Distortion Factor Research Articles

Interaction influence of harmonics in MIDC transmission systems

Owing to the particular distribution of energy and load, the high-voltage direct current transmission system has been greatly developed in China. A number of areas have formed the multi-infeed direct current (MIDC) transmission systems. In MIDC transmission systems, the electrical distance between the inverter stations is close and the coupling effect is strong, therefore, the interaction influence of harmonics is complex. In order to analyse this complex interaction influence, this study first introduces the influence factors multi-infeed influence factors of power (MIIF-Pd) and multi-infeed total harmonic voltage distortion (MITHDu), which are used to describe the interaction influence degree of harmonics between inverter stations. Then based on the Shanghai power grid, a simulation model of the MIDC transmission systems was built in PSCAD/EMTDC, and the interaction influence degree of harmonics in MIDC transmission systems was studied in the case of large disturbance and small disturbance exists in the inverter stations. The results show that the interaction influence of harmonics between inverter stations is related to the electrical distance, the style of disturbance, transmission power and so on. Meanwhile, the disturbance on a commutation bus mainly leads to the increase of the harmonic distortion rate in this inverter station, and has less influence on the other stations.

Dinuclear Ternary Copper(II) Complex: Synthesis, Characterization, Structure and DNA-Binding Studies

A dinuclear centrosymmetric copper(II) complex has been prepared and characterized via FT-IR, UV-Visible and electron spin resonance spectroscopy, electrochemical method, and powder and single crystal XRD techniques. The two copper(II) ions are connected by two μ-1,1-O atoms belonging to para-fluorophenyl acetate ligands. Each copper(II) ion is coordinated by two other carboxylate ligands in monodentate and a 2,2'-bipyridine molecule in bidentate manner. Thus the geometry around each penta-coordinated copper(II) ion is square pyramidal with distortion factor τ = 0.04. Purity and uniform crystalline nature of the complex was assessed from powder XRD spectrum. ESR signal consisted of partially resolved hyperfine splitting pattern while electrochemical studies revealed diffusion controlled electron transfer processes with diffusion co-efficient of 1.628×10-7 cm2 s-1. The results of all spectroscopic experiments support each other. The complex afforded mixed binding mode with DNA yielding DNA-binding constant values of 3.667×104and 1.438×104 M-1 using cyclic voltammetry and absorption spectroscopy, respectively. The preliminary studies heralded good structural and biological importance of the synthesized complex.

Comparative Analysis of Various Multicarrier Modulation Techniques for Different Multilevel Converters

The applications of Multilevel Converter (MLC) are increased because of the huge demand for clean power; especially these types of converters are compatible with the renewable energy sources. In addition, these new types of converters have the capability of high voltage and high power operation. A Nine-level converter in three modes of implementation; Diode Clamped-MLC (DC-MLC), Capacitor Clamped-MLC (CC-MLC), and the Modular Structured-MLC (MS-MLC) are analyzed and simulated in this paper. Various types of Multicarrier Modulation Techniques (MMTs) (Level shifted (LS), and Phase shifted (PS)) are used for operating the proposed Nine level - MLCs. Matlab/Simulink environment is used for the simulation, extracting, and analysis the results. Finally, a comparison is made between the results for all topologies that are implemented regarding to the criteria of the output voltage waveforms harmonic distortion factor, No. of the necessitated power components, and the complexity of each circuit. Based on simulation results, the MS-MLC is finer as compared to the other types of MLCs. It also observed that the MLCs (with three types) using Phase Opposition Disposition (POD) technique is performed better in terms of getting greater fundamental output voltage and lower THD% as compared to the other techniques.

Duty-Ratio Feedforward Controller Design to Minimize the Capacitor Effect of the Flyback Inverter Under the Light-Load Condition

We propose a new duty-ratio feedforward controller for the flyback inverter with a synchronous rectifier (SR) circuit. For grid-connected photovoltaic power systems, the power factor (PF) of the output current must be high under most of the load conditions. To improve the PF of the flyback inverter even under light load, we propose a compensation method for the output capacitor current. The proposed method improves the displacement factor as well as the distortion factor, so the flyback inverter with the SR circuit has high power quality. By means of the SR circuit, the flyback inverter can operate in reverse when the negative current is required. The derivation of the proposed method is presented based on time-domain analysis. We also provide the boundary of the region where the proposed scheme should be adopted. The effectiveness of the proposed method is demonstrated in experiments with a 120-W rated power prototype.

