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Investigation of Interline Dynamic Voltage Restorer with Virtual Impedance Injection

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Journal of Energy and Power Engineering 2012年第1期6卷 101-109页

作者： ahmed Elserougi ahmed Hossam-Eldin ahmed massoud Shehab ahmed Electrical Engineering Department Alexandria University Alexandria 21526 Egypt Electrical and Computer Engineering Department Qatar University Doha 23874 Qatar Electrical and Computer Engineering Department Texas A＆M University at Qatar Doha 23874 Qatar

The inter-line dynamic voltage restorer （IDVR） consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder （voltage control mode）, the other inverters pump the required power into the dc bus （power control mode）. Each inverter will have both voltage and power controllers; only one controller is in use during the abnormal conditions according to its feeder state. The voltage controller uses one of the dynamic voltage restoration techniques. In this paper, the in-phase technique is applied and two types of loads are considered （constant impedance and three phase induction motor）. Since the voltage restoration process may need real power injection into the distribution system, the power controller injects this power via voltage injection. This voltage injection is simulated by voltage drop across series virtual impedance. A new scheme is proposed to select the impedance value. The impedance value is selected such that the power consumed by this impedance represents the required power to be transferred without perturbing the load voltage. The performance of this system is also studied during voltage swell. A scheme for operation of multi-feeder IDVR system is proposed in this paper. Simulation results substantiate the proposed concept.

关键词： Dynamic voltage restorers IDVR voltage sag voltage swell power quality.

Flywheel Energy Storage System Based on Boost DC-AC Converter

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Journal of Energy and Power Engineering 2012年第11期6卷 1725-1732页

作者： ahmed Elserougi Ayman Abdel-Khalil ahmed massoud Shehab ahmed Electrical Engineering Department Alexandria University Alexandria 21544 Egypt Electrical Engineering Department Qatar University Doha 2713 Qatar Electrical and Computer Engineering Department Texas A & M University at Qatar Doha 23874 Qatar

To extend the operating speed range of a conventional configuration of FESS （flywheel energy storage system）, an additional DC-DC boost converter is required between the machine and grid side converters to regulate the output voltage. This paper presents a new FESS based on three-phase boost inverter topology. The proposed system facilitates voltage boost capability directly in a single-stage. The main advantage of the three-phase boost inverter is the deployment of only six switches and undersized passive elements to obtain a boosted AC output voltage weighed against the input DC supply. In this paper, FESS based on boost inverter topology is modeled and simulated using MATLAB/S1MULINK. An experimental setup has been built for the three-phase boost inverter to present its boosting capability. The simulation and experimental results sustain the proposed configuration.

关键词： Boost converter flywheel energy storage system FESS.

Magnetic Gearbox with an Electric Power Output Port and Fixed Speed Ratio for Wind Energy Applications

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Journal of Energy and Power Engineering 2013年第6期7卷 1141-1149页

作者： Ayman Abdel-Khalik Shehab ahmed ahmed massoud ahmed Elserougi Electrical Engineering Department Alexandria University Alexandria 21544 Egypt Electrical and Computer Engineering Department Texas A&M University at Qatar Doha 23874 Qatar Electrical EngineeringDepartment Qatar University Doha 2713 Qatar

Mechanical gearboxes are typically employed with doubly-fed induction generatur-based wind turbines. The main drawback of this solution is the gearbox＇s reliability and maintenance. Using magnetic gearbox in conjunction with the doubly-fed induction generator is an emerging alternative being promoted by the research community which maintains the reduced size doubly-fed machine and overcomes the mechanical gearbox problems reported by field experience. This paper proposes a novel magnetic gearbox configuration in which a conventional planetary magnetic gearbox is equipped with n-phase coils fitted around the ferromagnetic pole-pieces to extract output electrical power. The turbine mechanical power is thus divided into mechanical power to drive the electrical generator and extra electrical power that can be diverted into a storage system to perform the power leveling function. The proposed configuration can also be used to freely modify the power-speed characteristic as seen by the electrical generator, a highly needed feature for grid frequency support.

关键词： Gearbox magnetic planetary gear modular winding permanent magnets wind energy finite elements AC machines.

