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International Review on Modelling and Simulations Vol. 5 N. 2---- Part A
International Review on Modelling and Simulations Vol. 5 N. 2---- Part B
International Review on Modelling and Simulations (Vol.
5 N. 2) - April 2012 - Papers (Part A)
International Review on Modelling and Simulations (Vol.
5 N. 2) -
April 2012 - Papers (Part B)
International Review on Modelling and Simulations - Papers (Part A)
Voltage and Reactive Power Control in Distribution Systems in the Presence of
Distributed Generation
by Amir Bagheri,
Reza Norouzian, Abolfazl Jalilvand, Saeid Jalilzadeh
Vol. 5. n. 2, pp. 528-536
Abstract - Emerging
of distributed generation (DG) into power system has affected the
different aspects of the power systems planning and operation. One of
these aspects, which is influenced by DG units, is the voltage and
reactive power control in distribution networks. In this paper, Volt/Var
control problem in the presence of DG is implemented in different
scenarios, and the effect of DG on the result of problem such as loss,
voltage deviation and switching times of the controlling devices is
investigated in each scenario. For solution of the problem, the genetic
algorithm (GA) is employed. The proposed approach is applied on a
distribution system and the simulation results are evaluated. Comparison
of the output results verifies the effectiveness of proposed method in
optimal control of compensating equipment of distribution network.
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Keywords: Distributed Generation, Distribution System, Genetic Algorithm, Voltage and Reactive Power Control.
A Novel Algorithm for Harmonic, Reactive Power and Unbalanced Current
Compensation in Three-Phase Distribution Systems
by John George,
Jose T. L, Jeevamma Jacob
Vol. 5. n. 2, pp. 537-545
Abstract - In this
paper a new algorithm is presented for generating reference currents for
harmonic, reactive power and unbalance compensation, using active power
filters in three-phase four wire distribution systems. The proposed
method has the advantage that it performs well in generating the
reference currents irrespective of the supply voltage conditions and
load characteristics by providing sufficient decoupling with the mains
voltage and hence it ensures good compensation. This control algorithm
shows good performance even when the source voltage is distorted and/or
unbalanced. This method also ensures that the source currents after
compensation are balanced and maintains unity power factor. The validity
and practicability of the proposed method is established through
simulation results and the comparative evaluation presented in this
paper, for different load and supply voltage conditions.
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Keywords: Power Quality, Active Power Filters, Id-Iq Method, Reactive Power Compensation.
Large-Scale Metamodeling and Validation of Power Systems
by S. Shan, W.
Zhang, and G. G. Wang
Vol. 5. n. 2, pp. 546-560
Abstract - Modeling
the available transfer capacity of power systems is arduous due to
contingencies and commonly performed by simulation. Meanwhile, both
metamodeling and validating a large-scale computationally expensive
simulation system is challenging due to “curse of dimensionality.” This
paper applies the recently developed Radial Basis Function-High
Dimensional Model Representation (RBF-HDMR) to model the transfer
capability of a 50-variable electric power system subject to contingency
disturbances. The simulation-based transfer capability analysis has a
combination of high-dimensional, computationally-expensive, and
black-box features, which is called a HEB problem. The obtained RBF-HDMR
is useful for power system analysis and operation planning. In addition,
this work proposes two complementary sets of modified performance
metrics for validation of metamodeling techniques in general. The
proposed metrics overcome the deficiencies of some commonly-used
metrics, and also the potential risk of using an individual or an
arbitrary set of performance metrics, which is the common practice in
the field of metamodeling. The accuracy and efficiency of RBF-HDMR, as
well as the application of the two sets of performance metrics, are
demonstrated through three practical cases under different operating
scenarios for the given power system. The results show that RBF-HDMR is
effective and efficient in modeling this large-scale HEB problem, and
moreover, the two sets of performance metrics overcome the potential
misjudgment might have been brought by using individual metrics.
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Keywords: Power System Modeling, Power Generation Economics, Power System Interconnection, Power System Planning, Large-scale Systems, Power System Simulation, Metamodeling.
Optimal Number and Location of DGs to Improve Reliability of Distribution System
Using Genetic Algorithm
by
S.Chandrashekhar Reddy, P.V.N.Prasad, A.Jaya Laxmi
Vol. 5. n. 2, pp. 561-567
Abstract - DGs are
now commonly used in distribution systems to reduce the power disruption
in the power system network. Due to the installation of DGs in the
system, the total power loss in the can be reduced and voltage profile
of the buses and reliability of the system can be improved. The
significant process to decrease the total power loss and to improve the
reliability of the system is to identify the optimal number of DGs and
their suitable locations in the system. To accomplish the aforementioned
process and to evaluate the amount of power to be generated, a new
method is proposed using Genetic Algorithm. The reliability parameters
considered are EENS and ECOST. The proposed method is tested for IEEE 30
bus system, by connecting optimal number of DGs in the system. The
results showed a considerable reduction in the total power loss in the
system, stable voltage profiles and improved reliability indices.
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Keywords: DG, Genetic Algorithm, EENS and ECOST.
Modeling and Control of a Hybrid Energy System for a Grid-connected Applications
by T. Lajnef, S.
Abid, A.Ammous
Vol. 5. n. 2, pp. 568-575
Abstract - This
paper provides a simulation model of the hybrid system devices and of the
inverter energy management. These devices comprise wind and PV sources with PEM
fuel cell storage. A different converter is also needed in order to control the
power flow from these elements and to maintain required bus voltage. A non ideal
averaged model of the PWM-switch is a useful method for modeling pulse with
modulated converters. The advantages of the proposed averaged model are mainly
taking into account the semiconductors non linearity and estimating with
precision the power losses in the different circuit devices. Therefore we can
evaluate energy losses in the system during the unit sizing process. The
mathematical and electrical models of the proposed system are developed and
implemented in the MATLAB / SIMULINK.
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Keywords: Modeling, Control, Wind, Solar, Fuel cell, MPPT, PWM-Switch, Averaged model, Simulation.
Performance Comparison of FACTS Devices for Steady State Power Flow Control
by S. Sreejith,
Sishaj P. Simon, M. P. Selvan
Vol. 5. n. 2, pp. 576-588
Abstract -
Application of Flexible AC Transmission Systems (FACTS) devices in a
power system is a promising and more efficient way for the transfer and
control of bulk amount of power. This paper focuses on a comparative
analysis of steady-state power flow control of a power system
transmission network using FACTS devices namely Static Var
Compensator(SVC), Thyristor Controlled Series Compensator(TCSC), Static
Synchronous Compensator (STATCOM), Static Synchronous Series
Compensator(SSSC), Unified Power Flow Controller(UPFC) and Interline
Power Flow Controller(IPFC). The performance of all FACTS devices in the
control of power flow on a given test system is compared. Various
parameters including real, reactive power flow, loss and voltage profile
are compared at various locations in the test system. Reactance modeling
and Power Injection modeling techniques are used to incorporate the
FACTS devices into the existing Newton Raphson load flow algorithm. The
variation in power flow and network power and loss in the system with
each FACTS device are clearly illustrated. Numerical results on a
benchmark 5 bus test system with incorporation of each of the FACTS
devices are presented to illustrate the effectiveness of FACTS devices
in the power system network.
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Keywords: FACTS Devices, Power Flow Control, Modeling, Power Injection Model, Real Power, Reactive Power, Reactance, Compensation, Power Loss.
A Study of Electromagnetic Fields from AC 25 kV/50 Hz Contact Line Systems
by M. Mandić, I.
Uglešić, V. Milardić
Vol. 5. n. 2, pp. 589-595
Abstract - The
article presents a computational method of assessing low-frequency
electric and magnetic fields of AC 25 kV/50 Hz power supply systems.
Different measurements of magnetic flux density and electric field
strength on different contact line design were conducted. The fact that
the traction current varies trough time presents difficulty in measuring
the magnetic flux density. The comparison of measurements with
calculations’ results shows good agreement. Analysis of the results
shows that the amounts of magnetic flux density and electric field of
the contact network in areas where people reside are below the limit
prescribed by national legislation.
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Keywords: Electric Field, Magnetic Flux Density, Contact Line Design, National Legislation, Measurement, Calculation.
Signal Processing Techniques for Power Quality Analysis: A Review
by Suriya Kaewarsa
Vol. 5. n. 2, pp. 596-608
Abstract - The power
quality has become an important issue for electric power utilities and
its customers. The world wide increasing applications of non-linear
loads, mostly consisting of power electronics devices, have caused the
power quality problems. Power quality problems can be described as any
variation in the electric power supply such as voltage sags/swell,
interruptions, flickers, notches, harmonics, and transients. Nowadays,
several methods have been applied to power quality analysis. Most of
these methods are well-known signal processing techniques. This paper
presents a review of different signal processing techniques which are
widely used for power quality analysis and discusses the performance of
each technique.
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Keywords: Power Quality, Fourier Transform, Wavelet Transform, S-Transform, Tt-Transform, Prony Analysis, Slantlet Transform, Hilbert Transform, Teager Energy Operator.
