Transient Analysis Of Transmission Lines Research Articles

Transient Analysis of Transmission Lines With Mismatched Terminations Irradiated by Plane Waves Based on Reciprocity Theorem

The field-to-line coupling problem of the transmission line (TL) excited by external fields can be analyzed by adopting the electromagnetic (EM) reciprocity theorem. In this article, according to the frequency-domain expression of the test current along the line in the case of the TL is terminated by the mismatched loads, the time-domain formula, consisting of the original excitation, and multiple reflected waves caused by the loads, is derived. Furthermore, the analytical expression of the induced voltage is obtained based on the EM-reciprocity theorem. The correctness of the proposed method is verified by the numerical results generated by utilizing full-wave method.

A Phenomenological Approach Based on Two Unified Loss Parameters for Transient Analysis of Transmission Lines

This article proposes a causal, accurate, and case-independent model, which can be used for the transient analysis of lossy coupled transmission lines. In addition to propagation delay and characteristic impedance, the method uses a phenomenological study on the frequency dependence of the transmission lines and identifies two unified parameters that, respectively, correspond to conductor (skin-effect) and dielectric loss. An accurate transient response is derived, and a generic circuit library is established for efficient and case-independent SPICE simulation. Using peak distortion analysis, the eye diagram versus loss parameters is plotted into unified design charts for eye height and width, which depicts the signal quality without the need for pseudorandom bit sequence simulation. The proposed model is also generalized to coupled transmission lines. The far-end crosstalk noise is found to be significantly affected by the loss parameters, and the proposed circuit model ensures accurate simulation.

New Procedure for Computation of Time Delays in Propagation Function Fitting for Transient Modeling of Cables

The solution of traveling-wave equations for transient analysis of transmission lines and cables requires the identification of propagation function and characteristic admittance. A given modal propagation function can be approximated as a rational transfer function associated with an exponential time delay term. Time delays should be properly assigned prior to fitting in order to compensate excessive phase lag and avoid poor fitting results. In this paper, the existing time delay calculation formula of the universal line model (ULM) is first demonstrated using the Bode's magnitude-phase relation and its error source is explained. The underlying assumption is that a modal propagation function is a minimum phase system once a suitable time delay is removed. However, the numerical implementation of the procedure can generate delays that result in high fitting errors. Then, this paper contributes to a new method for estimating time delays and improving propagation function fitting accuracy.

Numerical Analysis of Transmission Line Telegraph Equation Based on FDTD Method

In order to investigate the theory of the time domain reflectometry (TDR) cable length measurement, the transmission line transient analysis iteration formula based on the finite difference time domain (FDTD) is derived based on the transmission line theory. The electromagnetic wave propagation theory and the regular pattern of the TDR signal propagating in cables are studied. The theoretical calculations are consistent with the experimental results, which verify the correctness of the transmission line transient analysis iteration formula studied in this paper. To further illustrate the theory of the time domain reflectometry cable length measurement, the iteration formula is applied to the TDR cable length measurement. The impacts of the shape, width and amplitude of the excitation signal on the cable length measurement are analyzed.

Analysis of Physically Symmetrical Lossy Three-Phase Transmission Lines in Terms of Space Vectors

The analysis of the three-phase transverse-electromagnetic (TEM) line based on the Park approach represents, under the theoretical and the applicative point of view, an important analytical tool. For these reasons, this paper presents the analysis of lossy (quasi-TEM) three-phase transmission lines in terms of three-phase vectors, based on the Park transformation. The three-phase transmission-line transient analysis presented in this paper emphasizes the conceptual contents specific to the Park approach. Furthermore, applied to some examples, it gives very important results for the practical analysis of a lossy three-phase transmission line.

