Distortion Factor Research Articles

An FPGA Based Novel Digital Controller for DSTATCOM to Enhance Power Quality in Distribution System

This paper proposes an FPGA based all-on-chip novel digital controller for DSTATCOM to compensate harmonics and reactive power existing in power distribution system. The proposed technique extracts reference current by considering instantaneous symmetrical component active power (ISCAP) theory based phase delay compensation (PDC) control technique. The proposed controller comprises positive sequence detector, PI-controller, low-pass filters (LPF) and hysteresis current controller. All these segments are configured on high speed, low cost field programmable gate arrays (FPGA) hardware resources intended to mitigate harmonics and compensate reactive power in power distribution network. Very high speed hardware description language (VHDL) implementation for each module are produced through system generator and implemented on SPARTAN-3 XC3S5000 FPGA chip through RT-XSG toolbox in Opal-RT platform. The performance of proposed controller is demonstrated through VHDL test bench, simulation and real-time experimental results with consideration of total harmonic distortion (THD) and power factor correction in steady state condition.

TINJAUAN FLUKS CAHAYA, SUHU WARNA, TOTAL HARMONIC DISTORTION, FAKTOR DAYA LAMPU PIJAR, LAMPU HEMAT ENERGI DAN LIGHT EMITTING DIODE

Requirements of energy in nowadays are directly proportional with human activities which use a lot of energy, especially for electrical energy, therefore, it is necessary to take energy saving measures such as lighting that use electronic devices with energy efficient. The latest lighting technology is used saving energy lamp (LHE) and light emitting diode (LED) which are designed to replace that use of incandescent lamps. The purpose of this research was to compare lamp based on light flux, colour temperature total harmonic distortion (THD) and power factor. The standard used for luminous lighting flux, the colour temperature standard of SNI 03-6575-2001 and THD using reference IEEE 519-2014.From the study has been done is obtained that level of lighting flux produced by LED type is bigger for twice than LHE type. The best colour temperature is LED with ratio value of 875oK/W. THD current for LHE and LED does not comply the standard, therefore THD current is smaller 4% - 7,3% from LED. The power’s factor produced by LHE and LED is 0.5 to 0.6.

Hierarchical faulted line section location method for low‐voltage active distribution network considering information distortion

Distortion of fault monitoring information is an important factor that affects the accuracy of faulted line section location in low-voltage active distribution networks (ADNs). This paper proposes a faulted line section location method that considers the layered solution for monitoring information distortion, to improve the accuracy and efficiency of fault location in low-voltage ADNs. A multi-target fault section location optimization model that considers information distortion, multipoint faults, and multiple information distortion types is formulated. A combination of information distortion factors is introduced to represent various types of information distortion and to transform the original optimization model into an unconstrained 0-1 programming problem. A hierarchical fault location algorithm for segmenting the distribution network is designed to solve the low accuracy and efficiency of direct solutions for fault location models resulting from a large number of active distribution line sections. Simulation results show that the fault location method considering information distortion effectively guarantees the accuracy and solution efficiency of faulted line section location of low-voltage ADN.

Impact of Hardware Impairments with Imperfect Channel Estimation for Cache-Enabled UAV Relaying Networks

The effects of hardware impairments with imperfect channel estimation for cache-enabled UAV networks are studied in this paper. The effects of the setup parameters, such as the number of cached or relaying nodes, the hardware impairment factor, the channel estimation error, and the transmission SNR, on the outage probability are present by deriving the exact closed-form expressions on outage probability. Also, the asymptotic results are present when the transmission SNR is large enough. From the asymptotic analysis, we can see that there is an error floor introduced by the hardware impairments and imperfect channel estimation. Specifically, the error floor is dependent on the channel estimation error factor, the hardware impairment distortion factor, and the QoS requirements. And the diversity order of the error floor for the cached/relaying links is equal to the number of cached/relaying UAV nodes.

