Analysis Of Transient Voltages Research Articles

Limitations in the electrochemical analysis of voltage transients.

Objective. Chronopotentiometric voltage transients (VTs) are used to assess the performance of bionic electrodes. The data obtained from VTs are used to define the safe operating conditions of clinical devices. Various approaches to analysing VTs have been reported, and a number of limitations in the accuracy of the measurements in relation to electrode size have been noted previously.Approach. The impact of electronic hardware and electrode configuration on VTs is discussed.Main results. The slew rate, rise time, sample time, minimum pulse length and waveform averaging characteristics of the electronic hardware, and electrode configuration will impact on VT measurement accuracy. Subsequently, activation and polarisation voltage measurements, and the definition of safe stimulation levels can be affected by the electronic hardware and electrode configuration.Significance. This article has identified some limitations in the previous literature related to the measurement and reporting of VTs and subsequent analysis of access and polarisation voltages. Furthermore, the commonly used Shannon plot used to define safe stimulation protocols does not correct for uncompensated resistance, account for electrode roughness or changes in electrode configuration. The creation of a safe stimulation plot which has been corrected for uncompensated resistance would generate more widely applicable stimulation guidelines for clinical devices used in different anatomical locations such as endovascular neural interfaces.

X-Type Five-Level Current Source Inverter

Current source inverters (CSIs) feature superior features such as low dv/dt, reliable short circuit protection, etc. Among the CSI-based topologies, the 5-level CSIs are attracting attention in multiple applications thanks to their superior harmonic performance. However, existing 5-level CSI topologies suffer a couple of issues, for example, the current imbalance issue which requires complicated balancing controls. In this paper, an X-type 5-level CSI is proposed. It features an inherent current balancing due to the process of charging the inductors in series. In addition, the proposed inverter has less switch count than the existing ones. An SVM-based modulation is proposed for the inverter. Detailed analysis and calculations regarding inverter gain, passive components, transient voltage analysis, and efficiency are provided. The performance of the converter is verified by both simulation and lab-scaled experiments.

Analysis of transient voltages and currents in short transmission lines on frequency-dependent soils☆

Accurate modeling of overhead transmission lines (OHTLs) for transient analysis require that the ground which the phase conductors are suspended be considered on the longitudinal impedance and transversal admittance matrices. In this framework, some models deal with the soil as an ideal conductor (constant resistivity ρg and relative permittivity εr). However, it is known fact that real soils are characterized by frequency-dependent (FD) electrical parameters (ρg(f) and εr(f)). Due to these conditions, different formulations to represent the soil with FD parameters have been developed in the last decades. In order to obtain a precise transient response, these models must be incorporated in longitudinal impedance, as the ground-return impedance, and transversal admittance matrices. In this article, an analysis to compute the impact of some FD soil electrical parameters on transient responses is carried out. These responses are calculated for an energization maneuver and ligtning direct strike on OHTLs with different lengths located above constant and FD soil parameter models of low and high soil resistive values. Results show significant differences between the transient responses obtained with the constant and FD soil models, which these variations are more pronounced for soils of high resistivity and for short OHTLs.

Fast and Accurate Transient Analysis of Large Grounding Systems in Multilayer Soil

One of the most accurate approaches to the lightning-related transient analysis of grounding systems in layered soil is based on the method of moments solution of the integral form of the Maxwell equations. The practical application of this rigorous model to large systems is hindered by a great amount of computer time required for the numerical integration of oscillatory and slowly convergent Sommerfeld integrals (SI). As a result, approximate methods that avoid the solution of SI, e.g., image theory-based methods, are often used for computation of the response of large grounding systems. In this article, we extend the application of the rigorous model for large grounding systems in multilayered soil by applying a procedure that minimizes the number of direct computations of the SI using interpolation over a grid of a small number of sample points. We implement a three-dimensional interpolation scheme that adapts to the problem to minimize the interpolation grid, maintaining the accuracy of the rigorous approach. The developed model is applied for the analysis of transient voltages that might couple to secondary cables and disrupt the operation of connected equipment in case of lightning. The analysis shows that there are cases when the image theory-based models might underestimate the possibly harmful transient voltages.