Lossy three‐phase transmission line transient analysis by Park approach

PurposeTo provide a unified analytical tool, based on Park transformation, for the theoretical and practical analysis of a lossy three‐phase transmission line.Design/methodology/approachThe results obtained in the study of TEM waves propagation in two‐wire line can be extended to a symmetric m‐wire line by employing the modal analysis. This approach relates the dynamic of m‐wire guided field to the propagation of m modal voltages and currents acting on m single‐wire decoupled transverse electromagnetic (TEM) lines. In the symmetric three‐phase system case, the modal analysis includes, as a particular case for m=3, the symmetric component theory. In previous papers, the authors applied the Park transformation to study the wave propagation of (TEM) three‐phase symmetrical lines. The formulation proposed and tested considers the lossless TEM wave propagation of a three‐phase line without consideration to the dissipations phenomena present in the line itself. Taking into account the obtained results, the extension of the developed approach to the lossy three‐phase transmission line transient analysis is very useful on both theoretical and practical points of view.FindingsThe symmetrical three‐phase line Park model for the lossy transmission line transient analysis, regarded as vector formulation of the line modal analysis, has been presented. The proposed examples highlight how, thanks to the Park model, the dynamic analysis of the three‐phase line in distorted and unsymmetrical systems becomes an integral part of the more general and well‐established power electric system dynamic theory.Originality/valueThe three‐phase transmission line transient analysis presented in this paper emphasizes the conceptual contents, specific to the Park approach. Furthermore, it gives some results very important for the practical analysis of a lossy three‐phase transmission line.

Correction to "A Comparison of Techniques for State-Space Transient Analysis of Transmission Lines"

In the April issue of IEEE TRANSACTONS ON POWER DELIVERY, PART 1, the paper “A Comparison of Techniques for State-Space Transient Analysis of Transmission Lines” by Jose A. Rosendo Macias, Antonio Gomez Exposito, and Alfonso Bachiller Soler (p. 894), TablesIII and IV are incorrect. The correct tablesare shown here.

A Comparison of Techniques for State-Space Transient Analysis of Transmission Lines

This paper reviews and compares several methods to analytically obtain the transient response of transmission lines in the time domain, in those cases where frequency independent parameters can be assumed. The distributed-parameter line is modeled by the cascaded connection of a number of lumped-parameter /spl pi/ circuits, each one representing a fraction of the line length, leading to a linear time-invariant (LTI) circuit. The associated state-space equations are formulated, allowing explicit expressions for the state variables to be written in the time domain. The solution is then obtained by means of three different approaches, all of them requiring that the natural frequencies be previously computed, namely: eigenvector-based procedure, Vandermonde matrix method, and Lagrange interpolation formula. Numerical integration by the trapezoidal rule is also considered for comparison. Two kinds of test results are presented. First, accuracy of the results provided by the LTI lumped-parameter model are compared with those obtained using the Electromagnetic Transients Program. Second, a comparison is performed in terms of the computational cost involved in each method. Two cases of practical interest are assessed, namely solving from scratch the state equations and updating the solution for a new set of initial conditions.

Remark on the Lumped Parameter Modeling of Transmission Lines

Transmission lines are distributed parameter systems. Instead of distributed parameter models, lumped parameter models are also used for steady-state and transient analysis of transmission lines. Lumped parameter modeling for transmission lines is obviously an approximation. This paper aims to investigate the theoretical error in the lumped parameter modeling of transmission lines for steady-state and transient analysis. To determine the error, steady-state and transient responses of the transmission line are calculated by using both distributed and lumped parameter modeling. The effect of number of sections used for lumped parameter modeling is investigated. Obtained results can be used for the determination of the number of sections.

Wavelet transform solution of multiconductor transmission line transients

In this paper a wavelet transform approach is used to solve multiconductor transmission line equations. By using wavelets on the interval, differential and integral operators are represented by sparse matrices. Then the time domain differential equations of multiconductor transmission lines are reduced to algebraic ones. The unknowns of the algebraic system are the coefficients of the wavelet basis functions. Therefore a Fourier-type approach is obtained for transient analysis of transmission lines. The procedure reduces the CPU times with respect to the usual transient analysis obtained by time stepping methods. An initial analysis of the numerical characteristics and performances of the method is carried out considering constant RLCG multiconductor lines.

