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International Review on Modelling and Simulations Vol. 5 N. 4---- Part A International Review on Modelling and Simulations Vol. 5 N. 4---- Part B
International Review on Modelling and Simulations (Vol. 5 N. 4) - August 2012 - Papers (Part A)
International Review on Modelling and Simulations (Vol. 5 N. 4) - August 2012 - Papers (Part B)
International Review on Modelling and Simulations - Papers (Part A)
Nine-Level SHE-PWM VSC Based STATCOM for VAR Compensation Vol. 5. n. 4, pp. 1375-1381
Abstract - The paper
presents a nine-level selective harmonic elimination pulse width
modulation (SHE-PWM) cascaded voltage source converter based STATCOM
system. The structure allows direct connection to the grid without the
need of any step-up transformers. The converter is controlled with the
SHE-PWM technique which provides an elimination to lower order harmonics
to improve output waveforms and furthermore, allowing the use of smaller
filters. The control methods used for voltage, stress balance and dc
voltage regulation are also described in the paper. The operations and
the performance of the STATCOM for reactive power (VAR) compensation are
validated by simulation studies using SIMULINK/MATLAB software which
confirm the theoretical predictions.
Keywords: Multilevel Converter, Pulse Width Modulation, STATCOM, Selective Harmonic Elimination, Control.
Design and Implementation of Clocked Sequential Circuit to Flying Capacitor
Multilevel Inverter Vol. 5. n. 4, pp. 1382-1388
Abstract - This
paper focused on the development of digital logic algorithm for generate
the pulse width modulation and fed flying capacitor multilevel inverter
(FCMLI). For improving the performance of flying capacitor multilevel
inverter, a clocked sequential circuit has implemented. The proposed
method has been designed a seven-level flying capacitor multilevel
inverter and controlled by using digital logic devices. The clocked
sequential circuit has been exposed to give superior performance in load
voltage, total harmonics distortion and capacitor voltage fluctuation.
The clocked sequential circuits based multilevel inverters offers
several advantages like simplicity of control circuitry-level,
simplicity of fault identification, low-cost, and less space and low
power consumption. The performance of proposed strategy is confirmed
through simulation investigations.
Keywords: Clocked Sequential Circuits, Total Harmonic Distortion, Flying Capacitor Multilevel Inverter, Pulse Width Modulation.
Modelling and Simulation of Non-Controlled and Controlled Rectifiers using
Simulink Vol. 5. n. 4, pp. 1389-1396
Abstract - This
paper presents a simple and original method in order to simulate the
behaviour of AC to DC converters with Matlab-Simulink. This approach
takes into account overlap phenomenon, continuous and discontinuous
conduction mode. The AC to DC converter is presented as a block (voltage
input and voltage output) which can be inserted in a complex structure.
The simplicity and the low computing-time of this method make it an
interesting alternative to the Matlab’s Power-Systems toolbox and hybrid
simulation with PSIM and Matlab. Simulations results for non-controlled
and controlled converters are presented and compared to experimental
results.
Keywords: AC/DC Conversion, Power Electronics Simulation, Matlab Simulink.
Voltage Regulation and Harmonic Reduction Using Multilevel Inverter as Series
Active Filter Vol. 5. n. 4, pp. 1397-1404
Abstract - This
paper presents a cascaded H-bridge multilevel inverter based series
active filter intended for installation on industrial and utility power
distribution systems. The control strategy based on Synchronous
Reference Frame theory is designed so that the voltage injected by
active filter is able to mitigate the voltage sag, imbalance in the
source voltage and reduce the harmonic content. The active power filter
which can be used under the condition of voltage sag and unbalanced or
distorted source voltages can compensate the harmonics, reactive and
negative sequence currents.Simulations have been carried out on MATLAB/Simulink
platform with various types of loads. The analysis and simulation
results under balanced, unbalanced load, three phase faulty condition
and dynamic loading are presented in this paper.
Keywords: Series Active Filter, Multilevel Inverter, Three Phase Cascaded H-Bridge Inverter, Synchronous Reference Frame Theory, Harmonic Distortion, Voltage Regulation.
