Transmission Line Effects Research Articles

Between Wires and Wings: What Are the Impacts of Power Transmission Lines on the Diversity of Insectivorous Bats?

Energy consumption in the world is growing every year, and there is an increasing demand on the energy system to meet the increase in consumption, resulting in the installation of new power transmission lines. The understanding of how power transmission lines affect biodiversity is predominantly focused on birds, with limited information available on other organisms. In this study, we assessed the potential effect of power transmission lines on bat communities in a locality in the Cerrado biome in Brazil. More specifically, we used a paired sample design and acoustically sampled bats in locations near and far from the transmission lines. Our findings suggest that power transmission lines do not have a generally positive or negative effect on insectivorous bat communities in the study area. However, their presence seems to be associated with increased diversity in specific functional groups and changes in the activity patterns of some bat species and families. We believe that this information is of particular importance for establishing appropriate programs during the environmental licensing process, assisting in the development of projects in the different stages of construction as well as in monitoring programs during operation.

Discussion on multi-condition load capacity evaluation algorithm of transmission line based on fusion algorithm

ABSTRACT High temperature, strong wind, ice cover and other problems may lead to transmission line breakage, tripping, tower toppling and so on. In order to reduce the probability of such problems, it is necessary to predict the load capacity of transmission line in multiple working conditions. In order to improve the accuracy of load capacity prediction of transmission lines under multiple working conditions and reduce the occurrence of bad transmission line problems, Particle Swarm Optimisation-Back Propagation neural network algorithm is used to simulate the prediction of transmission lines under different working conditions with different accuracy. The results show that the error of the optimised fusion algorithm is smaller than that of the pre-optimised algorithm. Combined with the prediction error results of the traditional neural network, it is found that the fusion algorithm can improve the prediction effect of transmission lines, has strong robustness, and can be popularised in practice.

Finite element analysis of pulse sharpening effect of gyromagnetic nonlinear transmission line based on Landau–Lifshitz–Gilbert equation

Ferrite-loaded gyromagnetic nonlinear transmission line (GNLTL) provides a possible option to compress an input pulse to a narrower width for its remarkable sharpening effect. However, it is difficult to accurately predict the output of the GNLTL due to the complex interaction between the magnetic moment of ferrite and the bias magnetic field. In this paper, a finite element model of the GNLTL is established based on the Landau–Lifshitz–Gilbert equation to investigate the performance of the GNLTL. To validate this model, a prototype is used for experimental comparison. The result demonstrates good agreement between experiment and simulation. This paper further explores the influence of the bias magnetic field and the length of the GNLTL on the output pulse. Moreover, a method to sharpen the falling edge is proposed based on the reflection and superposition of the GNLTL output. Simulation and experimental results show its effectiveness and feasibility.

Nonlinear Time-domain signal and noise analysis of an active CRLH transmission line for millimeter-wave frequencies

In this paper, time domain signal and noise behavior of an active CRLH transmission line was investigated in the nonlinear regime at millimeter wave frequencies. In this structure, the transistor is considered as three coupled transmission lines and all three drain,gate and source lines are CRLH transmission lines. The left-handed element values for the active CRLH transmission line are calculated in such a way that the phase cancellation effect and dispersion of the CRLH transmission line are reduced. In order to model this active CRLH transmission line, with the assumption of wave propagation in the form of Quasi-TEM, the distributed modeling method is used to extract stochastic telegraphic equation (STE) in the non-linear regime. To model noise sources in the non-linear regime, the Wiener process and modulation functions have been used to model white noise in the nonlinear regime and in the time domain. By applying the finite integration method to stochastic telegraphic equation, the behavior of the signal and noise of the active structure CRLH has been compared with a line of active structure RH and the obtain results of the numerical method have been verified with the results of the Agilent ADS software.

Disamenity or premium: Do electricity transmission lines affect farmland values and housing prices differently?

A substantial increase in electricity demand has triggered a rising investment in energy infrastructure in the US over the last decade. This paper examines the capitalization effects of electricity transmission lines (TMLs) on nearby farmland values and housing prices in the Midwest from 2015 to 2019, based on 16,026 parcel-level farmland sales data from FarmlandFinder and 1,905,280 housing transaction data from the Zillow Transaction and Assessment Dataset database. Our estimation results reaffirm the disamenity effects of TMLs on housing property values and find that the disamenity effects are larger on houses in urban areas than in rural areas. Nearby TMLs generate premiums for surrounding farmland, which contrasts with the disamenity evidence due to aesthetics (either visual or audible) in the literature. We further show that farmland parcels within 0–2 km of TMLs in high-wind areas are approximately 3.10% more expensive than comparable parcels in low-wind areas. Our paper provides novel and contrarian evidence on the effects of TMLs on property values amid rising investment in energy infrastructure.