Cascaded and Feedforwarded Control of Multilevel Converter Based STATCOM for
Power System Compensation
by K. Sundararaju,
A. Nirmal Kumar
Vol. 5. n. 2, pp. 609-615
Abstract - The
static synchronous compensator (STATCOM) is used in power system network
for improving the voltage of a particular bus which can be distorted or
unregulated if the loads in any part of the system are varied. It can be
connected to particular bus as compensating device to improve the
voltage profile and reactive power compensation. In this paper, a multi
function controller is proposed and discussed. The control concept is
based on a linearization of the d-q components with cascaded and
feedforwarded controller methods. It also proposes a scheme in which the
fundamental sequence components of a three phase signal can be computed
from its samples. In closed loop method, six pulse voltage source
converters (VSC) and seven level cascaded multilevel converters (CMC)
are analyzed and proposed to ensure the stable operation for damping of
power system oscillations and voltage variation.
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Keywords: FACTS, PWM, VSC, CMC, STATCOM, THD.
Solar PV and Grid-Connected Electricity System with Multiple Modes Operation for
Homes and Buildings
by Rosnazri Ali,
Ismail Daut, Soib Taib, T. M. Nizar T. Mansur, Nor Hanisah Baharudin
Vol. 5. n. 2, pp. 616-622
Abstract - This
paper presents the designed proposal of a solar PV and grid-connected
electricity system with multiple modes operation for homes and buildings. It
introduces to a more resourceful solar PV system that suits with the needs for
different occasions rather have to be limited to one particular application.
This concept uses a DC motor and synchronous generator as an electromechanical
inverter to alternatively present popular approach of using solid-state
inverters in converting the solar DC supply into AC, suitable to run common
electrical appliances. The block concept of the system and the main controller
with programming flowcharts for the multiple operations are proposed for a 2kW
output power.
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Keywords: Solar PV System, Grid-Connected System, BIPV, Electromechanical Inverter.
Intelligent Classification of Three Phase Fault and Voltage Collapse for Correct
Distance Relay Operation Using Support Vector Machine
by Ahmad Farid
Abidin, Azah Mohamed, Hussain Shareef
Vol. 5. n. 2, pp. 623-631
Abstract - The
conventional techniques used in distance relay operation are not fast
enough in distinguishing between a three phase fault and voltage
collapse and this may lead to unintended tripping of protection devices.
Therefore, there is a need for fast detection of voltage collapse so as
to improve the reliability of distance relay operation. This paper
presents an intelligent approach to classify a voltage collapse and a
three phase fault for distance relay operation by using the under
impedance fault detector and support vector machine (SVM). To illustrate
the proposed approach, simulations were carried out on the IEEE 39 bus
test system using the PSS/E software. Test results shows that the
proposed approach can accurately detect and classify fault and voltage
collapse events for correct distance relay operation. To demonstrate the
effectiveness of the SVM, a comparison is made with the results obtained
from the application of the probabilistic neural network.
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Keywords: Distance Relay, Under Impedance Fault Detector, Support Vector Machine (SVM), Fault and Voltage Collapse.
Small Signal Stability Analysis of Rectifier-Inverter Fed Induction Motor Drive
for Microgrid Applications
by Alireza Khadem
Abbasi, Mohd Wazir B. Muatafa
Vol. 5. n. 2, pp. 632-639
Abstract - This
paper presents a small signal model of a rectifier-inverter fed
induction motor drive system as the main dynamic load in the power
system by neglecting the effect of stator voltage harmonics. The dynamic
of DC link between rectifier and inverter and variations in voltage and
frequency of the network side is also considered in this study. The
investigation of the stability shows the system is stable during dynamic
and steady-state conditions, and oscillatory modes are well damped. In
addition, comparison between the proposed model and the typical model of
induction motor shows the transient response is significantly improved.
This model can be used as dynamic load in stability analysis of
Microgrid.
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Keywords: Microgrid, Induction Motor, Inverter, Rectifier, Small Signal Stability.
A Review of Investigations on the Formation and Detrimental Effects of Corrosive
Sulphur in Transformer Insulation System
by M.
Balasubramanian, G. Ravi, V. Dharmalingam
Vol. 5. n. 2, pp. 640-648
Abstract -
Operational life of power transformers and reactors are vastly
challenged by several phenomenons capable of causing complete disruption
to their insulations and winding structures. Corrosive sulphur is one of
the major concerns in the recent past because of its complex dynamics in
causing failures to power transformers and reactors. Several failures
have been reported due to deposition of copper sulphide (Cu2S) on copper
conductor and paper insulations. Effective identification of corrosive
sulphur, extraction of chemical compositions of oil and paper insulation
affected by corrosive sulphur and its reflection on the electrical
properties, development of possible long term mitigation techniques are
gaining importance among investigating agencies and industries. This
paper is mainly intended to survey major experimental investigations,
results and suggestions registered so far on the formation and effects
of corrosive sulphur in transformer insulation system.
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Keywords: Corrosive Sulphur, Dibenzyl Disulphide (DBDS), Metal Passivators, Breakdown Voltage, Permittivity.
Tracking the Direction of Switched Capacitor Banks in Distribution Systems Using
Modal Signal
by Siamak
Javaheri, Mohsen Saniei, Ali Saidian, Mahmood Joorabian
Vol. 5. n. 2, pp. 649-654
Abstract - This
paper presents an effective technique for tracking and finding the
direction of switched capacitor banks in distribution system generating
switching transient when certain number of power quality meters exist.
The proposed method is comprised of two independent algorithms.
Algorithm utilizing the steady-state power quality data based on changes
of the phase-angle difference between voltage and current and algorithm
utilizing the transient state power quality data based on branch voltage
and current changes immediately before and after the capacitor switching
instant. This technique uses modal current and voltage signals that can
be constructed by combining three-phase current and three-phase voltage.
Wavelet transform is used to detect the exact instant of switching
transient. The efficiency of proposed method was validated using IEEE
34-bus distribution system, modeled in PSCAD.
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Keywords: Modal Signal, Power Quality Monitoring, Switched Capacitor, Wavelet Transform.
Control of Grid Connected PMSG Based Variable Speed Wind Energy Conversion
System
by Y. Errami, M.
Ouassaid, M. Maaroufi
Vol. 5. n. 2, pp. 655-664
Abstract - With the
advance of power electronic technology, new circuit topologies permanent
magnet synchronous generators (PMSG) and novel control strategies have
increasingly drawn interests to wind energy conversion system (WECS).
This paper proposes the modeling and output power maximization control
strategy of WECS. The proposed control strategy combines space vector
modulation (SVM) and maximum power point tracking (MPPT) control method.
The block diagram of the WECS with the grid-side back-to-back PWM
converter and PMSG is established with the d-q frame of axes. The torque
of generator is suitably controlled according to a PMSG speed. So the
power from a wind turbine settles down on the maximum power point by the
proposed MPPT control without a wind speed detector. Space vector
modulation (SVM) and MPPT are integrated to achieve unity power factor
and low distortion currents. Reactive and active power can be controlled
by quadrature and direct current components, respectively. Under
fluctuating wind, the controller of generator side converter is capable
to maximize output of the WECS. In addition, under varying load and at
constant load condition, the controller of Grid-Side can maintain the
load frequency and voltage quite well. Simulation results have shown the
effectiveness of the proposed control methodology.
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Keywords: WECS, PMSG, MPPT, PWM, Variable-Speed Control, Unity Power Factor.
Transient Stability Analysis of Fixed Speed Wind Turbines Under Constant and
Variable Wind Speeds Using Resistive Superconducting
Fault Current Limiter
by Mohamed M. Aly
Vol. 5. n. 2, pp. 665-671
Abstract - This
paper proposes a novel method of transient stability enhancement of wind
turbine generation system (WTGS) by resistive superconducting fault
current limiter (R-SFCL). Of all wind power technologies, the fixed
speed systems employing the rugged squirrel cage induction generators (SCIGs)
are the cheapest and simplest for grid connection. Introducing R-SFCL in
wind power plants allows for using these generating units in large
numbers with no concerns about the transient stability following a
system fault. The study is performed on a test system using the model of
both WTGS and R-SFCL. The power system model was implemented in the
Simulink/MATLAB and Powersys/MATLAB environment. Mathematical equations
of the R-SFCL are discussed in details and the associated algorithm is
presented. Two types of wind speed during the fault were considered
namely, the constant speed and the variable speed wind. Computer
simulation examines the effectiveness of R-SFCL in enhancing the
transient stability of the WTGS without affecting the normal operation
of the system. Simulation results show that R-SFCL can stabilize the
wind generator system during severe faults for both constant speed and
variable speed wind.
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Keywords: Fixed Speed Wind Turbines Generation System (WTGS), Resistive Superconducting Fault Current Limiter (R-SFCL), Three-Phase Fault, Transient Stability.
A Novel Distributed Premium Power Park Design for Power Quality Improvement
by Masoud
Farhoodnea, Azah Mohamed, Hussain Shareef, Hadi Zayandehroodi
Vol. 5. n. 2, pp. 672-679
Abstract - In
deregulated power systems, voltage sag, harmonics, and rapid energy
interruptions are the most important reasons for power quality
disturbances. The basic concept of the Premium Power Park (PPP) is to
improve the power quality level compared with the standard configuration
offered by the utility. This paper presents a novel configuration of PPP
to mitigate voltage power quality disturbances using a combination of
custom power devices and spot network configuration. Furthermore, an
administrative power quality control strategy is presented to coordinate
the combined custom power devices in close electrical proximity and to
ensure maximum effectiveness of the proposed scheme on power quality
improvement. System responses to different power disturbances are
simulated using MATLAB/SIMULINK software program to evaluate the
performance of the proposed scheme. The results show that the proposed
PPP configuration is effective in improving power quality and in
providing different levels of power quality for conventional, sensitive,
and critical customers.