Managing noise in signalling effectiveness: an empirical test of listed companies in China

PurposeSignalling theory suggests how “strong” or “weak” the signal quality detected by a receiver (defined as signalling strength) is distorted by noisy factors (defined as noise). Although corporate cooperation signals are known to lead to receiver reaction, the effects of distortion factors on signal credibility are generally unexplored in signalling process. The paper aims to discuss this issue.Design/methodology/approachAfter analysing 264 contract announcements in 2013–2015 that befall publicly listed firms in China, the authors explore the signalling impact of contract value. the authors also incorporate the signalling noises, namely, signalling environment, external referents and other signallers, into the contracting context and investigate their effects on distorting the relationship between signal strength and receiver reaction.FindingsResults indicate that firms’ contract-signing announcement conveys an effective signal to investors: the larger the contract scale is, the more investor reaction the firms experience. The signalling effects of contract scale on investor reaction are moderated by the three distorting factors.Originality/valueThe findings contribute to the signalling theory literature on the effects of signalling noise on receivers’ perception of signal observability.

Promises and pitfalls of using high-throughput sequencing for diet analysis.

The application of high-throughput sequencing-based approaches to DNA extracted from environmental samples such as gut contents and faeces has become a popular tool for studying dietary habits of animals. Due to the high resolution and prey detection capacity they provide, both metabarcoding and shotgun sequencing are increasingly used to address ecological questions grounded in dietary relationships. Despite their great promise in this context, recent research has unveiled how a wealth of biological (related to the study system) and technical (related to the methodology) factors can distort the signal of taxonomic composition and diversity. Here, we review these studies in the light of high-throughput sequencing-based assessment of trophic interactions. We address how the study design can account for distortion factors, and how acknowledging limitations and biases inherent to sequencing-based diet analyses are essential for obtaining reliable results, thus drawing appropriate conclusions. Furthermore, we suggest strategies to minimize the effect of distortion factors, measures to increase reproducibility, replicability and comparability of studies, and options to scale up DNA sequencing-based diet analyses. In doing so, we aim to aid end-users in designing reliable diet studies by informing them about the complexity and limitations of DNA sequencing-based diet analyses, and encourage researchers to create and improve tools that will eventually drive this field to its maturity.

Bistatic inverse synthetic aperture radar imaging method for the high-speed motion target

Bistatic inverse synthetic aperture radar (ISAR) can help image the high-speed target for its advantage in tracking and more observation angle to provide more information than monostatic ISAR. However, the complex image geometry makes it difficult to achieve a clear image of the target with geometry distortion correction and calibration. Furthermore, high-speed motion will make the image blurred or defocussed. To address these problems, a bistatic ISAR (B-ISAR) imaging method for high-speed motion target with geometric distortion correction and calibration is proposed. According to the motion decomposition idea, we established the B-ISAR echo model of the high-speed motion target. Then, based on the range Doppler algorithm, we deduce the analytic formula of the geometric distortion factor and calibration factor, and transform the imaging problem into a parameter estimation problem. With the sparsity of the scattering points, the required parameters are solved using the expectation maximization algorithm based on the maximum a posteriori probability criterion. With the estimated parameters, a clear B-ISAR image of a high-speed motion target with geometric correction and calibration is obtained. The simulations show that the proposed method has better resolution and simultaneously attains geometric distortion correction and calibration of the image.

A Universal Input, Single-Stage AC–DC LED Driver for an Auditorium Light

Analysis, design and simulation of 126[Formula: see text]W power supply with better power quality are presented in the proposed work to run an auditorium light emitting diode (LED) light operating at universal AC input mains (90–270[Formula: see text]V). A single-ended primary inductance converter (SEPIC) topology is designed and driven in continuous conduction mode (CCM) with advance feedback system to maintain constant voltage at output. A proportional integral (PI) controller is also proposed to make the system stable, and stability analysis is discussed in detail with the help of transfer function derived from the state space model. Bode, Nyquist and Polar plots are clearly drawn using the MATLAB tool to claim the system stability. For justification of mathematical analysis, a simulation of the proposed LED driver is also performed in MATLAB–Simulink using sim-power toolbox. The simulation results show the improved value of power quality indices like power factor (PF), total harmonic distortion (THD) and crest factor (CF) with constant rating of 84[Formula: see text]V, 1.5[Formula: see text]A at output. Improved PF and reduced THD are under the limit of international standards like IEC-61000-3-2 Class C requirement.

