Transmission Line Behavior Research Articles

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.

Transmission line switching spread modelling of synchrophasor smart grid network with load uncertainty inspired by epidemic model: a study of reliability and vulnerability

ABSTRACT Monitoring and controlling of transmission lines become easier in real time with synchrophasor measurements technology. Phasor Measurement Units (PMUs) provide the time-stamped synchrophasor data of the system buses and transmission lines with a high reporting rate. In this paper, a mathematical model is implemented that allows the simulation of the characteristics of the spread of transmission line switching with load variations. In the model, the transmission lines are divided into three parts defined as susceptible, infected and recovered transmission lines inspired from epidemic model. In this paper, Reliability Test System (RTS − 1979) is divided into three zones to simulate the line switching spread behaviour with load variation for reliability and vulnerability analysis of the synchrophasor smart grid network. The anomaly exists with synchrophasor measuring devices due to cyber intrusion in communication network or failure of devices makes the system observable with the characterization of vulnerable behaviour of transmission lines.

Using the Exact Equivalent π-Circuit Model for Representing Three-Phase Transmission Lines Directly in the Time Domain

This paper presents a novel three-phase transmission line model for electromagnetic transient simulations that are executed directly within the time domain. This model relies on distributed and frequency-dependent parameters, as well as employs modal transformation for its implementation. The single-phase model of the exact equivalent π-circuit is utilized for each propagation mode. This model combines discrete components, such as resistors, inductors, and capacitors, to accurately emulate the transmission line behavior via linear circuit elements. This model can be seamlessly integrated into various electrical circuit simulation software, thus allowing easy utilization and incorporating time-varying elements to analyze transmission lines. The JMarti model, which comes by default in the Alternative Transient Program, and the numerical Laplace transform method implemented in MATLAB were utilized to validate the proposed solution across various scenarios. An advantage of this model is its independence from the prior calculation of travel time and its exemption from convolutions, inverse Laplace transforms, and Fourier transforms, thus streamlining the simulation process.

A novel and ultra-compact plasmonic filter with a fully controlled rejection band

In this article, we propose a novel approach to develop an ultra-compact spoof surface plasmon polariton (SSPP) band-rejection filter by loading T-shaped grooves on the SSPP transmission line (TL). This scheme is based on the interaction between two types of grooves, i.e. rectangular grooves of the SSPP TL and T-shaped grooves. This form of interaction has never been addressed before in order to achieve a highly efficient SSPP band-rejection filter. The working principle of this band-rejection filter is clearly revealed via investigation of the dispersion behavior of the SSPP TL in the presence and absence of T-shaped groove loading. Meanwhile, we simulate an SSPP TL loaded with T-shaped grooves. As proof of concept, we fabricate the filter in the microwave regime and perform an experiment which characterizes its functionality. The simulated and experimental results confirm the excellent filtering phenomena exhibited by our structure. The isolation of the filter can be less than −15 dB at rejection frequencies with excellent transmission efficiency in both passbands, before and after the rejection band. Furthermore, simulated near-electric-field results are also presented to demonstrate the authenticity of the filter. When the question of generating a highly efficient SSPP band-rejection filter arises, the proposed method facilitates us with T-shaped grooves, which are declared as an excellent alternative to metamaterial particles in this regard. The proposed band-rejection filter based on SSPPs demonstrates an outstanding capability to take part in the progress and the advancement of integrated plasmonic structures and systems at microwave frequencies.

Characterization of unidirectional and bidirectional transparencies in -symmetric quantum and classical systems