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Keywords: Custom Power Park, Premium Power, Premium Power Park, Power Quality Park.
Real Time Hardware in the Loop Simulation of Distribution Static Compensators
by María A.
Mantilla, Johann F. Petit
Vol. 5. n. 2, pp. 680-689
Abstract - This
paper presents the development of a real-time simulator for a
Distribution Static Compensator (DSTATCOM) considering the three-phase
four-wire Voltage Source Inverter (VSI) with split capacitor topology.
In order to develop the simulator, the DSTATCOM model and the
mathematical equations that represent the operation of the load and the
equivalent of the distribution system were determined. These
mathematical models were used to solve the state of the system variables
in real time. The real time simulator and the control system were
implemented in the d-SPACE 1104 controller board and the digital signal
processor TMS320F2812 of Texas Instruments, respectively. Comparisons
between real-time simulation waveforms and Matlab/Simulink simulation
signals were made to evaluate the right performance of the simulator.
This simulator allows validating the hardware implementation feasibility
of the DSTATCOM control strategies and verifying the control system
performance before the physical implementation of the real compensator.
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Keywords:
Custom Power Devices, Distribution Static Compensator,
Hardware in the Loop, Power Quality, Real-Time Simulation.
Optimal Location of Interline Power Flow Controller in a Power System Network
using DE Algorithm
by S. Sreejith,
Sishaj P Simon, M. P. Selvan
Vol. 5. n. 2, pp. 690-701
Abstract - This
paper presents an algorithm based on Differential Evolution (DE), a non
conventional computational intelligence approach, for the optimal
location of Interline Power Flow Controller (IPFC) in a multi machine
power system. The mathematical formulation of the methodology is based
on installation cost of the FACTS device and generation cost of the real
power. Besides locating the optimal position, this algorithm is applied
to find the optimal dispatch of the generating units and the IPFC
parameters, subject to various operating constraints. IPFC is modeled
using Power Injection (PI) model whose capability of controlling the
real and reactive power of multiple lines is exploited. The performance
of the algorithm is tested on standard test systems like 5 bus, IEEE 14
bus, IEEE 30 bus and IEEE 118 bus systems and the results are compared
with conventional LR method. Also, the discussion on voltage profile and
real power flow improvement in the power system network is presented.
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Keywords: IPFC, Differential Evolution, Modeling, Power Flow Control, Cost Minimization.
Computational Intelligence Techniques applied to Distribution Service
Restoration: A Survey of the State-of-the-Art
by Anoop Arya,
Yogendra Kumar, Manisha Dubey
Vol. 5. n. 2, pp. 702-713
Abstract - Power
system restoration decision-making is one of the most important and
indispensable issues for ensuring fast power supply restoration to end
users. In recent years, the power industry around the globe has been
undertaking an in-depth restructuring, and this has led to some new
challenges to the problem of service restoration. Service restoration is
a complicated combinatorial and multi objective, multi constraint
optimization problem that often has a great number of candidate
solutions to be evaluated by the operators. This paper presents a
comprehensive review of the various Computational Intelligence
Techniques applied to solve Distribution Service Restoration problem
reported in the specialized literature. As part of this review, a
classification of the approaches is included, and a main feature of each
proposal has been identified. In the last part of the paper, some of the
topics within this field that are considered as promising areas of
future research are listed.
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Keywords: Computational Intelligence, Distribution Systems, Service Restoration.
Adaptive Thyristor Controlled Series Capacitor Using Particle Swarm Optimization
and Support Vector Regression
by J. Pahasa, K.
Hongesombut, I. Ngamroo
Vol. 5. n. 2, pp. 714-721
Abstract - This
paper focuses on the application of support vector regression (SVR) to
design of an adaptive thyristor controlled series capacitor (TCSC). A
particle swarm optimization (PSO) is used to optimize the SVR parameters
based on k-fold cross-validation technique. The SVRs for an adaptive
TCSC are trained by the data obtained from a multi-machine power system,
and the optimal SVR parameters. The TCSC parameters can be adapted by
various operating conditions. Simulation results in a two-area
four-machine interconnected power system demonstrate that the proposed
SVRs for an adaptive TCSC is much superior to the conventional TCSC with
fixed parameters under various operating conditions and severe
disturbances.
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Keywords: Thyristor Controlled Series Capacitor, Support Vector Regression, Particle Swarm Optimization.
Harmonic Reduction in Wind Turbine Generators Using a Shunt Active Filter
by A. Hoseinpour,
R. Ghazi
Vol. 5. n. 2, pp. 722-730
Abstract - A wind
turbine is connected to grid with a converter system. There are two
types converter systems, the traditional fixed speed and the new
variable speed. Variable speed systems have several advantages over the
traditional one, such as the reduction of mechanical stress and increase
in energy capture. There is a Wound Rotor Induction Generator (WRIG) or
Permanent Magnet Synchronous Generator (PMSG) in configuration of
variable speed system, in which the machine is connected to the grid via
a series combination of rectifier and inverter. So, wind turbine is
connected by variable speed Wind Energy Conversion Systems (WECS)
comprises a Power Electronic (PE) converter as a main source of
harmonics. Harmonic reduction is essential to decrease the electrical
losses and improve the WECS power quality. In this paper a shunt active
filter is used to improve the output current harmonics of the system.
The filter contains three parts: the identification, modulation, and an
inverter. Most identification methods are sensitive to the
non-sinusoidal source but in the proposed filter an algorithm is used to
make it non sensitive to some extent. The simulation results confirm the
superior performance of the proposed SAF.
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Keywords: Turbine (WT), Shunt Active Filter(SAF), Total Harmonic Distortion(THD), Permanent Magnet Synchronous Generator (PMSG).
An Approach to Power Flow Calculation through Small or Zero Impedance Lines
by Bojan B.
Ivanovic, Stanko S. Jankovic
Vol. 5. n. 2, pp. 731-742
Abstract - Small or
zero impedance lines are frequent cause of power flow calculation
divergence or invalid convergence. Impedances of bus couplers are almost
equal to zero while impedances of lines which connect generators high
voltage busbars to neighboring substations are usually very small. This
paper presents an approach by which buses connected by small or zero
impedance lines are merged into single bus and nonlinear system of power
flow equations is solved without these lines. After solution of
nonlinear systems of power flow equations is found, power flows through
small or zero impedance lines are solved as system of linear equations.
The main advantage of solving system of linear equations comparing to
solving system of nonlinear equations is that linear system is solved in
one step without iterative procedure. The approach of solving the system
of linear equations representing active and reactive power flows through
lines with the same voltages and angles at their terminals is presented
in the paper.
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Keywords: Short Line, Small Impedance Line, Zero Impedance Line.
Closed-Loop Controllable Unified Power Flow Controller (UPFC) Based on Load
Demand Change
by Nashiren F.
Mailah, Senan M. Bashi, M. Norhisam, Tsuyoshi Hanamoto, Hiroaki Yamada
Vol. 5. n. 2, pp. 743-750
Abstract - Unified
Power Flow Controller offers a new alternative to power system control.
In this work, a closed-loop controllable UPFC has been designed and
developed using active power transfer and reactive power compensation
algorithm. These algorithms allow the UPFC to operate automatically
under varying load conditions and able to stabilize the busbar voltage
with required power supplied to the load. From the results obtained, it
has been shown that the active power demanded by the load is being
supplied by the SSSC by controlling the angle θ23, i.e the
phase angle between voltage V2 and V3. With this
angle θ23, the SSSC will transfer the correct amount of
active power to the load. At the same time, the SSSC will also transfer
a small amount of reactive power to the load. The angle of θ23
is obtained from active power transfer algorithm where it will determine
the value of additional voltage magnitude, |ΔV| and phase shift, Φ. The
STATCOM will supply or absorb the reactive power required by the system.
This is carried out by injecting current at the point of connection
using reactive power compensation algorithm where it will compare the
difference between system voltage, Vsystem and STATCOM
voltage, Vshunt.
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Keywords: Unified Power Flow Controller, Static Compensator, Static Synchronous Series Compensator, Active Power Transfer, Reactive Power Compensation.
Optimization of PI Compensator Parameters for Grid-Tied Photovoltaic with Energy
Storage Systems using Simplex Algorithm
by Muhamad Zalani
Daud, Azah Mohamed, M. A. Hannan
Vol. 5. n. 2, pp. 751-760
Abstract - The
performance of grid integrated renewable energy systems largely depends
on the control system used for each of the energy conversion process. An
abrupt change in input, variability of load conditions and grid faults
cause the DC bus voltage to fluctuate which is normally compensated by
PI controllers. This paper presents a parametric study carried out for
improving the system performance of grid-tied photovoltaic with battery
energy storage systems (BESS). The power converters such as the grid
side voltage-sourced converter and bi-directional DC/DC converter are
optimized by using the simplex optimization algorithm with objective of
minimizing the DC bus voltage fluctuations under severe operating
conditions. The advantage of adopting the proposed optimization method
is analyzed by comparing the simulation results carried out using a set
of optimized parameters with those of conventional trial and error
method. The benefits of using BESS as an additional source for
regulation are also discussed.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Photovoltaic, Battery Energy Storage Systems, Simplex Optimization, PI Controller.
