Two-port Network Theory Research Articles

Analysis of Limiting Measures of Three-phase Short-circuit Current of 500kV Intensive Receiving-end Power Grid in the Early Stage of UHV Construction

This paper took the intensive receiving-end power grid as the research object and analysed the problems of three-phase short-circuit current over-limited of 500kV intensive power grid in the early stage of UHV construction. Firstly, this paper analysed the influence factors of the short-circuit current based on self-impedance analysis model of two-port network theory and the equivalent model of UHV power grid. Then, the applicable current-limiting measures were put forward. Finally, this paper proposed one scheme to solve the problems of three-phase short-circuit current over-limited of 500kV buses in one practical receiving-end power grid and verified the feasibility of this scheme from three different aspects. Aiming at the over-limited influential factors, the applicable current-limiting measures can be taken as follows: separating the 500kV bus at UHV substation, lapping the lines outside the substation and decentralizing the power supplies. The proposed measures can effectively solve the problems of short-circuit current over-limited in the early stage of UHV construction and provide reference for other power grid.

A High Frequency Strictly Passive Model for Transformer Based on the Image Method under Lightning Overvoltage

In the power system electromagnetic transient simulation, the establishment of a stable power transformer simulation model is crucial. Therefore, the high frequency strictly passive model of the transformer is investigated, which is suitable for the lightning strokes. The proposed model is introduced based on two-port network theory where its scattering parameters are measured through network analyzer firstly, and then the scattering parameters are transformed into the impedance parameters, finally the transformer T-equivalent circuit is established. The image method is used to fit frequency dependent impedance parameter, and according to different types of the parameter, the combination of circuit elements R, L, C is needed. By using the image method the values of the elements achieved are all positive and the strictly passive conditions of the circuits are guaranteed. Furthermore, the experiment and simulation results of a 10kV single-phase transformer under lightning overvoltage is presented, confirming the validity of the proposed method.

Análisis de formulaciones aproximadas de impedancia interna para el estudio de transitorios de alta frecuencia en cables subterráneos de alta tensión

En este artículo se presenta un análisis de las formulaciones aproximadas de impedancia interna para el estudio de transitorios de alta frecuencia en cables subterráneos de alta tensión. El análisis se desarrolla en el dominio de la frecuencia y la conversión al dominio del tiempo se realiza utilizando la transformada rápida de Fourier. El cable se modela como una línea de transmisión multiconductora, utilizando análisis modal y la teoría de redes de dos puertos. Las formulaciones aproximadas de impedancia interna que se analizan son las propuestas por Gary y Wedepohl-Wilcox, las cuales son utilizadas en el modelado de líneas de transmisión aérea y subterránea, respectivamente. Para efectuar el análisis se realiza una comparación de las formulaciones aproximadas con el modelo exacto de impedancia interna y se determina el error relativo de cada formulación para los valores reales como para los valores imaginarios. Los resultados muestran que la formulación aproximada propuesta por Gary para el modelado de líneas de transmisión aéreas se puede utilizar en cables subterráneos para analizar fenómenos transitorios electromagnéticos de alta frecuencia con resultados aceptables. Para realizar el estudio comparativo de las formulas aproximadas de impedancia interna se propone una serie de casos de estudios en los cuales se determina la magnitud del voltaje transitorio, el tiempo de viaje y la atenuación de la onda en líneas monofásicas subterráneas utilizando diferentes longitudes.

Modeling and optimization of noise coupling in TSV-based 3D ICs

This paper first proposes an impedance-level model of coupling channel between through silicon vias (TSVs) based on the two-port network theory. In order to get an accurate estimation of the coupling level from TSV-TSV in the early designing stage, we convert the impedance parameters of the model into the ABCD matrix to derive the formula of coupling coefficient, and the accuracy of the proposed formula is validated by comparing with 3D full-wave simulations. Furthermore, a design technique of optimizing the coupling between TSVs is proposed, and through SPICE simulations the proposed technique shows a desirable result to reduce the TSV-TSV coupling.