Analysis and Stabilization of Signal Reflections in Gate-to-Gate Connections for AQFP Circuits

Signal integrity of transmitted data is critical for achieving highly dense, large-scale superconductor circuits. Transmission line effects, such as signal reflections, are investigated and concepts from microwave circuit theory and conventional digital logic circuits are applied to AQFP circuits. The lossless transmission line model is used for interconnection modelling. The frequency content and timing characteristics of data signals are used to analytically predict a maximum propagation delay of 6.1 ps before failure due to reflections. This coincides well with our own results, and with those obtained in a separate study using simulation techniques. The investigation then extends towards the design of an impedance matching network with the aim of reducing reflections. The input impedance of a standard buffer gate is derived, and then matched to an 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Omega$</tex-math></inline-formula> transmission line. The proposed impedance matching network maintains data signal integrity up to 3 millimetres. Energy analysis of the matching network is also performed and a 36 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> increase in length for similar energy consumption is achieved over alternative solutions.

Identifying and Modeling Resonance-Related Fluctuations on the Experimental Characteristic Impedance for PCB and On-Chip Transmission Lines

It is well known that the fluctuations in experimentally obtained characteristic impedance versus frequency curves are associated with resonances originated by standing waves bouncing back and forth between the transitions at the transmission line terminations. In fact, microwave engineers are aware of the difficulty to completely remove the parasitic effect of these transitions, which makes obtaining smooth and physically expected frequency-dependent curves for the characteristic impedance a tough task. Here, we point out for the first time that these curves exhibit additional fluctuations within the microwave range due to standing waves taking place within the transition itself. Experimental verification of this fact was carried out by extracting this fundamental parameter from measurements performed on on-chip and printed circuit board (PCB) lines using probe pad adapters and coaxial connectors. We demonstrate that the lumped circuit approach to represent the transitions lacks validity when the additional fluctuations due to the connectors become apparent, and we propose a new model including transmission line effects within the transition.

Study on Dynamic Line Rating of Overhead Transmission Line Based on Large-Scale New Energy Power Grid Connection

With increasing new energy power grid connections and increasingly complex user loads, higher ampacity is required during peak power demand. Construction of new transmission lines can cost a lot and is limited by the environment and the shortage of land resources. Considering the intermittency of new energy power generation, dynamic line rating can increase the power transmission capacity of existing lines by exploiting their potential capacity. In this paper, the ampacity of transmission lines is calculated accurately, and influencing factors of ampacity are studied. Additionally, temperature change patterns and field distribution of the lines are studied. The results show that wind speed, ambient temperature, and sunshine intensity are the three main factors affecting the ampacity. Wind speed is proportional to ampacity, while ambient temperature and sunshine intensity are opposite. Then, it is found that the thermal inertia effect of transmission lines that temperature change lags behind current change can be utilized for ampacity enhancement. Furthermore, the radial temperature difference is found in the lines, and excessive temperature differences may accompany the risk of strand breakage. It is of great significance to study the temperature field of the lines for dynamic line rating based on large-scale new energy power grid connections.

Small Signal Equivalent Circuit Model of MESFET with Effect of Transmission Line

For the design of Integrated Circuit GaAs MESFET is Suitable by considering the transmission line character of the gate length at high frequencies. In the conducting channel, a stationary high field domain under saturation current condition. Small signal equivalent circuit of the channel is derived and equivalent circuit has been optimized by simulating average S-parameters for the process calculated between 1-65GHZ and 150 nm gate length of the device.

Study on the Interference Law of AC Transmission Lines on the Cathodic Protection Potential of Long-Distance Transmission Pipelines

Through inductive coupling, AC transmission lines can generate large amounts of voltage to buried oil and gas pipelines in areas with common corridors, posing a threat to the cathodic protection effect of pipelines. Therefore, this paper investigates the effect of AC transmission lines on the cathodic protection of long-distance pipelines through inductive coupling. COMSOL Multiphysics finite element simulation software is used to calculate the distribution of cathodic protection potential of long-distance pipelines under different voltage levels, parallel spacing, conductor-to-ground height, conductor arrangement and pipeline burial depth for normal operation of AC transmission lines. Comparison and analysis of the AC transmission line on the pipeline cathodic protection potential interference law is conducted. The results show that: 1. AC transmission lines cause serious electromagnetic interference with the pipeline cathodic protection system, which will cause the pipeline cathodic protection potential to shift out of the effective protection area. 2. The maximum value of the induced voltage of the pipeline will appear at the two ends of the pipeline, and the induced voltage of the pipeline in the middle position is 0. 3. The shift of the pipeline cathodic protection potential increases with the increase of voltage level and decreases with the increase of parallel spacing, conductor height and burial depth. The pipeline cathodic protection potential shift is highest when the wires are arranged horizontally and lowest when they are arranged in an umbrella shape.