Vol. 5. n. 4, pp. 1405-1415
Abstract - This
paper proposes a space vector pulse width modulation (SVPWM) technique
for a three-phase three-level neutral point clamped (NPC) inverter which
is used in a photovoltaic system. The system comprises a photovoltaic
array, DC/DC converter, DC/AC inverter and load. The SVPWM can very much
increase the obtainable DC voltage utilization ratio and a better total
harmonic distortion (THD) factor as compared to other pulse width
modulation techniques. Maximum power point tracking (MPPT) technique is
utilized to obtain a suitable buck and boost, high efficiency and
minimum ripple voltage necessary for residential power production
applications, grid / standalone or any other system. The proposed method
is simulated using MATLAB/simulink. Experiments using LabVIEW DAQ card
validate the simulation results.
Keywords: PV Array, DC-DC Converter, SVPWM, Multilevel Inverter, Total Harmonic Distortion.
Simulation of a New Forward Converter Using SDSR Technology with High Efficiency Vol. 5. n. 4, pp. 1416-1421
Abstract - In this
study, a new forward converter with self driven synchronous
rectification (SDSR) with high efficiency and low output voltage has
been introduced. In the proposed converter, soft switching conditions (ZCS
turn on and ZVS turn off) for main switch, via an auxiliary circuit is
provided. However, auxiliary circuit does not use any extra switch and
as a result, extra driver is not needed. Since the number of turns of
auxiliary transformer is very low , so does not impose high conductive
loss of the proposed converter and in output circuit the two side
transistors switch with very low conductive loss are used and also soft
switching condition are prepared for them. The converter is controlled
by PWM (pulse width modulation) and as a result, implementing its
control circuit is very simple. To confirm theoretical analysis, the
introduced converter has been simulated by Pspice.
Keywords: Forward Converter, Soft Switching, Self Driven Synchronous Rectifier, Zero-Current Switching (ZCS), Zero-Voltage Switching (ZVC).
Automatic Power Factor Correction Using a modified Statcom as a Continuously
Controlled Capacitive Static VAR Compensator Vol. 5. n. 4, pp. 1422-1428
Abstract - In this
paper an automatic power factor correction system based on a new vision
to statcom concept is presented. The reactive component of the load
current is supplied by a statcom built of a halt-bridge voltage source
inverter feeding a reactor and shunted by two dc capacitors. The passive
components and control scheme of this configuration are approached in
such a manner that the devised statcom behaves as pure capacitive
impedance. The control strategy is based on governing the statcom
current by its modulation index, while the passive components are
designed such that all harmonic current harmonics are suppressed by the
statcom reactor. The modulation index is controlled linearly by a
precision gain-controlled linear amplifier which is specifically
designed for this compensator and directly controlled by the load
reactive current component. Modeling and performance of the proposed
system was verified on PSpice.
Keywords: Compensator, Power Factor, Power Quality, Reactive Power, Statcom.
Comparative Study on Carrier over Lapping Bipolar PWM Strategies for Three Phase
Five Level Diode Clamped Inverter Vol. 5. n. 4, pp. 1429-1438
Abstract - This
paper presents the comparison of Carrier Overlapping Pulse Width
Modulation (COPWM) techniques for Diode Clamped Multi Level Inverter (DCMLI).
The DCMLI is controlled with Sinusoidal PWM (SPWM) technique, Third
Harmonic Injection (THI) PWM technique, Sixty degree PWM and Stepped
wave techniques with Carrier Overlapping (CO). The variation of Total
Harmonic Distortion (THD) in the output is observed for various
modulation indices. Simulation is performed using MATLAB-SIMULINK. It is
observed that COPWM-C strategy provides output with relatively low
distortion for all the four strategies developed. It is also found that
lowest distortion exists for stepped wave reference with COPWM-C
carrier. COPWM-A is also found to perform better since it provides
relatively higher fundamental RMS output voltage for all the four
references. De distortion exists for stepped wave reference with COPWM-C
carrier. COPWM-A is also found to perform better since it provides
relatively higher fundamental RMS output voltage for all the four
references. Depending on the performance measure required in a
particular application of chosen MLI, appropriate PWM strategies may be
employed.
Keywords: THD, DCMLI, Stepped, THIPWM, 60 degree PWM, COPWM.
A New Method for Calculating the Reference Current of Shunt Active Power Filters
Based on Recursive Discrete Fourier Transform Vol. 5. n. 4, pp. 1439-1446
Abstract - This
paper presents a new method based on the fundamental active current
component determined from a recursive discrete Fourier transform block.