Time response enhancement for variable speed drive systems by using five-level cascade four quadrant chopper in dc-link

This research introduces a filtering circuit design integrated with the DC-link of a medium power variable speed drive (VSD) system. The designed filtering circuit employs modern power electronic circuits to improve time response characteristics in both grid and dc-link sides. Depending on the widely used multi-level converters, a conventional three-level H-bridge four-quadrant chopper scheme was developed into a cascade five-level H-bridge four-quadrant chopper scheme. The time response of the proposed system was performed with both choppers, and results showed that voltage drop on cascade chopper transistors was reduced to half in comparison with voltage drop on conventional four-quadrant chopper transistors. Moreover, the sharp fluctuations in system's waves were mitigated; consequently, time response characteristics in both steady and transient states were remarkably improved. The total harmonic distortion factor THD% of the input current and voltage was reduced to 26.2% and 2.43% respectively and the ripple factor RF for DC-link current was reduced to 0.196.

Tunnel–framed building interaction: comparison between raft and separate footing foundations

In this paper, the influence of the foundation configuration (raft or separate footings) on tunnel–soil–framed building interaction is investigated using geotechnical centrifuge testing. Tunnelling-induced soil movements and deformation fields, framed building displacements and structure shear distortions (with associated modification factors) are illustrated. Framed building stiffness and footing bearing capacity are also evaluated experimentally. Results show that the foundation configuration plays an important role in determining the ground response to tunnelling, affecting soil displacement fields, as well as the distribution of soil shear and volumetric strains. In particular, foundation settlements and differential horizontal displacements are larger for separate footings compared to raft foundations. The effects of building width, weight and eccentricity (with respect to the tunnel) on foundation settlements and structural distortions are quantified for separate footings and contrasted against results for raft foundations. The modification factor of the maximum building shear distortion is linked to the relative soil–building shear stiffness; interestingly, for buildings with similar values of relative stiffness, the level of shear distortion within framed buildings is lower for separate footings than rafts.

Development of a Data Acquisition and Monitoring System Based on MODBUS RTU Communication Protocol

MODBUS is a serial communication protocol use in industry, which developed by Modicon in 1979. The most common usage of the MODBUS communication protocol is the Programmable Logic Controllers (PLC). The aim of this study is to develop a system for acquiring and analyze measured values from the power measuring device and display them on C# developed GUI. The main objective is to develop an algorithm for MODBUS RTU communication protocol for data acquisition process. In this study, a single power measuring device was used with the aid of MODBUS RTU and RS-485 communication protocols, and data shown in the device was visualized on the C# developed GUI application and analyze them according to the user’s requirement. Data acquisitions from the holding registers were made by using the MODBUS Function Code three. The test results were observed and verified accuracy by performing several trials. Data was collected from the power measuring device which was attached to the industrial soft starter panel of a milling machine. Voltage, Current, Total Harmonic Distortion and Power Factor for each phase were retrieved to the C# devolved computer application and verify results with the real-time data of the power measuring device.

Improved multifunctional controller for power quality enhancement in grid integrated solar photovoltaic systems

PurposeThis paper aims to propose an improved multifunctional control strategy for achieving real, reactive power flow control and the mitigation of power quality issues in grid integrated photovoltaic (GIPV) systems.Design/methodology/approachThe paper proposes a dual stage, three phase, multifunctional GIPV system with modified instantaneous reactive power (IRP) theory-based and modified synchronous reference frame (SRF) theory-based control algorithms for reference template generation with continuous load power requirement tracking. The control structure is designed so as to impart virtual distribution static compensator functionality to the photovoltaic inverter. The dual mode operation in active filter and renewable power injection modes provides enhanced capability to the GIPV system. A comprehensive evaluation of the dynamic behaviour of the GIPV system is carried out for various conditions of irradiance and load under MATLAB/Simulink platform. The performance comparison is done considering an uncompensated system and the GIPV system with both proposed control algorithms.FindingsThe extensive simulation results demonstrate that the proposed modified SRF theory-based multifunctional control strategy shows superior performance in real and reactive power flow control; reduction in real and reactive burden of the utility grid; and regulation of dc bus voltage under varying scenarios of irradiance and load. Furthermore, there is improvement of grid power factor and reduction in total harmonic distortion of grid currents in compliance with the IEEE 519 standard even with highly non-linear loads at the point of common coupling.Originality/valueThe proposed modified SRF theory-based multifunctional controller offers a viable solution for power quality enhancement as well as the realization of effective real and reactive power flow control in GIPV systems. Thus, the penetration level of distributed generation can be increased in this era of global energy crisis.