97/02887 A simple and efficient method for including frequency-dependent effects in transmission line transient analysis

The CODAC system is responsible for integrating all ITER plant system Instrumentation and Control systems and enabling operation of ITER machine as a single integrated facility. The different ITER plant systems and their Instrumentation and Control systems are distributed in several ITER buildings on the ITER platform. The CODAC systems have to interface with all these distributed plant system I&C systems. CODAC systems will be composed of several physical systems or components like networks, servers, workstations (terminals), large displays, PSH, storage systems etc. Several rooms in different buildings have been defined to house all above equipment. The site-wide CODAC network infrastructure will be based on a dual (redundant) star topology. The two redundant star points will house the core networking switches. These redundant core switches will be installed in different buildings. Cubicles used for network infrastructure are distributed among “hutches,” where a CODAC hutch is a room or area equipped with appropriate heating, ventilation, air conditioning and uninterruptible power which will be directly connected through two star points. The responsibility of CODAC infrastructure ends up to the plant system I&C cubicles so several passive CODAC network panels have identified in all I&C rooms of different plant buildings. This CODAC Network Panel will be the physical termination point for CODAC Network infrastructure. The CODAC Network cables running from the nearest CODAC Network hutch will terminate in these panels. Network panels are installed at strategic locations close to plant system I&C cubicles. This paper will describe more details about the physical arrangement of CODAC systems in different buildings on ITER platform for different purpose and their planned connectivity. This paper will also provide more information about the volume allocations for CODAC components, planned cabling arrangement and other infrastructure requirements like electrical and cooling etc.

A simple and efficient method for including frequency-dependent effects in transmission line transient analysis

This paper proposes a simple and efficient method for calculating transmission line transients including frequency-dependent effects. The frequency-dependent distributed-parameter line is modeled by a combination of a distributed-parameter lossless line and an impedance circuit representing the frequency dependence of the original line. The impedance circuit is derived from a four-terminal parameter theory. Calculated examples by the proposed method are compared with the accurate results of a frequency-domain transient program FTP and a field test result. The accuracy of the proposed method is confirmed to be satisfactory.

Some Renovations in Transient Analysis of Transmission Lines by State-Space Techniques

A method for transient analysis of single phase transmission lines based on state-space technique is presented. Transmission lines are considered as the interconnection of many lumped parameter sections. By this approach state equations are formulated for the system by choosing the capacitor voltages and inductor currents as the state variables. These equations are solved by state space techniques to compute steady-state and transient responses of transmission lines for various source and load connections. A computer program called LPTLAP (Lumped Parameter Transmission Line Transient Analysis Program) has been prepared for both formulation and solution steps.

Lossy transmission line transient analysis by the finite element method

A time-domain finite-element (TDFE) method applied to the analysis of electrical transients on lossy transmission lines is presented. The general telegraph equations are solved numerically at discrete time steps. Examples of voltage waveform on lossy single-phase lines are shown. Preliminary results indicate that the TDFE method works well for single-phase lossy transmission line transient analysis.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Waveform relaxation analysis of RLCG transmission lines

F.H. Branin's method of characteristics (1967) has been extended for the transient analysis of transmission lines with constant RLCG parameters. It has been further generalized for iterative waveform relaxation analysis. The sequence of waveforms relaxation generated by the iteration process has been identified as the series expansion of the transmission-line response functions. By incorporating the fast Fourier transform in the waveform analysis, a phenomenal two-order reduction of CPU time and one-order savings in computer memory have been achieved. Examples of RLCG lines driven by bipolar logic gates are given to illustrate the advantage of waveform relaxation over the discrete time simulation. >

Forward and Backward Response Functions for Transmission Line Transient Analysis

This paper concerns the numerical evaluation of transmission line transient response using travelling-wave methods in which the effects of frequency dependent parameters are taken into account. Transmission line behaviour is considered in terms of forward and backward response functions, special emphasis being placed on the latter, which is introduced because of the time dependent nature of the line characteristic impedance. Relatively simple formulae are derived so that both response functions may be included in a general purpose computer program without difficulty. The validity of the approach is confirmed by comparing results with those obtained from the modified Fourier transform method.

Transient analysis of transmission lines with nonlinear terminations

Transient analysis of transmission lines with nonlinear terminations