} \times \ 0.25\lambda _{0} \times \ 0.007\lambda _{0} $ 0.3 λ 0 × 0.25 λ 0 × 0.007 λ 0 at a frequency of 2.29 GHz. The antenna prototype has been fabricated and measured. The measured −10 dB fractional bandwidths are 48.1% (from 2.29 to 3.74 GHz), 30.5% (from 5.19 to 7.06 GHz), 7.1% (from 8.33 to 8.94 GHz), and 13.9% (from 9.74 to 11.19 GHz). Moreover, the measured maximum realized gain is 7.05 dBi. These features make the proposed antenna an attractive candidate for various wireless communication systems. [ABSTRACT FROM AUTHOR]

Radio stations are seriously affected by transmission line reradiation interference, but most of the existing methods for analyzing and solving reradiation interference on transmission lines focus on approximating the physical problem through mathematical models and algorithms, and it is difficult to study the correlation between transmission lines and reradiation interference in depth. This paper introduces the characteristic mode theory to study the influence factors of reradiation interference on transmission lines, which can decompose the surface induced current of transmission lines into a series of mutually orthogonal mode currents. This paper verifies the correctness of applying the MS (mode significance) value of the characteristic mode theory to analyze the reradiation interference through a simple transmission line example. Taking a line with 5 towers as an example, by analyzing the characteristic mode currents of transmission lines with different forwarding angles and linear arrangements, we not only verified that the characteristic mode currents can well characterize the reradiation interference, but also verified that the characteristic currents of different modes have a direct connection with the structure of the line, which can be applied in the process of designing or reconstructing the towers of the transmission lines, to predict the influence of different structural parameters on electromagnetic scattering, so as to optimize the tower design to reduce the reradiation interference effects and thus optimize the tower design to reduce reradiation interference. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to maintain the technical leadership of the economic sector in any nation, there is currently a greater focus on guaranteeing the fail-safe operation of electrical networks and electrical equipment. This paper presents a model for evaluating the fault location procedure based on computer simulation in MATLAB/Simulink of complex 6(10)-35 kV power line systems. The proposed algorithm for preprocessing electrical network signals in normal and emergency modes uses a negative statistical correlation of all possible electrical parameters, while the resulting percentage errors when estimating the location of the fault are within acceptable limits. Algorithms and significant parameters have been determined for effectively carrying out the procedure for searching for the location of a fault through the use of modeling programs, namely: zerosequence voltage, negative-sequence voltage, initial current value. and the positive sequence voltage is the transition resistance at the accident site. An assessment of the results of preliminary modeling may indicate that devices for finding the location of a fault in the 6(10)-35 kV electrical network will be able to use information obtained about the object using the developed methodology, adjust calculation algorithms and take into account the operating modes of the electrical network. [ABSTRACT FROM AUTHOR]

This study presents a novel approach to enhance the precision of calculating sag and magnetic fields beneath overhead transmission lines. The Biot-Savart law is integrated with parabolic equations to assign multiple magnetic field sources to each conductor, resulting in improved prediction accuracy. Addressing oversimplifications in traditional models improves the analysis of transmission lines in real-world scenarios. An analysis was performed using MATLAB and Simulink to validate the effectiveness and broad applicability of different configurations. The results demonstrated a significant improvement in precision compared to traditional methods, indicating that this approach has the potential to establish new benchmarks in the field. This methodology makes significant contributions to electromagnetic studies, offering engineers a reliable tool for designing transmission systems that are both safer and more efficient. This advancement in electrical engineering greatly improves transmission network performance by enhancing sag and magnetic field prediction accuracy. This aids in better maintenance planning and reduces outage risks, resulting in more efficient operations and improved overall performance. [ABSTRACT FROM AUTHOR]

Copyright of Zhejiang Electric Power is the property of Zhejiang Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There is a pressing need to expand electricity production in Aotearoa New Zealand to meet sustainability goals and lower energy costs. This new generation needs to be based on renewable sources, chiefly wind and solar, for both sustainability and economic reasons. While there remains a role for the legacy grid, microgrids provide a means of co-locating generation with load, minimising transmission line investment and energy losses. This paper explores the advantages of smart community microgrids in this context, but also examines the challenges in terms of the existing legacy grid approach. Three case studies are given as examples, covering an isolated community with no grid connection, a more conventional residential community of 30 households, and a community with local commercial/industrial loads in addition to housing. These case studies show the benefits in terms of local consumption of locally generated electricity coupled with sharing or local trading within the community. Microgrids can support New Zealand’s transition to a more electrified, equitable, economical and low-emissions energy system, but their development does require not just exploitation of new technologies, but also adjustment to the legacy grid model and a fresh approach to electricity infrastructure planning and management. [ABSTRACT FROM AUTHOR]

