International Review on Modelling and Simulations (IREMOS)

Published by Praise Worthy Prize, s.r.l.
Online ISSN: 1974-983X
Publications
Conference Paper
A wind farm is a collection of wind turbines built in an area to provide electricity. Wind power is a renewable energy resource and an alternative to nonrenewable fossil fuels. In this paper impact of wind farm in power system reliability is investigated and a new procedure for reliability assessment of power systems with wind farm in HLII is proposed. In proposed procedure, a wind farm is given as a generation with probabilistic and stochastic generation. Historical wind velocities in past years are used for extraction of probabilistic distribution function for velocity and therefore for output electric power. Using this function, the output power of wind farm is divided into multi state. Each state shows a certain output electric power with certain probability for occurrence. The effect of wind farm on composite system reliability is evaluated with consideration proposed model for wind power and mathematical expectation concepts. As case study a portion of Iran power system grid in south east of Iran is selected. As historical data, wind velocity for twenty past years is gathered and used for modeling. The results in this real network are reported in this paper
 
Conference Paper
Application of distributed generation (DG) in distribution system is expected to increase in the near future due to its positive impacts such as voltage support, improved reliability, small size and losses reduction. However DGs may have negative impacts on power quality, such as voltage regulation, harmonic distortion, islanding and confliction with relaying and reclosing. This paper investigates the effect of the Distributed Generation (DG) and its size on voltage flicker and voltage sag which is considered recently as an urgent power quality problem that can affect motor starting, temperature rise, overloading of generators, motors and may cause health risk problems due to the annoying light flicker which is consequence of voltage fluctuation. The effect of different sizes of DG on the voltage flicker and voltage sag in different buses of IEEE 34 buses meshed distribution system has been investigated. To support this argument, simulations are achieved on MATLAB/SIMULINK, where the results reveal the amount of effect of DG on voltage flicker and voltage sag for different types of buses of meshed distribution system.
 
Article
A simple step and search control strategy for extracting maximum output power from grid connected Variable Speed Wind Energy Conversion System (VSWECS) is implemented in this work. This system consists of a variable speed wind turbine coupled to a Permanent Magnet Synchronous Generator (PMSG) through a gear box, a DC-DC boost converter and a hysteresis current controlled Voltage Source Converter (VSC). The Maximum Power Point Tracking (MPPT) extracts maximum power from the wind turbine from cut-into rated wind velocity by sensing only by DC link power. This system can be connected to a micro-grid. Also it can be used for supplying an isolated local load by means of converting the output of Permanent Magnet Synchronous Generator (PMSG) to DC and then convert to AC by means of hysteresis current controlled Voltage Source Converter (VSI).
 
RBNN based nonlinear approximator. 
Conference Paper
In order to avoid catastrophic situations when the dynamics of a physical system (entity in Multi Agent System architecture) are evolving toward an undesirable operating mode, particular and quick safety actions have to be programmed in the control design. Classic control (PID and even state model based methods) becomes powerless for complex plants (nonlinear, MIMO and ill-defined systems). A more efficient diagnosis requires an artificial intelligence approach. We propose in this paper the design of a Fuzzy Pattern Recognition System (FPRS) that solves, in real time, the main following problems: 1) Identification of an actual state; 2) Identification of an eventual evolution towards a failure state; 3) Diagnosis and decision-making. Simulations have been carried for a fictive complex process plant with the objective to evaluate the consistency and the performance of the proposed diagnosis philosophy. The obtained results seem to be encouraging and very promising for application to fault diagnosis of a real and complex plant process.
 
Article
This paper presents a design flow and an optimization methodology of an ultra wideband up-conversion mixer designed on CMOS 0.18 μm technology. The circuit, designed to be integrated in IR-UWB transmission architecture for a medical application, is based on a doubly balanced Gilbert topology. Models for conversion gain, noise figure and linearity were developed for the Gilbert cell to estimate optimum transistors sizing and biasing and thus to obtain good performances. Based on these models and trying to enhance the performances of the mixer's characteristics, a new method using a current injection technique was presented to design the mixer. The circuit has shown good results since it exhibits about 11.5 dB conversion gain, a moderate noise figure of about 8.8 dB, a better linearity with an IIP3 of about 2.3 dBm and a low power DC consumption in the range of 5.6 mW.
 
