High-speed Transmission Lines Research Articles

High-speed non-unit transmission line protection using single-phase measurements and an adaptive wavelet: zone detection and fault classification

This work describes a transmission line protection scheme with two protection functions: directional zone and fault classification. The proposed scheme requires no information from remote ends and uses current measurements of only one phase of the three-phase systems for determining the fault direction, the faulted line and the fault type. Information concerning the high-frequency components of transient current signals is extracted with discrete wavelet transform (DWT) by using an adaptive wavelet, which has been specifically designed for relaying purposes, as analysis filter. After that, Bayesian linear discriminant analysis is employed for data classification. The present work highlights that the adaptive wavelet used here presents advantages for transmission line protection rather than predefined mother wavelets. Results demonstrate that the proposed scheme effectively distinguishes the faulted zone, the fault direction and the fault type. Therefore it offers primary protection to total line length, remote backup protection for the next transmission line and also the possibility to implement single-pole tripping. Current signals of roughly 2 ms are analysed then the proposed methodology can be implemented in high-speed protection schemes for extra- and ultra-high voltage (EHV/UHV) networks.

A Novel Approach to the Measurement and Characterization of Losses due to Surface Roughness in High Speed Transmission Lines

An accurate measurement technique is required to fully characterize the losses observed at high frequencies in transmission lines. Evaluation of losses seen at high frequencies is necessary to meet the high-speed data transfer rates that future applications will demand. Conductor properties and losses are two critical issues in signal path characterization. The nature of conductor losses is not well understood at high speeds. Classical models used for predicting the effects of surface roughness on signal propagation are known to breakdown around 5 GHz. Novel methods are sought to quantify the effects beyond 5 GHz. In this paper, a simple methodology to extract conductor loss is derived and validated based on a stripline configuration of two different widths. The proposed methodology is applicable to surface roughness loss characterization of both organic and ceramic packaging materials.

High-speed transmission line protection using principal component analysis, a deterministic algorithm

A novel methodology to provide effective fault protection featuring high speed and excellent selectivity is presented. Principal component analysis made up of a set of travelling wave current signals, measured at one end of the transmission line, exhibits a well-defined pattern for faults of the same type. This work discloses that the fault current signal projected on the principal component coordinates can define the position, the insertion angle and the fault type (single-phase to ground, isolated two-phase, two-phase to ground and three-phase faults) on transmission lines. In this manner, it is possible to effectively categorise internal faults as well as distinguish when the fault is outside the line. Time windows less than a quarter of cycle of the power frequency are used to measure the current signals, thus the methodology is applicable for high-speed protection systems.

Towards a PCB production floor metric for go/no go testing of lossy high speed transmission lines

PurposeThe aim of this paper is to demonstrate that root impulse energy (RIE) testing is a practical and robust “go/no go” test technique for PCB material losses that can be deployed on the PCB production floor.Design/methodology/approachThe study used the RIE method, employing time domain reflectometry techniques on industry standard impedance test coupons modified to include short reference lines and longer test lines. Practical considerations for the use of the methodology on the production floor, such as coupon design, probe layout and environmental conditions were investigated.FindingsRIE with a 250 ps reflected risetime appears suitable for discerning significant differences in material loss properties provided proper coupon design is incorporated into the panel design and frequencies of interest are limited to a limit commensurate with high reliability and repeatability.Research limitations/implicationsThe RIE test proposed does not replace conventional impedance control techniques that are currently in use. However, a suitable standard for loss and cross test equipment calibration is key and will need to be established before this new measurement technique can gain widespread trust throughout the industry.Originality/valueThe paper shows RIE testing is a practical and achievable test method; it is easily deployed and offers repeatable, reliable discrimination between PCBs fabricated with a range of varying base material loss characteristics.