Application of Two-Port Network in Bilateral Control for a Haptic Interface with Force-Position Compensation

The two-port network theory for describing the characteristics of the haptic interface is presented; the four-channel bilateral control architecture is introduced, and two control methods named position-error-based control and direct force reflection control (PEBC & DFRC) are also presented. Two main problems caused by the coupling between position and force information for transparency improvement of the haptic interface are also be discussed and a Model-Based Force-Position Compensation Strategy to enhance the transparency of the haptic interface is proposed. By embedding the compensation unit into the DFRC architecture, the Haptic Interface could be controlled with precise position and high-fidelity force feedback.

Lightning-Induced Overvoltages Transmitted Over Distribution Transformer With MV Spark-Gap Operation—Part I: High-Frequency Transformer Model

In Finland, distribution transformers are frequently subjected to lightning strokes. Therefore, it is worthy to study the voltage transferred to the secondary terminal of the transformer due to lightning strokes hitting the primary terminals. In order to do conduct this study, the high-frequency model of the distribution transformer is to be investigated. In this paper, an accurate and simplified high-frequency model of the distribution transformer under lightning strokes is presented. The proposed model is introduced based on two-port network theory where its parameters are calculated at two resonance frequencies experimentally measured. The model is suitable for unloaded and loaded conditions and it is experimentally verified under different balanced loads considering two different practical distribution transformers. Then, the model verification is extended to study the impact of medium-voltage spark-gap operation on the transmitted voltage. The experimental results have validated the proposed transformer model.

Synchronization of bilateral teleoperators with time delay

Bilateral teleoperators, designed within the passivity framework using concepts of scattering and two-port network theory, provide robust stability against constant delay in the network and velocity tracking, but cannot guarantee position tracking in general. In this paper we fundamentally extend the passivity-based architecture to guarantee state synchronization of master/slave robots in free motion independent of the constant delay and without using the scattering transformation. We propose a novel adaptive coordination architecture which uses state feedback to define a new passive output for the master and slave robots containing both position and velocity information. A passive coordination control is then developed which uses the new outputs to state synchronize the master and slave robots in free motion. The proposed algorithm also guarantees ultimate boundedness of the master/slave trajectories on contact with a passive environment. Experimental results are also presented to verify the efficacy of the proposed algorithms.

Correction to the Classical Two-Species Hall Coefficient Using Twoport Network Theory

By the use of twoport network theory, the classical expression for the two-species Hall Coefficient, [Formula: see text] is, on admission of terms neglected by earlier authors, corrected to [Formula: see text] The new expression approximates the old when | By| « min {1/ μn, 1/ μp}. The condition of approximation establishes the range of field strength in which the classical expression is acceptable. Since the Hall Effect is part of the stock-in-trade of electrical engineers, however, it seems important that students should be aware of the correct expression.

An automated system for frequency response analysis with application to an undergraduate laboratory of electrical machines

This paper describes a LabVIEW-based automated system to carry out frequency response tests in electrical machines. The system is being used by undergraduate students in the laboratory of electrical machines, where they can experiment with the application of frequency response analysis and the characterization of mathematical models. An advantage of the system is its friendly user interface to a laboratory experiment. The system avoids the risky utilization of oscilloscopes for data acquisition and shortens the time taken to analyze the measured data. The Automated System for Frequency Analysis (ASFFA) can carry out tests within a bandwidth of 0.001-900 Hz. In addition, the ASFFA can estimate the transfer function parameters based on one- or two-port network theory. Design details of the interface, system structure, frequency response tests, electrical machine modeling, and signal processing are presented. Finally, ASFFA is applied to synchronous, induction, and direct-current machines.

C502 IMPROVEMENT MEASURES OF POWER QUALITY ON SEOUL-TAEGU LINE IN KYONBU HIGH SPEED RAILWAY

This paper presents two power quality issues in electrified railway, voltage unbalance and harmonics. For a useful method to estimate voltage unbalance, power simulation procedure is added to the conventional formula. The proposed method can be practically used and easily applied to evaluation of voltage unbalance indices. For a new model to analyse harmonics in 2×25kV traction power supply system including inverted feeder, contact line, rails and auto-transformer, the system model based on eight-port representation is derived which is an extension of two-port network theory. In order to verify the proposed approach, we have analysed and tested real traction power feeding system focused on the amplification of harmonic current. The calculation results from the proposed approach and the measurement data from the test are widely discussed in the paper.