Article
These papers describe the result of measurement and evaluate the behaviours of inplane flux distribution on 100kVA 3phase distribution transformer assembled with the combination of 60°-45° T-joint. Methodology that is used in this investigation is measurement of flux distributions in transformer core by using no load test and arrays of search coil in Cold Roll Grain Oriented (CRGO) material of transformer core lamination. The measurement involves the fundamental and third harmonics component of the easy and hard direction of flux density at each location measurement. The instantaneous flux flow through the core within one magnetising cycle is analysed with displaced by 120° in time. The locus of the localised flux distribution throughout the magnetising cycle is illustrated the rotational flux produced in the T-joint region of the threephase three limbs transformer core. The localized flux density at the outer of combination of 60°- 45° T-joint is 1.4T and rises to be 1.68T at the inner edges of right yoke passes over to the butt joint of middle limb when the transformer core energized at flux density 1.5 T 50Hz. At the same place the high third harmonic of peak in-plane flux is 0.23T. The transfer of flux between lamination takes place until a point is reached where the material in the region butt joint of yoke lamination, which is directly above the butt joint and the flux higher but did nott, reaches saturation.
 
Article
This paper describes the simulation of flux distribution on 100kVA 3 phase distribution transformer assembled with 60°-45° T-joint and mitred lap corner joint with stagger yoke and limb. The core that being used is 3% Silicon Iron Cold Rolled Grain Oriented (CRGO) material. The flux distributions have been simulated using 2 Dimensions Finite Element Method (2DFEM) based on a vector potential formulation. The loss of transformer core lamination is calculated using the hysteresis curve. The simulation shows that 1.78 T flux density was maximum at the centre limb of transformer core, hence produced the losses of 2.54 W/kg. The transformer core assembled with 60°-45° T-joint is more efficient than the transformer core assembled with 90° T-joint.
 
DC-DC converter with PI controller
The open loop inverter results
Article
Rooftop solar panels and solar farms has become popular as a means of generating green and emission free electric energy. A standalone Microgrid is fully controlled by sophisticated controlling scheme and ready to contribute to utility grid. A standalone solar Microgrid is an economic solution in residential area as well in far off location. It consists of PV panels, DC/DC converters, storage blocks, MPPT controller, Inverter, main controller and loads. A standalone PV system has two stages design. In power stage, all components will properly be sized to supply demand loads. Control stage contains all controllers to meet the predefined requirements. There is plenty of research on each individual element; however, for system integrator there are only a few studies which have considered the whole system. This study tries to show a systematic step design for Photovoltaic-based (PV) Microgrid. All power and control design stages will be discussed. IEEE standards and recommendation for standalone PV grid and storage banks (batteries) are used as guideline.
 
The results of the investigation of sample No. 2 with SEM and EMA. Scanning line: (a) general view of inclusion; (b) distribution of lanthanum; (c) distribution of cerium; (d) distribution of oxygen
Article
The thermodynamic modeling and the experimental study of phase equilibria realized in the Cu-Ce-La-O system in the 1100-1300 °C temperature range were performed. The aim of the thermodynamic modeling was to estimate the possible deoxidization depth of a copper melt by cerium and lanthanum when they are simultaneously present in liquid copper, as well as the determination of the oxide phases that can result from such deoxidation. To simulate phase equilibria, a method to construct the solubility surface of the components in the metal melt was applied, in the calculation of which the equilibrium constants of the reactions occurring in the metallic melt of the system under study and the interaction parameters of the first order (according to Wagner) elements in liquid copper were used. As a result of modeling, the diagrams linking micro-changes in the composition of a metallic melt with qualitative changes in the composition of interaction products were constructed. Moreover, during the calculation, isotherms of oxygen solubility in a copper melt containing cerium and lanthanum were constructed. During the experimental part of the work, samples of the metal of the Cu-Ce-La-O system were melted and then examined with a scanning electron microscope equipped with an energy-dispersive spectrometer for electron microprobe analysis to determine the type of nonmetallic inclusions formed. The results of the work can be used to analyze the technological processes of the production of copper and its alloys.
 