Power quality control based on voltage sag/swell, unbalancing, frequency, THD and power factor using artificial neural network in PV integrated AC microgrid

Abstract In the present scenario of microgrid system, conversion of electrical energy has initiated a challenge to maintain the power quality within a satisfactory range. It can be influenced by the voltage deviation, sag/swell, unbalancing, frequency, total harmonic distortion (THD) and power factor as per nature of local loads and the condition of distributed energy resources (DERs). The relationship between power quality and the set of these variables are non-linear in nature. The existing literature show that the above mentioned parameters are not considered simultaneously for the assessment and controlling of power quality in PV based AC microgrid. To minimize the effect of these variables, a novel artificial neural network (ANN) based control approach has been proposed which can control the power quality as per IEEE/IEC standards. The proposed method has shown fast, smooth and stable operation while the performance of the same is verified with that of the proportional–integral (PI) and fuzzy-PI controllers using Matlab-Simulink software. The small size microgrid model is tested with the effect of line impedance and communication delay for the assessment of power quality parameters. This model is extended to a large size realistic microgrid structure for the feasibility of control methodology. The realistic microgrid structure is verified under the analysis of line impedance, communication delay, demand response and off-nominal conditions. The proposed control methodology is validated in a realistic microgrid structure and simulation results are presented to show the performance of proposed controller under different test conditions to identify an ANN library.

Metal particle encouraged surface charge accumulation on epoxy insulator with multi-arc surface profile under DC voltage

Surface charge accumulation on epoxy insulator installed in gas insulated switchgear (GIS) or gas insulated transmission line (GIL) has been recognized as an important factor for electric field distortion that results in reduction of surface flashover voltage. This paper reports on surface charge accumulation behavior on a actual epoxy insulator for 100 kV GIL prototype with multi-arc surface profile. A coaxial electrode system is used to investigate the charging behavior under DC voltages with metal particles positioned at various positions of the surface so as to estimate its influence on the charge accumulation behavior using a Kelvin type probe. The results show that positive charges are accumulated mainly on the nonplanar region around the high voltage electrode in the shape of speckles, and the average charge distribution along the radial direction presented a double-peak feature. Moreover, the charge accumulation is enhanced by metal particles contacting to the grounded electrode. Using a numerical simulation method, it is suggested that the charge accumulation is mainly determined by gaseous ionization which is enhanced by the metal particle induced electric field distortion.

Quantitative insights into the chemical trend of four-coordinated Mn2+ emission in inorganic compounds

Pursuing of the capabilities of predicting the luminescent properties of 3d ions doped phosphors before performing experimental exploitation is always a focus of experimental investigation, which is still suspended so far. As a tentative step in this work, we developed a simple relationship to predict the emission peak of Mn2+ only based on its three local-environmental-related parameters: the average bond length between Mn2+ and its ligand anions, ligand orbitals energy and the distortion of its crystal field by focusing on tetrahedral sites. With the relationship, it offers a possible and easier approach to access the emission peaks of Mn2+ in a tetrahedral site, as we find the emission energy increases dominantly with the increase of the bond lengths between Mn2+ and its ligand anions and decreases with the rise of the ligand orbitals energy, while the factor of crystal field distortion could make the emission of Mn2+ red-shifted normally in a margin of several dozens of meV with a rare exception for an extremely large crystal field distortion with larger red-shift about 100–200 meV. We believe this high prediction accuracy of Mn2+ emission peak energy could facilitate more experimental efforts in synthesizing new Mn2+ activated phosphor with target emission position in future.