In this paper, we propose a sub-terahertz PAM4 modulator based on transmission characteristic reconstruction by combining meta-unit, GaAs Schottky diode, and fan branch lines. This method combined the significant electromagnetic resonant characteristics of meta-unit, the high-speed controllability of GaAs Schottky diode, and the high integration of on-chip transmission line together to realize high-speed modulation. Then, we achieve transmission characteristic reconstruction by adjusting the resonance strength under different applied voltages through fan branch lines, enabling high-order amplitude modulation of sub-terahertz waves. The experimental results show that the PAM4 modulation of sub-terahertz waves is achieved with a nearly linear variation of the transmission coefficient in the whole voltage range and a maximum modulation rate of 21 Gbps, providing a promising prospect for the development and application of integrated sub-terahertz direct high-order modulation technology. [ABSTRACT FROM AUTHOR]

Pole tower grounding bodies are part of the normal structure of the power system, providing relief from fault currents and equalizing overvoltage channels. They are important devices; however, in the harsh environment of the soil, they are prone to corrosion or even fracture, which in turn affects the normal utilization of the transmission line, so accurately assessing the condition of grounding bodies of the power grid is critical. To assess the operational status of a grounding body in a timely manner, this paper proposes a multi-parameter pulsed eddy current (PEC) time-domain characteristic signal corrosion classification method for the detection of the state of a pole tower grounding body. The method firstly theoretically analysed the influence of multi-parameter changes on the PEC response time-domain feature signal caused by grounding body corrosion and extracts the decay time constant (DTC), and the decay time constant stabilization value (DTCSV) and time to stabilization (TTS) were obtained based on the DTC time domain characteristics for describing the corrosion of the grounding body. Subsequently, DTCSV and TTS were used as inputs to a support vector machine (SVM) to classify the corrosion of the grounding body. A simulation model was constructed to investigate the effect of multiparameter time on the DTCSV and TTS of the tower grounding body based on the single-variable method, and the multiparameter time-domain characterization method used for corrosion assessment was validated. Four defects with different corrosion levels were classified using the optimized SVM model, with an accuracy rate of 95%. Finally, a PEC inspection system platform was built to conduct classification tests on steel bars with different degrees of corrosion, and the results show that the SVM classification model based on DTCSV and TTS has a better discriminatory ability for different corrosive grounders and can be used to classify corrosion in the grounders of poles towers to improve the stability of power transmission. [ABSTRACT FROM AUTHOR]

The complex terrain of China frequently leads to wildfires, which in turn pose a threat to the safe operation of power transmission lines. Studying the breakdown characteristics of air gaps under wildfire conditions is of great significance for understanding wildfire propagation mechanisms, risk assessment and management, and ecological environment protection. This paper establishes an experimental platform simulating wildfire climatic conditions and conducts experimental research on air gaps between rod–rod gaps and conductor–ground gaps. The experimental voltage types include direct current, power frequency, and standard operating waves. The impact of wildfire factors on the breakdown voltage and discharge characteristics of air gaps was obtained. The results indicate that the main factors affecting the air gap breakdown characteristics during wildfires are flame height and smoke. Flame height directly influences the gap insulation distance. Under flame bridging conditions, the maximum decrease in breakdown voltage reaches 70–80%. As the concentration of smoke increases, the degradation of insulation performance becomes more pronounced, with a reduction ranging from 20% to over 50%. [ABSTRACT FROM AUTHOR]

High-voltage transmission lines face significant challenges due to environmental exposure, including corona discharge, ice accretion, and corrosion, which impact their durability and operational efficiency. This study investigates the performance of hydrophilic and superhydrophilic organosilane coatings applied to high-voltage wires to address these issues. Using a combination of experimental setups simulating real-world conditions, we evaluated corona discharge losses, ice adhesion, and corrosion resistance on coated and uncoated wires. The results reveal that hydrophilic and superhydrophilic organosilane coatings offer a substantial reduction in corona discharge power losses, with a 25–60% decrease compared to bare wires. Additionally, the proposed hydrophilic coating exhibits ice adhesion characteristics similar to bare wires, in contrast to the higher ice adhesion observed for superhydrophilic samples. Corrosion tests further highlight the performance of the hydrophilic coating, which reduces corrosion currents by approximately threefold compared to bare wires, demonstrating enhanced protection and long-term stability. While superhydrophilic coatings offer some advantages in corona discharge reduction, their increased ice adhesion and higher corrosion rates limit their applicability. The hydrophilic organosilane coating thus emerges as the optimal tradeoff, balancing effective corona discharge mitigation, moderating ice adhesion, and enhancing corrosion resistance, making it a promising solution for improving the performance and longevity of high-voltage transmission lines. [ABSTRACT FROM AUTHOR]