We studied the scattering state behavior of tight-binding quantum system and classical electrical transmission lines. We distributed on-site energies ϵ n and resistances R n , respectively, according to a parity-time -symmetric distribution. Using the formalism of scattering matrix S and transfer matrix M, we derived analytical expressions for components of transfer matrix M, and through them, we found transmission coefficient T and left (R L ) and right (R R ) reflectance. In addition, we found a generalized conservation relation that relates T, R L and R R , valid for quantum and classical -symmetric systems. We numerically studied the general behavior of T, R L , R R and eigenvalues s ± of scattering matrix S in the full range of possible values of the gain and loss parameters. We observed the existence of unidirectional and bidirectional transparency for specific energies E (quantum case) and specific frequencies Ω (transmission line case), for which the following conditions were simultaneously fulfilled: i) T was unitary (T = 1), ii) eigenvalues s ± were degenerate and unimodular , iii) the product of reflectances tended to zero, , and iv) phases ϕ of one or both reflection amplitudes showed abrupt change of π. This way, we characterized the unidirectional and bidirectional transparency for classical and quantum systems as a function of the gain and loss parameters that describe both models. In addition, the theoretical results showed complete agreement with the numerical calculation. We hope that our work contributes to a better understanding of the influence of the -symmetric distribution of gain and loss parameters on the scattering properties of quantum and classical systems.

RF and Crosstalk Characterization of Chip Interconnects Using Finite Element Method

This paper presents new finite element method (FEM) based approach for radio frequency (RF) and crosstalk (X talk) characterization of chip interconnects. Being based on scattering parameters (S-parameters), this approach truly and accurately demonstrates the transmission line behavior of chip interconnects over a wideband of frequencies. To demonstrate FEM based method, a single-line and a 3-line interconnect test structures on SiO2-Si substrate have been designed and simulated in High Frequency Structure Simulator (HFSS). The RF and crosstalk characterization of chip interconnect materials Copper (Cu), doped multilayer Graphene Nanoribbon (DMLGNR), and neutral multilayer Graphene Nanoribbon (NMLGNR) have been demonstrated in terms of transmission coefficient (Sij & Smn) from 1 to 1000 GHz. The single-line three-dimensional (3D) structures comprising of Cu, DMLGNR, and NMLGNR have maximum transmission loss values of -15.93 dB, -22.03 dB, and - 13.73 dB at frequencies of 643 GHz, 402 GHz, and 643 GHz, respectively whereas three-line bus structure exhibit maximum victim-line transmission loss values of -15.28 dB, -17.47 dB, and -15.98 dB at frequencies of 247 GHz, 829 GHz, and 377 GHz, respectively. Further, the crosstalk results have demonstrated that as frequency increases significant crosstalk is observed between nearby lines due to electromagnetic interference and coupling (EMI/EMC) issues.

Study on the influence of 30 mA leakage current on the atmospheric corrosion behavior of transmission lines

Under the action of 30 mA leakage current, in order to study the influence of atmospheric corrosion behavior on metal materials of transmission lines, this article analyzes the corrosion weightlessness of metal materials under different SO2 concentrations and leakage current conditions by placing metal materials in three corrosive environments. When the content of SO2 is relatively small, the leakage current has little effect on the corrosion weightlessness of the sample. However, when the content of SO2 is relatively large, the leakage current accelerates the corrosion of metal materials, and the surface of the sample will have more γ-FeOOH metastable crystalline phase. When the corrosion products accumulate to a certain extent, some of the corroded samples γ-FeOOH become relatively stable α-FeOOH and Fe3O4, the corrosion products will reduce the occurrence of corrosion phenomena, and on the contrary, the corrosion resistance of the sample will be improved.

Transient response of nonparallel frequency-dependent transmission lines due to nearby lightning strikes in the presence of finitely-conducting ground

Overvoltage transients due to lightning strikes is a common occurrence in power transmission lines which can ultimately lead to line outages. Simulation of transmission line networks under the influence of lighting plays a vital and essential role in predicting their transient behaviour . The transient behaviour of uniform transmission lines due to lightning has been studied extensively. However, in modern transmission line networks, nonuniformities and discontinuities such as nonparallel wire, line crossings or bends are becoming increasingly common. Therefore, in such cases, inaccuracies might be present in analysis performed using conventional uniform transmission line approaches. A recent publication by the authors analysed the transient behaviour of nonparallel and crossing transmission lines above perfect electric conductor (PEC) ground. However, the PEC assumption can only be used in a limited scope. In this paper a nonuniform transmission line model with external field coupling is presented to analyse the transient behaviour of a nonuniform wire structure due to the field coupling from a nearby lightning strike in the presence of lossy ground. Simulation results generated by the proposed model is compared with full-wave simulations and results published by other researchers. A case study to compare the results from the proposed model with a conventional uniform transmission line model under various ground-conductivity values and terminating conditions is also performed. The study indicates that the presence of nearby nonparallel lines can cause the transient behaviour of the structure to deviate from the behaviour predicted using uniform approaches. • The transient behaviour of a nonuniform wire structure a nearby lightning strike in the presence of lossy ground is studied. • Simulation results generated by the proposed model is compared with full-wave simulations and results published by other researchers. • Results from the proposed model have been compared with a conventional uniform transmission line model. • The study indicates that the presence of nearby nonparallel lines intensify the transient behaviour.