Power quality control through automated demand side management in microgrid equipped with battery energy storage for protection

Apparently, battery energy storage (BES), intelligent protection and power quality are considered as independent issues. These three factors can be interlinked effectively for control of microgrid through automated demand side management (ADSM). In this context, the proposed approach may change the conventional way for microgrid operation and control giving priority to the power quality issues considering protection and BES systems. The control algorithm is implemented through fuzzy inference system based power quality monitoring index and ADSM. As a part of intelligent protection, logic table for circuit breaker (CB) coordination has been developed without/with backup for relay devices to provide ADSM. The model has been simulated using Matlab-software and validated experimentally using OPAL-RT OP4510 real-time simulator through the assessment of power quality-related parameters such as voltage, frequency, total harmonic distortion and power factor. The results are found satisfactory showing the feasibility of the proposed microgrid model.

GaAs0.5Sb0.5/ In0.53Ga0.47As heterojunction dopingless charge plasma-based tunnel FET for analog/digital performance improvement

Abstract A dual side doping-less (DL) GaAs0.5Sb0·5/In0.53Ga0.47As heterojunction tunnel FET (DDL-HTFET) configuration together with hetero-gate-dielectric material (HfO2/SiO2) has been proposed in this article. Hence, N+-pocket with varying electron concentration has been implemented by changing the length of source-side channel (LSC) beneath the gate. The impact of interface trap charges (ITCs) on the execution of the proposed device has been examined by initiating dual (donor and acceptor) sort of confined charges near the semiconductor/insulator intersection. An assessment has been carried out among proposed HTFET and Si-based devices having similar dimensions with respect to dc, analog/RF, and linearity distortion factors thoroughly in existence of ITCs. ATLAS simulations illustrate that the proposed DDL-HTFET is more protected in terms of performance deviation than its Si-based contenders with various ITCs existing at semiconductor/insulator intersection. Hence, DDL-HTFET model can be a promising candidate for the low-power RF applications and can offer improved linearity and less distortion.

Quantitative prediction of grain boundary thermal conductivities from local atomic environments

Quantifying the dependence of thermal conductivity on grain boundary (GB) structure is critical for controlling nanoscale thermal transport in many technologically important materials. A major obstacle to determining such a relationship is the lack of a robust and physically intuitive structure descriptor capable of distinguishing between disparate GB structures. We demonstrate that a microscopic structure metric, the local distortion factor, correlates well with atomically decomposed thermal conductivities obtained from perturbed molecular dynamics for a wide variety of MgO GBs. Based on this correlation, a model for accurately predicting thermal conductivity of GBs is constructed using machine learning techniques. The model reveals that small distortions to local atomic environments are sufficient to reduce overall thermal conductivity dramatically. The method developed should enable more precise design of next-generation thermal materials as it allows GB structures exhibiting the desired thermal transport behaviour to be identified with small computational overhead.

The end of the Multi Fiber Arrangement and the pattern of US apparel trade

PurposeThis paper analyzes the effects of the expiration of the Multi Fiber Arrangement (MFA), which ended quota restrictions on US textile and apparel imports in 2005, on the sourcing of US apparel. We test if the realignment in trade following the phase out of quotas can be explained by comparative advantage and market size.Design/methodology/approachWe use a gravity framework to investigate the role of comparative advantage (labor costs) and other factors such as exporter size, PTAs and tariff reductions on the pattern of US apparel imports. Detailed data on quotas by country-product pair are used for the purpose.FindingsOur empirical results show a significant increase in imports from large quota constrained countries once the MFA ended. Moreover, the pattern of trade seems to favor low wage countries that have a comparative advantage in producing apparel, which is highly labor intensive.Originality/valueThe end of quotas removed a major distorting factor in US apparel trade. This study examines the role of trade theory in the changing pattern of apparel imports that followed the end of the MFA. We use a gravity framework to test the theory of comparative advantage and the role of exporter size. Previous studies on the end of the MFA and its effects, do not examine the causal factors behind the realignment of US apparel trade.