Accurately measuring the thickness of the oxide film that accumulates on nuclear fuel assemblies is critical for maintaining nuclear power plant safety. Oxide film thickness typically ranges from a few micrometers to several tens of micrometers, necessitating a high-precision measurement system. Eddy current testing (ECT) is commonly employed during poolside inspections due to its simplicity and ease of on-site implementation. The use of swept frequency technology can mitigate the impact of interference parameters and improve the measurement accuracy of ECT. However, as the nuclear assembly is placed in a pool for inspection, a cable several dozen meters in length is used to connect the ECT probe to the instrument. The measurement is affected by the transmission line and its effect is a function of the operating frequencies, resulting in errors for swept frequency measurements. This paper proposes a method for precisely measuring oxide film thickness based on the swept frequency technique and long transmission line impedance correction. The signals are calibrated based on a transmission line model of the cable, effectively eliminating the influence of the transmission cable. A swept frequency signal-processing algorithm is developed to separate the parameters and calculate oxide film thickness. To verify the feasibility of the method, measurements are conducted on fuel cladding samples with varying conductivities. It is found that the method can accurately assess oxide film thickness with varying conductivity. The maximum error is 3.42 μm, while the average error is 1.82 μm. The impedance correction reduces the error by 66%. The experimental results indicate that this method can eliminate the impact of long transmission cables, and the algorithm can mitigate the influence of material conductivity. This method can be utilized to measure oxide film thickness in nuclear power maintenance inspections following extensive testing and engineering optimization. [ABSTRACT FROM AUTHOR]

Generally, the electrocardiography (ECG) system plays an important role in preventing and diagnosing heart diseases. To further improve the amenity and convenience of using an ECG system, we built a customized capacitive electrocardiography (cECG) system with one wet electrode, sixteen non-contact electrodes, two ADS1299 chips, and one STM32F303-based microcontroller unit (MCU). This new cECG system could acquire, save, and display the ECG data in real time. The bias feedback as a critical technique was routed to the left hand with the wet Ag/AgCl electrode, which could greatly suppress the power line noise. After all artifacts were removed, the ECG signals could be discerned clearly. We demonstrated that the ECG signals acquired with the capacitive electrodes were similar to those with the wet electrode. Thus, we successfully provide a new configuration for cECG monitoring at home or in a clinical setting. [ABSTRACT FROM AUTHOR]

In radio frequency identification (RFID), differences in spectrum policies and tag misreading in different countries are the two main issues that limit its application. To solve these problems, this article proposes a composite right/left-handed transmission line (CRLH-TL)-based reconfigurable antenna for ultra-high frequency near-field and far-field RFID reader applications. The CRLH-TL is achieved using a periodically capacitive gap-loaded parallel plate line. By deploying the CRLH-TL operating at zeroth-order resonance, a loop antenna with in-phase radiating current is obtained, which contributes to a strong and uniform H-field and a horizontally polarized omnidirectional radiation pattern. By introducing additional tunable components, frequency and reading range reconfigurabilities are enabled. The frequency tuning range is from 833 MHz to 979 MHz, which covers the worldwide UHF RFID band. Moreover, each operation mode has a narrow frequency band, which means it can operate without violating different countries' radio frequency policy and reduce the design difficulty of designing multiple versions of a reader. Both the near-field interrogation zone and maximum far-field reading distance of the antenna are adjustable. The near-field interrogation zone is 400 mm × 400 mm × 50 mm and can be further confined. The tuning range for far-field reading distance is from 2.71 m to 0.35 m. [ABSTRACT FROM AUTHOR]

The process of establishing relay protection and automation (RPA) settings for electric power systems (EPSs) entails complex calculations of operating modes. Traditionally, these calculations are based on symmetrical components, which require the building of equivalent circuits of various sequences. This approach can lead to errors both when identifying the operating modes and when modeling the RPA devices. Proper modeling of measuring transformers (MTs), symmetrical component filters (SCFs), and circuits connected to them effectively solves this problem, enabling the configuration of relay protection and automation systems. The methods of modeling the EPS in phase coordinates are proposed to simultaneously determine the operating modes of high-voltage networks and secondary circuits connected to the current and voltage transformers. The MT and SCF models are developed to concurrently identify the operating modes of secondary wiring circuits and calculate the power flow in the controlled EPS segments. This method is effective in addressing practical problems related to the configuration of the relay protection and automation systems. It can also be used when establishing cyber–physical power systems. For a comprehensive check of the adequacy of the MT models, 140 modes of the electric power system were determined which corresponded to time-varying traction loads. Based on the results of calculating the complexes of currents and voltages at the MT terminals, parametric identification of the power transmission line was performed. Based on this, the model of this transmission line was adjusted; repeated modeling was carried out, and errors were calculated. The modeling results showed a high accuracy when calculating the modules and phases of voltages using the identified model. The average error value for current modules was 0.6%, and for angles, it was 0.26°. [ABSTRACT FROM AUTHOR]