EMC Analysis of High-Speed On-Chip Interconnects via a Mixed Quasi-Static Finite Difference—FEM Technique

We present a new technique to investigate electromagnetic compatibility/electromagnetic interference (EMC/EMI) interactions in high-speed transmission lines on the chip level. The time-domain method is based on the different nature of the problem in conductors and semiconductors, compared to the insulating media that separate them. Therefore, the static problem in the silicon oxide is separated from the diffusion problem in conductors. The latter one is solved by an efficient DuFort-Frankel technique, while the static problem is solved in a coarse finite element method (FEM) mesh. In each step, the two problems are appropriately coupled by means of the interface conditions. The time-domain nature of this method permits the use of proper fast Fourier transform (FFT)-based postprocessing procedures to calculate the per unit length parameters in a fast and efficient manner

Wideband passive multiport model order reduction and realization of RLCM circuits

This paper presents a novel compact passive modeling technique for high-performance RF passive and interconnect circuits modeled as high-order resistor-inductor-capacitor-mutual inductance circuits. The new method is based on a recently proposed general s-domain hierarchical modeling and analysis method and vector potential equivalent circuit model for self and mutual inductances. Theoretically, this paper shows that s-domain hierarchical reduction is equivalent to implicit moment matching at around s=0 and that the existing hierarchical reduction method by one-point expansion is numerically stable for general tree-structured circuits. It is also shown that hierarchical reduction preserves the reciprocity of passive circuit matrices. Practically, a hierarchical multipoint reduction scheme to obtain accurate-order reduced admittance matrices of general passive circuits is proposed. A novel explicit waveform-matching algorithm is proposed for searching dominant poles and residues from different expansion points based on the unique hierarchical reduction framework. To enforce passivity, state-space-based optimization is applied to the model order reduced admittance matrix. Then, a general multiport network realization method to realize the passivity-enforced reduced admittance based on the relaxed one-port network synthesis technique using Foster's canonical form is proposed. The resulting modeling algorithm can generate the multiport passive SPICE-compatible model for any linear passive network with easily controlled model accuracy and complexity. Experimental results on an RF spiral inductor and a number of high-speed transmission line circuits are presented. In comparison with other approaches, the proposed reduction is as accurate as passive reduced-order interconnect macromodeling algorithm in the high-frequency domain due to the enhanced multipoint expansion, but leads to smaller realized circuit models. In addition, under the same reduction ratio, realized models by the new method have less error compared with reduced circuits by time-constant-based reduction techniques in time domain.

Teaching physiology to health sciences students using interactive television

The Univ of KY trains health science students at several rural campuses. Instruction comes from high-speed digital transmission lines that convey real-time audio and video between campuses (interactive television, or ITV). Presented are our experiences with teaching human physiology to these distant students. Most of the problems encountered were related to the preparation and delivery of course materials, instructional coordination, student-faculty interaction, instructional technique, and ITV equipment. Instructors initially placed more emphasis on learning to control the equipment than on adopting appropriate instructional methods. Faculty accustomed to traditional teaching were often slow to realize that ITV instructors must plan for the distribution of course materials far ahead of class time. Team teaching had drawbacks since all instructors had to master the technology and reorient their teaching styles. The use of multiple faculty often made establishing good faculty-student rapport difficult. An acceptable level of student-faculty interaction cannot be taken for granted when using ITV. Both students and instructors complained of communication problems, often made worse when instructors taught simultaneously to local and distant-site students. Traditional teaching styles are often not effective for ITV. Technical problems with equipment frequently arise, and contingency plans must be formulated.

A Hybrid Algorithm for High Speed Transmission Line Protection

A common method used in UHV transmission line protection is based on impedance measurement technique. The fault detection speed of impedance protection schemes cannot be improved without sacrificing the relay reach limit. Protection algorithms based on fault generated transient signals have shown promising results in improving the speed, but these methods have inherent reliability problems. This paper examines how the fault generated transient information can be used to achieve fast fault detection speeds in a distance protection scheme while maintaining a high reliability level.