Article
A penetration of an electric field intensity generated by an underground cable and a detailed model for demonstrating the actual characteristics are still a challenge. Hence, this article has proposed a mathematical model for diagnosing the electric field intensity of the 115 kV underground power cable, using the 3D finite element method to simulate the electric field while the 115 kV underground cable is available. The proposed finite element method-based 3-D model utilizes a linear sub-derivative equation method, which consists of the weighted residuals and the Galerkin’s methods. The flat and the trefoil formations are considered for the modeling and the simulations of the electric field distributions using the proposed 3-D finite element method. The simulated results demonstrate that the proposed method can reveal the graphical electric field distribution in 3-D around the 115 kV underground cables with detailed characteristics. Moreover, the electric field distributions using the proposed model at various underground depths are demonstrated in comparison between the flat and the trefoil formations. Thus, the proposed method can demonstrate the actual characteristics of the underground cable and the cable arrangement penetration at the various formations. Copyright © 2021 Praise Worthy Prize - All rights reserved.
 
Schematic arrangement of a thin film-based solar cell layers
The cells band diagram: (R1) Back contact recombination, (R2) Quasi-Neutral recombination, (R3) space charge region recombination, (R4) Buffer/Absorber interface recombination
Article
Abstract – In this study, Zinc Telluride (ZnTe)-based solar cells, which are metallic dichalcogenide materials, are used as a solar cell absorbent with the formation appropriate for solar cell use. The data has been analyzed by SCAPS-1D structures software. The replacement of Cadmium Sulfide CdS (buffer) layer by other green and save suitable materials has been investigated. The substituted buffer layers have been ZnSe, ZnS, CdSe, and In2S3. The higher device performance efficiency parameters have been found out when using CdS and ZnSe as buffer layers. SCAPS-1D shows that the optimal p-n junction device eff]iciency parameters have been achieved when the ZnTe (absorber) layer thickness is between 1200-1500 nm, while the ZnSe (buffer) layer thickness is between 20-60 nm, and the thickness of ZnO:Al (window) layer is 25 nm. The results of the simulation provide important hints that may enhance the performance of the cell with empirical studies useful in practical implementation. Copyright © 2021 The Authors. Published by Praise Worthy Prize S.r.l.. This article is open access published under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Keywords: Heterojunction, ZnTe, ZnSe, Solar Cell, SCAPS-1D
 
Article
Abstract – In this paper, SCAPS-1D simulation program is used to calculate the effect of layers thickness of Mo/CdTe/CdS/ITO device on the solar cell performance parameters (short-circuit current density Jsc, open-circuit voltage Voc, fill factor efficiency FF%, and cell efficiency η%). SCAPS-1D numerical simulation results show a significant effect of the absorber layer thickness on the device performance. An optimal absorber layer thickness has been achieved. The variation in CdS (buffer) layer thickness shows no observable effect in the values of FF% and Voc values, while a significant effect has been observed in the values of Jsc, and η%. There is no observable change in the device performance parameters with variation in the ITO (window) layer thickness. The Quantum efficiency percentage has been also affected both by the absorber and by the buffer layers thickness to a limit. The QE% achievement has been consistent with the optimal layer thickness.
 
Conference Paper
This paper compares a Five-Level Neutral Point Clamped Voltage Source Converter (5L-NPC VSC), a Five-Level Series Connected H-Bridge Voltage Source Converter (5L-SCHB VSC), and a new Five-Level Auxiliary Series Connected H-Bridge Voltage Source Converter (5L-ASCHB VSC) on the basis of the state-of-the-art 3.3kV, and 1.7kV IGBTs for a 2.3kV Medium Voltage Converter (MVC). To derive specific converter characteristics of the afore mentioned topologies the power semiconductors utilization, the installed switch power, converter losses, the semiconductor loss distribution, efficiency, and the harmonic spectra are discussed in detail. Matlab/Simulink is used as a simulation tool for analysis and comparison.
 
Article
The most important part of any machine is the Stator. This fact tells the requirement for inspection of the electrical machine insulation along with the electromagnetic and thermal tensions. Therefore with respect to insulation system improvement of stator, the HV generator can be optimized. Dielectric parameters such as material types, permittivity and electrical conductivity are major design consideration. A very powerful method available to analyse electromagneticthermal performance is Finite Element Method (FEM) which is used in this paper. The analysis of various stator slot insulation configurations are used to design the better dielectric system to reduce electrical and thermal stresses and uniform the electrical field distribution in order to increase the power of generator in the same volume of core. These processes of optimization have been done according the proposed optimization algorithm. In this algorithm the technical constraints have been considered. This paper describes the process used to perform classical design and improvement analysis of stator slot's insulation with respect to objective function and constraints.
 