Geomagnetically Induced Current (GIC) refers to the electromagnetic response of the Earth and its conductive modern infrastructures to space weather and would pose a significant threat to high-voltage power grids designed for the alternative current operation. To assess the impact of space weather on the power grid, one needs to calculate the GIC on a national or continental scale. In this study, we developed a smart and parallelized GIC modelling algorithm, Graph GIC. This algorithm deploys a graph representing a power grid in a single-line diagram, in which substations/transformers act as nodes and transmission lines as edges. With these denotations, a power grid and its electric parameters are mathematically represented with an adjacency matrix and an admittance matrix. We used sparse matrix and parallelisation techniques to expedite the intensive computation in cases of large-scale power grids. The Graph GIC was validated with a benchmark grid, applied to the GIC calculation of the 500 kV power grid of Guangdong, China, and conducted preliminary analysis on the grid's susceptibility to geomagnetic storms. The Graph GIC algorithm has the advantage of an intuitive and highly scalable graph representation of a power grid at any scale. It achieves high-accuracy calculation and a speedup of about 18 times after parallelisation. This algorithm could be applied to assess the impact of space weather on a power grid up to continental scales and could be incorporated into global space weather modelling frameworks. [ABSTRACT FROM AUTHOR]

We report on the fabrication and characterization of superconducting magnesium diboride (MgB2) thin films intended for quantum-limited devices based on non-linear kinetic inductance (NLKI) such as parametric amplifiers with either elevated operating temperatures or expanded frequency ranges. In order to characterize the MgB2 material properties, we have fabricated coplanar waveguide (CPW) transmission lines and microwave resonators using ≈ 40 nm thick MgB2 films with a measured kinetic inductance of ∼ 5.5 pH/ □ and internal quality factors Q i ≈ 3 × 10 4 at 4.2 K. We measure the NLKI in MgB2 by applying a DC bias to a 6 cm long by 4 μm wide CPW transmission line and measuring the resulting phase delay caused by the current dependent NLKI. We also measure the current dependent NLKI through CPW resonators that shift down in frequency with increased power applied through the CPW feedline. Using these measurements, we calculate the characteristic non-linear current parameter, I * , for multiple CPW geometries. We find values for corresponding current density, J * = 12 – 22 MA/cm2, and a ratio of the critical current to the non-linear current parameter, I C / I * = 0.14 – 0.26 , similar to or higher than values for other superconductors such as NbTiN and TiN. [ABSTRACT FROM AUTHOR]

Position sensorless control has been widely used in permanent magnet synchronous motor (PMSM) drives in low-cost applications or in the fault-tolerance control of position sensors. Conventional sensorless control methods often adopt a back electromagnetic force (EMF)-based position observer, which results in bandwidth reduction in signal processing and lower estimation accuracy. This paper introduces a numerical solution based on transmission line modeling (TLM) to obtain the back EMF. The TLM method is used for the numerical calculation of electromagnetics due to the clear algorithm structure, robust convergence and stability, and easy implementation in dynamic circuit analyses. This paper first analyzes the 2D TLM method techniques. Then, a new application of TLM theory in position sensorless control of PMSMs is put forward. The proposed TLM-based sensorless control scheme can estimate the back EMF without decreasing the bandwidth, thereby enhancing the dynamic performance of the sensorless control. All numerical results are implemented using the proposed approach, which validates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In light of the issues associated with the laying process of transmission line cables, including concealed security risks and contact collisions between pulleys and cables, which primarily stem from reliance on drawings, this paper introduces a simulation methodology for the cable laying construction process utilizing Building Information Modeling (BIM) technology. Initially, two-dimensional DWG graphic data are employed to develop a model of the target equipment and construction environment using BIM software (Solid works 2020). Subsequently, the cable is accurately modeled by applying ADAMS virtual prototype technology, the bushing force connection method, and the macro command language. This allows for the construction of a three-dimensional real cable laying system for transmission lines, enabling the simulation of the dynamic cable laying process in the field. Subsequently, an error analysis is conducted to compare the axial tension and laying speed of the cable with theoretical calculation values. The study then proceeds to analyze tension fluctuations during the cable laying process and assess the load-bearing capacity of the pulleys, thus facilitating effective control of the construction process and enhancing safety measures. The findings indicate that the proposed method can accurately and efficiently simulate the on-site cable laying construction process, with numerical errors maintained below 5%, thereby validating the integrity of the model. Furthermore, the traction overload safety protection amplification coefficient is determined to be α = 1.5. It is highlighted that the bearing capacity of the block must exceed 60% of the load carried by the conductor at constant speed. This research provides a theoretical foundation for addressing safety hazards in cable laying engineering and holds certain engineering value. [ABSTRACT FROM AUTHOR]