Real time FPGA Implementation of PWM Chopper Fed Capacitor Run Induction Motor

<span>This paper presents the performance enhancement of capacitor run induction motor by pulse width modulated AC chopper.The phase angle control faces severe shortfall in the performance improvement for larger triggering angles. In this paper the comparison of phase angle control and sinusoidal pulse width modulation technique is encountered for effective speed control of single phase capacitor run induction motor. The necessary parameters are taken into considerations are higher efficiency, lesser total harmonic distortion and high input power factor. The results are compared by using the simulations using matlab Simulink environment. The validation of result in hardware is implemented using Field programmable gate array for sinusoidal pulse width modulation technique.</span>

Improved Power Quality Switched Inductor Cuk Converter for Battery Charging Applications

Most of the two-stage converters for electric bike battery charging comprise of a boost converter for power factor correction (PFC) followed by a dc–dc converter with universal input voltage. These two-stage conversions suffer from poor efficiency and increased component count. In this paper, a single-stage switched inductor Cuk converter based PFC converter is proposed, which offers high step-down gain, low current stress, high efficiency, and reduced component count. The operational analysis and design equations for various components of the proposed converter are carried out in continuous current mode. This paper presents mathematical modeling, analysis, simulation, and experimentation on the proposed converter rated for 500 W, 48 V/10.4 A. The performance investigation of the proposed converter with respect to power quality indices like voltage total harmonic distortion (THD), current THD, and total power factor is carried out with various types of loads such as resistive load and battery load in both constant voltage (CV) and constant current (CC) mode. Furthermore, the dynamic performance of the proposed converter with battery charging is investigated in CV mode and CC mode with respect to the wide range of supply variations.

Real time FPGA Implementation of PWM Chopper Fed Capacitor Run Induction Motor

<span>This paper presents the performance enhancement of capacitor run induction motor by pulse width modulated AC chopper.The phase angle control faces severe shortfall in the performance improvement for larger triggering angles. In this paper the comparison of phase angle control and sinusoidal pulse width modulation technique is encountered for effective speed control of single phase capacitor run induction motor. The necessary parameters are taken into considerations are higher efficiency, lesser total harmonic distortion and high input power factor. The results are compared by using the simulations using matlab Simulink environment. The validation of result in hardware is implemented using Field programmable gate array for sinusoidal pulse width modulation technique.</span>

A Comparative Study of PWM Techniques for Multiphase Induction Motor Drives

Abstract This paper deals with the performance analysis of different PWM techniques for three-phase and dual three-phase induction motors. In this paper, the dual three-phase induction motor is reconnected as a three-phase and six-phase winding configurations and its performances are investigated. The comparative evaluation for the aforesaid machine configurations are carried out in terms of quality of stator current waveform with different PWM techniques. Total harmonic distortion are obtained in terms of harmonic distortion factor for stator current. The theoretical findings are further verified through simulation and experimental results.

Prediction of the tensile force applied on surface-hardened steel rods based on a CDIF and PSO-optimized neural network

The features traditionally extracted from hysteresis loops are highly sensitive to both the variation of case depth and uncontrollable factors in repeated testing cycles, thus increasing the difficulty in predicting the tensile force applied on surface-hardened steel rods with different case depths. In this study, in order to eliminate the influence of such high sensitivity, a case depth-insensitive feature (CDIF) was proposed to characterize the tensile force, and a particle swarm optimization (PSO)-optimized neural network was used to establish the correlation between the CDIF and tensile force in order to predict the tensile force applied on steel rods with different case depths. Five classical features (including remanent magnetic induction intensities, coercive force, hysteresis loss, maximum magnetic induction, and distortion factor) and the CDIF were successfully used to characterize the tensile force. Then, the linear regression model and PSO-optimized neural network model were used in turn to establish the relationship between each feature and tensile force to predict the tensile force applied on steel rods with different case depths. The CDIF was insensitive to the variation of case depth and linearly correlated with the tensile force. Even though the CDIF is affected by the unknown and uncontrollable factors in repeated testing cycles, the PSO-optimized neural network model based on it can be used to accurately predict the tensile force applied on steel rods with different case depths with a prediction error of 0.67%.