Uninterrupted Operation of Grid Connected to Wind Turbine Using Energy Capacitor
System Based DFIG
by Mozhgan Balavar,
Amin Nazarloo, Mohammad Bagher Bannae Sharifian
Vol. 5. n. 2, pp. 761-770
Abstract - The
voltage sags at the connecting point of the wind turbine equipped with
double fed induction generator (DFIG) to the grid can result in over
current in the stator winding. Due to the magnetic coupling between
stator and rotor, similar high current appears in the rotor winding,
consequently, the rotor side converter may be damaged. Therefore, it may
be necessary for the wind turbines with DFIG to be interrupted during
some voltage sags in the power systems. This paper proposes a new method
which uses energy capacitor system (ECS) to achieve uninterrupted
operation of the wind turbine with DFIG during grid faults. This system
controls the active and reactive powers at the connecting point of wind
turbine to the grid. Simulation results clearly show that ECS enhances
the transient stability and therefore helps the wind turbine generator
system to remain in the service during grid faults.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Doubly Fed Induction Generator, Transient Stability, Energy Capacitor System, Fuzzy Logic Controller.
Improved Switched
Inductor (SL) Z-source
by M.
A. Ismeil, A. Kouzou, Ralph Kennel, A. A. Ibrahim, M. Orabi, M. E. Ahmed
Vol. 5. n. 2, pp. 771-778
Abstract - This
paper present an improved SL Z-source inverter topology. Because of the
limitation of classical Z-source inverter the SL Z-source inverter has
been proposed to increase the voltage gain but still have limitation
such as stress, so with improved SL Z-source inverter topology the
capacitor voltage stress can be reduced. This paper investigates the
third harmonic injection with simple constant boost, maximum boost and
constant maximum boost. The analyses are verified by simulation.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Template, Switched Inductor, Z-source, Boost Ability, PWM, Harmonic Injection.
Introducing a New Soft Single Switching Step-up DC-DC Converter
by M. M. Akbari,
M. Delshad, E. Borzabadi
Vol. 5. n. 2, pp. 779-784
Abstract - In this
Paper, a new nonisolated single switch DC-DC converter with high voltage
gain is proposed. The proposed converter introduces a hybrid switched
capacitor technique for providing high voltage gain without high switch
duty cycle. In addition, an auxiliary circuit has been applied to the
proposed converter for providing soft switching condition. This circuit
consists of two coupled inductor and one diode. Therefore, converter
switch is turned on under ZCS condition. The other advantages of the
proposed converter include: Continuous input/output current, simple
structure and PWM control. The principle of operation in continuous
conduction mode (CCM) and discontinuous conduction mode (DCM) are
analyzed. The proposed converter is simulated by PSPICE to confirm the
results of theoretical analysis.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: DC-DC Converter, Pulse Width Modulated (PWM), Step-Up Converter, Zero Current Switching (ZCS).
Voltage
Balance Modeling in Multi-Phase Flying Capacitor Multicell Converters Employing
a Balance Booster Circuit
by Vahid Dargahi,
Arash Khoshkbar Sadigh, Mostafa Abarzadeh, Mohammad Reza Alizadeh Pahlavani,
Abbas Shoulaie
Vol. 5. n. 2, pp. 785-792
Abstract - This
paper provides a mathematical model for voltage natural balancing
process in multi-phase capacitor-clamped multicell converters. The
analysis leads to state-space model of the multi-phase flying capacitor
multicell converters. This analytic model can be utilized to investigate
the start-up and steady states of clamping capacitor voltages. To
provide verification, numeric solution results for multi-phase
capacitor-clamped multicell converter’s analytic model in different
cases are presented.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Multi-Phase Flying Capacitor Multicell Converter, Self-balancing, Analytic Model, Numeric Solution, Voltage Balance Booster Circuit.
Optimal Design of Power Converter Using Multi-objective Genetic Algorithm
by Hanen. Mejbri,
Kaiçar Ammous, Hervé Morel, Anis Ammous
Vol. 5. n. 2, pp. 793-802
Abstract - In the
development of power electronics systems, the increasing efficiency or
the decreasing costs and volume have been of primary concern. This paper
provides a continuous optimization approach for design of power
converters. An important Pareto-based multi-objective optimization
algorithm namely Non-dominated Sorting Genetic Algorithm (NSGA-II) is
used to obtain the design. As an example, a boost converter under some
electrical constraints is synthesized for minimum costs, volume and
losses.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Power converter, Design, Optimization, Multi-objective optimization, Genetic based algorithms.
Investigations on Current Error Space Phasor Based Self Adaptive Hysteresis
Controller Employed for Shunt Active Power Filter with Different Techniques of
Reference Compensating Current Generation
by Siddharthsingh
K. Chauhan, Mihir C. Shah, P. N. Tekwani
Vol. 5. n. 2, pp. 803-817
Abstract - Current
harmonics, which are injected in the utility by nonlinear loads, cause major
problems that tend to deteriorate the power quality at the mains. To reduce such
harmonics, Shunt Active Power Filters (SAPF) are commonly employed. This paper
presents a current error space phasor based hysteresis controller for SAPF,
which allows precise compensation of harmonic currents produced by nonlinear
loads. The proposed controller is self-adaptive in nature and does not require
any particular calculation of Point of Common Coupling (PCC) voltage vector (E)
because of proper sector change detection logics used. Detailed Modelling and
performance analysis of the proposed controller for SAPF with different
compensating current generation methods, along with simulation results, is
presented in the paper. The controller operation is studied for two different
self-adaptive logics for detection of sector changes. Distortion in supply
current is further reduced by avoiding the outer hysteresis band and generating
the SAPF compensating currents by synchronizing the sector change with supply
frequency. The controller keeps the current error space phasor within the
hexagonal boundary (fixed band) by applying SAPF voltage vectors which are
adjacent to the reference voltage vector (voltage vector at the point of common
coupling i.e. E). This leads to the switching of optimal voltage vector unlike
the random selection of the voltage vectors in conventional hysteresis
controller based schemes. Region detection logic enables switching of SAPF
voltage vector which keeps the current error well within the prescribed
hexagonal boundary. The versatile nature of the controller is proved by
analyzing its performance for three different reference compensating current
generation techniques. The performance of controller for SAPF is tested for
balanced as well as unbalanced mains voltage and is found to be satisfactory.
Effect of dc-link voltage variations on the performance of the controller is
also analyzed. Under steady-state and transient conditions controller
performance is found fast and precise. Hence the proposed current controller
gives generalized solution for any method of reference compensating current
generation. The SAPF based on the proposed controller provides adequate
compensation for mitigation of harmonics. Detailed theoretical analysis,
modelling and simulation studies are presented in the paper and the claimed
performance of the proposed controller is evident from the simulation results
provided in the paper.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Compensating Current, Current Error Space Phasor, Hexagonal Boundary, Hysteresis Current Controller, Self Adaptive Sector Change Logic, Shunt Active Power Filters.
Analysis and Implementation of a Novel T-Source Inverter for High Voltage Gain
Application
by P Sivaraman, A
Nirmal Kumar
Vol. 5. n. 2, pp. 818-825
Abstract - Power
conversion scheme play vital role in high voltage gain applications
especially renewable energy source like photo voltaic, wind and fuel
cell based power conversion system. To overcome the setbacks of Z Source
inverter (ZSI), the T Source inverter is proposed. This paper presents a
novel mathematical modeling and analysis of T-Source inverter (TSI) with
a turn ratio greater than one and equal to one is used, this can perform
buck and boost operation in a single stage. The TSI is used as an
interface circuit between source and load; it is controlled by a maximum
constant boost control (MCBC) method. Performance of TSI is analyzed and
compared with ZSI in the aspects of voltage stress, voltage gain and
boost factor for same modulation index. Their performances are validated
using simulation and experimental setup.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Energy Conversion, Inverters, Mathematical Analysis, Power Conversion, Power Semiconductor Switches, Pulse Width Modulation Converters.
Multi-Objective Optimization of Power Converter Sizing Based on Genetic
Algorithms: Application to Photovoltaic Systems
by Hanen Mejbri,
Kaiçar Ammous, Hervé Morel, Anis Ammous
Vol. 5. n. 2, pp. 826-839
Abstract - In the
development of power converters interfacing photovoltaic panels with the
grid, the increasing efficiency and the decreasing of coasts and volume
are the important criteria. To achieve these requirements, sophisticated
computer –aided design optimization is required. Optimization techniques
using genetic algorithms (GA) have received attention in power
electronics optimization, since GA have the ability of handling discrete
design variable. This paper provides a discrete optimization approach
for the sizing of power converters. An important Pareto –based
multi-objective optimization algorithm namely Non-dominated sorting
Genetic Algorithm (NSGA-II) is used to obtain the design. As an example,
a boost converter used for photovoltaic applications under some
electrical constraints is sized for minimum costs, volume and losses.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Power Converter, Multi-Objective Optimization, Genetic Based Algorithm.