Landslides and ground subsidence pose significant threats to the successful construction and operation of transmission line projects in the Loess Plateau region. This study aims to explore an accurate early identification method for geological hazards, providing support for the construction and smooth operation of the transmission project along the route from Baishui County, Weinan City, Shaanxi Province to Lantian County, Xi'an City, Shaanxi Province. Small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) technology was used to acquire the surface deformation data of the study area from 4 February 2018 to 21 May 2023. The deformation data were spatially analyzed through kernel density analysis, which quickly and intuitively identified 52 potential geological hazard points in the region, including eight landslides and 44 ground subsidence. Detailed field investigations of the hazards confirmed the accuracy of the identification results. A thorough analysis of typical hazards, such as landslide No. 9 and ground subsidence No. 29, revealed severe deformation, posing a threat to the proposed transmission project. This study indicates that combining InSAR, kernel density analysis, and field investigations can accurately and quickly identify geological hazards around transmission lines, providing support for the site selection and implementation of transmission projects. [ABSTRACT FROM AUTHOR]

Aerial images are commonly used for detecting insulators in transmission lines to ensure their safe operation. However, each capture session generates thousands of insulator images, requiring manual collection, organization, and analysis. Therefore, to achieve automation in insulator state detection, this paper proposes a method based on deep learning for insulator state detection in transmission lines. Firstly, an insulator state detection model is built based on YOLOv7, and the model is improved using a bi-level routing attention mechanism and a content-aware up-sampling operator. Then, combined with dataset augmentation, including cropping, flipping, rotating, scaling, and splicing and a bounding box loss function incorporating a dynamic non-monotonic focus mechanism, 4000 visible images from different voltage levels of transmission lines are used for training. Finally, using a confusion matrix combined with comparative and ablation experiments, the results of insulator state detection are analyzed. Experimental results show that the proposed method achieves a detection accuracy of 97.1%. The detection accuracies for insulators exhibiting self-explosion, damage, flashover, and insulator strings are 93.5%, 98.6%, 97.5%, and 98.9%, respectively. Analysis results demonstrate that the proposed method can effectively realize insulator status detection. [ABSTRACT FROM AUTHOR]

In the work presented in this paper, a microwave sensor is investigated for estimating the glucose level in the blood of a diabetic patient. The microwave sensor consists of a planar microstrip transmission line printed on one side of the substrate while four Circular Complementary Split Ring Resonators (CCSRR) arranged in compact beehive arrangement are etched out from the ground plane on the other side, thus forming a Defected Ground Transmission Line (DG-TL). It is well known that the dielectric properties of blood to a large extent depend on the intrinsic glucose concentration. Placing fingertip on the CCSRR cells is expected to disturb the electric field in the vicinity by changing the inductance-capacitance of the configuration and thus mirroring a change in the S-parameters of the transmission line. The changes, a shift in the resonance frequency and a change in the amplitude, is proportional to the dielectric strength of the adjacent medium which in turn is proportional to the blood glucose level. To mimic a human finger, a tiny glass container containing aqueous glucose solution is placed on the CCSRR configuration and by varying the glucose concentration; the changes in the S-parameters were observed. The sensor has planar dimensions of 60 mm × 20 mm and offers a resolution of 0.75 MHz per mg/dL of glucose concentration. Simulations and measurements indicate the applicability of the design for identifying glucose levels in the blood. [ABSTRACT FROM AUTHOR]

Extreme weather events, particularly snow and ice storms, present significant threats to the stability and reliability of high-voltage transmission lines, leading to substantial disruptions in power supply. This study delves into the causes and consequences of transmission line trip faults that occur under severe winter conditions, with a focused case study in Inner Mongolia—an area frequently impacted by snow and ice hazards. By systematically analyzing field data collected during critical periods of ice accumulation, this research identifies and examines key factors contributing to faults, such as conductor galloping, insulator degradation, and structural fatigue. These issues are often exacerbated by prolonged exposure to low temperatures and high wind speeds, which further compromise the integrity of transmission infrastructure. In addition to field observations, comprehensive testing of the affected insulators and components reveals mechanical and electrical vulnerabilities that play a significant role in the occurrence of trip faults. To combat these challenges, the paper proposes a series of mitigation and prevention strategies. These include enhancing design specifications to ensure resilience against increased ice and wind loads, deploying real-time monitoring systems capable of detecting early indicators of conductor galloping and ice accumulation, and employing advanced de-icing technologies to reduce the risk of ice-related failures. Moreover, the integration of unmanned aerial vehicles (UAVs) and artificial intelligence (AI)-based fault detection tools presents promising opportunities for improving remote monitoring capabilities and enabling proactive maintenance interventions. By leveraging these innovative technologies, the resilience of transmission lines in harsh climates can be significantly enhanced. The findings of this study not only provide a comprehensive framework for minimizing the impact of extreme weather on transmission infrastructure but also contribute valuable insights toward fostering a more reliable and resilient power grid capable of withstanding the challenges posed by an increasingly volatile climate. [ABSTRACT FROM AUTHOR]