The reference source current and the reference compensating current for
shunt active power filters is calculated based on this method to
eliminate harmonics, compensate the reactive power of the three-phase
diode bridge rectifier with RL load, and to increase power quality. An
interval type-2 fuzzy logic controller is used to maintain the DC-link
voltage at the reference value. The proposed method is presented and
applied to the control system of the voltage source shunt active power
filter to evaluate its performance.The results are compared with p-q
theory of other reference generation methods.The simulation results
confirm the effectiveness of this method in reducing total harmonic
distortion and reactive power.
Keywords: Shunt Active Power Filter, Interval Type-2 Fuzzy Logic Controller, Reference Source Current,Recursive Discrete Fourier Transform, Non-Linear Load.
Simulation of a New Zero Voltage Switching High Voltage Gain Converter Vol. 5. n. 4, pp. 1447-1453
Abstract - In this
paper, a new soft switching PWM converter with active clamp circuit and
high voltage gain is proposed. The active clamp circuit in this
converter provides soft switching conditions for both main and auxiliary
switches. All switches are PWM controlled which simplifies the control
implementation. The principle of operation and system analysis are
presented. The simulation results obtained from the proposed converter
verifies the theoretical analysis.
Keywords: Boost Converter, Cascade Connection, Zero-Voltage-Switching.
Neuro-Evolutionary Controller for Performance Enhancement of a Single Phase
Inverter Vol. 5. n. 4, pp. 1454-1459
Abstract - Power
Electronic inverters generate harmonics, which cause trouble in
Induction motor operation. 3rd harmonic, comparable to fundamental
voltage, gets eliminated in 3Φ circuit; however, remains active in 1Φ
circuits. Lower order harmonic elimination from inverter output is a
critical problem and continuous work is still undergoing on this topic.
The work presented here, deals with reduction of harmonics order,
3rd-11th, in output voltage of 1Φ inverter by MPM technique for
Selective Harmonic Elimination method (SHEM). Conventional method of
Newton-Raphson cannot give accurate pulse-positions as non-linearity is
involved in computation of transcendental equations. In this paper, a
Neuro-Evolutionary controller is designed for determination of trigger
Pulse positions for Harmonic minimization and fundamental voltage
maximization in 1Φ inverter output voltage. A significant improvement is
observed in output voltage spectrum if pulses are generated at positions
given by controller. Device ratings for the inverter get reduced
resulting in reduction of equipment cost. MATLAB simulation shows that
running performance of 1Φ Induction motor improves and torque can be
controlled as per requirements. This can make the cheap 1Φ IM to
conveniently replace costly PMAC motors in commercial appliances. This
shows feasibility of design of a controller for performance enhancement
of a single phase VSI.
Keywords: Controller, Evolutionary Programming, Harmonic Reduction, Neural Network, Single Phase Inverter.
Energy Balance of Optimized High Voltage Power Supply for Microwaves Generators
Used in Various Industrial Applications Vol. 5. n. 4, pp. 1460-1469
This paper deals with the energetic balance of a new
optimized power supply for microwaves generators, such as those found in
different industrial applications, through the use the model of the
transformer with EMTP code (ElectroMagnetic Transients Program). In this
article we will validate the functioning of the current power supply by
comparing the forms of waves obtained by EMTP with those obtained by the
experiment. Then, we will establish an energetic balance of the current
power supply by computing its performance. We will define a strategy of
optimization aims at restricting the study of the effect of simultaneous
variation of pertinent parameters on the magnetron current. This will
lead to find an optimized solution of the transformer. The later, with
reduced volume, weight, and therefore cost, will make the power supply
more economical. The conception of this new power supply uses a
transformer originating from the optimized solution, which will supply a
voltage doublers and current stabilizer. This doubler, in turn, will
supply one single magnetron. In order to make the saving of weight and
volume effective, it’s compulsory to keep an energy performance almost
identical to that found in the power supply currently used. In other
words, to have a magnetron functioning in its maximum power, an average
power close to 1220watts will be needed. In addition so as to protect
the magnetron from possible high voltage variation line (Imax
<1.2A), the regulation process of the magnetron current has been checked
up.
Keywords: Energy Balance, Performance, EMTP, Modeling, Optimization, Power Supply.