A Novel Technique for Common Mode-Voltage Elimination and DC-link Balancing in
Three-Level Inverter
by J. Prakash,
Sarat Kumar Sahoo, S. Prabhakar Karthikeyan
Vol. 5. n. 2, pp. 840-845
Abstract - The paper
presents the effects and importance of parameters like harmonics and
currents that are to be accounted for the satisfactory performance of an
inverter. Practically known problems such as common-mode voltage between
inverter and motor neutral and the dc-link unbalance of source
capacitors are affect the performances of the inverter. A novel solution
is discussed for these issues.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Multilevel Inverter, Natural Point Clamped, Common Mode Voltage And DC Link Balancing.
The
Influence of Topology on Reliability of PC’s SMPS
by M. Askari, E.
Ghadaksaz1, B. Abdi, M. I. Ghiasi, R. Ghasemi
Vol. 5. n. 2, pp. 846-853
Abstract - Recently,
reliability is one of the serious requirements of electronic systems.
The numbers of system failures, repair cost, guarantee, etc are
estimated by reliability estimation. In this paper, the reliability of a
switching power supply, which is used for personal computers, is
evaluated. It will show that the most of failure rates depends on power
circuit which it is named topology. Reliability of different topologies,
including half-bridge, double switch forward and flyback, will be
discussed in this paper. It will be shown that flyback topology has
better reliability during less power parts. Part stress manner utilizes
for failure rate prediction and a prototype’s waveforms uses for stress
detection and calculation of dissipations.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Failure Rate, Reliability, Life Time, SMPS, PC, Topology.
International Review on Modelling and Simulations - Papers (Part B)
Predictive DTC-ISVM for Doubly-Fed Induction Machine System Fed by Indirect
Matrix Converter
by Majid Aghasi,
Vahid Faraji, Hamid Behnia, Davood Arab Khaburi Ali Dehghan Banadaki
Vol. 5. n. 2, pp. 854-864
Abstract - This
paper presents a novel predictive Direct Torque Control (DTC) based on
Indirect Space Vector Modulation (ISVM) technique for Doubly-Fed
Induction Machine (DFIM) using Indirect Matrix Converter (IMC), which is
characterized by a simple structure, minimal torque ripple and constant
switching frequency. In Conventional DTC technique, good transient and
steady-state performances were obtained but it presents non constant
switching frequency behavior. In this paper, using predictive DTC
strategy not only the fixed switching frequency is obtained but also the
good tracking behavior with reduced torque and flux ripple for both
motoring and generating modes are achieved. The DFIM is connected to the
grid by the stator and the rotor is fed by an indirect matrix converter.
To improve the motor drive system performance and reduce losses caused
by snubber circuits, the rectifier four-step commutation method in
rectifier-bridge is used. In the inverter stage, the predictive DTC
method is employed. By suitable selecting switching pattern in IMC, the
achievement to constant frequency and reduced electromagnetic torque
ripple is possible. Despite of increasing complexity, its superior
feature make this control system suitable for wide area of applications
such as wind power generation. The simulation results of predictive
DTC-ISVM system based on IMC confirms its effectiveness and accuracy.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Doubly-Fed Induction Machine (DFIM), Indirect Matrix Converter (IMC), Indirect Space Vector Modulation (ISVM), Predictive Direct Torque Control.
Improvement of Thermal and Electrical Field Distribution in 24 SlotsAC Generator
Using Multi Parameters Optimization
by Diako
Azizi,Ahmad Gholami,Alireza Siadatan
Vol. 5. n. 2, pp. 865-871
Abstract - 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, permittivityand
electrical conductivity are major design consideration. A very powerful
method available to analyse electromagnetic-thermal 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.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Insulation, Objective Function, Stator, Voltage.
Flux
Distribution at Three Phase Power Transformer Core under Nonlinear Load
Operation
by
Syafrudin Masri, Mokhzaini Azizan, Mohamad Kamarol
Vol. 5. n. 2, pp. 872-878
Abstract -
Characteristic of loads available in power system today has caused
operational problems to equipments such as power transformer. Nowadays
more electronics are used in wide range of applications, which in turn
produce more harmonics in power system. Under nonlinear load operation,
solenoids that form the windings carry harmonic current into each of the
limbs in the power transformer. Thus the associated flux density, B and
its distribution at the core are changed from linear to nonlinear
pattern. This paper examines the changed flux density and its
distribution inside a 2kVA three phase E-I core test power transformer.
FEM model of the unit is introduced in order to find and focus to the
additional distributions of flux across the cross sectional area of the
limbs as the harmonics exists in current flowing in the windings. Other
information includes measurement of flux density at the core and winding
areas.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Current Harmonics, Electromagnetic Distribution, Flux Density, Power Transformer Modeling, Total Harmonic Distortion.
Effect of the Stator Mutual Leakage Inductance for Low and High Power
Applications of Dual Star Induction Machine
by Hajer Kouki,
Mouldi Ben Fredj, Habib Rehaoulia
Vol. 5. n. 2, pp. 879-886
Abstract - This
paper treats the static and dynamic modeling of dual star induction
machines (DSIM) by proposing three electric models. The induction
machine has two sets of three-phase stator windings spatially shifted by
30 electrical degrees. The emphasis is placed on an extensive
presentation of the effect of the stator mutual leakage inductance
between two stator stars, for low and high power applications, by
examining the electrical, magnetic and mechanical quantities. In the
following, in order to confirm this impact, the machine is supplied by a
multilevel voltage inverter. The simulation results confirm the effect
of the stator mutual leakage inductance on the machine performances and
particularly its transients.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Dual Star Induction Machine, Electrical Models, Stator Mutual Leakage Inductance, Multilevel Voltage Inverter.
MPPT
Strategy and Direct Torque Control of PMSG Used for Variable Speed Wind Energy
Conversion System
by
Y.Errami, M. Benchagra, M. Hillal, M. Ouassaid, M. Maaroufi
Vol. 5. n. 2, pp. 887-898
Abstract - Over the
last years, the importance of Wind Energy Conversion Systems (WECS),
based on Permanent Magnet Synchronous Generators (PMSG), has been
increasing. Thus, with the advance of power electronic technology, new
circuit topologies PMSG and novel control strategies have increasingly
drawn interests to WECS. This paper proposes the modeling and output
power maximization control strategy of WECS. A Direct Torque Control (DTC)
algorithm-based controller is proposed for the PMSG. Generator torque
reference is derived based on Maximum Power Point Tracking strategy (MPPT).
The block diagram of the WECS with PMSG and the grid-side back-to-back
converter is established with the d-q frame of axes. In addition, to
limit the output power produced by the turbine, a pitch control scheme
for variable speed wind turbines is propose. However, the objectives of
grid-side converter are to deliver the energy from the PMSG side to the
grid, to regulate the DC-link voltage and to achieve unity power factor.
So, Direct Power Control (DPC) of three phases PWM inverter is adopted
and Grid-side active and reactive power decoupling method is applied.
Simulation results confirm that the proposed strategy has excellent
performance.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: WECS, PMSG, MPPT, DTC, DPC, Unity Power Factor.
Design and Optimization of BLDC Generator for Wind Turbine Applications
by S. M. M.
Mirtalaei, B. Abdi, K. Shaloudegi, R. Ghasemi
Vol. 5. n. 2, pp. 899-904
Abstract - Permanent
magnet synchronous generators are used widely in wind power generation
recently. The huge amount of torque during low speed and high power
beside great amount of poles and slots make this kind of generators with
the other applications. This paper presents a simplified analytic design
method for brushless DC generators used in wind turbine application.
Simplified proposed design is good for direct optimization. This manner
of optimization is used in this paper because of its perspicuity.
Efficiency and weight can be optimized together by utilizing this manner
of optimization. Magneto-static and parametric finite element-based
simulations are used to confirm the design and optimization process.
Simulation results show less than 3% error in the design process.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Wind Energy, Generator, PM, BLDC, Analytic Design, Optimization.
A Hybrid Method Based on Multi-Objective Ant Colony Optimization and
Differential Evolution to Design PID DC Motor Speed Controller
by I. Chiha, H.
Liouane, N. Liouane
Vol. 5. n. 2, pp. 905-912
Abstract - This
paper treats a tuning of PID Dc Motor Speed controllers method using
Multi-Objective Differential Evolution, MDE, Multi-objective Ant Colony, MACO
and a hybrid method based on Multi-objective Ant Colony Optimization and
Differential Evolution, MACODE. The objective was to apply the above-mentioned
methods in the aim of tuning the optimum solution of the PID Dc Motor Speed
controllers (Kp, Ki and Kd) by minimizing the
Multi-objective function. The potential of using Multi-objective optimization
problems is to find the best compromise between multiple and conflicting
objectives and identify Pareto-optimal solution. These methods are applied to
make comparisons with a classic approach based on the « Ziecgler_Nichols ».
Simulation results demonstrate that the new hybrid tuning method MACODE is
efficient, feasible and has a better control system performance compared with
the MACO method, MDE algorithm and the classic approach.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: PID Controllers, DC Motor Speed, Multi-Objective Differential Evolution, Multi-Objective Ant Colony, Multi-Objective Optimization.