ABSTRACT The paper presents a new fault location method with traveling waves (surge) on distribution line to restore power supply as soon as possible. The proposed method builds a diagram that describes transmission and reflection of traveling waves over the lines and generates pseudo waves based on the diagram. The least error condition including fault point is estimated by numerical analysis comparing measured waves and pseudo waves. The method is robust and accurate without line parameters such as the speed of traveling waves. The method can be applicable for multiple faults and branch line faults without any additional modification. [ABSTRACT FROM AUTHOR]

The transmission line tower foundation is the key to determining the safe and stable operation of transmission lines under high current impact, and conductive concrete plays a vital role in the safe and stable operation of transmission lines. However, the mechanical and electrical properties of conductive concrete have a competitive relationship, and balancing these properties simultaneously is a current research problem. This paper proposes a new method for the preparation of novel multiphase electrically conductive concrete fiber composites and elucidates the mechanism of its electrical resistivity and compressive and flexural properties. The effects of concrete, graphite and stainless steel fibers as conductive phase materials on the changing law of physical properties of conductive concrete were compared, and the optimal ratio of the content of conductive phase materials was explored. A numerical calculation model of multi-field coupling of a new type of conductive concrete under high current impact was established. The results demonstrate that when the graphite content is 20% and the stainless steel fiber content is 2.75% ± 0.1%, the mechanical and electrical properties ratio is the best. The resistivity was reduced by 54%, the compressive strength was increased by 47.4%, and the flexural strength was increased by 151.4% compared to graphite conductive concrete. The new conductive concrete has promising frontiers of steady-state electricity and transient heat under 20 kA high current impingement, with its current density value dropping to 3280A/m3 and the maximum module temperature dropping to 2270 K. Relevant research provides a theoretical reference for guaranteeing the safe operation of power systems. [ABSTRACT FROM AUTHOR]

This article examines the impact of goaf collapse on overhead transmission lines, delving into various aspects such as foundation deformation, tower foundation and simulation calculation errors, tower deformation, and the effects at hanging points. Through a detailed analysis of surface deformation, the study reveals the laws and characteristics of surface deformation in goaf areas and proposes corresponding coping strategies. At the same time, it emphasizes the importance of precise monitoring, structural optimization design, long-term monitoring and maintenance, and emergency plan formulation to ensure the stable operation of the power system. [ABSTRACT FROM AUTHOR]

This study analyzed the impact of surface deformation on the stability of overhead transmission lines and proposed corresponding countermeasures. The research first explored the mechanical effects of tower tilt, displacement, and suspension point changes caused by surface deformation on transmission lines. These effects include redistribution of conductor tension and deviation of insulator strings. Through mathematical models and engineering approximations, the specific effects of tower foundation settlement and horizontal displacement along the line direction on the operating conditions of various levels of overhead lines were analyzed in detail. The research has shown that surface deformation can cause suspension points to become stress concentration areas, leading to deformation or damage of suspension plates and their fixing components, thereby affecting the stability of the power system. To accurately assess these impacts, it is recommended to use high-precision measuring instruments for regular data collection and analysis. In addition, this study emphasizes the importance of considering the role of additional forces in structural design and selecting tower materials with sufficient strength, stiffness, and corrosion resistance. Finally, this paper proposes a series of maintenance and adjustment measures, such as re-tensioning wires, adjusting tower positions, or adding additional support structures, to ensure the safe and stable operation of the line. [ABSTRACT FROM AUTHOR]

This article conducts a thorough investigation into the spatial state variations of overhead lines in response to foundational changes, as well as alterations in the electrical distance between the conductor and both the ground and tower structures. These changes are crucial for maintaining the stability and safety of the power system. By establishing an appropriate coordinate system and analyzing how tower sinking affects the position of overhead lines, this study examines the combined effects of multiple factors on the position of overhead lines. These factors include the degree of tower sinking, the elasticity and tension of the overhead lines, the positions and heights of adjacent towers, wind force, temperature, and other environmental elements. A mathematical model was developed to describe the positional changes of overhead lines following tower sinkage, and formulas were used to calculate the new suspension point positions and electrical distance variations of the wires. In addition, the effects of wire oscillations due to wind forces on the electrical clearance at tower heads and the impact of insulator string deviation on wire stability and safety were analyzed. Finally, a series of measures were proposed to ensure the safe operation of the power system. [ABSTRACT FROM AUTHOR]