Y-displacement of the membrane in-plane direction (Contact BP/GDL) for high current density i=9000A/m 2
Article
In this study, a 2D FEM (Finite Element Method) analysis model of a representative unit of fuel cell has been set-up and solved using COMSOL Multiphysics. The heat transfer module with plane stress has been used. Implementation of the interfacial boundary conditions and heat sources allow evaluating temperature and stress distribution in the fuel cell during variation of the current density. By taking advantage of symmetry conditions, temperature and Van Mises stress have been simulated in the through-plane and in-plane direction on two scales. A global scale on the path of the entire cell, and locale scale on the path of membrane electrodes are assembled. The results show that displacement, temperature gradient and stress are directly related to level of current density and local section statement. Hence increasing the current density pushes the high temperature distribution to the cathode under the center of the gas channel.
 
Article
In the present study a 2D thermo-mechanical model is developed to analyze the effects of welding current, sequence and workpiece geometry on the of residual stresses in dissimilar TIG welds between low carbon steel CK4 and ferritic stainless steel AISI409. To perform the simulation, a finite element program, ANSYS, is used. To verify the predictions, the model results are compared with residual stresses measured by X-ray diffraction and good agreement is found. The results show that the magnitude of tensile residual stresses increases by increasing the welding current while larger residual compressive stresses are produced in the longer samples. Evaluating of residual stresses with various types of welding layouts also shows that symmetric and back-step welding sequences have little effects on minimum of residual stress however, the magnitudes of residual stresses significantly decrease in the middle part of the welded sample as symmetric welding sequence is employed.
 
Article
A new design of interface circuit for CMOS Light sensor for pH monitoring applications is presented here. The proposed design is useful to read color (wavelength) values with the help of a photodiode and output a digital word representing the color value. It operates by continuously comparing analog voltage output from an optical transducer against a pre-stored reference levels in two cascaded stages. The design provides few advantages such as faster speed; higher resolution with smaller number of storage units; and small area for on-chip integration. A simulation result using the CMOS 0.35 AMS technology implementing 32 levels of resolution is presented.
 
Article
The performance evaluation of cryptographic algorithms has guided to serious studies of its implementations. The efficiency of these algorithms is improved by applying good design rules adapted to devices and to its resources constraints. In this paper, we present a careful study of three possible designs of the Advanced Encryption Standard (AES) targeting 32-bit embedded system; we examined AES implementations which use arithmetic properties of the AES S-box and structures based on hardware look-up tables. We have analyzed and compared different characteristics like clock frequency, occupancy area, and power consumption of these implementations. The resulting designs are implemented using Xilinx XC5VFX70t FPGA device and an ASIC CMOS 40 nm technology. Our results show that AES implementation based on hardware look-up table shows the lowest power consumption and highest frequency. The AES implementations which use arithmetic properties of the S-box are characterized by the smallest silicon area.
 
Article
The paper introduced the work principle of the 10/350μs impulse current generation and analyzed the feature of the crowbar trigger circuit. Crowbar trigger circuit with 10/350μs impulse current and follow current of voltage switching type surge protective device (SPD) has been researched using EMTP simulation. In order to simulate voltage switching type SPD, the equivalent impedance of the sample and the acting time of crowbar can be obtained from test. The simulation showed that follow current trend of positive and negative polarity were almost the same under impulse of 10/350μs impulse current. With the same synchronous trigger angle, the initial part of follow current of SPD can be influenced due to the different polarity of impulse current.
 
Simplified block diagram of DSP48E1 block in Virtex-6 [19].
Top level block diagram of matrix multiplication module.
Data Processing Unit of the module.
Block diagram of the Core Unit.
Article
A typical animation scene of a computer animation may include hundreds of mathematically defined objects. Applying Three Dimensional (3D) affine transformations to such scenes requires huge amount of CPU time. In this study, an improved hardware module was designed to speed-up 3D graphic transformations using FPGA (Field Programmable Gate Array) chips. In the module design, for multiplication and addition operations, 32-bit multipliers and adders formed on FPGA fabric by IP CORE Generator tool were utilized. The module was tested and functionally verified. Module's data processing speed was compared to various PCs and to our previous module design. Results showed that, 3D graphic transformations can be speeded-up by factor of up to 40 times using the designed module compared to the PCs. Employing multipliers and adders formed with Xilinx's IP CORE Generator in the module design provided 1.4 times performance gain over our previous module design.
 