Effect of Transionospheric Transmission Lines on the Probabilistic Characteristics of Reception of Phase-Shift Keyed Signals

The paper presents methods for describing distortions of signals during their propagation in transionospheric transmission lines, which cause inter-symbol and inter-channel interferences. A technique for estimating the statistical characteristics of the interference noise has been developed and their estimation for digital phase-shift keyed signals is carried out by simulating transionospheric lines. The probabilistic characteristics and asymptotic probabilities of erroneous reception of the considered signals with an increase in their frequency band are estimated using the calculated statistical characteristics for the lines of the P range.

Effect of Transionospheric Transmission Lines on the Probabilistic Characteristics of Reception of Phase-Shift Keyed Signals

Effect of Transionospheric Transmission Lines on the Probabilistic Characteristics of Reception of Phase-Shift Keyed Signals

Surface Wave, Skin Effect, and Per Unit Length Parameters of the Single-Wire Transmission Line at Low Frequency, for Nonmagnetic and Magnetic Wires

Surface Wave, Skin Effect, and Per Unit Length Parameters of the Single-Wire Transmission Line at Low Frequency, for Nonmagnetic and Magnetic Wires

Ac corrosion phenomenon and mitigation in buried pipeline due to very-high-voltage (VHV) overhead transmission line effect

The presence of a very-high-voltage (VHV) electricity transmission line nearby a metallic pipeline can be a source of dangerous effects for this pipeline due to the electromagnetic field generated by this power line, it can induce a considerable voltage which may threaten the safety of operating personnel and the integrity of the pipeline. The main purpose of this paper is to evaluate the electromagnetic coupling effect in a buried metallic pipeline located in close proximity to a very-high-voltage (VHV) overhead transmission line using the Faraday's law and nodal network analysis under steady state conditions, as well as to estimate the possibility of AC induced corrosion of the metallic pipeline. The obtained results show that the induced voltage on the metallic pipeline exceeds the maximum threshold value recommended by the international regulations CENELEC and NACE, the AC corrosion current density surpasses the allowable value indicated by the specialized majority of corrosion studies. Therefore, a mitigation technique based on a pipeline grounding system is proposed to reduce the voltage induced on the pipeline to safe limits, in order to remedy the hazardous potential effects. The adopted mitigation technique has achieved better efficiency by reducing the induced voltage well below the safety limit.

Capacitive Sensing for 2-D Electrostatic MEMS Scanner in a Clinical Endomicroscope.

A flexible fiber-coupled confocal laser endomicroscope has been developed using an electrostatic micro-electromechanical system (MEMS) scanner located in at distal optics to collect in vivo images in human subjects. Long transmission lines are required that deliver drive and sense signals with limited bandwidth. Phase shifts have been observed between orthogonal X and Y scanner axes from environmental perturbations, which impede image reconstruction. Image processing algorithms used for correction depend on image content and quality, while scanner calibration in the clinic can be limited by potential patient exposure to lasers. We demonstrate a capacitive sensing method to track the motion of the electrostatically driven two-dimensional MEMS scanner and to extract phase information needed for image reconstruction. This circuit uses an amplitude modulation envelope detection method on shared drive and sensing electrodes of the scanner. Circuit parameters were optimized for performance given high scan frequencies, transmission line effects, and substantial parasitic coupling of drive signal to circuit output. Extraction of phase information further leverages nonlinear dynamics of the MEMS scanner. The sensing circuit was verified by comparing with data from a position sensing detector measurement. The phase estimation showed an accuracy of 2.18° and 0.79° in X and Y axes for motion sensing, respectively. The results indicate that the sensing circuit can be implemented with feedback control for pre-calibration of the scanner in clinical MEMS-based imaging systems.

