Series Impedance Research Articles

A Fully Analytical Model for the Series Impedance of Through-Silicon Vias With Consideration of Substrate Effects and Coupling With Horizontal Interconnects

This paper introduces a fully analytical and physical model capable of extracting high-frequency series impedance of through-silicon vias (TSVs) in 3-D integrated chips with consideration of the eddy currents in the surrounding Si substrate and coupling with horizontal interconnects. The model employs the vertical-to-vertical and horizontal-to-vertical 3D vector potential Green's function in layered media and is concise and sufficiently accurate in the entire range of interest for both the frequency and the center-to-center distance between TSVs. Along with the series impedances between horizontal wires, which are extracted from the discrete complex image method, as well as the TSV and horizontal wire capacitance values, the total loop impedance can be obtained. Our approach is verified against a full-wave finite- element-method electromagnetic solver High Frequency Structure Simulator, and it shows good accuracy (<; 7% error) in the entire frequency range examined (up to 100 GHz). Given the fact that the formulated TSV series impedance model is purely analytical, the model could be efficiently used for system-level interconnect impedance extraction in emerging 3-D integrated systems.

Low Reset Current in Stacked $\hbox{AlO}_{x}/ \hbox{WO}_{x}$ Resistive Switching Memory

The complex impedance spectroscopy method associated with capacitance-voltage is employed to investigate the resistive switching behavior of the bilayer structure for the first time. The reset current is reduced by more than one order for the AlOx/WOx bilayer compared with that of the single-layer structure. It is distinguished that each layer plays an important role. The AlOx layer is the dominating switching layer, while the WOx layer has the functions of controlling the conductive filaments in the AlOx layer and acting as a series impedance to reduce the reset current.

Application of the Partial Element Equivalent Circuit Method to Analysis of Transient Potential Rises in Grounding Systems

This paper presents calculations of lightning transient potential rises in grounding systems. A partial element equivalent circuit (PEEC) method, adopting a modified image method, is employed in this paper. The modified image method in this paper has two options either including or neglecting images of conduction currents along conductors for calculating series impedances. The effect of retardation in the PEEC method is also investigated. Comparisons of simulation results by the proposed method with those by the method of moments, the finite-difference time-domain method, and experimental results collected from the literature show that the PEEC method with the modified image method is quite effective in the evaluation of transient potential rise in a grounding system.

Use of STATCOM in wind farms with fixed-speed generators for grid code compliance

The increasing penetration of wind energy into power systems has pushed grid operators to set new requirements for this kind of generating plants in order to keep acceptable and reliable operation of the system. In addition to the low voltage ride through capability, wind farms are required to participate in voltage support, stability enhancement and power quality improvement. This paper presents a solution for wind farms with fixed-speed generators based on the use of STATCOM with braking resistor and additional series impedances, with an adequate control strategy. The focus is put on guaranteeing the grid code compliance when the wind farm faces an extensive series of grid disturbances.

Chlorinated indium tin oxide as a charge injecting electrode for admittance spectroscopy

Admittance spectroscopy (AS) is a simple technique to measure the carrier mobility of organic semiconductors, but requires an Ohmic contact for charge injection. Chlorinated indium tin oxide (Cl-ITO) is shown to be a good charge injecting electrode for AS due to its high work function of >6.1 eV. The mobility of N,N′-diphenyl-N,N′-bis-(1-naphthyl)-1-1′-biphenyl-4,4′-diamine (α-NPD) measured with Cl-ITO was found to be in excellent agreement with the value measured by time of flight. Cl-ITO is therefore an ideal electrode for AS since it possesses a high work function, but does not introduce any series impedance into the device structure.

Effect of Field-Voltage Source Impedance on Load-Rejection Test Results of Large-Rating Synchronous Generators

This paper presents a technique to determine the effect of the field-voltage circuit during the load-rejection test of a large-rating salient-pole synchronous generator. Once the circuit powered by a six-pulse converter connected to the excitation transformer of the generator unit corresponds to a power-supply voltage not constant immediately after the load rejection, a careful evaluation of the resulting signals is necessary to extract rotor and stator parameters from the comparison with theoretical expressions derived under the assumption of constant-field terminal voltage and excluding external effects. The results obtained in the load-rejection test of a 179-MVA, 13.8-kV generating unit at Nova Ponte power plant show the parameters that are more affected by the external impedance in series with the rotor circuit and how to compensate them.