Article
In this paper Type I FGM cylindrical shell has Nickel on its inner surface and stainless steel on its outer surface and Type II FGM cylindrical shell has stainless steel on its inner surface and nickel on its outer surface. The study is carried out based on third order shear deformation shell theory. The objective is to study the natural frequencies, the influence of constituent volume fractions and the effects of configurations of the constituent materials on the frequencies. The properties are graded in the thickness direction according to the volume fraction power-law distribution. The governing equations are obtained using energy functional with the Hamilton's principle. The boundary conditions in this cylindrical shell made of two material is Free-simply support (F-SS). Results are presented on the frequency characteristics, the influence of the constituent various volume fractions on the frequencies for a Type I, II FGM cylindrical shell.
 
Article
In this paper, X/Γ rays photodetectors are designed using a proposed set of CAD oriented tools. These tools are handled to study not only the device behavior, but also its possible drawbacks. First of all, we develop an efficient time-domain electromagnetic wave simulator for modeling a PiN diode in a micro-wave circuit. In fact, both the active semiconductor devices and passive interconnection domains are introduced. They combine accurate modeling of the transport phenomena in the diode and electromagnetic wave effects present around the device. A “leapfrog” algorithm of a 3-D FDTD method, the spurious waves coming from any direction, is used for the simulation of Si-PiN and CCD cells. This physical method is powerful as it can give, starting from microscopic phenomena, the scattering parameters, after some FFT’s, tools very useful for the engineers. The obtained results are in agreement with those from other commercial simulators and also in agreement with theoretical concepts. A 2D numerical simulation of space charge under Xray irradiation, in a CdTe phodetector, is investigated. It provides important information on the distribution and the dynamics of the electric phenomena of the detector; it is the first time, up to our knowledge, that an electrical field-induced parasitic space charge is described with simulations. We think that some experiment, based on some linear electro-optic effect - Pockels effect - could confirm these results. This local charge collection properties can be also accessed by performing IR pulsed laser experiments. Finally, some fast transimpedance amplifier has been designed in a quarter micron technology. The architecture has been adapted to the characteristics of the technology through a careful optimization of the design, resulting in an extremely fast amplifier, with fall time near 1 ns at room temperature.
 
Article
This work deals with performance investigation of a linear actuator intended for Electronic Valve Control. Geometric, electric and magnetic parameters insuring valve maintain are carried out through a 3D finite element calculation. None polarized configuration, suffering from permanent supply of actuator coils, is upgraded to an enhanced hybrid topology arranged in an “A” way with nonmagnetic core-backs. Under extreme thermal conditions, it has been found that upgraded structure reduces energy consumption with an improvement of actuator’s capability of force generation.
 
Article
In this paper the simulation of the phenomenon of homogeneous and isotropic turbulent flow in free-surface channels is studied in 3D.The method of finite volumes is used to solve the non linear transport equations (convection-diffusion problem) which are equations of quantity of motion, kinetic energy, dissipation, and tracking the volume fraction of each fluid in the whole filed. Numerical results are obtained by two models, the multiphasic model V.O.F (Volume of Fluid) and the k-ε model for turbulence.
 
Article
Very Fast Transient Over voltages(VFTO) are generated due to switching operations and faults in a Gas Insulated Substation(GIS) needs lot of insight to safe guard the equipment and insulation of various systems. VFTOs can also cause malfunction of protection circuits and control circuits. These transients have traveling wave behavior; they travel to the external systems through enclosures, bushings, cable joints etc., and cause damage to the outside equipment. They can lead to secondary break downs in GIS and may give rise to electromagnetic interference. Thus it is important to develop a suitable simulation models for estimation of these over voltages. In order to estimate the over voltages, equivalent electrical network models are developed. This paper focused on 420 kV GIS system and equivalent model of GIS bus duct have been considered for the simulation of VFTOs. GIS equivalent models have been developed for various lengths of bus duct and simulations to estimate VFTOs are carried out with switching operations of Disconnector switch and fault conditions at various locations. The suppression of VFTOs are also simulated by inserting resistance across the disconnector switch. Comparison has been made in terms of voltage magnitudes with and without suppression methods. Significant reduction of voltage magnitudes are observed in this work. For simulation of equivalent GIS models Electro Magnetic Transient Programming (EMTP) is used.
 