A PMU-based back-up protection scheme for fault detection considering uncertainties

In this paper, a supervisory PMU-based protection scheme is proposed to prevent mis-operation of conventional protection systems against stress conditions at the transmission level. According to the proposed method, a vulnerable area in power systems is identified using the buses, equipped PMU, with the highest distortion in voltage magnitude following an event. For a suitable implementation of the PMU-based proposed scheme, an analytical strategy is employed to optimize the installed PMUs number in the power system regarding the protection approach. Then, equivalent admittances between every two PMU-buses, surrounding the specified area, are calculated and analyzed as the key indices for fault detection. The equivalent admittance, emulating the transmission line behavior, is a function of the voltage and current of the monitored buses, and hence could be used to accurately detect the occurrence of a fault. Besides, a load-flow-based scheme is proposed for accurate fault distinction from load-increasing events. Afterwards, the impact of measurement errors on the proposed method performance is analyzed using the sensitivity analysis approach. Verification of the proposed method has been evaluated on a two-area power system and a IEEE 73-bus benchmark in the Simulink/MATLAB environment.© 2017 Elsevier Inc. All rights reserved.

Galloping Vibration Monitoring of Overhead Transmission Lines by Chirped FBG Array

A distributed online fiber sensing system based on the phase-sensitive optical time domain reflectometer (Φ-OTDR) enhanced by the drawing tower fiber Bragg grating (FBG) array is presented and investigated experimentally for monitoring the galloping of overhead transmission lines. The chirped FBG array enhanced Φ-OTDR sensing system can be used to measure the galloping behavior of the overhead transmission lines (optical phase conductor or optical power ground wire), which are helpful for monitoring the frequency response characteristics of the ice-induced galloping, evaluating the motion tendencies of these cables, and avoiding the risk of flashover during galloping. The feasibility of the proposed online monitoring system is demonstrated through a series of experiments at the Special Optical Fiber Cable Laboratory of State Grid Corporation of China (Beijing, China). Results show that the proposed system is effective and reliable for the monitoring of galloping shape and characteristic frequency, which can predict the trend of destructive vibration behavior and avoid the occurrence of cable breaking and tower toppling accidents, and these features are essential for the safety operation in smart grids.

Data mining model and Gaussian Naive Bayes based fault diagnostic analysis of modern power system networks

In this paper, different machine learning (ML) algorithms like Gaussian Naïve Bayes (GNB), K-Nearest Neighbours (KNN), Decision Tree (DT), Support Vector Machine (SVM), Random Forest (RF) and Adaptive Boosting Classifier (ABC) are used to classify the different types of faults on the transmission line. The faults and non-faults on the transmission line are created by simulating the transient behaviour of the long length transmission line by using PSCAD/EMTDC software. While simulating the faults and non-faults on the transmission line, fault resistance, fault inception angle, fault location and fault type are varied within their practical range. During the simulation, currents and voltages of three phases on both sides of the TL are measured using Current Transformers (CT) and Potential Transformers (PT) . Measured currents and voltages are pre-processed to produce the time series and frequency series parameters data set by using Fourier Transform in full cycle, half cycle, and quarter cycle from the fault instant. Feature reduction techniques select very important parameters among the calculated time series and frequency series parameters. After completing the data generation and pre-processing and application of feature reduction techniques, the machine learning algorithms are applied to the data in python software to get the comparative analysis. Noise analysis is also carried out in this work to assess the performance of the ML algorithms in dealing with the nonlinear data due to CT, PT saturation, and measurement errors.