An Advanced DPC-Self Excited Induction Generator Drive Scheme for an Isolated
Wind turbine Boost System
by Noureddine
Hidouri, Samah Hammadi, Lassaad Sbita
Vol. 5. n. 2, pp. 913-920
Abstract - In this
paper, the Authors present a Direct Power Control scheme of an Induction
Generator (IG) associated with a wind turbine system. The turbine is
used to drive the IG in order to feed an isolated DC load. It receives
the required active power from the generator through a rectifier, DC bus
and a boost converter. The models of the system components are developed
and used in the system control scheme. Mathematical relations treating
the system components are presented and studied. The generator and the
turbine dynamic performances are analyzed. The simulation results of the
system entire control have shown that the proposed methodology is an
efficient and promising control procedure.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: DPC, IG, Wind Turbine System, Boost Converter, DC Bus, DC Load.
Fault Diagnosis PWM Inverter Permanent Magnet Synchronous Machine Drive Based on
Current Signature Analysis
by M. Khedri, M.
Yousefi Kia, M. A. Shamsi Nejad, H. R. Najafi
Vol. 5. n. 2, pp.
921-929
Abstract - Rapid and
correct diagnosis of different faults in drive has been focused on
recent years but a few literatures have been investigated coordination
in diagnosis. In this paper three common non-catastrophic faults of
drive includes transistor open-circuit fault, increase contact
resistance and irregular source fault are considered. Then a novel
algorithm is developed to online diagnosis of these electrical faults.
This algorithm is presented to identify electrical faults based on both
the wavelet analysis and mean value computation of the permanent magnet
AC drive currents. The different fault types are classified by threshold
technique. The main advantages of presented flowchart are high
reliability, covering the whole area of operations and coordination
between faults diagnosis. Simulation results are confirmed the
validation of this algorithm.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Coordination, Current Signature Analysis, Fault Diagnosis, Permanent Magnet Synchronous Machine Drive, Wavelet Transform.
On-line Efficiency Optimization of Induction Machine Drive with Both Rotor and
Stator Resistances Estimation
by F. Farhani, C.
Ben Regaya, A. Zaafouri, A. Chaari
Vol. 5. n. 2, pp. 930-937
Abstract - The
minimization of the electric energy consumption has become a decisive
goal in the design of control systems, control and supervision while
maintaining the performance and features required by these systems. In
this perspective, this article proposes a new adaptive control of
induction machine aimed at reducing energy losses. We will therefore
present a new approach to online search of optimum magnetic flux that
promotes the energy loss reduction of the three-phase induction motor,
taking into account the robustness and stability of the global system.
The simulation in Simulink was used to validate the proposed approach.
The results show the effectiveness of the method which can be easily
adapted to any other machine, without great complexity.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Adaptive Flux Control, Full Order Observer, Induction Machine, IFOC, Power Save.
Comparison between Two Methods for Adjusting the Rotor Resistance
by C.
Ben Regaya, F. Farhani, A. Zaafouri, A. Chaari
Vol. 5. n. 2, pp. 938-944
Abstract - In this
paper, the indirect vector control with rotor resistance adaptation is
presented, since the command performance depends greatly on the
variation of rotor time constant, therefore two adaptive mechanisms have
been proposed to identify this constant in order to have a robust
control that reflects this kind of change while ensuring decoupling
between flux and torque. The first adjustment mechanism based on fuzzy
logic, a study was made to present the steps needed to design a fuzzy
controller of the rotor resistance. The second mechanism has been
developed from an adaptive observer to design an observer for the rotor
resistance. Finally, tests show the robust performance of the control
law obtained by these two types of adaptive mechanisms.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Adaptive Observer, Fuzzy Logic, Induction Machine, Indirect Vector Control, Rotor Time Constant.
Comparison of Control Strategies of Wind Turbines with Permanent Magnet
Synchronous Generator
by M. J.
Mercado-Vargas, D. Gómez-Lorente, O. Rabaza, E. Alameda-Hernandez
Vol. 5. n. 2, pp. 945-952
Abstract - This
paper studies the behaviour of a wind turbine with permanent magnet
synchronous generator connected to the grid, under different control
strategies, in the presence of a wind fluctuation or a grid disturbance.
These control strategies applied to the generator-side converter include
rotor speed, torque and generator power control. The low-voltage
ride-through capability of the wind turbine is also evaluated. MATLAB/Simulink
has been used for the simulations and the results show that generator
power control strategy combined with the pitch angle control strategy,
that activates when the rotational speed is overrated, provide the best
performance in power stability studies.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Generator Power Control, Low-Voltage Ride-Through Capability, Permanent Magnet Synchronous Generator, Pitch Angle Control, Rotor Speed Control, Torque Control.
Cox
Model in Reliability Theory of Power Oil Transformers
by Miloš Hammer,
Jakub Ertl, Ondřej Janda
Vol. 5. n. 2, pp. 953-958
Abstract -
Reliability assessment of power oil transformers is very important
analysis in technical practice. Reliability characteristics explain how
to service machine and save financial means. In the first part of this
paper, the Cox model for reliability characteristics modeling is
described. In the second part of this paper, the Cox model is enhanced
by factor analysis which allows to estimate all reliability
characteristics. Obtained results are compared with real behavior of
tested power oil transformers during operation.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Power Oil Transformer, Reliability Assessment, Cox Model, Factor Analysis.
Detection of Broken Bars in Railway Induction Motors Fed by Frequency Converter
Using Spectral Analysis of Line Current
by Oscar
Duque-Perez, Daniel Morinigo-Sotelo, Marcelo Perez-Alonso
Vol. 5. n. 2, pp. 959-966
Abstract - Induction
motors fed by Voltage Source Inverters are widely used nowadays in
railway locomotives. Detection of faults in induction motors based on
spectral analysis of line current is a well-known technique in the case
of sinusoidal supply, but the use of inverters makes necessary to modify
the existing fault detection methods. In this paper, it is analysed the
influence of broken bars on line current spectra and propose a
formulation for the calculation of the characteristic fault frequencies.
Next, it is experimentally verified this formulation with tests of
locomotive motor drives fed by a six-step converter. The proposed
technique can be used on-line, providing early detection of faults
avoiding catastrophic consequences and is specially adapted for the
maintenance personnel, since a fault condition is detected observing the
spectra. So it is not necessary to perform precise measures or further
spectral analysis.
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Keywords: Railway Locomotives, Fault Diagnosis, Induction Motors, Monitoring, Spectral Analysis.
The Effect of Generator Modeling on Multi Machine Power System Stability and PSS
Tuning
by Ebrahim Babaei,
Leila Mohammadian, Meisam Sadeghi
Vol. 5. n. 2, pp. 967-981
Abstract - In this
paper in order to investigate the effect of generators modeling in
stability analysis of multi machine power systems and PSS tuning, a
sample 4-machine 2-area system (Kundur system) have analyzed and two
orders of generator models (4th and 6th order) have been applied in
power system modeling. Firstly, the dynamic stability of multi machine
power system has been analyzed using power system state matrix. Then,
the eigen values and damping factor of oscillatory modes have been
derived and compared according to the types and order of generator
modeling. Then, in order to examine the effect of excitation system in
oscillating modes movement and their damping factor, three usual samples
of excitation systems according to IEEE standards have been added to
generators model. Afterwards, by considering the new state matrix of
system and new obtained modes, the effect of each kind of excitation
system in power system stability, local and inter area modes movement
have been analyzed and compared. Furthermore, the effects of these
parameters in PSS placement have been mentioned. Also, by according to
the PSS location, tuning of PSS parameters by considering 4th and 5th
order of generator models and excitation system has been done and it’s
effect in power system stability have been analyzed.
Copyright © 2012 Praise Worthy Prize S.r.l. -
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Keywords: Dynamic Stability, Multi Machine, Generator Model, Excitation System, PSS.
Fuel-Cell/Battery Hybrid Vehicle Modeling and Fuzzy Controller Design for Power
Management
by P. Naderi, A.
Samimi
Vol. 5. n. 2, pp. 982-990
Abstract - A
Fuel-Cell/Battery hybrid vehicle with an intelligent controller has been
designed in this work. Using electrical machine instead to gasoline
engine, the requested power for driving and braking can produce by
electrical machine and regenerative braking is possible. Considering a
Fuel-cell connected to a battery pack via a DC/DC converter, control of
the fuel-cell power can be done by converter switching. Using of power
demand feedback, the real time controller task is base on the power
demand at the previous time step. In addition, braking pedal
displacement and the battery state of charge are considered for power
split between the batteries and fuel cell. Finally, a series of
simulation results shows the effectiveness of proposed method and
performance of modeled vehicle.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Fuel-Cell.
The Consideration Nonlinear Characteristic of Soil around Grounding Electrode by
Finite Element Method
by Rasim Gačanović,
Hamid Zildžo
Vol. 5. n. 2, pp. 991-997
Abstract - The goal
of this paper is to calculate the response of an elementary grounding
electrode under high speed and high intensity current impulse. This
consideration takes into account some nonlinear characteristic of the
soil around the electrode. This paper presents the solution to this
problem in the time domain by Finite Element Method using the “Comsol”
program. In this case the ionization phenomenon around the grounding
electrode is taken into calculation through the function of varying the
conductivity of every soil element vs. electric field intensity.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Grounding Electrode, Soil, Conductivity, Response, Finite Element Method, Current Impulse, Ionization, Electric Field Intensity.