Article
Tool life estimation for the cutting tool before the machining process is important due to economic and quality consideration. Thus, developing a model that can predict the tool life with high accuracy is an important issue. This paper deals with developing a new model of tool life for mixed ceramic tools in turning hardened steel AISI 4340 based on experimental tests. The experiments were planned and implemented using Central Composites Design (CCD) of Response Surface Methodology (RSM) with three input factors: cutting speed, feed rate and negative rake angle. The Face Central Cubic Design has been used as a special case of CCD. The analysis of variance (ANOVA) has been conducted to analyze the influence of process parameters and their interaction during machining. The first and second order models have been developed. It was found that the second order model provide higher accuracy prediction than the first order model. It was observed that the cutting speed is the most significant factor that influences the tool life for the two models, followed by the feed rate then the negative rake angle. The predicted values are confirmed by using validation experiments.
 
Article
Ensuring the dependability techniques of electrical systems is a serious problem for the Algerian power distribution company. Choosing the network components is usually based on a practical approach. To address this lack, we propose in the present article to use methods dependability hat would efficiently enable to investigate the safety of electrical systems in terms of components choice, hence resulting in time and cost optimization. The method is based on functional analysis followed by modeling of system operation in the regime of normal power flow. On the basis of this model, the probabilistic characterization of system RAM is performed. Introducing the factors of importance enables to identify the most critical components of the system and to determine its RAM performances that should be improved for achieving a better global performance of the whole system. In order to demonstrate the advantage of such optimization methods, this work will be illustrated by a real case based on a 60/10 kV electrical distribution station.
 
Article
In swarm intelligence PSO is not so popular algorithm but ABC is recently developed and most popular whereas PSO is lagging in finding global solutions however the ABC's neighborhood search is not sufficient to accelerate the convergence rate. The hybrid technique is developed in such a way that it can solve the issues arising in individual PSO and ABC. As ABC outperforms in the most problems, it will be selected as the primary algorithm and the swarming behavior of the particles are included in the bees. A compromising neighborhood search model is developed for ABC to aid accelerated neighborhood search by considering the property of PSO's particles updating behavior along with the ABC's neighborhood search. The introduction of such neighborhood search model fine tunes the neighborhood search property of employed and onlooker bees that helps to converge faster than conventional ABC and PSO. The tests will be carried out using standard benchmark test function models and the performance will be compared against the individual PSO and ABC algorithms.
 
Article
Interfaces formed by gas dielectric and solid insulating spacer represent the weakest point in Gas Insulated Systems (GIS). It is essential to determine the electric field distribution along the spacer surfaces and evaluate the degree of their reliability. A key aspect in the design and optimization process of insulating spacers is the precise simulation and geometric optimization of the electric field distribution on the dielectrics. The breakdown strength of GIS is strongly influenced by the roughness of the spacer's surface like protrusions and depressions and defects produced from improper manufacturing. One of these forms is the loss of adhesion at electrode/epoxy interface which leads to initiating delamination. Bulk dielectric failure of spacers can be attributed to delamination at the electrode/epoxy interface. Electric field distribution at the protrusions, dispersions on the surface of the spacer, delamination and voids plays a critical factor affecting the breakdown of spacer. Field emission from the cathode triple junction is the primary initiating mechanism of surface flashover of insulators. In this work, the electric field distribution on the surface of the insulator is studied at the cathode end triple junction for a cone type spacer with and without metal insert along with the effect of protrusion, depression, delamination and void. The Finite Element Method, an efficient technique for solving field problems, is employed to compute the electric field.
 
Article
The purity of CO2 in a urea plant is strongly influenced by the absorption process, starting from operation temperature and pressure until the concentration of the absorbent material. All the independent variables of the process should be maintained and adjusted to reach optimal condition which is 99% (v/v) of the purity of CO2 Response Surface Methodology (RSM) installed in Design-Expert® 10 software was applied to develop a reliable model that can be used to optimize the absorption of CO2 using methyldiethanolamine (MDEA) activated by piperazine. Training data of 54 runs with constrained different values of six independent variables correlated with the Box-Behnken design were taken into account from the Main CO2 Removal unit at the PT. Pupuk Iskandar Muda-2 of ammonia plant in Lhokseumawe of Aceh Province. As the result, the model-based result was in a very good agreement with the experimental result (R2 = 0.99) which was also confirmed by the ANOVA, and an optimized CO2 purity of 99.20% (v/v) was obtained by desirability function. Using the model and Levenberg-Marquardt method, further optimal condition of CO2 absorption was also worked out by minimizing the MDEA concentration to 39.00% (v/v). The final optimized CO2 purity was approximately 99.46%.
 