Operation of Three-Phase Induction Motor with Line to Ground Fault at its
Terminal Vol. 5. n. 4, pp. 1470-1474
Abstract - Single
line to ground fault at any terminal of a three-phase induction motor
blows out the fuse of the faulted phase to disconnect the voltage supply
of that phase but the open conductor may remain grounded at the fault
point. The motor gets a two-phase supply with the healthy phases
connected to the two terminals of the supply while the third terminal of
the motor is grounded. Very high negative sequence current is produced
at all values of slip. Difference in the magnitudes of current in the
three input terminals is small and the single phasing protection fails
to operate. In the normal single-phasing condition the open terminal
remains isolated from ground.
Keywords: 3-Phase Induction Motor, LG Fault at any Terminal, Negative Sequence Current, Protection against Single Phasing.
Modeling Methodology in View of Predicting Desynchronized Multi-Alternators
Behavior in Embarked Network Vol. 5. n. 4, pp. 1475-1485
Abstract - This
paper deals with an approach of modeling and simulation for
multi-alternators system in embarked electrical network. The system is
constituted by various alternators defined as generator or receptor with
strong interactions and its components can be linear or not. The
constraint of the simulator building is reproducing alternators coupling
behavior, in embedded network, as precisely as needed with a reduced
computing time. The proposed modeling methodology allows simulating
desynchronized alternators. The software benchmark developed under
Matlab/Simulink is a powerful tool able to predict the system dynamic
behavior in both transient and steady states. The proposed methodology
is illustrated thanks to an example of all electrical ship embarked
network.
Keywords: Embarked Electrical Network, Variable Topology, Dynamic Modeling, Computation Time Optimization, Simulation, Alternators Desynchronization.
Condition Assessment of Power Transformers- Logical Process of Decision Making
to Successful Diagnosis Vol. 5. n. 4, pp. 1486-1490
Abstract - Power
transformers are one of the most important and vital apparatus in power
plants, transmission lines and distribution networks which any failures
into these elements directly reduce network reliability and increase
maintenance costs. Consequently, condition monitoring, fault diagnosis
and maintenance of power transformers are increasingly developed. Having
a systematic manner and specified framework is the most important
requirement to reach a successful fault diagnosis. This paper is focused
on how to deal with the problem and how to make decisions facing with a
suspected transformer. In this regard, available requirements and
assessment methods for monitoring and maintenance of transformers are
described and classified briefly. Afterwards, field experiences on a
230/63kV, 125 MVA power transformer are represented. Applied manners and
corresponding decisions can be valuable and helpful for the engineers
who work on power transformers.
Keywords: Power Transformer, Fault Diagnosis, Transformer Tensions.
Sensorless Control of Two Mechanical Coupled BLDC Motors for Enhancement of
Electrical Drives Efficiency Vol. 5. n. 4, pp. 1491-1499
Abstract - Maximum
efficiency of a conventional electric motor normally takes place near
its rated load and its efficiency decreases as the motor load reduces.
So for the applications such as the submarine propeller systems in which
the motor output power and its speed vary over a wide range, the motor
efficiency decreases significantly at low speeds. As we will show in the
section III, by the help of a design in which one large brushless dc (BLDC)
motor is replaced by two BLDC motors with different rated powers, the
efficiency can be improved. When these two BLDC motors are mechanically
coupled, due to different characteristics of the motors and also
sensorless control of them, a complex controller is required to control
this two-input/two-output system in which we wish to adjust the desired
speed and simultaneously share the variable load between the motors. To
realize this controller, it is shown that the controller can
considerably be simplified by separation of this MIMO system into two
SISO systems and also selecting a proper sensorless control algorithm
for correct driving of the BLDC motors. Finally it is shown that we can
propose a stable sensorless controller -that improves the efficiency of
electrical drives- by using these simplified controller and sensorless
control algorithm.
Keywords: Current Commutation, Flux Linkage, Propulsion System, Sensorless Control.
Study and Simulation of PMBLDC Motors as the Proper Choice for Electric and
Hybrid Electric Vehicles Vol. 5. n. 4, pp. 1500-1509
Abstract - Electric
Motor Drive is considered as the most important part of the Electric
Propulsion System in manufacturing of EVs and HEVs. So, appropriate
selection of electric motor drive in addition to achieving the ideal and
proper vehicle, we can use the energy sources perfectly. One of the main
problems of the EVs and HEVs is the unsuitable performance of the
electric motor in electric propulsion system of these vehicles. This
article, with the aim of EVs and HEVs technology development, has
addressed these problem by selecting and utilizing the proper electric
motor. Investigations which have been carried out in this paper are
based on the comparisons between structure and performance of four
different types of electric motors including: DC Motors, Induction
Motors, Switched Reluctance Motors, and Permanent Magnet Brushless
Motors. In these comparisons by investigating some of essential
characteristics, including: starting torque, power density, over loading
tolerate, regenerative braking capability and etc, the PMBLDC motors are
selected as the better choice for utilizing in the electric propulsion
system. Finally, the performance of this motor for the Extra Urban
Driving Cycle and Emission Certification of light duty vehicles in
Europe which called EUDC+ECE driving cycle, and three speed and torque
profile which have various conditions, has been simulated in MATLAB/Simulink.