High frequency oscillation damping for the VSC-HVDC connects to a wind farm via a cable transmission line

When a wind farm connects to the grid via a high voltage direct current transmission based on voltage source converter (VSC-HVDC), high frequency oscillation (HFO) is a critical issue that threatens the system stability, this issue has been reported in many HDVC projects all over the world. The current research proved the negative resistance brought by the effect of control delay in VSC-HVDC is a primary cause of instability. This paper ulteriorly analyzes the influence on system stability caused by the long ac cable between the wind farm and the VSC-HVDC, and indicates that the effect of the cable transmission line can contribute to the system instability as well, while the existing damping methods did not consider this effect. Then the control failure of the exiting damming methods when considering the cable transmission line is analyzed and verified by the impedance analysis theory. Thereby, this paper proposed a vector modified resonant controller (VMRC) which can independently and flexibly regulate the magnitude and phase of HVDC impedance, to solve the HFO issue caused by the combined effect of the control delay and the cable transmission line. Also, the design procedure of the proposed control strategy is detailly presented. Finally, experimental results are provided to verify the correctness of the mechanism analysis and the validity of the proposed control strategy.

An Improved Thru-Line De-Embedding Technique up to 80 GHz

With the rapid increase of high-speed communications, the frequency range of integrated circuits enters the field of millimeter wave, and the size of devices has become smaller and smaller. In the measurement of microwave devices, the probe cannot contact the device directly. The actual device under test (DUT) is surrounded by metal traces called leads, which provide the interface between the probing pads on the wafer and the DUT itself. The probes are pressed on the pads at both ends of the DUT. The parasitic effect of pads and transmission lines is significant at high frequency. The established technique such as Short-Open-Load-Thru (SOLT) and Line-Reflect-Reflect-Match (LRRM) move the reference plane up to the tip of the probes by means of Cascade Microtech impedance standard substrate (ISS). To obtain accurate parameters of DUT, a deembedding method must be implemented to eliminate the influence of pads and interconnect transmission lines.

Transmission Line Effects of Long Gate-to-Gate Interconnections in Adiabatic Quantum-Flux-Parametron Logic Circuits

Adiabatic quantum-flux-parametron (AQFP) logic is an energy-efficient superconductor logic family that utilizes adiabatic switching of logic gates. At present, a pure inductance is used to model a gate-to-gate interconnection in AQFP logic circuits. However, it is necessary to consider the transmission line effects when the interconnection length becomes long to take into account the propagation delay. This study investigated the transmission line effects of a long gate-to-gate interconnection in AQFP logic circuits. We observed reflection effects in a long transmission line between AQFP gates. These effects induced errors when the interconnection length exceeded several hundred micrometers. We adopted a damping resistance to stabilize the reflection effect to realize an error-free long gate-to-gate interconnection. The circuit simulations confirmed that a damping resistance connected in parallel to the transmission line effectively stabilizes the reflection effect, enabling an interconnection length that is longer than 1 mm. We fabricated AQFP buffer chains that included a long transmission line with and without a parallel damping resistance, and measured their bit error rates. The results showed that the parallel damping resistance effectively improves the bit error rate at high frequencies.

Research on the Influence of Various Attribute Factors on Passive Interference in UHV Transmission Lines Based on Orthogonal Test

Considering the problem of passive interference caused by electromagnetic scattering effects of transmission lines to neighboring radio stations and other communication equipment, this paper refines the passive interference calculation model for UHV transmission lines. The solution calculation is carried out by the Method of Moments, and the law of passive interference effect of the tower structure, auxiliary angles, and ground roughness under different frequency incident waves, is summarized. By designing an orthogonal test, the degree of influence of the above attributing factors on passive interference results in the established joint model of three towers with two stall distances was explored by using Analysis of Variance. The results demonstrate that both auxiliary angles and rough ground show a pattern of enhanced electromagnetic scattering effect with increasing plane wave frequency in single-factor analysis. When multiple factors are combined, the rough ground has a significant effect on the results. This method effectively evaluates the passive interference influence factor while reducing the modeling and simulation engineering and provides a reference for the passive interference prediction in subsequent practical projects.

A compact magnetic resonance system with inside-out sensor for soil moisture measurement

Accurate measurement of soil moisture parameters plays a vital role in promoting agricultural production. Nuclear magnetic resonance (NMR) measuring instruments have become increasingly compact, especially in low field applications. However, NMR soil moisture measurement instruments still have problems with portability. We report on a compact NMR measuring instrument that focuses on the circuit’s design and construction. The instrument includes an inside-out sensor, NMR spectrometer, radio frequency power amplifier, low-noise preamplifier, and duplexer. They are integrated into a slim 3D-printed cylinder. The integrated NMR instrument is portable and user-friendly and can reduce the influence of nonideal factors, such as transmission line effects and electromagnetic interference. We conducted different soil moisture experiments with the prototype using Carr–Purcell–Meiboom–Gill pulse sequence to obtain the corresponding transverse relaxation time (T 2) decay curves. Then, the T 2 1D spectrum distributions were obtained by inverse Laplace transformation. Finally, the results reveal that the area of long T 2 component decreases as the soil moisture content decreases.