Article
The present work deals with the problem of PV generators connected to public threephase networks through a DC-AC inverter. Unlike conventional systems, the great benefit of the proposed system is its reduced cost since it does not involve a chopper, as well as its higher reliability. In this paper, the main aim is to achieve three control objectives: (i) extracting the maximum power point from the PV generator (MPPT), (ii) regulating the DC link voltage to perfectly track its desired array voltage reference, (iii) fully achieving the unity power factor requirement (UPF). In order to attain these objectives, a nonlinear controller is designed based on a non-linear model of the entire system. The results of the numerical simulation show that the performance of the proposed controller overcomes the Challenges of Climate Change and external disturbances, besides its ability to achieve the desired control objectives (MPPT and UPF).
 
Article
In this paper, a set of fuzzy logic rules is designed to maintain the system frequency is parallel AC-DC interconnected non- reheat thermal power system. When an interconnected AC system is subjected to a load disturbance, the system frequency may be disturbed. By utilizing the control channel of HVDC link in parallel with the AC link, the system dynamic stability is improved and reduces the area control error. In the design of power modulation controller, the overlapping decomposition techniques and Eigen value assignment method are applied to establish the system control. The system responses to various load changes in the multi area system are studied with help of MATLAB simulation. The conventional integral control does not yield adequate control performance. To overcome this problem fuzzy logic controller is employed with a set of rules. The study shows that the proposed controller is effective in damping the oscillation. The performance of the proposed approach was verified from simulation and comparison.
 
Article
The paper proposes a practical new formula for calculation of active power and root mean square (RMS) value of AC signals, within a twice shorter time interval, compared to other methods in standard use. The proposed method offers a significant improvement in computational efficiency over the standard algorithms for calculation, at a lower numerical error. The new concept provides simple calculation of active power by the summation of samples of instantaneous power in time domain without need for synchronization. There is a computer simulation that demonstrates the accuracy of these algorithms.
 
Article
Due to continuous exploitation of oil and gas reserves combined with the effect of global warming has brought renewed interest in alternative energy sources. Renewable power resources are safe, clean, and abundant in nature. Recent research and development in renewable power generation techniques such as photovoltaic, wind has shown excellent potential towards building a sustainable energy economy in the next decade. The energy sources and connecters need to be integrated to meet sustained load demand while considering the natural whether conditions. The paper focuses on the combination of wind and photovoltaic system to ensure that system performs under all conditions. The system consists of a wind generator and alternate energy conversion systems such as PV cells. However, due to the power fluctuation of renewable energy sources, voltage and frequency deviations are occurred in island power systems whose ability to maintain stable supply-demand balance is low. Therefore, it is necessary to control the system frequency and voltage. From this viewpoint, a smart grid, which maintains stable supply- demand balance, is necessary. The proposed system has advantages of both dc and ac grids. Output from the wind, PV cell and battery are maintained at same voltage and connected to the common DC bus while the conventional power supply modeled as three phase voltage source and several controllable loads of different capacities are connected to the AC bus. The system is analyzed under fault conditions. The Model is developed using MATLAB- Simulink.
 
Article
This paper presents various pulse width modulation (PWM) strategies capable of reducing conducted electromagnetic interference (EMI) generated in PWM voltage-source inverter systems. EMI problems caused by both conducted and radiated noise emissions have become a great concern in electrical/electronic systems. Thus, their effects are currently considerably taken into account in circuit design phase in order to restrict or reduce these severe problems. The proposed PWM strategy, which is one of different traditional and/or novel reduction techniques to solve such a problem, is chosen as an EMI reduction method and studied herein. The simulated results show that active vector PWM strategy seems to be a good alternative for inverter system. The impact of dead time of PWM signals is also investigated and discussed.
 