A De-Noising Scheme for Wavelet Based Power Quality Disturbances Detection and
Classification System
by Chuah Heng Keow,
Perumal Nallagownden, K. S. Rama Rao
Vol. 5. n. 2, pp. 998-1004
Abstract - A Power
quality Classification system can easily extract features from the
second detail signal obtained after Discrete Wavelet Transform and using
these features to construct a Rule Based Algorithm for identifying types
of disturbances that exist in the captured power signal. Unfortunately,
the signal under investigation is often polluted by noises, rendering
the extraction of features a difficult task, especially if the noises
have high frequency spectrum which overlaps with the frequency of the
disturbances. The performance of the Classification system would be
greatly degraded, due to the difficulty in distinguishing the noises and
the disturbances. To overcome this difficulty and to improve the
performance of the system, this paper proposes a suitable de-noising
scheme to be integrated into the system so that the classification
system is still workable in a noisy environment. In the proposed
de-nosing scheme, a noise shrinkage threshold used to minimize or
eliminate the noise coefficient in the 2nd compressed detail obtained
after discrete wavelet transform is determined adoptively according to
the background noises of the signal. The ability of the Classification
system can then be restored. To test the effectiveness of the de-noising
scheme, the system is tested with noise-added disturbance signals
generated by MATLAB programming language and some field data obtained
from the PQDIF resource centre. Using the de-noising scheme proposed in
this paper, a higher tolerance to noise can be achieved by the Power
Quality Problem Classification system.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Power Quality Classification System, De-Noising Scheme, Noise
Shrinkage Threshold, Discrete Wavelet Transform.
Modeling of on-Chip Solenoid Integrated Inductor for High Q-Factor
Applications
by M. Adibzadeh,
E. Kargaran, H. R. Naghizadeh, A. Golmakani
Vol. 5. n. 2, pp. 1005-1008
Abstract - A new
structure of the solenoid inductor is presented in this paper. The
proposed solenoid inductor has been simulated in a standard 0.18um
one-poly-six-metal (1P6M) CMOS process. The proposed inductor products
higher quality factor and inductance value in compare with the
traditional designs. Furthermore, the new structure shows more
improvement in the peak of quality factor so the number of turn
increases.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Solenoid Inductor, High Quality, High Inductance, On Chip.
A MIMO State Space Non Linear Modelling of a PEM Fuel Cell With a DC/DC Boost
Converter
by Sami Ben Slama,
Abderrahmen Ben Chaabene, Adnane Cherif
Vol. 5. n. 2, pp. 1009-1016
Abstract -
The aim of this paper is to propose an approach of Multi Input Multi
Output (MIMO) state space modeling of a Proton Exchange Membrane Fuel
Cell (PEMFC) with a DC/DC boost converter. The developed model was used
to implement a Pulse-Width Modulation (PWM) control strategy in order to
stabilize the output voltage. Simulation results and a comparative study
of the global system were given.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Proton Exchange Membrane Fuel Cell, DC/DC Converter, Pulse-Width Modulation, Control.
Optimization of Inclination of a Cavity Formed By Three-Cylinders in a Natural
Convection
by B. Tahri, K.
Bouhadef, A. Slimani, M. Rebhi
Vol. 5. n. 2, pp. 1017-1023
Abstract - A
numerical study of two-dimensional steady state natural laminar
convection inside an enclosure formed by three cylinders is presented.
The bottom wall, which is represented by both internal cylinders, is
heated with a uniform heat flux; the top wall formed by the outside
cylinder is thermally insulated. The contained fluid is air. The aim of
this work is to study the transfers which occur by natural convection in
the cavity formed by three cylinders. Another purpose is to bring to
light the influence of the slope of the surrounding wall characterized
by the angle (α), on the structure of the fluid flow, and on the
variations of both temperature and the local and average (Nusselt)
numbers at the level of the non-uniform surface formed by the two inner
cylinders . The influence of the Rayleigh number is also presented.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Natural Convection, Half-Cylinder, Non-Uniform Wall.
Simulation of Longitudinal Surface Settlement Due to Tunnelling Using Artificial
Neural Network
by A. Marto, M.
Hajihassani, R. Kalatehjari, E. Namazi, H. Sohaei
Vol. 5. n. 2, pp. 1024-1031
Abstract - A series
of artificial neural networks modelling was conducted to investigate the
ground deformation induced by tunnelling along the line 2 of Karaj urban
railway, Iran. The tunnels were excavated using New Austrian Tunnelling
Method. During excavation, surface settlement was monitored using
optical survey points installed on the centre, left and right sides of
the tunnel axis. The measured data have been used to establish an
artificial neural network model to predict longitudinal surface
settlement. This paper focuses on the prediction of ground deformation
due to tunnelling using artificial neural networks, particularly
longitudinal settlements in relation to the ground condition and
tunnelling method. The obtained results demonstrate that artificial
neural networks are applicable techniques for predicting longitudinal
surface settlement due to tunnelling.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Longitudinal Surface Settlement, New Austrian Tunnelling Method, Artificial Neural Networks, Karaj Urban Railway.
Integrated Robotic System for Indoor Spatial Perception and Navigation for the
Blind
by Mohammad A. Al-Khedher
Vol. 5. n. 2, pp.
1032-1037
Abstract - An
interactive intelligent robotic system is presented to assist blind
people with indoor activities. The integrated system employs practical
human scene perception characteristics to achieve intelligent guidance
through indoor environment. This system models the environment using
topological maps and learns these cognitive maps gradually via a
lead-through algorithm. A first-depth searching algorithm is implemented
to achieve an optimized selected path. Multiple navigation sensors were
utilized for obstacle detection and avoidance in addition to
localization purposes. Sensors limitations and errors were corrected by
implementing a sensor fusion algorithm using discrete Kalman filter.
Also, visual landmarks were used as beacons for internal error
correction in odometry and mapping. A comprehensive structural design of
the robot is accomplished; besides, a human-robot interaction unit is
designed using speech synthesis and recognition modules. The proposed
system represents an integrated technology to assist the blind with
daily indoor activities and to facilitate performing necessary personal
tasks.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Blind Navigation Robot, Sensor Fusion, Discrete Kalman Filter, Human-Robot Interaction.
Velocity Tracking Control of a Two-Wheeled Inverted Pendulum Robot: A
Comparative Assessment between Partial Feedback Linearization and LQR Control
Schemes
by M. Muhammad, S.
Buyamin, M. N. Ahmad, S.W. Nawawi, Z. Ibrahim
Vol. 5. n. 2, pp. 1038-1048
Abstract - A
Two-Wheeled Inverted Pendulum (TWIP) mobile robot attracted the interest
of researchers worldwide due to its nonlinear and unstable dynamics.
Literature review shows that, most of the nonlinear controllers proposed
for the TWIP mobile robot are based on dynamic model derived using
Lagrange approach. Thus, this paper shows the study of the TWIP mobile
robot using Kane’s method. The paper investigates and compares the
performance of nonlinear (partial feedback linearization (PFL)) and
linear (linear quadratic regulator (LQR)) control schemes in controlling
a TWIP mobile robot. The nonlinear dynamical equations of the TWIP
mobile robot were first derived using Kane’s Method. The dynamical
equations were then linearized around an operating point. Two
controllers were designed for the TWIP mobile robot. The first
controller is partial feedback linearization (PFL), while the second
controller is linear quadratic regulator (LQR). The performance of the
two controllers was compared in terms of reference command tracking and
parameter variation via simulations.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Linear Quadratic Regulator (LQR), Partial Feedback Linearization (PFL), Two-Wheeled Inverted Pendulum (TWIP).
Simulation of Adaptive Temperature Control in a Tubular Chemical Reactor
by P. Dostál, J.
Vojtěšek, V. Bobál
Vol. 5. n. 2, pp. 1049-1058
Abstract - The paper
deals with continuous-time adaptive control of a tubular chemical
reactor with the countercurrent cooling as a nonlinear single input –
single output process. The mean reactant temperature and the output
reactant temperature are chosen as the controlled outputs, and, the
coolant flow rate as the control input. The nonlinear model of the
reactor is approximated by an external linear model with a structure
chosen on the basis of controlled outputs step responses. Its parameters
are estimated via corresponding delta model. The control system
structure with two feedback controllers is considered. The resulting
controllers are derived using polynomial approach. The method is tested
on a mathematical model of the tubular chemical reactor.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Tubular Chemical Reactor, Approximate Linear Model, Parameter Estimation, Polynomial Approach, Pole Assignment.
Mobile Robot Navigation Modelling, Control and Applications
by Leonimer Flávio
de Melo, Silas Franco dos Reis Alves, João Maurício Rosário
Vol. 5. n. 2, pp. 1059-1068
Abstract - This work
presents and discusses the main topics involved on the design of a
mobile robot system and focus on the control and navigation systems for
autonomous mobile robots. Introduces the main aspects of the Robot
design, which is a holistic vision about all the steps of the
development process of an autonomous mobile robot; discusses the
problems addressed to the conceptualization of the mobile robot physical
structure and its relation to the world. Presents the dynamic and
control analysis for navigation robots with kinematic and dynamic model
and, for final, presents applications for a robotic platform of
Automation, Simulation, Control and Supervision of Mobile Robots
Navigation, with studies of dynamic and kinematic modelling, control
algorithms, mechanisms for mapping and localization, trajectory planning
and the platform simulator.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Mobile Robots Navigation, Embedded Control Architectures, Mobile Robots Dynamic and Kinematic Modelling and Simulation.