Transient Voltage Analysis for Dynamic Positioning Closed Bus Electrical System on Ship in Laboratory Scale

Ships equipped with a dynamic positioning system has a more number of thuster than ships that are not equipped with a dynamic positioning system. The addition of this thruster resulted in a significant increase in electrical loads so that the power plant will be added to the vessel. Dynamic positioning is a system used to support offshore vessel work consisting of a collection of equipment and control systems that work simultaneously to maintain the position of a vessel in accordance with which has been input into the system. Installation of the dynamic positioning system on the vessel affects the electrical system of the vessel. In the operation of electrical system on the vessel found the disturbances that arise one of them is transient interference that causes the change of voltage and frequency value in a short time. A Transient voltage occurs within a few seconds where the system conditions are unstable. The research was conducted in a laboratory scale by modeled a series of vessels that have the system with existing laboratory equipment where transient interference occurred due to the starting motor so that it is done Analysis of the magnitude of the voltage and frequency in the specified scenario as well as finding a solution to correct emerging interference that exceeds the standard. In the experiments made some configuration changes and obtained the result that the configuration of Split Plant 1 generator thruster has good system stability capable of achieving a stable condition with a loading of 50%. As for the loading of 60% stability of the system is unstable and can be improved again with the addition of capacitor.

An Analysis of Transient Impedance-like Diagnostic Signals in Batteries

Electrochemical impedance spectroscopy (EIS) is an established technique for monitoring and testing of electrochemical systems, including batteries. Parameters related to electrochemical phenomena such as charge-transfer kinetics and mass transport can be estimated from the impedance response over a range of frequencies1. The classical description for impedance of an electrochemical system, subjected to a periodic input perturbation, depends upon achieving a steady periodic output state2. However, there may be value in analyzing the joint time-frequency response of a dynamic impedance-like output signal under conditions that are not steady periodic3. For example, it has been shown that using a dynamic impedance-like response allows parameter estimation to be carried out in shorter times than waiting for a steady periodic state to be reached4. This may be particularly valuable for accessing low frequency (slow) phenomena such as thermodynamic and diffusion effects. As a result, dynamic impedance-like signals may be a valuable tool for real time diagnostics of battery degradation processes. The objective of this study is to develop time and frequency dependent solutions for existing battery models to further investigate the full dynamic response of the system. Devan et al. has performed transient voltage analysis for a porous electrode model5 and short-time current density response for an intercalation particle model4. A comparison to the steady periodic response for parameter estimation and the choice of optimum frequencies for measurements will be explored. While the analysis will begin with a simple physics-based model, the goal is to develop a fast and efficient tool for porous electrode 2D models. In particular, the focus will be on the gain in estimating parameters with specific confidence intervals, and mechanism validation from using the transient data compared to steady state models. References Yu, B. N. Popov, J. A. Ritter, and R. E. White, Journal of The Electrochemical Society, 146, 8 (1999).Ceder, M. Doyle, P. Arora, and Y. Fuentes, MRS Bulletin, 27, 619–623 (2002).Doyle and J. Newman, in Tutorials in Electrochemical Engineering—Mathematical Modeling, edited by R.F. Savinell, J.M. Fenton, A.C. West, S.L. Scanlon, and J. Weidner (The Electrochemical Society, Seattle, 1999) p. 144.Devan and R. E. White, Journal of The Electrochemical Society, 154(2007).Devan, V. R. Subramanian, and R. E. White, Journal of The Electrochemical Society, 152 (2005).

Transient voltage analysis on a series capacitor of the floating probe for plasma diagnostics

An electrical plasma diagnostic method is proposed to determine plasma density and electron temperature. When two square voltages with different amplitudes are applied to a probe tip, a capacitor connected to the probe is charged due to the current flowing from the plasma. To obtain the plasma parameters, a circuit model with a nonlinear sheath and capacitor is proposed. The electron temperature and plasma density given by the model can be obtained from the ratio of the capacitor voltages. The results are in agreement with those obtained from electron energy probability functions in argon inductively coupled plasma discharge.

Switched differential system approach to voltage transient analysis in power delivery systems with switching capacitors

The authors present new results regarding the analysis of voltage transients induced by switching capacitors in power delivery systems. Their approach is based on a systematic technique that facilitates the computation of initial conditions when the switch occurs. This set-up permits an efficient parametric exploration that is suitable for accomplishing safe voltage peaks according to customer specifications. The authors discuss upper and lower bounds corresponding, respectively to (i) the worst-case scenario in a lossless system, and (ii) the damped case with a shunt load and equivalent series resistances. Experimental measurements corroborate the underlying principles and results presented in this study.