Two-port network theory based thermal characterization of power module packages

For thermal analysis, power module packages can often be considered as plane multilayered systems for which it has been demonstrated that appropriate Fourier transforms associated with the two-port network theory permit to develop very efficient solutions of the static or the time dependent 3D heat flow equation. However, in practice, the thermal resistances of soldered or pasted interfaces are most often not well known. Most of these parameters are theoretically unpredictable, therefore it is of highest interest to develop an experimental procedure intended for an adequate characterization of the 3D thermal behaviour of the cooling substrates. A two-port network theoretical basis for experimental characterization of the thermal behaviour of multilayered substrates (96% Alumina, AU4G, IMS), which are classically used for power module packaging, is presented. In spite of some difficulties in setting perfectly the boundary conditions for temperature and heat fluxes, the experimental results demonstrate the validity of the characterization method, and the soughted parameters can be measured for wide ranges of spatial pulsation. Suggested improvements of the existing experimental set can give rise to an industrial measurement set intended for thermal characterization of power module packages.

Analysis and design of thin film resonator ladder filters

This work presents a new simulation method for the analysis and design of bandpass filters based on thin film resonators (TFRs). The method is based on linear two-port network theory and can be applied for of ladder filters in general. Analytical equations for the case of TFR ladder filters are extracted by the proper modeling of the TFR.

RF CMOS Noise Characterization and Modeling

This paper presents a through description of radio frequency (RF) noise characterization and modeling of CMOS transistors. It begins with the definition of the four noise parameter of a two-port network - minimum noise figure (NFmin), equivalent noise resistance (Rn), optimized source impedance (Ropt) and optimized source reactance (Xopt). These four parameters are used in device characterization and it is shown how they can be calculated by using the noise two-port network theory and a circuit simulator. Then two de-embedding procedures are discussed in detail for noise and scattering parameter de-embedding to get rid of the parasitic effects from the probe pads and interconnections in the device-under-test (DUT). Ideally there is no frequency and geometry limitation for the method based on a cascade configuration. Methods to directly extract the channel noise, induced gate noise and their correlation from the RF and noise measurements are developed and the extracted noise sources as a function of frequency and bias condition for different channel lengths a presented. Some design consideration for the design of low noise circuits - how to select the device size, choice of DC bias conditions and design device layout, are presented. Finally, some published noise models for the channel noise, induced gate noise and their correlation are discussed.

RF CMOS NOISE CHARACTERIZATION AND MODELING

This paper presents a through description of radio frequency (RF) noise characterization and modeling of CMOS transistors. It begins with the definition of the four noise parameter of a two-port network - minimum noise figure (NFmin), equivalent noise resistance (Rn), optimized source impedance (Ropt) and optimized source reactance (Xopt). These four parameters are used in device characterization and it is shown how they can be calculated by using the noise two-port network theory and a circuit simulator. Then two de-embedding procedures are discussed in detail for noise and scattering parameter de-embedding to get rid of the parasitic effects from the probe pads and interconnections in the device-under-test (DUT). Ideally there is no frequency and geometry limitation for the method based on a cascade configuration. Methods to directly extract the channel noise, induced gate noise and their correlation from the RF and noise measurements are developed and the extracted noise sources as a function of frequency and bias condition for different channel lengths a presented. Some design consideration for the design of low noise circuits - how to select the device size, choice of DC bias conditions and design device layout, are presented. Finally, some published noise models for the channel noise, induced gate noise and their correlation are discussed.

Three-dimensional thermal modeling based on the two-port network theory for hybrid or monolithic integrated power circuits

This paper recalls how the two-port network theory can be extended to three-dimensional (3-D) conductive heat transfer in multilayered plane structures. Then it is shown how to build efficient computation tools by implementing this theory with help of fast Fourier transform (FFT) algorithms. These tools are particularly well-suited for the rapid thermal analysis of power components or hybrid and integrated power circuits. An illustration is given concerning thermal analysis of an insulated gate bipolar power transistor (IGBT) power module and computed results are compared with experiment.