Application of Stochastic Methods for the Identification of Mechanical
Parameters of Soil
by M. Moussaoui,
S. Messast
Vol. 5. n. 2, pp. 1069-1074
Abstract - The
problem of the choice of soil parameters is a delicate task, it requires
a lot of experience. To answer this question, methods of identification
of parameters, based on the principle of inverse analysis are developed
which consist to adjust a numerical model on observed experimental data.
The objective of this work is to apply the principle of inverse analysis
using stochastic optimization methods (genetic algorithm and hybrid
genetic algorithm with tabu search) to identify the parameters of the
behavior model of soil Mohr-Coulomb, from a synthetic excavation
problem.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Hybrid Genetic Algorithm, Genetic Algorithm, Mohr- Coulomb, Optimization, Stochastic Methods.
Trajectory Tracking and Disturbance Rejection for Nonlinear Periodic Process: a
Nonlinear Gain-Scheduling Design
by Charfeddine
Samia, Jerbi Houssem
Vol. 5. n. 2, pp. 1075-1083
Abstract - An
advanced strategy for the design of nonlinear controllers of an
asymptotic trajectory tracking and/or disturbance rejection is
presented. This allows the control of oscillations in isothermal
continuous stirred tank reactor. Based on the input-output feedback
linearization technique and a gain-scheduling approach, a feedback
linearzing gain-scheduling control synthesis is implemented. An input
control which guarantees closeness and swiftness along a desired
trajectory is consequently constructed. The control design relies
particularly on reversing trajectory method for estimating an asymptotic
region of stability around the desired operating points. Furthermore, a
Lyapunov parameter of estimator is designed and implemented to ensure
the robustness of the proposed approach. The explored control scheme
provides high performance versus parameter uncertainties and load
disturbances. Our results are illustrated via a numerical simulation.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Attraction Domain, Chemical Process, Disturbance Rejection, Feedback Linearization, Gain-Scheduling, Lyapunov Function, Periodic Systems, Trajectory Tracking.
Solution
by the Finite Volume Method of Coupling Electromagnetic and Thermal Phenomena
Applied to the Induction Plasma
by A.
Tibouche, A. Bourouina, K. Boudeghdegh
Vol. 5. n. 2, pp. 1084-1087
Abstract - The aim
of our work is the development of a mathematical model for induction
plasma. The differential equations that describe the three phenomena,
thermal, electromagnetic and flow are respectively the heat diffusion
equation with velocity, Maxwell’s equations and the equations of Navier-Stokes.
The nonlinear laws of behavior, which exclude all resolution to the
alone classic, sense only the numerical simulation can make it possible
to obtain the solution. The establishment of the general equations to
solve is made by the finite volume method (FVM) with nonlinear boundary
conditions. The application of our model for current feeding permits us
to plot the curves showing the thermal phenomena for the energy source
distribution and flow velocity of the plasma gas.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Inductor Current, Frequency, Electromagnetic Power, Flow Velocity, Electrical And Thermal Conductivity, Temperature.
Extended Finite Element Method for Moving Discontinuities
by Y.
Abdelaziz, K. Bendahane, A. Chabani
Vol. 5. n. 2, pp. 1088-1091
Abstract - In this
work, we introduce an implementation of the X-FEM method for
discontinuity problems within the finite element software XFr. The
proposed implantation approach overcomes a number of difficulties
associated with the use of standard finite element method. Several
numerical examples illustrating the main features and the computational
efficiency of the XFr program for discontinuity propagation are
presented.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Discontinuities, Fracture Mechanics, Singularity, Extended Finite Element, Level Sets Method.
A Power Efficient Multi-Standard Continuous-Time ∑∆ Converter for 4G Radios
by Mojtaba
Khoddam, Esmaeil Najafi Aghdam
Vol. 5. n. 2, pp. 1092-1100
Abstract - This
paper presents a low-power digitally controllable, fully reconfigurable
continuous time delta sigma modulator with using a continuous time
quantizer with no clock at the system level for low-voltage 4G Software
defined radio applications. Operation of the proposed quantizer in both
the FF and the FB topologies has been explored toward low power analog
to digital implementations. The proposed modulator uses different
combination of design parameters depends on different specifications
which needed. The simulation results have confirmed that power is saved
in every mode compared to previously published multi-mode designs due to
clock less nature of proposed quantizer.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Analog to Digital Converter ADC, Continuous Time Delta Sigma Modulator CT-DSM, Reconfigurable Delta Sigma Modulator, Software Defined Radio (SDR).
Low-Frequency
Dimming Control for HID Lamps
by M. N. Nehdi, A.
Chammam, W. Nsibi, H. Elloumi, G. Zissis
Vol. 5. n. 2, pp. 1101-1106
Abstract - There is
an increasing demand to maximize energy savings of lighting sources.
While High- Intensity-Discharge (HID) lamps are inherently very
efficient, many users would like to further increase the energy savings
of HID lamps through dimming. This paper presents a two-stage electronic
ballast for HID lamps based on an adjustable rectifier followed a full
bridge inverter. It is able to offer input utility current shaping with
low frequency square wave sources without accompanying acoustic
resonance. Dimming control method by varying DC link voltage and
Duty-cycle control are utilized in the designed ballast. Theoretical
analysis and experimental results of prototype ballast for 400W HID lamp
are presented. They show the efficiency of the DC link voltage method
compared to the other method for the energy saving while preserving all
lighting requirement and gives a stable high-efficient lighting output.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: HID Lamps, Dimming Control, Electronic Ballast.
Characteristics of Breakdown Voltage of RBDP Olein and Envirotemp FR3 Mixtures Under AC Voltage
by Kiasatina Azmi, Mohamad Kamarol Mohd Jamil, Mohd Azmier Ahmad
Vol. 5. n. 2, pp. 1107-1114
Abstract - This paper reported the experimental result of breakdown voltage characteristics of Refined, Bleach and Deodorized Palm Olein (RBDP Olein) with 10-50% of Envirotemp FR3mixture. The experiment was conducted at temperature of 40˚C to 100˚C under quasi-uniform electric field of AC applied voltage. In addition, the dissipation factor, water content, and the chemical compositions of the oil mixture were also investigated. Experimental result for RBDP Olein/FR3 mixtures revealed the increase trend of breakdown voltage with the increasing of FR3 ratio. All the breakdown voltage of RBDP Olein/FR3 mixtures are fulfill the IEC 156 standard which is greater than 30kV. The result of dissipation factor shows the increment trend for the RBDP Olein with ascending ratio of FR3 mixture. Analysis of chemical composition of RBDP Olein/FR3 mixtures shows the decrease of palmitic acid and significant increment of linoleic acid and linoleic acid. Gas Chromatography result also reveals the presence of BHT which is antioxidant additives in FR3 liquid. The water content in RBDP Olein/FR3 mixtures shows the decrease trend with the increase of FR3 ratio that yield to higher breakdown voltage of the oil mixture. The antioxidant presence in FR3 might be affecting the result of water content in this experiment.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: RBDP Olein, FR3, Breakdown Voltage, Dissipation Factor, Water Content, Antioxidant.
Hole
Location Determination in Insulation by Using Ultrasonic
by E.
Goodarzy, B. Vahidi
Vol. 5. n. 2, pp. 1115-1121
Abstract - Due to
the important role of insulation in insulating high voltage equipments
and devices, safety and health of them become an important problem. One
of the cases that causes problem in insulation is existence of small
holes inside insulation. This holes decrease insulating strength. There
are different methods for detecting these defects. According to
conventional methods of non-destructive test which are based on
ultrasound waves, a novel device was invented for detecting insulation
defects.The main advantages of this new method are the ability to detect
very small defects, locate their position, have high speed in detecting
defect and most important of all is that this method is non-destructive
and has low cost comparing to other methods.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Ultrasonic, Cavity, Insulation.
A
Predictive Control of a DPWM Quasi Resonant Inverter Feeding Induction Motors
by S.
Meo, A. Perfetto
Vol. 5. n. 2, pp. 1122-1127
Abstract - The paper
deals with a discrete pulse modulation (DPWM) strategy oriented to
control a quasi resonant inverter (QRI) feeding induction machines. The
QRI is a very simple configuration which has a switch connected between
dc voltage source and resonant inductor. The proposed predictive control
algorithm is able to predict step by step the inverter state switching
and to control inserted switch of the (QRI), according to field oriented
strategy. Because of the different periods of the QRI resonant cycle and
of the sampling interval of the adopted control algorithm the reference
space vector is adequately modulated. The paper shows the best dynamic
performances obtainable by means of the use of a full vectorial control
of induction machines feed by a quasi resonant dc link inverter.
Copyright © 2012 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords: Quasi Resonant Dc Link Inverter, Digital Control, Induction Motor, Soft Switching Inverter, Zero Switching Loss Inverter.
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