A New Analytical Design Methodology for a Three-Section Wideband Wilkinson Power Divider

In this paper, a new analytical design technique for a three-section wideband Wilkinson power divider is presented. The proposed design technique utilizes the dual-frequency behavior of commensurate transmission lines for the even-mode analysis and contributes a set of completely new and rigorous design equations for the odd-mode analysis. Measurement of a fabricated prototype utilizing the proposed technique shows an excellent return-loss (>16 dB), insertion loss (<3.35 dB), and excellent isolation (>22.7 dB) over 104% fractional bandwidth extending beyond the minimum requirements.

A Novel Analytical Design Technique for a Wideband Wilkinson Power Divider Using Dual-Band Topology.

In this paper, a novel analytical design technique is presented to implement a coupled-line wideband Wilkinson power divider (WPD). The configuration of the WPD is comprised of three distinct coupled-line and three isolation resistors. A comprehensive theoretical analysis is conducted to arrive at a set of completely new and rigorous design equations utilizing the dual-band behavior of commensurate transmission lines. Further, the corresponding S-parameters equations are also derived, which determine the wideband capability of the proposed WPD. To validate the proposed design concept, a prototype working at the resonance frequencies of 0.9 GHz and 1.8 GHz is designed and fabricated using 60 mils thick Rogers’ RO4003C substrate. The measured result of the fabricated prototype exhibits an excellent input return loss > 16.4 dB, output return loss > 15 dB, insertion loss < 3.30 dB and a remarkable isolation > 22 dB within the band and with a 15 dB and 10 dB references provide a fractional bandwidth of 110% and 141%, respectively.

Dynamic Characterization of Wind Speed under Extreme Conditions by Recurrence-Based Techniques: Comparative Study

AbstractTransmission lines (TLs) are vulnerable to wind actions. Notwithstanding the fact that the behavior of transmission lines under strong winds has been investigated in numerous studies, wind-...

EIS Characteristics of Galvanic Couple of Aluminum Alloy and High-strength Steel under Thin Solution Films

Galvanic corrosion of 6061-T6 (AA) coupled with high-strength steel (HSS) under 2 M NaCl solution films was investigated by electrochemical impedance spectroscopy (EIS). The AA is passivated in a 2 M NaCl solution and suffered pitting corrosion by galvanic coupling with HSS of the same surface area. Impedance of the AA/HSS couple was successfully measured under thin solution films (25–100 μm) using a potentiostat as a zero-resistance ammeter. The obtained impedance data shows a typical transmission line behavior above 1 kHz, owing to a nonuniform current distribution. Impedances for the AA and HSS were separately measured in the frequency domain. The average growth rate of pits on the AA surface, estimated from the charge transfer resistance for AA, increased with decreasing solution film thickness.

Estimation performance of the lightning protection system in an urban 110 ​kV grounding grid substation

A lightning protection system (LPS) of an urban 110 ​kV substation is designed and analyzed according to NFPA 780 and IEC 62305-3 standards. The analysis of the LPS is established on the value of risk assessment. The total area of the substation has been described based on the modern designs represented by the real operational efficiency of the facility. This study aims to improve the understanding of the unexpected manner of the grounding system beneath lightning currents by clarifying the basic concepts of the lightning protection level. The mode was represented by the CDEGS software package, which provides effective geometrical modeling with object and result visualization. Furthermore, module and automated Fast Fourier Transform (FFT) is implemented in this study to simulate electromagnetic fields in the time and high-frequency domains. These current values are compared to the desired protection levels within the standards. The study results show that for the improved protection of the primary system against lightning, the total power grid must be considered as a source of improvement for studying shielding influence and the protection levels provided inside this substation. The lightning behavior of overhead transmission lines is associated with line flashover protection consequent to lightning strokes.