Brushless Doubly-Fed Induction Machine as a Variable Frequency Transformer

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Journal of Energy and Power Engineering 2013年第1期7卷 110-117页

作者： Ayman Abdel-Khalik ahmed Elserougi ahmed massoud Shehab ahmed Electrical Engineering Department Alexandria University Alexandria 21544 Egypt Electrical Engineering Department Qatar University Doha 2713 Qatar Electrical and Computer Engineering Department Texas A & M University at Qatar Doha 23874 Qatar

VFT （variable frequency transformer） has been recently used as art alternative to HVDC （high voltage direct current） to control power flow between asynchronous networks. VFT consumes less reactive power than a back-to-back HVDC system, provides faster initial transient recovery, and has better natural damping capability. VFT is simply a DFIM （doubly-fed induction machine） where the machine torque controls the power flow from stator to rotor and vice versa. The main disadvantage of this VFT is the slip rings and brushes required for the rotor circuit, especially in bulk power transmission. The BDFM （brushless doubly-fed machine） with nested cage rotor machine is proved to be a comparable alternative to conventional DFIM in many applications with the advantage that all windings being in the stator frame with fixed output terminals. In this paper, the BDFM is used as a BVFT （brushless variable frequency transformer）. A prototype machine is designed and simulated to verify the system validity.

关键词： Variable frequency transformer brushless doubly-fed machines AC machines induction machine.

A Matlab/Simulink-Based Photovoltaic Array Model Employing SimPowerSystems Toolbox

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Journal of Energy and Power Engineering 2012年第12期6卷 1965-1975页

作者： Samer Said ahmed massoud Mohieddine Benammar Shehab ahmed Department of Electrical Engineering Qatar University Doha P.O. Box 2713 Qatar Department of Electrical and Computer Engineering Texas A&M University at Qatar Doha P.O. Box 23874 Qatar

The modeling of PV （photovoltaic） systems is very crucial for embedded power system applications and maximum power point tracking. This paper presents a PV array model using Matlab/Simulink with the assistance of SimPowerSystem toolbox. The PV cell is considered as the main building block for simulating and monitoring the PV array performance. The PV model has been developed and used as Simulink subsystems where the effect of solar insolation and PV array temperature on commercial PV modules have been studied throughout the simulated I-V and P-V output characteristics. The proposed model facilitates simulating the dynamic performance of PV-based power systems. The effect of different partial shading patterns of PV arrays under different configurations has been studied.

关键词： Modeling PV solar energy Matlab shading.

Consecutive narrow and broad quasi-periodic fast-propagating wave trains associated with a flare

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 200-211页

作者： Xinping Zhou Yuandeng Shen Chengrui Zhou Zehao Tang ahmed ahmed Ibrahim College of Physics and Electronic Engineering Sichuan Normal UniversityChengdu 610068China State Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Department of Physics and Astronomy College of ScienceKing Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia

The excitation mechanism of coronal quasi-period fast-propagating(QFP)wave trains remains *** Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory observations,we study a narrow and a broad QFP wave trains excited one after another during the successive eruptions of filaments hosted within a fan-spine magnetic system on October 20,*** consecutive occurrence of these two types of QFP wave trains in the same event provides an excellent opportunity to explore their excitation mechanisms and compare their physical *** observational results reveal that narrow and broad QFP wave trains exhibit distinct speeds,periods,energy fluxes,and relative intensity amplitudes,although originating from the same active region and being associated with the same GOES C2.9 *** wavelet analysis,we find that the narrow QFP wave train shares a similar period with the flare itself,suggesting its possible excitation through the pulsed energy release in the magnetic reconnection process that generated the accompanying *** the other hand,the broad QFP wave train appears to be associated with the energy pulses released by the successive expansion and unwinding of filament ***,it is plausible that the broad QFP wave train was also excited by the sequential stretching of closed magnetic field lines driven by the erupting *** findings shed light on the different excitation mechanisms and origins of the QFP wave trains.

关键词： narrow wave excitation

Study of scalar particles through the Klein–Gordon equation under rainbow gravity effects in Bonnor–Melvin-Lambda space-time

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Communications in Theoretical Physics 2024年第4期76卷 113-125页

作者： Faizuddin ahmed Abdelmalek Bouzenada Department of Physics University of Science&Technology MeghalayaRi-Bhoi793101India Laboratory of theoretical and applied Physics Echahid Cheikh Larbi Tebessi UniversityAlgeria

In our investigation,we explore the quantum dynamics of charge-free scalar particles through the Klein–Gordon equation within the framework of rainbow gravity,considering the Bonnor–Melvin-Lambda(BML)space-time *** BML solution is characterized by the magnetic field strength along the axis of the symmetry direction which is related to the cosmological constantΛand the topological parameterαof the *** behavior of charge-free scalar particles described by the Klein–Gordon equation is investigated,utilizing two sets of rainbow functions:(i)f(χ)=■,h(χ)=1 and(ii)f(χ)=1,h(χ)=1+βХ/*** 0<(Х=■)≤1 with E representing the particle's energy,Ep is the Planck's energy,andβis the rainbow *** obtain the approximate analytical solutions for the scalar particles and conduct a thorough analysis of the obtained ***,we study the quantum dynamics of quantum oscillator fields within this BML space-time,employing the Klein–Gordon *** also,we choose the same sets of rainbow functions and obtain the approximate eigenvalue solution for the oscillator ***,we demonstrate that the relativistic approximate energy profiles of charge-free scalar particles and oscillator fields get influenced by the topology of the geometry and the cosmological ***,we show that the energy profiles of scalar particles receive modifications from the rainbow parameter and the quantum oscillator fields by both the rainbow parameter and the frequency of oscillation.