FDTD simulation of direct lightning strike to a phase conductor: Influence of corona on transient voltages at the tower

In this paper, a simplified model of corona discharge for the finite-difference time-domain (FDTD) computations has been applied to analysis of transient voltages at the tower of a transmission line caused by direct lightning strikes to an upper phase conductor. In the simulations, three 40-m towers, separated by 300m, with one overhead ground wire and three phase conductors are employed. Corona is assumed to occur only on the upper phase conductor struck by lightning. The progression of corona streamers from the conductor is represented as the radial expansion of cylindrical conducting region around the conductor. The reduction of transient-voltage peak due to corona is not very significant, so that the voltage at the nearest tower exceeds the insulation level of 66/77kV power line considered in this paper. For a 10-kA peak current, the upper-phase-conductor voltage peaks are reduced by 26% and 21% for a positive stroke with 1-μs- and 3-μs-risetime currents, respectively, and those for negative-stroke case are reduced by 18% and 13%, respectively. For a 20-kA peak current, the corresponding upper-phase-voltage peaks are reduced by 32% and 25% for the positive-stroke case, and those for the negative-stroke case are reduced by 22% and 15%.

Effect of current mode on PEO treatment of magnesium in Ca- and P-containing electrolyte and resulting coatings

Plasma electrolytic oxidation (PEO) coatings were produced on commercially pure magnesium in a biologically friendly electrolyte composed of 2gL−1 Ca(OH)2 and 12gL−1 Na3PO4·12H2O using pulsed unipolar and bipolar current regimes with negative biasing varying from 0 to 20mAcm−2. Analysis of voltage transients was performed to characterise the PEO processes. The coating morphology and phase composition were studied by scanning electron microscopy and X-ray diffraction technique, respectively. In vitro corrosion performance of the coatings was evaluated in a simulated body fluid at 37±1°C, using electrochemical techniques including open circuit potential monitoring, electrochemical impedance spectroscopy and potentiodynamic polarisation scans. The influence of the negative biasing on the PEO process and resulting coating characteristics is discussed. Unlike generally recognised beneficial effects of the negative biasing in PEO treatments of some other metal-electrolyte systems, it was found that detrimental effects are induced to the coatings on cp-Mg produced in the studied electrolyte when the negative current amplitude increases, which may be attributed to hydrogen liberation at the coating/substrate interface during the negative biasing cycles. As a result, a deterioration of vitro corrosion performance was observed for the pulsed bipolar PEO coatings compared to those produced using the pulsed unipolar regime which provides better quality coatings.

Dynamic Analysis of Transient Voltage for Distribution Network with the Consideration of Wind Power

Distributed wind power will bring great impact on transient voltage of distribution network. Based on the characteristics of distributed wind power, this paper presents a doubly-fed induction Generator with four wind speed model and Crowbar protection model in DigSILENT/PowerFactory. The analysis is carried out for a test distribution system representative of the Benchmark 20kv grid. Firstly, this paper respectively provide simulation results showing the effects of distributed wind power on the dynamic voltage in wind fluctuation and a faulted system. Then, a static synchronous compensator (STATCOM) is used to improve the voltage profile of the distribution system.

FDTD Simulation of Insulator Voltages at a Lightning-Struck Tower Considering Ground-Wire Corona

In this paper, a simplified model of corona discharge for the finite-difference time-domain (FDTD) computations has been applied to the analysis of transient voltages across insulators of a transmission line struck by lightning. In the simulation, three 60-m towers, separated by 200 m, with one overhead ground wire and three-phase conductors are employed. The progression of corona streamers from the ground wire is represented as the radial expansion of cylindrical conducting region around the wire. On the basis of the computed results, the effect of corona discharge at the ground wire on transient insulator voltages is examined. The insulator voltages are reduced by corona discharge on the ground wire. The reduction of insulator-voltage peak due to the ground-wire corona is not very significant: the upper-, middle-, and lower-phase-voltage peaks are reduced by 15, 14, and 13% for a positive stroke with 50-kA-peak and 3-μs-risetime current, and those for the negative stroke with the same current waveform parameters are reduced by 10, 9, and 8%, respectively.