An innovative technique to evaluate network equivalent for voltage stability assessment in a widespread sub-grid system

The equivalent two-bus network models currently available are obtained by lumping all the series impedances and shunt admittances of transmission lines within a series equivalent impedance, to assess voltage stability of multi-bus power system. This paper reports the development of an equivalent pi-network model using a new methodology considering series and shunt parts of line loss separately obtained from the operational parameters of optimal power flow solution of the original multi-bus power network, which can be applied to assess the overall voltage stability status of the system accurately by developing the concept of a generalized global voltage stability margin (GVSM). Simulation results for a typical longitudinal power supply (LPS) system and a robust practical (Indian Eastern Grid) system establish that the pi-equivalent model obtained by the proposed method is highly promising for assessing voltage stability of any power system at any operating point in global scenario in a better way as compared to available series equivalent model. Continuation power flow (CPF) method has also been adopted here to verify the potential of the proposed method for voltage stability assessment. In the proposed equivalent network the generators have been modeled more accurately considering optimal operating criteria.

Fault current limiter using a series impedance combined with bus sectionalizing circuit breaker

The necessity and procedure for application of series fault current limiter (FCL) composed to bus sectionalizing in power network of IRAN have been discussed. In this regard, all of the high voltage substations in the power network of IRAN were evaluated in point of view of the fault current amplitude. The short circuit analysis of the power network was done based on the actual and future network specifications which have been designed and published by Iran Generation Transmission & Distribution Company in 2005. The overall results of this analysis and the detail data of using FCL together bus sectionalizing for two of the most important high voltage substations of Iran are presented. This method allows decreasing of 27% in fault current amplitude. The economical observation shows this method can be profitable if high voltage substation contains more than four feeders.

New saturable‐core fault current limiter topology with reduced core size

AbstractFault current limiters (FCLs) are expected to play an important role in protection of future power grids. By inserting a limiting impedance in series with a line, they limit the increasing levels of the fault currents to acceptable values. Inductive FCLs based on core‐saturation effect are particularly interesting due to their inherent reaction on a fault. However, some challenges are to be solved: too large amount of required material and induced over‐voltage across the DC winding that is used to drive the core into saturation. This paper introduces a new configuration of the inductive FCLs, where the amount of the required material is reduced considerably and the induced over‐voltage across the DC winding is decreased. The amount of magnetic material is reduced by employment of one core per‐phase instead of two. The middle leg of the three‐leg core is used as a shunt path for the AC flux. It enables a gap insertion in the AC magnetic circuit without influencing the DC magnetic circuit, i.e. the amount of DC winding material. Thus, a smaller core (less magnetic material) can be used for the same power level. Results obtained from the lab prototype match very well the one from simulations. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Equivalent-Circuit Modeling of Nonradiative Surface Plasmon Energy Transfer Along the Metallic Nanowire

An analytical methodology for establishing an equivalent-circuit network of nonradiative surface plasmon (SP) energy transport along the metallic nanowire (MNW) is presented. To find out the passive elements for MNW, the SP dispersion and damping relation through modified Bessel function electromagnetic (EM) field expansion was derived, thus demonstrating the low-pas transmission-line (TL) model. Specifically, the low-pass TL parameters, such as series impedance (Z) and shunt admittance ( Y) can be calculated based on the lumped-element model and harmonic-voltage (current) distribution. Furthermore, the equivalent-circuit parameters, such as resistance (R), inductance (L), capacitance (C) and conductance (G), are obtained by employing the finite difference (FD) discretization method such as T-cell RLCG networks. These equivalent-circuit elements can be verified by the HSPICE circuit simulation and 3-D scattered finite-difference time-domain (FDTD) method. Finally, the parallel MNWs are modeled as equivalent-circuit networks by using the electrostatic coupling.

