Voltage Magnification Research Articles

A Thermoelastic Piezoelectric Fixed Rod Exposed to an Axial Moving Heat Source via a Dual-Phase-Lag Model

Piezoelectric ceramics are used more in the active control of noise and vibration with sensors and actuators. As a result, a one-dimensional homogeneous thermoelastic fixed piezoelectric rod subjected to a moving heat flow has been considered. The heating rod is affected by three fields, namely, thermal, mechanical, and electric potential. In order to design a reliable smart structure, this study is necessary and the thermopiezoelectric behavior of piezoelectric ceramics must be understood clearly. The Laplace transform method is applied to acquire the distributions of stress, deformation, and temperature fields. The effect of heat source velocity and phase lag parameters on the considered physical fields is displayed graphically, and the results are compared with other models of thermoelasticity. The present findings could find possible applications for designing receiving portions of transformers of Rosen type for voltage magnification.

Transient Characteristics Analysis of Shunt Capacitor Asynchronous Energizing

The capacitor energizing transient as a kind of typical disturbance is used in the studies of power quality, condition monitoring, and other fields, and all studies heavily rely on transient characteristics. However, most characteristics are established based on the three-phase capacitor synchronous energizing (SE), and the effect of asynchronous energizing (AE) is neglected, which may affect the relevant studies. In this paper, the main characterizations of the capacitor AE transient, such as the oscillation frequency, time constant, and transient magnitude are analyzed considering the operation modes of the system and capacitor neutral points. The effect of the three-phase circuit asymmetry on the characterizations is investigated. The downstream voltage magnification phenomena in not only positive-sequence circuit but also zero-sequence circuit caused by the capacitor AE are also revealed. The theoretical analysis, computer simulation and lab experiment results have verified the effectiveness of the characteristics.

Matlab Simulation For Fault Analysis of Electrical Circuit on Hyperspectral Signal Processing

The power system contains generation, transmission and Distribution. Abnormal conditions which cause flow of huge current in the conductors through improper paths in the circuit can be defined as a fault. The fault created transient parts which contain inexhaustible flaw data and are resistant to the framework's anomaly have been broadly utilized in the fault examination. The simulation findings demonstrate the system voltage and load currents effects of faults. In this paper, the different voltage circuit information levels will be evaluated using Hyperspectral processing and it is used to determine the exact difference in voltage magnification and evaluate it through signal processing.

Enhanced magnetoimpedance and magnetodielectric effect in LaFeO3 – Organic paraffin wax hybrid nanocomposites

Abstract Room temperature magnetoimpedance and magnetodielectric effects for (100 − x)% LaFeO3 − x% organic paraffin wax (x = 0, 0.5, 1, 1.5%) hybrid nanocomposites have been investigated. The enhancement of magnetoimpedance (∼226%) and magnetodielectric (∼75%) effects at low frequency region are obtained for x = 0.5% nanocomposites for strain mediation of piezomagnetic materials. The observed current – voltage characteristics both in absence and presence of magnetic field at room temperature have corroborated with the enhanced effect. It is also showing electrical memory effect with electrical switching. The Nyquist plots have been fitted considering the parallel combination of resistance-constant phase element circuit. AC electrical studies reveal the conduction mechanism in the system controlling through the grain and grain boundaries of nanocomposites. The minimum grain and grain boundaries resistance are found for x = 0.5% nanocomposites. The electric modulus of these nanocomposites has been studied to separate the grain and grain boundaries contributions of the system. A phenomenological model has been demonstrated to explain the observed result considering the barrier width of paraffin wax layer across the grain boundaries of LaFeO3 nanoparticles. The observed transport behavior attributes the phenomenological model. The organic hybrid nanocomposites (x = 0.5%) may be worked as a resistance-capacitance-inductance circuit with voltage magnification.

Research on harmonic and overvoltage of photovoltaic power plant electricity energy collection system based on passive network model

In large-scale photovoltaic (PV) power plant, the output power of each grid-connected inverter is collected by electricity energy collection system and then is put into the grid. Previous studies have demonstrated that the harmonic problem may occur when PV inverters run in parallel even if all the PV inverters output power do individually satisfy the standards. Considering the electricity energy collection system, this study builds the model of harmonic transfer passive network for the typical topological structure of large-scale grid-connected PV power plant, and study the generating mechanism of harmonic and overvoltage. The harmonic power flow of a given calculation example is calculated by using node matrix method and the harmonic voltage magnification of each node is got. The point of common coupling is chosen as the study object. In this study, the impacts of cable parameters, the equivalent impedance of power grid and operation mode of PV power plant on the voltage magnification properties of the transfer network are analysed.