Analysis of an accelerated trip scheme for faults in the second zone of protection of a transmission line

An analysis of a scheme of accelerated trips for faults in the second zone of a transmission line distance protection system is given. By the use of the two-port network theory, variations of the sequence currents and voltages are analyzed when the fault occurs on the protected line followed by a trip of the circuit breaker on the other side. The analysis is supported by tests performed on a laboratory model of a power system. The new scheme can improve sensitivity and avoid improper operation. Thus, it may be possible to use this scheme instead of pilot protection and alleviate any problems caused by the nonavailability of a sufficient number of communication channels for remote control and relaying. >

Unifying view of transient responses for determining lifetime and surface recombination velocity in silicon diodes and back-surface-field solar cells, with application to experimental short-circuit-current decay

Two main results are presented. The first deals with a simple method that determines the minority-carrier lifetime and the effective surface recombination velocity of the quasi-neutral base of silicon solar cells. The method requires the observation of only a single transient, and is amenable to automation for in-process monitoring in manufacturing. Distinct from many other methods in use, this method, which is called short-circuit current decay, avoids distortion in the observed transient and consequent inaccuracies that arise from the presence of mobile holes and electrons stored in the p-n junction space-charge region at the initial instant of the transient. The second main result consists in a formulation of the relevant boundary-value problems that resembles that used in linear two-port network theory. This formulation enables comparisons to be made among various contending methods for measuring material parameters of p-n junction devices, and enables the option of putting the description in the time domain in the form of an infinite series, although closed-form solutions are also possible. The advantage of an infinite-series formulation is the possibility of identifying dominant relaxation times of the transient, leading thereby to simplified descriptions. By outlining the derivation of open-circuit-voltage decay and junction-current recovery from this two-port formulation, we systematically compare these methods with the short-circuit-current decay method that is emphasized here. Small-signal admittance measurement methods also emerge as special cases of the two-port formulation, as is discussed briefly.

An Approach to the Teaching of Difference Amplifiers

The bisection theorem is normally used in the analysis of difference stages. An approach utilising only the basic circuit theorems, is presented. Generalisation is demonstrated for arbitrary input, output and stage configuration using the Z-matrix of linear, two-port network theory.

Analysis of Simulatenous Faults by Two-Port Network Theory

Simultaneous faults of common configuration may be described mathematically in terms of two-port network theory with one port for terminating the network at each fault point. Combining the sequence networks, with appropriate phase shifts, will then permit-direct solution of the network voltages and currents in a general way. This approach to solving for simultaneous fault quantities is very orderly and makes solution by hand computation or by computer more straightforward than previous methods.

Solid state VHF frequency converter

This paper describes the design of a transistor frequency converter suitable for use in mobile communication receiver equipment. Two-port network theory is used to design a 250-Mc RF amplifier, a 250- to 60-Mc mixer, a 310-Mc local oscillator and a two-stage 60-Mc IF amplifier. Performance of silicon planar transistors are first predicted from calculations based on y parameters of these transistors and then compared with experimentally determined performance. The mathematical techniques used in the design of this circuitry are discussed in some detail. Basic design philosophy using terminal, rather than internal, parameters is introduced. Power gain and stability are described in terms of terminal admittance parameters and high frequency performance curves of a popular high frequency silicon transistor are presented. Finally, a transistor frequency converter system suitable for mobile communications equipment is discussed. In particular, the sensitivity, noise figure, selectivity and stability are developed. The over-all converter performance values are: Conversion Gain 65 db Bandwidth 4 Mc Noise Figure 6 db Image Rejection 25 db Temperature sensitivity data indicated that the local oscillator was most sensitive to temperature change and caused the over-all gain to vary from 62.5 db @ 5°C to 65 db at 25°C to 60 db @ 50°C. Center frequency changes (in the same order) were 57 Mc, 60 Mc and 65 Mc.