Linking optical and electrical small amplitude perturbation techniques for dynamic performance characterization of dye solar cells

This paper unifies the analytical models used widely but thus far mostly separately for electrical and optical small amplitude perturbation measurements of nanostructured electrochemical dye solar cells (DSC): electrochemical impedance spectroscopy (EIS), intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS). The models are linked by expressing the kinetic boundary condition used for solving the time-dependent continuity equation of electrons in IMPS and IMVS analysis in terms of the series and parallel impedance components found in the complete equivalent circuit impedance model of DSC. As a result, analytical expressions are derived for potentiostatic IMPS and galvanostatic IMVS transfer functions of complete DSCs that are applicable at any operating point along the solar cell current-voltage (IV) curve. In agreement with the theory, impedance spectrum calculated as a ratio of IMVS and IMPS transfer functions measured near the maximum power point matches exactly with the impedance spectrum measured directly with EIS. Consequently, both IMPS-IMVS and EIS yield equal estimates for the electron diffusion length. The role of the chemical capacitance of the nanostructured semiconductor photoelectrode in the interpretation of the so-called RC attenuation of the IMPS response is clarified, as well as the capacitive frequency dispersion in IMPS and IMVS.

Power Flow and Stability Control Using an Integrated HV Bundle-Controlled Line-Impedance Modulator

This paper presents a flexible ac transmission system device under development for the management of power flow under steady-state and dynamic conditions, the bundle-controlled line-impedance modulator (LIM). In its simplest form, an LIM is made of switching modules connected in series with transmission-line segments whose bundles have subconductors insulated from each other. A module contains one switch in series with each subconductor of a bundle and the modules are anchored to dead-end towers in place of yoke plates. Together, with the measurement of sensors and controls, these modules can be used to change series impedances of transmission lines and implement functions, such as deicing, power-flow control, stability control, and line monitoring. In order to illustrate the LIM capabilities, two load-flow studies and one stability study are presented in this paper. Finally, the LIM performance is qualitatively compared to the thyristor-controlled series compensator technology.

2-D Niblett-Bostick magnetotelluric inversion

A simple and robust imaging technique for two-dimensional magnetotelluric interpretations has been developed following the well known Niblett-Bostick transformation for one-dimensional profiles. The algorithm processes series and parallel magnetotelluric impedances and their analytical influence functions using a regularized Hopfield artificial neural network. The adaptive, weighted average approximation preserves part of the nonlinearity of the original problem, yet no initial model in the usual sense is required for the recovery of the model; rather, the built-in relationship between model and data automatically and concurrently considers many half spaces whose electrical conductivities vary according to the data. The use of series and parallel impedances, a self-contained pair of invariants of the impedance tensor, avoids the need to decide on best angles of rotation for identifying TE and TM modes. Field data from a given profile can thus be fed directly into the algorithm without much processing. The solutions offered by the regularized Hopfield neural network correspond to spatial averages computed through rectangular windows that can be chosen at will. Applications of the algorithm to simple synthetic models and to the standard COPROD2 data set illustrate the performance of the approximation.

Audiomagnetotelluric investigation of seawater intrusion using 2-D inversion of invariant impedances

An audio-magnetotelluric survey was conducted to estimate the extension of the seawater intrusion in a coastal aquifer, in Ensenada, Baja California, Mexico. The survey consisted of 134 closely spaced sites along three profiles 5 to 6 km long. The four elements of the impedance tensor were measured at every observation site and used to estimate the series and parallel (s-p) invariant impedances. 2-D resistivity models were obtained along each profile using a Gauss-Newton regularized inversion process. The seawater intrusion is clearly shown in the resulting models as highly conductive anomalies. In some places, the resistivity models show the bedrock and the basement faults in good agreement with structures interpreted from gravity and magnetic modeling. Based on the information provided by the resistivity models and using the available hydrogeologic information, we used Archie's law in an attempt to gain insights about porosity and TDS distributions in the aquifer. Porosity values between 15 and 25% near the surface reasonably predict the TDS values observed in several shallow wells in the area. TDS values range from 40 g/l typical for seawater to 1 g/l in the eastern edge of the basin, 4 km away from the coastline. The best conditions were found in Profile 2, were the resistivity model predicts TDS values close to 1 g/l below 100 m depth at sites located further than 1 km from the coast. The above results show that s-p invariant impedances produced geologically plausible resistivity models. Hence, they might be a convenient set of magnetotelluric responses to be used for routine 2-D inversion of AMT data.