Radio‐frequency performance comparison of several H ‐plane rectangular waveguide filters loaded with circular dielectric posts

The study presents a radio-frequency performance comparison between several H-plane geometry filters based on rectangular waveguide technology. The basic all-metal filter of resonant cavities is compared with filters loaded with circular dielectric resonators, either in propagative or evanescent mode. The use of these resonators is claimed to reduce the length of the filter, increase the rejection band until the first spurious frequency and to improve the voltage magnification factor (VMF), at the cost of increasing the losses. Therefore, in order to properly assess and quantify the possible advantages of these filters, an accurate analysis of six of them has been developed. All the filters have been designed to have the same electrical response, and the length, losses, rejection band, VMF, and fabrication cost for all the filters are compared.

Passively Self-Tuning Piezoelectric Energy Harvesting System

Real world systems that are candidates for vibrational energy harvesting rarely vibrate at a single frequency, nor are these frequencies constant over time. This necessitates that vibration harvesters operate over a wide bandwidth or tune their resonance. Most tunable devices require additional energy or active control to achieve resonance over various frequencies. This work presents a passively self-tuning energy harvester that autonomously adapts its resonant frequency to the input without requiring additional energy. The system consists of a clamped- clamped beam, a movable proof mass, and a piezoelectric patch bonded to the underside of the beam. It demonstrated an open-circuit voltage output of 668 mVrms at 160Hz, 0.65g input excitation. Discrepancies between displacement and voltage magnification factors upon tuning at higher frequencies are discussed, as well as instabilities of the system and sensitivity to proof mass characteristics.

Study of capacitor energising transient limiter with a half-wave rectifying compensating voltage system

This study presents a capacitor energising transient limiter (CETL) with a half-wave rectifying compensating voltage system. The proposed CETL provides a transient inductance to restrain capacitor energising transients at the instant of energisation. After completing the restraint, the limiter provides zero impedance based on the compensating voltage principle, and the capacitor seems to be connected directly to the system voltage source without requiring any control. Therefore in the steady state the capacitor current and voltage waveforms are undistorted, and no voltage rise occurs across the capacitor terminals. Further, this study offers a comparison of the levels of the total harmonic distortion (THD) in the capacitor voltage and current that occurs when different kinds of compensating voltage systems are used, and the relationship between THD and the resistance of the limiting reactor for the proposed CETL is simulated and discussed. In addition, this study also discusses that when the proposed CETL is applied to the low-voltage (LV) capacitor, voltage magnification appears on the capacitor because of the switching of the high-voltage (HV) utility capacitor. During the study period, a single-phase 220 V 0.9 kVAR capacitor was developed for demonstration, and the proposed method is verified by theory, in simulated results, and in field tests.

Analytical Study of Voltage Magnification Transients Due to Capacitor Switching

This paper addresses the voltage magnification phenomena at the terminals of customer transformers due to switching the medium-voltage utility capacitors. The traditional approach to understanding the voltage magnification phenomena is analyzed and its drawbacks are shown. The closed-form expressions for the magnified transient voltage waveforms are derived. The simulation results using the analytical expressions were found to be in very good agreement with those obtained using the Electromagnetic Transients Program. Novel relationships between the network parameters corresponding to maximal peak values of the overvoltages are developed. A simple procedure for evaluation of the maximum magnified overvoltages is presented. The developed procedure has been applied in a real-world power utility. The envelope of maximum expected overvoltages on the secondary side of the customer transformers has been obtained. The customer transformers, wherein the magnified overvoltages may exceed the permissible level, have been found.

Solving customer power quality problems due to voltage magnification

Reports by a Duke Power customer concerning equipment malfunctioning coincident with the switching of a 100 kV shunt capacitor bank led to field measurements and EMTP simulations to identify the possible sources of the problems and to find an economical solution. Measurements and simulation revealed the occurrence of voltage magnification at the customer's site due to the effects of three different distribution capacitor banks on the feeder supplying the customer. A comparative evaluation of commercially-available capacitor-switching transient mitigation switching devices suggested the use of low-resistance pre-insertion inductors applied with circuit switchers to energize the 100 kV capacitor bank. Field measurements of capacitor-switching events after installation of pre-insertion inductors verified the elimination of voltage magnification and customer power quality problems.