Article
The paper presents an AC grid connection for wind energy conversion system (WESC) based on the doubly-fed induction generator (DFIG). A direct voltage control (DVC) approach is designed for applying the DFIG system to obtain a sinusoidal waveforms of the stator voltage. In order to compensate the harmonic produced by the three-phase Diode Bridge supplied by a passive circuit (rd, Ld), a shunt active power filter (SAPF) is connected between DFIG and this nonlinear load at the point of common coupling (PCC). In this work we are all deeply concentrated on development of a new control strategy using nonlinear predictive control (NPC) for SAPF. The proposed control strategy consists of two blocks. The first one is the calculation unit of SAPF reference currents that allows us to identify the disturbance currents. The second one is the nonlinear predictive controller based on currents control loop that provides the switching function of the three half-bridges based on IGBT transistors. The presented work in this paper is validated via simulation under MATLAB/Simulink on a 1.5 MW DFIG-based wind turbine connected to an AC grid, taking into consideration the compensation for the disturbance currents. The results obtained in this work appear to be satisfactory and promising.
 
Conference Paper
Maximization of power from a solar photovoltaic module is of special interest as the efficiency of the solar PV module is very low. A peak power tracker is used for extracting the maximum power from the solar PV module. In the present work we analyze the design and the simulation of the maximum power point tracker (MPPT) for the solar PV array connected to three phase grid. In our studies, we conceived a PV system where the PV generator is the panel NA-901(WQ). The MPPT system has been tested on Solar PV Module (Micro-amorphous silicon thin-film) rated 90Wpeak at 49.3V, 1.83A at 25 degree Celsius and 1000W/m2 (STC). The simulation studies are carried out in MATLAB /SIMULINK.
 
Article
This paper presents the single-phase symmetrical multipulse modulated topology, derived from the matrix converter, of the ac voltage controller with power MOSFET embedded four-quadrant switch (4QSW) realizations and investigates from the power quality perspective the potential for deployment of the controller for ac power control. The investigation is conducted for resistive load by theoretical estimate of the current harmonic content and power factor at the source. The symmetrical multipulse modulation (SMM) provides output voltage with equidistant pulses and has two control parameters; the number of pulses per half cycle (M) and the duty cycle (M). It is established theoretically and corroborated experimentally that manipulation of M and δ alters the harmonic profile of the source current significantly and, therefore, can be used for mitigation and even selective elimination of harmonics. The SMM strategy can be used to design compact and economical harmonic filters.
 
Article
In this study we present the results of the simulation of ternary liquid-liquid equilibrium (LLE) using Genetic Algorithm and Threshold Acceptance Algorithm with two hybrid functions (Nelder-Mead Simplex method: NMS and Quasi-Newton method: QN). These methods show that the hybridization of both GA and TA algorithms give good values of tie-lines. The RMSD values obtained were compared to UNIQUAC and NRTL models using GA and TA algorithms with NMS and QN hybrid functions. The Levy function was used in the test performances of GA and TA algorithms. The experimental protocol considered in this work was a ternary system (Trichloromethane-Acetic acid-Water) at two different temperatures. The thermodynamic models considered for the calculation of the interaction parameter are UNIQUAC and NRTL models. The interaction parameters were presented; the experimental and theoretical tie-lines were plotted on triangular coordinates. Copyright © 2016 Praise Worthy Prize - All rights reserved. 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One of the issues rarely discussed in the IP camera is the system's difficulties in accessing the IP camera from different manufacturers. This problem is caused by the fact that each IP camera has an individual manufacturing preset access addresses that make the users unable to integrate IP cameras from other manufacturers automatically. It is complicated to access ubiquitous IP cameras automatically in an advanced surveillance system. This research proposes a selection of IP camera access links using the NLP extraction approach. TF-IDF is one of the NLP extraction techniques used in this research, which has been combined with a statistical approach as a novel method in order to select the reliable candidate address from the address data of the IP camera provided by the ISPY dataset. The experiment has been conducted using several schemes based on the percentage of degradation of the original access address. There are four proposed links results, which are 242 links (25%), 288 links (50%), 363 links (75%), and 388 links (100%). The evaluation using 10-fold validation in several simulations reveals that the proposed list can produce the range around 89% to 97% of average accuracy. Moreover, brute force complexity evaluation has denoted that the selected access address has a lower complexity than the original one.
 
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Ammar Fakhir Abdulwahid
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Zaid S. kareem
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Shahrir Abdullah
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