Design of a DC Resistive SFCL for Application to the 20 kV Distribution System

A DC-operating resistive-type superconducting fault current limiter for AC applications (in short a DC Resistive SFCL) is based on the synergistic use of the "resistive" and the "rectifier" fault current limiter concepts, and allows the superconductor to operate in nearly DC current conditions. This regime of operation drastically reduces the AC losses and therefore opens up completely new perspectives with regard to the materials, the architecture of the cable, the layout of the windings and the cryogenics. In this paper the design of a DC resistive SFCL for application to the 20 kV distribution system is presented. A bus tie position with nominal rate of 25 MVA is considered as case study. The resistance and the inductance of the superconducting winding are arrived at by means of the parametric analysis of voltage transients, harmonic distortion and peak fault current. The design of the windings of the real scale device is carried based on a optimized MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> cable. The detailed design of the bridge rectifier is carried out and the power losses due to diodes are evaluated.

On the use of continuous-wavelet transform for fault location in distribution power systems

The paper illustrates a procedure based on the continuous-wavelet transform (CWT) for the analysis of voltage transients due to line faults, and discusses its application to fault location in power distribution systems. The analysis carried out shows that correlation exists between typical frequencies of the CWT-transformed signals and specific paths in the network covered by the traveling waves originated by the fault. The paper presents a procedure for determining fault location in MV distribution systems, which exploits the above-mentioned correlation. The MV distribution system analysed in the paper is accurately represented by means of an EMTP model; various fault types and network characteristics are examined. The paper presents also the basic concepts of a measurement and fault location prototype system with distributed architecture.

22kV実規模配電線路(全ケーブル系統)における過渡性過電圧の測定および解析

22kV実規模配電線路(全ケーブル系統)における過渡性過電圧の測定および解析

Time- and frequency-domain transient signal analysis for defect detection in CMOS digital ICs

A novel approach to testing CMOS digital circuits is presented that is based on an analysis of voltage transients at multiple test points and I/sub DD/ switching transients on the supply rails. We present results from hardware experiments that show distinguishable characteristics in the transient waveforms of defective and nondefective devices. These variations are shown to exist in both the time domain and frequency domain for CMOS open-drain and bridging defects, located both on and off sensitized paths.

Computer analysis of transient voltages in large grounding systems

A computer model for transient analysis of a network of buried and above ground conductors is presented. The model is based on the electromagnetic field theory approach and the modified image theory. Validation of the model is achieved by comparison with field measurements. The model is applied for computation of transient voltages to remote ground of large grounding grid conductors. Also computation of longitudinal and leakage currents, transient impedance, electromagnetic fields, and transient induced voltages is possible. This model is aimed to help in EMC and lightning protection studies that involve electrical and electronic systems connected to grounding systems.

Fast computation of multiport parameters of multiconductor coupled microstrip lines

A fast approximate analysis method is presented for computing multiport parameters of uniform and nonuniform multiconductor coupled microstrip lines based on physical parameters considering dispersion and loss. A method for transient voltage analysis based on multiport S-parameters is also presented. The method is adequate for microwave and high-speed integrated circuit CAD software. Computed results for both S-parameters and transient voltages waveforms show good agreement with those by other methods or by measurement. >

230 kV Operation of a Substation Designed for 115 kV by Controlling Voltage Transients

Arresters applied at the terminals of gas Insulated substations have been used successfully for protection from switching and lightning surges. This arrester application for gas Insulated substations permits the use of lower insulation levels and therefore more economical substations. In principle, the same technique can be applied to air Insulated substations. This paper describes the analysis of transient voltages In a substation designed for 115 kV which Is scheduled for operatlon at 230 kV. Both arrester rating and location are considered In this analysis. It is shown that complete substation protection is possible by addition of both arresters and capacitors.

Pyroelectric Voltage Response to Step Signals of Infrared Radiation in Triglycine Sulphate and Strontium-Barium Niobate

Theoretical and experimental analysis of voltage transients obtained in triglycine sulphate and strontium-barium niobate in response to step radiation signals yields information important for pyroelectric ir detection. The response transients are shown to be symmetrical with respect to the electronic and thermal time constants τe and τT of the samples. When τe and τT differ appreciably, the rise of the response and its decay are exponentials whose time constants are, respectively, the smaller and the larger one from among τT and τe. The peak voltage values are proportional to the load resistance RL when τe≪τT; they become independent of RL and proportional to τT when τe≫τT. The initial slope of the response in a given sample is found to be independent of RL for a given radiation flux. The pyroelectric coefficient of a material, divided by the product of its permittivity, density, and specific heat is shown to be a figure of merit for use in pyroelectric ir detection