Theory of Raman effect on solitons in optical fibre systems: impact and control processes for high-speed long-distance transmission lines

We examine the effects of stimulated Raman scattering on ultra-short pulses propagating in optical fibre systems. We demonstrate that the existing theories for the Raman-induced soliton self-frequency shift give consistent results in a restricted domain of pulse width which excludes important practical applications to high-speed soliton transmission systems. We present a general theory for the soliton self-frequency shift (SSFS), which applies to any pulse whose spectral bandwidth lies within the third-order telecommunication window. We also show that the harmful impact of the SSFS in high-speed long-distance transmission lines can be suppressed by use of filters whose central frequency is appropriately up shifted with respect to the transmission frequency.

Analyzing jitter at high data rates

Jitter is timing noise that causes bit errors in high-speed data transmission lines. If the data rate of a system is increased, the magnitude of jitter measured in seconds is roughly unchanged, but measured as a fraction of a bit period, it increases proportionally with the data rate and causes errors. Emerging technologies require the ratio of the number of errors to the total number of transmitted bits (the bit error rate, BER) to be less than one in a trillion (10/sup -12/). As datacom, bus, and backplane data rates have increased, many different techniques for characterizing jitter have been introduced, each using a variety of different types of laboratory equipment. To fix difficult jitter problems at high data rates, engineers need to understand the diverse jitter analysis techniques used in both synchronous and asynchronous networking. The article focuses on data rates of emerging technologies above 3 Gb/s. Below 3 Gb/s, real-time oscilloscopes can capture a contiguous data stream that can be analyzed simultaneously in both the time and frequency domains; at higher data rates jitter analysis is more challenging. This discussion is from the perspective of a digital engineer, drawing on the experience of synchronous optical network/synchronous digital hierarchy (SONET/SDH) where many challenges have already been addressed.

SIGNAL PROPAGATION IN HIGH SPEED DIFFERENTIAL TRANSMISSION LINE USING PARALLELIZED FINITE-DIFFERENCE TIME-DOMAIN METHOD

This paper presents the investigations in the electric performance of differential signalling transmission lines used for high speed integrated circuits (IC's) and boards by using the parallelized finite-difference time-domain (FDTD) method. The FDTD method is firstly parallelized with single-program multiple-data (SPMD) architecture using the MPI protocol and experimentally validated. The key electrical factors, crosstalk, impedance of high-speed differential transmission lines, are simulated and investigated for various configuration using the developed parallelized FDTD code. The discussions presented in this paper shall be used a guideline for engineers to optimize high-speed circuit designs with differential signaling transmission lines for signal integrity (SI) and electromagnetic compatibility (EMC).

Neural Network–Based Fault Direction Discrimination for High-Speed Transmission Line Protection

Detection of the direction of a fault on a transmission line is essential to the proper performance of a power system. W ith the advent of large generating stations and highly interconnected power systems, shorter fault clearing times are becoming necessary. To classify forward and backward faults on a given line rapidly, a neural network's abilities in pattern recognition and classification could be considered as a solution. To demonstrate the applicability of this solution, neural network technique is employed to design two different fault direction discrimination modules. Results of performance studies with the proposed networks are presented in this paper. Results obtained indicate that the direction of fault on a transmission line can be identified rapidly and correctly by the proposed approaches.

00/01922 High-speed transmission line relaying using artificial neural networks

An ANN(Artificial Neural Network)is presented,which has the functions to determine and locate the faults within or outside the protection zone of a transmission line.The EMTP simulative tests for single-phase grounding fault and three-phase fault show that the fault can be exactly located and indicated by ANN within one period.It verifies this method is practical.

High-speed transmission line relaying using artificial neural networks

A novel feedforward neural network that indicates whether a fault is within or outside the protection zone (fault indicator) of a transmission line is presented. The same technique has been extended to locate the distance of the fault (fault locator). The proposed scheme utilizes the frequency spectrum of the voltages and currents to make a decision. Data obtained from the electromagnetic transient program for single-line-to-ground faults and three-phase faults have been tested and the results are found to be accurate. Using this neural network the relaying decision is obtained within a cycle after the fault inception. The performance of the trained neural network shows promise and has the potential for implementation in a digital relay for transmission line protection.