Evaluating capacitor-switching devices for preventing nuisance tripping of adjustable-speed drives due to voltage magnification

Nuisance overvoltage tripping of pulse-width modulated adjustable-speed drives, due to switching of shunt capacitor banks at a utility's substation and the subsequent voltage magnification which can occur at an industrial customer's utilization-voltage bus, is discussed. Adjustable-speed drive design considerations affecting transient overvoltage ride-through capability are identified and discussed. A comparative evaluation of three switching devices equipped with transient overvoltage control, namely, circuit breakers with pre-insertion resistors, circuit switchers with highly damped pre-insertion inductors, and controlled closing devices, is presented.

Magnification of transient voltages in multi-voltage-level, shunt-capacitor-compensated, circuits

The transient response of two, three, and four series L-C loop systems is examined, and results are presented of a case study of voltage magnification on an actual system with shunt capacitors at four different voltage levels. On this system, equipment damage occurred within an industrial plant in the same time frame of the energization of a capacitor bank in a utility substation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

“Quantitative” Electron Probe Analysis of Low-Atomic-Number Samples with Irregular Surfaces

The quantitative electron probe analysis on irregular surfaces via the two-voltage technique was assessed for light elements. This analysis can be performed without the knowledge of the local tilt angle, i.e., the take-off angle. Data are presented of compositions determined on crystal facets with widely varied orientations with respect to the detector. A range of model compounds and commercial products was investigated with special emphasis on those consisting of low-atomic-number elements. The usefulness of the technique, its disadvantages, and limitations are critically evaluated. The precision and accuracy obtainable in routine laboratory work are quantified and the effect of the selection of the accelerating voltage pairs and magnification is discussed.

乳房の低電圧同位相拡大撮影法

We examined in the simultaneous photography of mamma with low voltage magnification and contact. The minute focus X-ray tube for low valtage, the photographying bed and the film slide were made for this purpose. The sensitizing paper which only has the back was used for the magnifying photograpey and nonscreen for the contact photography. The magnifying power of three to four times is actually useful and greater power than this can never find any minute substanes. The magnifying photography showed the excellent results that the scattered rays decreased due to the Groedol efficiency, and minute lime precipitated images and fibrous index images were found which cannot be recognized by the contact photography.

Magnification of switching surges

MAGNIFICATION of transient voltages in one part of an electric power system may occur in another part of that system, possibly at a different voltage level. Experiences such as these have resulted in system flashovers or equipment damage. The degree of voltage magnification does not necessarily involve circuit-breaker restriking or prestriking, although these factors may increase the severity of the disturbance.

Magnification of Switching Surges

MAGNIFICATION of transient voltages in one part of an electric power system may occur in another part of that system, possibly at a different voltage level. Experiences such as these have resulted in system flashovers or equipment damage. The degree of voltage magnification does not necessarily involve circuit-breaker restriking or prestriking, although these factors may increase the severity of the disturbance.

A generalized analysis of the triode valve equivalent network

The paper gives an analysis of the variation with the resultant anode circuit load of the input impedance and voltage magnification factor of a triode valve. A new mode of presentation is adopted which enables the total range of variation of these quantities to be represented as finite functions of a variable with a limited range of variation.The most important conclusion is that at very high radio frequencies the voltage magnification factor may appreciably exceed the voltage factor of the valve, this condition being reached for a finite pure inductive load. Under the same conditions, however, the shunt input impedance is very low.The most efficient means of associating a tuned circuit with a receiver of relatively low input impedance is considered in an Appendix.

A generalized analysis of the triode valve equivalent network

The paper gives an analysis of the variation with the resultant anode circuit load of the input impedance and voltage magnification factor of a triode valve. A new mode of presentation is adopted which enables the total range of variation of these quantities to be represented as finite functions of a variable with a limited range of variation.The most important conclusion is that at very high radio frequencies the voltage magnification factor may appreciably exceed the voltage factor of the valve, this condition being reached for a finite pure inductive load. Under the same conditions, however, the shunt input impedance is very low.The most efficient means of associating a tuned circuit with a receiver of relatively low input impedance is considered in an Appendix.