Keywords: Electric and Hybrid Electric Vehicle, Electric Motor, PM BLDC, Electric Propulsion System.
Control the Flywheel Storage System by Fuzzy Logic Associated with the Wind
Generator Vol. 5. n. 4, pp. 1510-1516
Abstract -
Conversion system of wind energy has become a focal point in the search
for renewable energy sources. This article then exhibits a study of the
overall operation of a wind generator to provide a constant power or
variable the consumer demand while providing services system. In order
to provide system services, we consider a variable speed wind turbine
coupled to a double-fed induction generator (DFIG) combined with energy
storage system. We consider the Flywheel Energy Storage System (FESS)
based on fuzzy logic controlled by IM. Due to the use of power
converters, the double fed induction generator and the storage system
are electrically coupled by a DC bus. Simulation results showing the
benefits of using energy storage.
Keywords: Wind Energy, Doubly Fed Induction Generator (DFIG), Induction Machine (IM), Flywheel Energy Storage System (FESS), Fuzzy Logic Controller (FLC).
Extension of Architecture of Single-Pulse Controller to Drive Linear Switched
Reluctance Motor Vol. 5. n. 4, pp. 1517-1523
Abstract - In this
study, the performance of longitudinal flux linear switched reluctance
motor (LSRM) using an extension in the aarchitecture of single-pulse
controller is analysed. In proposed method, a controller is implemented
and the duty cycle is used for two series converters. LSRM using
extension method according to Matlab results has the smooth current
profile. The smooth current increases the instantaneous driving force of
LSRM. The peak value of the current decreases using the proposed method
so the primary core of LSRM is saturated at higher load. The proposed
method improves the speed characteristic of the motor, smooths the
current profile and enhances the mechanical performance of LSRM.
Keywords: Linear Switched Reluctance Motor, Longitudinal Flux, Architecture Of Single-Pulse Controller.
Electric Vehicle Powertrain Analysis: Comparison between PMSM and HESM Vol. 5. n. 4, pp. 1524-1531
Abstract - Autonomy
is one of the key points for the electric vehicles commercial success.
One of the solutions is to reduce the electric powertrain consumption by
the efficiency improvement. This paper presents a comparative study
between a powertrain driven by a standard Permanent Magnet Synchronous
Motor (PMSM) drive and a Hybrid Excitation Synchronous Motor (HESM) one.
Simulation results for an urban cycle prove that the HESM drive has
lower copper losses (thanks to the optimization of the flux through the
DC excitation current), therefore a better efficiency is obtained.
Keywords: Permanent Magnet Synchronous Motor, Hybrid Excitation Synchronous Motor, Electric Vehicle, Efficiency, Copper Losses, Vector Control.
Modified Gibbs Sampler Procedure for Bearing-Only Multitarget Tracking Vol. 5. n. 4, pp. 1532-1540
Abstract - While
Probabilistic MHT (PMHT) highly reduces computational burden by avoiding
enumeration of all possible data association events, its implementation
still suffers from intractable manifold integrals. MCMC particle
filters, rendering the task of PMHT implementation, found it difficult
to face with both data association uncertainty and violations of the
presumptions of no more than one measurement could be assigned to a
target at each time step. Coping with these difficulties, we suggest a
modified Gibbs sampling approach that utilizes current measurement
information efficiently to estimate PMHT parameters recursively. We use
scenarios of Bearing-Only multi-target tracking to compare our proposed
method with the famous counterpart Gibbs sampler method.
Keywords: Probabilistic MHT, Modified Gibbs Sampler, Bearing-Only Multi-Target Tracking, Gaussian Approximate to the Optimal Proposal Density.