关键词： quantum fields in curved space-time relativistic wave equations solutions of wave equations bound-state special functions

Application of Synthetic Iron Oxyhydroxide with Influencing Factors for Removal of As(Ⅴ) and As(Ⅲ) from Groundwater

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Journal of Earth Science 2024年第3期35卷 998-1009页

作者： Shakeel ahmed Talpur Muhammad Yousuf Jat Baloch Chunli Su Javed Iqbal Aziz ahmed Hafeez ahmed Talpur School of Environmental Studies China University of GeosciencesWuhan 430078China DiSPUTer Department of PsychologicalHealth and Territory SciencesUniversity“G.d′Annunzio”Chieti-Pescara66100 ChietiItaly College of New Energy and Environment Jilin UniversityChangchun 130021China School of Plant Environment and Soil SciencesLouisiana State University Agricultural CentreBaton Rouge LA 70803USA Department od Engineering and Geology University“G.d′Annunzio”Chieti-Pescara66100 ChietiItaly

Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V)and As(III)from the aquas ***,this investigation highlighted the synergistic effect of calcium carbonate in conjunction with iron oxyhydroxide,resulting in enhanced removal *** experiment was conducted under various conditions:concentration,dosage,pH,agitation,and *** characterizations such as Brunauer Emmett Teller,X-ray diffraction,scanning electron microscopy,and Fourier transform infrared spectroscopy were implied to understand adsorption *** Langmuir model revealed optimal concentrations for As(V)=500μg/L at pH-5 and As(III)=200μg/L at pH-7,resulting in 95%and 93%adsorption efficiencies,*** adsorption capacities“qm”were found to be 1266.943μg/g for As(V)and 1080.241μg/g for As(III).Freundlich model demonstrated favorable adsorption by indicating“n>1”such as As(V)=2.542 and As(III)=2.707;similarly,the speciation factor“RL<1”for both species as As(V)=0.1 and As(III)=0.5,*** kinetic study presented a pseudo-second-order model as best fitted,indicating throughout chemisorption processes for removing As(V)and As(III).Furthermore,incorporating calcium carbonate presented a significant leap in the removal efficiency,indicating As(V)from 95%to 98%and As(III)from 93%to 96%,*** findings offer profound motivation for developing effective and sustainable solutions to tackle arsenic contamination,underscoring the exceptional promise of iron oxyhydroxide in conjunction with calcium carbonate to achieve maximum removal efficiency.

关键词： adsorption arsenic As(V) As(III) iron oxyhydroxide isotherms kinetics groundwater.

Topological defects on solutions of the non-relativistic equation for extended double ring-shaped potential

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Communications in Theoretical Physics 2024年第8期76卷 29-43页

作者： Badredine Boudjedaa Faizuddin ahmed Natural Sciences and Materials Laboratory University Center Abdelhafid BoussoufMilaAlgeria Department of Mathematics Institute of Mathematics and Computer ScienceUniversity Center Abdelhafid BoussoufMilaAlgeria Department of Physics University of Science&Technology MeghalayaRi-Bhoi793101India

In this study, we focus into the non-relativistic wave equation described by the Schrodinger equation, specifically considering angular-dependent potentials within the context of a topological defect background generated by a cosmic string. Our primary goal is to explore quasi-exactly solvable problems by introducing an extended ring-shaped potential. We utilize the Bethe ansatz method to determine the angular solutions, while the radial solutions are obtained using special functions. Our findings demonstrate that the eigenvalue solutions of quantum particles are intricately influenced by the presence of the topological defect of the cosmic string,resulting in significant modifications compared to those in a flat space background. The existence of the topological defect induces alterations in the energy spectra, disrupting ***, we extend our analysis to study the same problem in the presence of a ring-shaped potential against the background of another topological defect geometry known as a point-like global monopole. Following a similar procedure, we obtain the eigenvalue solutions and analyze the results. Remarkably, we observe that the presence of a global monopole leads to a decrease in the energy levels compared to the flat space results. In both cases, we conduct a thorough numerical analysis to validate our findings.

关键词： non-relativistic wave-equation:Schrödinger equation topological defect:cosmic string point-like global monopole potential:extended ring-shaped potentials Bethe ansatz method