Space charge dynamics in double-layered insulation cable under polarity reversal voltage

To investigate space charge behavior in double-layered cable insulation, a one-dimensional axisymmetric model for bipolar charge transport is built in this work. Effects of temperature gradient and electric field gradient in the radial direction are considered. The transient distribution of space charge and electric field under polarity reversal voltage is simulated with the developed model, and then the influence of interface position is analyzed to guide the design of double-layered insulation. The results indicate that space charge and electric field distributions are affected by temperature gradient and voltage polarity. Under polarity reversal voltage, the electric field is intensified by the residual space charge generated before polarity reversal, which causes the severe electric field distortion. In addition, the comprehensive electric field distortion factor is the least when the interface is located at the middle of the insulation layer, which is more beneficial to the stable operation of cable.

Machining Stresses and Initial Geometry on Bulk Residual Stresses Characterization by On-Machine Layer Removal.

Prediction and control of machining distortion is a primary concern when manufacturing monolithic components due to the high scrap and rework costs involved. Bulk residual stresses, which vary from blank to blank, are a major factor of machining distortion. Thus, a bulk stress characterization is essential to reduce manufacturing costs linked to machining distortion. This paper proposes a method for bulk stress characterization on aluminium machining blanks, suitable for industrial application given its low requirements on equipment, labour expertise, and computation time. The method couples the effects of bulk residual stresses, machining stresses resulting from cutting loads on the surface and raw geometry of the blanks, and presents no size limitations. Experimental results confirm the capability of the proposed method to measure bulk residual stresses effectively and its practicality for industrial implementation.

Robust features for text-independent speaker recognition with short utterances

Speaker recognition systems achieve good performance under controlled conditions. However, in real-world conditions, the performance degrades drastically. The principal cause being when limited data are presented. The presence of background noise is another main factor of performance distortion. In spite of the major advances in speaker recognition field, the effect of noise and the limitation of the amount of available speech data are still open problems, and no optimal solution has been found yet to cope with them. In this paper, we propose a new system using new enhanced and reduced gammatone coefficients in order to improve robustness with limited speech data duration. We demonstrate the usefulness of these coefficients compared to the well-known features with speakers taken from different databases recorded under different conditions.

Magnetic Noise Reduction of In-Wheel Permanent Magnet Synchronous Motors for Light-Duty Electric Vehicles

This paper presents study of a multi-slice subdomain model (MS-SDM) for persistent low-frequency sound, in a wheel hub-mounted permanent magnet synchronous motor (WHM-PMSM) with a fractional-slot non-overlapping concentrated winding for a light-duty, fully electric vehicle applications. While this type of winding provides numerous potential benefits, it has also the largest magnetomotive force (MMF) distortion factor, which leads to the electro-vibro-acoustics production, unless additional machine design considerations are carried out. To minimize the magnetic noise level radiated by the PMSM, a skewing technique is targeted with consideration of the natural frequencies under a variable-speed-range analysis. To ensure the impact of the minimization technique used, magnetic force harmonics, along with acoustic sonograms, is computed by MS-SDM and verified by 3D finite element analysis. On the basis of the studied models, we derived and experimentally verified the optimized model with 5 dBA reduction in A-weighted sound power level by due to the choice of skew angle. In addition, we investigated whether or not the skewing slice number can be of importance on the vibro-acoustic objectives in the studied WHM-PMSM.

Sol–gel synthesis, structural, and dielectric properties of terbium-modified $$\hbox {BaTiO}_{3}$$ ceramics

Tb-doped $$\hbox {BaTiO} _{3}$$ nanoparticles are prepared using the sol–gel method. The characterization was carried out using X-ray diffraction powder (XRD), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy spectroscopy (SEM). The FTIR analysis does not provide clear evidence on the effect of the doping amount. All diffraction peaks were perfectly matched with the pure phase of $$\hbox {BaTiO} _{3}$$. The tetragonal distortion factor is smoothly dependent on the doping amount. The grains decrease in size when Tb concentration is increased. The diffusion coefficient and phase transitions do not change greatly when introducing Tb into the crystal. Fitting values of $$\gamma$$ also support the evidence of normal ferro-paraelectric transition. Doped materials have a dielectric constant greater than undoped material, a meanwhile low loss is observed. The presence of Tb inhibits the formation of oxygen vacancies and promotes the stabilization of the oxygen-deficient system with the support of tetragonal phase formation during the sintering process.