Vol. 5. n. 4, pp. 1541-1549
Abstract - This work analyses the effect of image charges and dielectric coating on metallic particle movement in a Three Phase Common Enclosure Gas Insulated Busduct(GIB) with electric field calculated using Charge Simulation Method(CSM). The presence of free metallic particles in GIB can result in loss of as much as 90% of the SF6 gas dielectric strength and can be a problem with Gas Insulated Substations(GIS) operating at high electric fields. A study of CIGRE group suggests that 20% of failures in GIS are due to the existence of various metallic contaminations in the form of loose particles. The purpose of this paper is to develop techniques for formulating the basic equations that will govern the movement of metallic particles in a dielectric coated/uncoated GIB. Numerical techniques have been developed to describe the effect of image charges and dielectric coating on the particle movement. The simulation has been carried out to obtain the particle trajectories at various voltages on Aluminium and Copper particles. From the results it is observed that in a Gas Insulated Busduct the maximum height reached by a free conducting particle without Image Charge Effect is less than with image charge effect and also observed that dielectric coating on enclosure improves the insulation performance by reducing the movement of free conducting particles. The results have been analyzed and presented in this paper.
Keywords: Three Phase Gas Insulated Busduct, Electric Field, Charge Simulation Method, Free Metallic Particles, Image Charges, Particle Movement.
The Same Phase Method to Suppress the Triple Transition Reflection of
Littlewood-Paley Wavelet Transformation Device of SAW Vol. 5. n. 4, pp. 1550-1554
Abstract - A Wavelet
transformation (WT) device of Surface Acoustic Wave (SAW) technology is
developed on the basis of acoustics, electronics, wavelet theory,
applied mathematics and semiconductor planar technology. The Triple
Transition Reflection (TTR) error is the primary reason for this kind of
device. To suppress the TTR error, a mathematic model of
Littlewood-paley wavelet was established first in this paper, which is
matched with the model of SAW. Using same phase method to design IDT of
Littlewood-paley WT device of SAW in L-edit software, the TTR error can
be reduced.
Keywords: Surface Acoustic Wave (SAW), Interdigital Transducer (IDT), Triple Transition Reflection (TTR) Littlewood-paley WT, L-edit Software.
Vol. 5. n. 4, pp. 1555-1532
Abstract - This
paper addresses the problem of modeling input data classes of the input
data dictionary (IDD) file of the Building energy simulation program
EnergyPlus. Our endeavor is to provide an easy way for elaborating a
behavior specifications of an interactive user interface intended for
input data of the IDD file, using hierarchical colored Petri nets. The
modeling approach used in this work comprises two levels of abstraction:
the use case level corresponding to the use case diagram model as
defined in the unified modeling language (UML) and the scenario level as
refinement of the former one. The color aspect of Petri-nets is used at
the scenario level to preserve the independence of several scenarios
after their integration. The benefit of the approach consists in the
structuring of the scenario acquisition and the approach of merging
scenarios using composite color sets.
Keywords: EnergyPlus, IDD File, Scenarios, UML, Colored Petri-nets.
A CMOS Interface Circuit Design for a 32-level Resolution Light Sensor Vol. 5. n. 4, pp. 1563-1568
Abstract - 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 outputs 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; less power consumption; higher
resolution with smaller number of storage units; and small area for
on-chip integration. A simulation result implementing 32 levels of
resolution is presented.
Keywords: CMOS, Light Sensor, 2-Stage Interface Design, 32-Level Resolution.
Combining Coverability and Invariants to Diagnose Multiple Faults in
Discrete-Event Systems Vol. 5. n. 4, pp. 1569-1579
Abstract - In this
paper, we focus on on-line multiple faults diagnosis in discrete
event-systems modeled by Petri nets (that can be bounded or unbounded as
well). We assume that both places and transitions faults can occur. The
proposed solution consists in defining a state vector, which components
are the system places and transitions. This state vector sums up the
state of each component whether it is faulty or normally functioning. To
get this result, we were initially based on the construction of
coverability trees to which, we integrate the use of invariant notions
(T-invariants and P-invariants). This approach gives promising diagnosis
results. Nevertheless, it causes a storage complexity problem affecting
the diagnosis duration. Thus, we propose an improvement of this approach
by diagnosing multiple faults using the combination of the coverability
sets instead of coverability trees and invariant notions. To discuss the
effectiveness of the proposed approaches, we rely on the simulation of
the three-tank hydraulic system.
Keywords: Multiple Faults Diagnosis, Petri Nets, Coverability Tree, Coverability Set, T-Invariant, P-Invariant.