Electrical behavior and structure – property correlations in La1–xPrxMnO3 (0 ≤ x ≤ 1) ceramics

In this communication, we report the results of the electrical studies on La1–xPrxMnO3 (LPMO; 0 ≤ x ≤ 1) single valent manganites synthesized by conventional solid state reaction route. Structural studies reveal a single phasic nature of all LPMO samples having orthorhombic unit cell structure without any detectable impurity or structural phase transformation. Dielectric constant and impedance are found to increase while ac conductivity gets suppressed effectively upon increase in Pr content (x). This has been discussed in detail on the basis of structural distortion and tolerance factor in LPMO manganites. Temperature dependent dielectric behavior indicates an anomaly near respective magnetic transition temperature. Obtained dielectric and ac conductivity results have been theoretically fitted using relaxation formula and power law, respectively. Obtained fitting parameters have been discussed in the context of various structural aspects of LPMO manganites.

A three-dimensional active zero state PWM for common-mode voltage reduction of a three-phase four-leg voltage-source inverter

PurposeThis paper aims to investigate the common-mode voltage (CMV) issue of a three-phase four-leg voltage-source inverter. A new space vector modulation method, named as three-dimensional active zero state Pulse-width modulation (PWM) (3-D AZSPWM), is proposed to reduce the CMV level.Design/methodology/approachPWM is a general method to generate the switching signals of the power converters in order to obtain high-quality output voltages. However, the CMV produced by PWM methods has become a serious problem. 3-D AZSPWM is proposed to solve this issue. In 3-D AZSPWM, instead of using zero voltage vectors with high CMV level, appropriate complementary non-zero vectors are introduced to synthesize reference vector. The proposed method is classified into four types of AZSPWM1(a), AZSPWM1(b), AZSPWM2(a) and AZSPWM2(b) based on different complementary vectors chosen for each type. An extend software simulation using MATLAB/Simulink is performed to verify the superior performance of the proposed methods.FindingsCompared to other reduced CMV methods, the proposed method not only reduces the CMV but also retains the positive characteristics of the three-dimensional classical space vector PWM (3-D CSVPWM).Originality/valueThe proposed method does not suffer from linear modulation region limitation and also does not impose additional switching loss. Furthermore, calculated output voltage harmonic distortion factor illuminates acceptable quality of output voltage produced by the proposed method.

Accuracy Assessment of Surface Current Velocities Observed by OSMAR-S High-Frequency Radar System

High-frequency (HF) radar receives the sea echo backscattered from the fluctuating ocean surface to remotely sense ocean surface currents over a large area with a high space-time resolution. To advance our understanding on this technology, we carried out an experiment for verifying the performance of ocean state monitoring and analyzing radar, model S (OSMAR-S) in ocean surface current measurement. The hourly radial currents measured by this radar system show a good agreement with acoustic Doppler current profilers (ADCPs) with correlation coefficients ranging in 0.40–0.93 and root-mean-square-error (rmse) values in 0.11–0.18 m/s. The u/v components of the radar-derived vector currents show a similar deviation from the ADCPs with correlation coefficients varying from 0.56 to 0.93 and rmse values varying in 0.13–0.18 m/s. Also, the bearing offset of this radar system in current extraction is in the range from $-$ 11 $^{\circ }$ to 18 $^{\circ }$ . In consideration of the fact that the ideal antenna pattern was used in determining the bearing of the radials, we assume the main source resulting in the bearing offset is the antenna pattern distortion. Thus, a quantitative relation between the antenna pattern distortion factor and the bearing offset has been deduced. With this relation, we estimated the bearing error in the moorings’ bearing with the aid of the current information recorded by ADCPs. As expected, the result indicates that the antenna pattern distortion dominates the error of the bearing determination.