Design Analysis and Evaluation of a W-Element Model for a Twisted-Pair Cable

Unlike the twisted pair cable's simple installation mechanism, evaluating a circuit equivalent and certifying it is not very convenient anymore. Although the best way to model transmission lines is to use the field solver software programs such as ANSYS Maxwell or HFSS, this procedure is very overwhelming and time-consuming. This paper presents a straightforward approach to extract a W-element model for the twisted pair cable based on its structural and electrical characteristics. The W-element model employs a novel state-of-the-art transmission line simulation method which is very fast, accurate and robust. Both system designers and cable manufacturers can easily exploit the presented equations and the derived models to predict the behavior of the balanced transmission lines with two conductors using simulators such as HSpice, etc. Nexans unshielded CAT6 twisted pair cable, one of the most common types of cables used in today's networks, is selected as a case study in this paper to verify the proposed model. A variety of simulations have been carried out to evaluate the performance and accuracy of the proposed model. Furthermore, the validity of the model is assessed against the real Fluke test results.

DC corona characteristics derived from corona cage tests and simulations

This study presents experimental and simulation studies on DC corona characteristics to investigate the behavior of high voltage direct current transmission (HVDC) lines. Experimental studies are performed using an indoor corona cage and various conductor configurations, which are the scaled models of the prospective HVDC line in Turkey. Following the preliminary tests with single line models of aluminum rods and stranded conductors, DC corona inception voltages (CIVs) of prospective bundled conductor configurations are measured by using a daylight UV corona camera and a high-sensitive micro ammeter. Measurements include three different sub-conductor spacing both for the positive and for the negative DC voltages. Corona currents are measured for the voltages above the CIV levels. Experimental studies are varied by complementary simulations using a FEM based software, COMSOL Multyphysics. Following the development of 3D models of the corona cage and the prospective conductor configurations, electric field distribution along the conductor surfaces are determined. CIV measurements and simulation results are used to compute the corona inception electric field strengths of the aforementioned configurations. Radio interference voltages and audible noise levels of the configurations are finally calculated at a constant test voltage using the empirical formulations and the field simulation results. The results are discussed at the end to guide the design of intended HVDC line in Turkey.

Optimal power flow considering transient thermal behavior of overhead transmission lines

Electrothermal coordination (ETC) is a concept which exploits the potential transfer capability of transmission lines by coordinating the transient thermal behavior of the conductor and the system control actions. For the realization of ETC decision, the model of optimal power flow considering transient thermal behavior (OPFCTTB) of overhead lines and the solution methods are proposed in this paper. The OPFCTTB model is established by introducing the heat balance equations (HBEs) of overhead lines as equality constraints and the temperature of lines as the decision variable into the ac optimal power flow model. To solve the OPFCTTB model whose constraints consist of nonlinear differential-algebraic equations, the model is first discretized into a dynamic optimization problem whose constraints are algebraic equations, and then the primal-dual interior point method (PDIPM) is utilized to solve the discretized model. To improve the solution efficiency, the large-scale correction equations of the Karush-Kuhn-Tucker conditions in PDIPM are decoupled into several small-scale groups which can be solved in parallel. Numerical simulations on benchmark systems verify the validity of the proposed OPFCTTB model and corresponding solution methods.

Aggregation Strategy for Reactive Power Compensation Techniques—Validation

Reactive power provision is a vital ancillary service, which provides opportunities to service market and power generators. The net reactive power in a balanced power grid needs to be zero, and the imbalance occurs due to the capacitive and inductive behavior of the extensive transmission lines, and because of the intermittent behavior of load-demand. This mismanagement in reactive power causes voltage instability, and hence the paper compares the most common reactive power compensation techniques, which are prevalent in both literature and commercial levels. The paper perceives the trade-off between the compared techniques, and realizes to use the aggregation of different techniques to present a coordinated control mechanism that complies with the Italian regulations. The parameters for the proposed aggregation include the amount of reactive power, real power losses during reactive power provision, and response time. The paper then implements IEEE 9 bus transmission-generation system in DIgSILENT to set up the platform for validation of the proposed strategy. Finally, it simulates Transmission System Operator (TSO) test cases on the implemented test system.