Fault detection and classification in transmission lines are critical for maintaining the reliability and stability of electrical power systems. Quick and accurate fault detection allows for timely intervention, minimizing equipment damage, and reducing downtime. This study addresses the challenge of effective fault classification, particularly when dealing with smaller, more practical datasets. Initially, the study examined the performance of conventional machine learning algorithms on a comprehensive dataset of 7681 samples, demonstrating high accuracy owing to the inherent symmetry of sinusoidal voltage and current signals. However, the true efficacy of these algorithms was evaluated by minimizing the dataset to 231 training samples, with the remainder being used for testing. A novel Multi-Target Ensemble Classifier was developed to improve classification accuracy. The proposed algorithm achieved an impressive overall accuracy of 0.829165, outperforming traditional methods, including the K-Nearest Neighbors Classifier, support vector classification, random forest classifier, decision tree classifier, AdaBoost classifier, gradient boosting classifier, and Gaussian NB. This research highlights the importance of efficient fault classification techniques in power systems and proposes a superior solution in the form of a multitarget ensemble classifier. [ABSTRACT FROM AUTHOR]

We examine the skill associated with sustained wind forecasts in the High-Resolution Rapid Refresh (HRRR) model, extending and enhancing previous work. Some utilities use numerical weather prediction models like the HRRR to anticipate electrical transmission line shutdowns for public safety reasons, increasing the importance of forecast accuracy and motivating the need to understand sources of bias and differences among observation networks. We demonstrate that the HRRR forecasts for airport stations are very good albeit with a tendency to underpredict the highest wind speeds and at the windiest locations. Forecasts for non-airport networks are much less accurate owing to a variety of factors, including differences in the way winds are measured and the environments they are measured in, and this results in predictions with excessive temporal variation relative to observations. We demonstrate a practical approach to modifying sustained wind forecasts so that they are more useful proxies for conditions being observed in the field. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method to enhance the performance of a random number generator (RNG) that exploits ring oscillators (ROs). Our approach employs additional phase detectors to extract more entropy; thus, RNG uses fewer resources to produce bit sequences that pass all statistical tests proposed by National Institute of Standards and Technology (NIST). Generating a specified number of bits is on-demand, eliminating the need for continuous RNG operation. This feature enhances the security of the produced sequences, as eavesdroppers are unable to observe the continuous random bit generation process, such as through monitoring power lines. Furthermore, our research demonstrates that the proposed RNG's perfect properties remain unaffected by the manufacturer of the field-programmable gate arrays (FPGAs) used for implementation. This independence ensures the RNG's reliability and consistency across various FPGA manufacturers. Additionally, we highlight that the tests recommended by the NIST may prove insufficient in assessing the randomness of the output bit streams produced by RO-based RNGs. [ABSTRACT FROM AUTHOR]

Overhead power lines are important components of power grids, and the status of transmission line equipment directly affects the safe and reliable operation of power grids. In order to guarantee the reliable operation of lines and efficient usage of the power grid, the tension of overhead power is an important parameter to be measured. The tension of power lines can be calculated from the modal frequency, but the measured acceleration data obtained from the accelerometer is severely contaminated with noises. In this paper, a multiscale-based peak detection (M-AMPD) algorithm is used to find possible modal frequencies in the power spectral density of acceleration data. To obtain a reliable noise-free signal, median absolute deviations with baseline correction (MAD-BS) algorithm are applied. An accurate estimation of modal frequencies used for tension estimation is obtained by iteration of the MAD-BS algorithm and reduction in frequency range technique. The iterative range reduction technique improves the accuracy of the estimated tension of overhead power lines. An accurate estimation of overhead power line tension can contribute to improving the reliability and efficiency of the power grid. The proposed algorithm is implemented in MATLAB R2020a and verified by comparison with measured data by a tensiometer. [ABSTRACT FROM AUTHOR]

This paper presents a new method for fault location in transmission lines with series compensation, using data from voltage and current measurements at both terminals, applied to artificial neural networks. To determine the fault location, we present the proposal of using current phasors, obtained from the oscillography recorded during the short circuit, as the input to the neural network for training. However, the method does not rely on the internal voltage values of the sources or their respective equivalent Thevenin impedances to generate training files for the neural network in a transient simulator. The source data are not known exactly at the time of the short circuit in the transmission line, leading to greater errors when neural networks are applied to real electrical systems of utility companies, which reduces the dependency on electrical network parameters. To present the new method, a conventional fault location algorithm based on neural networks is initially described, highlighting how the dependency on source parameters can hinder the application of the artificial neural network in real cases encountered in utility electrical systems. Subsequently, the new algorithm is described and applied to simulated and real fault cases. Low errors are obtained in both situations, demonstrating its effectiveness and practical applicability. It is noted that the neural networks used for real cases are trained using simulated faults but without any data from the terminal sources. Although we expect the findings of this paper to have relevance in transmission lines with series compensation, the new method can also be applied to conventional transmission lines, i.e., without series compensation, as evidenced by the results presented. [ABSTRACT FROM AUTHOR]