High speed transmission line directional protection evaluation using field data

The performance of an Elman recurrent network-based relay in determining the fault direction on a power transmission line on fault data recorded in the field is described in this paper. The network uses samples of voltage and current signals to learn the hidden relationship existing in the input patterns. Studies show that the proposed network is able to identify the fault direction correctly and rapidly. Results obtained indicate that the proposed network is robust, fast and accurate.

Transient analysis of high-speed multi-port transmission line via hybrid model composed of distributed and lumped elements

In analyzing integrated circuits such as VLSI, transients of interactions among integrated circuit devices have received little attention. Interconnection lengths have been disregarded in VLSI technology and the circuits have been handled as lumped models. But as the speeds of integrated circuits increase and the density of packages increases, signal delays and crosstalk on interconnection lines are no longer negligible and the study of high-speed signal propagation on interconnection structures becomes very important. So, the circuits must be handled as hybrid models composed of lumped elements and distributed dispersive interconnection lines. In this study, dispersive interconnection lines are replaced by a multiport lumped network connected by sources and linear or nonlinear elements at every port. We first obtain the step response of the impedance matrix of quasi-matched multiconductor dispersive transmission lines in the s domain via the Laplace transform; quasi-matched condition is achieved by artificially inserting two pairs of resistive elements between the transmission line and terminal networks. Next, we perform the inverse numerical Laplace transform of the step response matrix to obtain time domain numerical series. Finally, we consider a line with nonlinear terminal networks and convolve the time series with the voltages at the line ports to obtain a time-stepping solution for the port voltages and currents in the t domain. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 3, 80(8): 11–19, 1997

High-speed coplanar transmission lines

The authors present measurements of picosecond pulse propagation on coplanar strip transmission lines for which speed (i.e., group velocity), as well as phase and amplitude information are measured. Electrode effects are studied using transmission line loops 1 mm in diameter with cumulative propagation distances as long as 6 cm. The intrinsically low dielectric constant of coplanar-air transmission lines is shown to result in high signal speed and low attenuation. The authors use the data to verify the applicability of a model based largely on empirical formulae for radiation loss (geometry) and conductor absorption. The model is then used to identify optimal design criteria (for a given bandwidth) and is extended to the case of small dimensions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

THz time-domain spectroscopy of high Tc substrates

Using the method of time-domain spectroscopy, we have measured the absorption and dispersion from 0.2 to 2 THz of the high Tc substrates, magnesium oxide, yttria-stabilized zirconia (YSZ), and lanthanum aluminate. Our measurements on YSZ and LaAlO3 at both room temperature and 85 K show unacceptably large absorptions for high-speed transmission line applications. At 85 K, MgO is shown to be an excellent material in terms of its low loss at THz frequencies.

A fast microprocessor-based computational algorithm for transmission line fault impedance

The paper presents a fast microprocessor-based algorithm to calculate impedance. The developed computing procedure employs simple circuit theory and avoids unnecessary complicated mathematics. The algorithm is most suitable for microprocessor applications in high speed transmission line protection. The algorithm calculates the positive-sequence impedance from the relaying location to the fault using sampled values of current and voltage. The algorithm is accurate and reliable in practice.

High-speed optoelectronic pulse generation and sampling system

A very-high-frequency (>100-GHz) optoelectronic pulsing and sampling system is presented. This system is used for the characterization of high-speed electronic devices and transmission line structures, and for the study of electronic transport phenomena at picosecond time scales. The signal-to-noise ratio obtained in this system is greater than 50 dB, the sensitivity limit is approximately 1 mu V/Hz/sup 1/2/, and the temporal resolution can be less than 1 ps, thereby permitting studies of very fast low-level signals. >