The Energy Efficiency of the Semiconductor Converters of Engines or Locomotives

The calculated power characteristics of the traction drive of the 2ES5K electric locomotive have been considered in the middle of a feeder zone of the overhead contact system. The traction drive with the developed converter of input electric resistance demonstrates advantages over the entire range of control, especially in the initial low-power region. The voltage waveform distortion factor for a current collector of the locomotive with a reversible converter is about 10.87%; if an electric semiconductor variator is used, this factor is 7.5% in the same mode of engine handling. It has been shown that control over the power of a locomotive by means of changing the electric resistance during the transfer and consumption of electricity from the overhead contact system leads to an increase in the energy efficiency and electromagnetic compatibility with power-supply systems without using additional equipment.

A study on the effect of interelectrode gap in the electrochemical additive manufacturing process

Electrochemical additive manufacturing (ECAM) is achieved by localized electrochemical deposition (LECD). The ECAM can print metal parts directly from computer models at macro-, micro- and nanoscales at room temperature without any thermal defects. This study aims to (1) simulate the effects of the interelectrode gap (IEG) on cation concentration and current density in the deposition zone during ECAM; (2) quantify the localization of the desired deposit, as well as unintended plating when using various IEGs, and (3) determine the rate of deposition for different IEGs. Current density patterns under stationary and moving anode conditions were analyzed to calculate deposition rate and the corresponding time to fill an IEG. Experiments were performed to monitor current density and time to fill IEG during deposition and compared with the simulation results. Studying the migration behavior of cations and the current density allowed deposition height to be predicted and the extent of plating to be quantified, using a distortion factor. It was found that for the ECAM conditions used in this study, smaller IEGs (<10 µm) result in lower rates of deposition due to the cation depletion, while larger IEGs (50 µm) result in an increase in plating tendency due to cation migration.

Simple and effective open switch fault diagnosis of single-phase PWM rectifier

In order to obtain lower harmonics distortion and higher power factors, single-phase pulse-width modulation (PWM) rectifiers are adopted in AC railway drive systems. Therefore, its reliability is of most importance with regard to the safe operation of the train. In this paper, a fault diagnosis method for open switch fault in single-phase PWM rectifier is proposed based on the switching system theory. It requires no additional sensor, nor extra operation states need to be set. Four observers which correspond to four kinds of open switch faults are utilized to detect and locate the faults. Real-time simulations are carried out to validate the effectiveness of this method.

The evaluation of structure and optical properties of CH3NH3[LaxPb1-x]I3; (0 ≤ x ≤ 0.07) trihalide perovskite films prepared by solution growth approach

Highly crystalline CH3NH3[LaxPb1-x]I3 (0 ≤ x ≤ 0.07) films are developed on quartz substrates using solution growth approach. The influence of lanthanum ions on the structural, morphological and optical properties of the La-doped methylammonium lead iodide perovskite films were examined by the X-ray diffraction, scanning electron microscope, Raman spectroscopy and UV-vis spectrophotometery. The films exhibited polycrystalline orthorhombic perovskite crystal structure, suggesting the solubility of the La ions in the CH3NH3PbI3 perovskite crystals. The orthorhombic distortion factor disclosed the incorporation of 3 mol% of La ions in the CH3NH3PbI3 perovskite crystal promote the symmetry of these crystal. The Raman spectra revealed three transverse optical phonon modes and three longitudinal optical phonons modes. The decrease of the ratio of the 96/110 bands and the peak position shift towards low frequency, implying the decrease of the concentrations of the PbI2 into the orthorhombic perovskite crystal and these films become more polarizable. Among all films, the CH3NH3[La0.03Pb0.07]I3 film has shown high optical absorption, low transmittance and very low reflectance. The increase of the amount of La ions from 0 to 3 mol% resulted in a decrease of the band gap from 1.51 eV to 1.44 eV, then an increase to 1.47 eV when the concentration reached to 7 mol%. The CH3NH3[La0.03Pb0.07]I3 film showed very low dissipation factor and high optical conductivity, implying the opportunity to use this composition for the development of photovoltaics and photodiodes applications.