Three-phase diode bridge rectifiers are widely employed in various industrial applications because of their inherent simplicity, robustness, low electromagnetic interference and good overall performance. However, their use causes harmonic distortion in the electric power network line currents due to their nonlinear nature, which, in turn, affects the electric power quality. The fundamental approach to limit the line currents' total harmonic distortion (THD) introduced by the diode bridge rectification systems is based on increasing the number of steps in their waveform per power supply cycle and drawing them closer to the pure-sine waveforms. This can be achieved by employing the conventional twelve-pulse rectification system composed of two parallel connected six-pulse diode bridge rectifiers, in which the DC circuit is expanded on the auxiliary circuit responsible for adequately shaping the line currents' waveforms per power supply cycle. When the auxiliary circuit is connected to the interphase reactor (IPR) additional (secondary) winding, the ability of the rectification system to reduce the line current THD depends mainly on the auxiliary circuit current waveform and its parameters. This paper provides a space vector analysis of the twelve-pulse diode bridge rectifier operation. It leads to devising a formula for the auxiliary circuit current related to the phase angle of the rectification system line currents' space vector and the load current, which has been missing in the literature so far. The formula explicitly defines the auxiliary circuit current waveform that guarantees the optimal line currents' THD for the twelve-pulse diode bridge rectifier which is expanded with the auxiliary circuit connected to the IPR secondary winding. The theoretical studies are validated through experimental investigations. [ABSTRACT FROM AUTHOR]

In the present study, our emphasis was directed towards the fabrication process of long multi-core superconducting wires, each spanning several hundred meters. These wires feature an in situ MgB2 core, an ex situ MgB2 barrier, and a copper shield. The cost-effectiveness of these constituent materials, coupled with a judicious arrangement of internal components, facilitates the utilization of an economical shielding material for the resulting wire. Our ongoing efforts have successfully yielded several hundred-meter-long wire sections possessing favorable superconducting characteristics, making them suitable for self-field applications, such as direct current (DC) power lines. [ABSTRACT FROM AUTHOR]

AC transmission expansion planning (ACTEP) is one of the most critical issues in electric power system expansion planning. In existing research on ACTEP, the reduction of power losses is often overlooked due to the significant computational workload associated with ACTEP problem. While in some instances, minimizing power loss is included as an objective function in the TEP problem, this approach may impact the addition of new lines. Consequently, to address this issue, a four-stage strategy is proposed in this paper for resolving ACTEP problem while considering power loss reduction. Specifically, the reduction of power losses is addressed after the deployment of new transmission lines. Moreover, a hybrid approach, referred to as differential evolution (DE) combined with teaching–learning-based optimization (TLBO) algorithms, called (DE-TLBO), is proposed for optimizing reactive power planning and determining the size of thyristor-controlled series compensators (TCSC) to minimize power loss in ACTEP problem. Simulation results conducted on Graver 6 bus, IEEE 24 bus, and modified IEEE 118 bus systems demonstrate the efficacy of the proposed algorithm when compared to conventional methods such as differential evolution (DE), modified artificial bee colony, and real genetic algorithms (RGA). Additionally, the proposed method also illustrates the effectiveness of utilizing TCSC to reduce power loss in the Graver 6 bus and the IEEE 24 bus systems by 3.72% and 11.95%, respectively. [ABSTRACT FROM AUTHOR]

Penetration of distributed generators (DGs) to the grid is transcending because of the importance given to green energy. Microgrids are gaining attention because of DGs and local control to reduce peak demand on the grid. Power flow analysis in microgrids must be considered while expanding the microgrids. Even though the conventional methods for power flow analysis apply to grid-connected mode, they cannot be used for an islanded mode of microgrid operation. Many modifications to the existing approach were proposed in the literature such as no slack bus, variable system frequency, and droop-controlled generators. A low-voltage microgrid of short distance which is for small communities is considered in the work. For such transmission lines, the resistance will be more than the line reactance. This paper focuses on modifying the conventional Gauss–Seidel method for the power flow analysis in low-voltage short transmission islanded microgrid. The power flow equations are modified considering there is no slack bus, and DG models are formulated for low-voltage, short transmission networks with droop control. The effectiveness of these considerations is illustrated by conducting simulation studies on a six-bus network and its effect on system frequency, real, and reactive power losses are also analyzed. The results obtained are compared with the existing results in the latest literature in which optimization techniques were used for droop coefficients calculation, and it is found that in the proposed approach, the real power losses are reduced by 2 kW without using any optimization algorithm for calculating the droop coefficients. Hence, the proposed approach is a good choice for power flow analysis in low-voltage microgrids for smaller communities. [ABSTRACT FROM AUTHOR]