How to Find Wave-Scattering Parameters from the Causal Bond Graph Model of a High Frequency Filter

Problem statement: The aim of this study is to use the bond graph technique and the wave-scattering formalism, jointly, to determine the scattering matrix of a high frequency filter with cut-off frequency 10 GHz. Approach: The first step consist to model the high frequency filter by bond graph approach, afterward, we decomposed the obtained causal bond graph model under an elementary structures of a cascaded sub-model, where, each one containing only 0-junction (parallel admittance) and 1-junction (series impedance). The causal ways and algebraic loops present in each causal bond graph sub-model, allows us to derive the elementary wave matrix W(i) of each sub-model. Results: The total or global wave matrix W(T) of the high frequency filter is given by the product of all elementary wave matrixes W(i). Conclusion: The scattering matrix S of the studied filter can be inferred by use of the founded wave matrix W(T) which relates the incident and reflected waves at one port directly to the incident and reflected waves at the adjacent port and the relations linking the S coefficients to the W coefficients. Finally, the scattering parameters, founded from the wave matrix, will be checked by comparison of the simulation results.

Broadband Five-Port Direct Receiver Based on Low-Pass and High-Pass Phase Shifters

A simple five-port direct receiver achieving broadband performance and high local oscillator to RF isolation is presented. The new circuit comprises three power detectors exhibiting high series impedance, four resistors, and two low-pass and two high-pass phase shifters. It is shown that the phase-shift networks can be designed to optimize receiver operation over a theoretical decade bandwidth. A 300-MHz-2.7-GHz prototype is built and measured to prove feasibility of this proposal.

Modeling the Series Impedance of a Quad Cable for Common-Mode DSL Applications

New digital subscriber line (DSL) technologies are being developed to meet the ever-increasing bandwidth demand of the user. One very promising approach injects ¿common-mode¿ signals that superimpose a signal on two regular differential pairs. This technique requires new reliable multiconductor models for the telephony cables. Therefore, good approximations of the series impedance of the line are indispensable. In this paper, a model for this series impedance is theoretically derived and validated with measurements.

Circuit Loading in Radio-Frequency Current Measurements: The Insertion Impedance of the Transformer Probes

Considerable inaccuracy can be introduced in RF current measurements through loading effects from the transformer-type RF current probes. A physical model, which consists of a lumped impedance in series with the flow of the current under measurement, is obtained. The correlation between the loading (insertion) impedance and the geometrical and physical characteristics of the probe is clearly described through formulas that are useful for design purposes. The model is compared with those existing in the technical literature, and the main differences are highlighted and discussed. The theoretical predictions are experimentally confirmed. A direct application of the concepts discussed here to the improvement of the accuracy of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> -type vector impedance measurements is also shown. This paper is an extended version of the work by Carobbi and Millanta, including a more detailed description of mathematical derivations and experimental results and an updated list of references.

Synthesis of Perfectly Causal Parameterized Compact Models for Planar Transmission Lines

Per-unit-length series impedance and shunt admittance are extracted from electromagnetic analysis of a transmission line at a few discrete frequencies. Compact models are synthesized from the per-unit-length extraction. The lumped models are then used to rapidly calculate characteristic impedance, effective dielectric constant, and RLGC parameters at all frequencies, including dispersion and loss. The resulting models are perfectly physically (i.e., speed of light) causal, a critical consideration for time-domain analysis. To demonstrate feasibility, the models are parameterized as a function of transmission linewidth. Total error is carefully quantified and is typically less than 1%. The process is demonstrated for several planar transmission lines. New concepts, ?modal? and ?environmental? sensitivity, are introduced and quantified.

A Long-Pulse Generator Based on Tesla Transformer and Pulse-Forming Network

An approach for producing a long pulse up to 100 ns is presented. The generator based on this approach consists of a Tesla transformer and a set of pulse-forming networks (PFNs). The Tesla transformer is used to charge pulse-forming lines (PFLs) and PFNs which are in parallel. When the voltage increases to a certain value, the main switch will close, and the PFLs and PFNs will discharge rapidly to the load. Therefore, a high-voltage long pulse is formed on the load. The amplitude of this pulse is dependent only on the charging voltage and the matching state between the load and the PFL (PFN). The pulsewidth is determined by the transmission time of the PFL and PFN. The rise time is determined by the working state of the main switch and the impedance of the PFL and is independent of the parameters of the PFN. The PFN is multistage and assembled in series. The single-stage PFN is formed with ceramic capacitors placed between two unclosed annular plates. The total series impedance is equal to the sum of every single-stage PFN's impedance. A nine-stage PFN is used in the generator, and the total impedance is 40 Omega. Experimental results show that a high voltage of an amplitude of 300 kV, current of 6.9 kA, and duration of 110 ns is obtained at a repetition rate of 10 Hz, with a rise time of approximately 7 ns.