Prediction of Centrifugal Compressor Performance by Using Adaptive Neuro-Fuzzy
Inference System (ANFIS) Vol. 5. n. 4, pp. 1580-1587
Abstract - Adaptive
neuro- Fuzzy Inference System (ANFIS) was used to predict the efficiency
of a small modified centrifugal compressor. Data were generated from
earlier studies which were obtained from a three dimensional, steady
state and turbulent flow by using a CFD analyse on aerodynamic flow
field characteristics. Equations were analysed using finite volume
method. The results obtained from numerical solutions were used for
training and testing the (ANFIS). In this paper, is the use adaptive
neuro-fuzzy inference systems (ANFIS) approach is developed a
performance prediction method of centrifugal compressor, to use it as
performance predictor. A comparison was performed among the ANFIS method
and Computational Fluid Dynamic (CFD) code. It is observed that the
ANFIS method can be used to predict the performance and gives more
significant value to actual value, moreover; the computation time,
memory space and effort were reduced.
Keywords: ANFIS, Centrifugal Compressor, Performance Prediction, CFD.
Computations of Pollutant Dispersion in Coastal Waters of Tangier’s Bay Vol. 5. n. 4, pp. 1588-1595
Abstract - This
article describes a pollutant dispersion and transport in the large
domain such as Tangier’s bay by a model of pollutant transport by
shallow water flows on non-flat topography that are numerically solved
using a finite volume scheme. The method uses unstructured meshes,
incorporates upwinded numerical fluxes and slope limiters to provide
sharp resolution of steep bathymetric gradients that may form in the
approximate solution. To evaluate the numerical flux we use the Roe
approximate Riemann solver with centered discretization for advection
terms and the Vazquez scheme for source terms. The scheme is
non-oscillatory and possesses conservation property that conserves the
pollutant mass during the transport process. The evaluation using an
imaginary test shows that the implementation makes a good usage of the
computational resources, the results indicate also that this simple
approach can be very effective in modeling pollutant transport in
coastal regions.
Keywords: Convection-Advection Equations, Pollutant Dispersion, Shallow Water Equations, Tangiers’s Bay.
Removal of Chromium (III) by Complexation-Ultrafiltration: Experimental and
Calculation Approach of Complexation Reaction Vol. 5. n. 4, pp. 1596-1602
Abstract - A process
for purifying aqueous solutions containing heavy and toxic metals such
as chromium has been investigated. Hexavalent chromium compound is
present at high concentration in the shovels and cranes factory, it is
used in the electrodeposition container; after its reduction by sodium
bisulfites it changes into trivalent chromium. The present work deals
with the investigation and optimization of chromium (III) ions removal
from aqueous solutions by complexation enhanced ultrafiltration using
experimental and calculation approach; diamine tetra-acetic acid (EDTA)
has been used as chelating agent for Chromium (III) complexation; in the
first part the study of experimental optimum conditions of complexation
reaction is carried out; the second one the calculation of optimum pH,
initial concentration of chelating agent and the influence of chromium
hydroxides forms on complexation reaction using MATLAB language has been
determined. Its shown that the Complexation reaction is favoured at pH
equal to 5.1, at excess EDTA concentration ([EDTA]0=0.095 M
for [Cr(III)]0=0.003M), at ordinary temperature (T=20°C), and
600 tr/min for agitation, trivalent chromium concentration at solution
increases with ionic strengths, it also increases with high CaCO3
values. The calculated pH, initial concentration of ligand and presence
of chromium hydroxides forms shows a little variation with experimental
ones.
Keywords: Trivalent Chromium, Complexation, EDTA, Ultrafiltration, MATLAB.
International Review on Modelling and Simulations - Papers (Part B)
Performance Comparison of Genetic Alorithm and Particle Swarm Optimization Based Techniques for Power System Voltage Stability Problem Using Facts Devices Vol. 5. n. 4, pp. 1603-1611
Abstract - In a Power system, minimization of transmission line losses is an important issue. Since it is a necessary condition for the Power systems being operated closer to their stability limits, voltage stability enhancement is very important in planning and operations of the Power systems. With increased demand for electricity, voltage stability is a major concern for the last two decades. Installation of Flexible AC Transmission Systems (FACTS) devices on the transmission system improves the stability of the system and also reduces the losses in the system. This necessitates the identification of optimal location and operating requirement of the FACTS devices in order to maintain the bus voltages at the desired levels and to improve the voltage stability margins. In this paper, a performance analysis has been made and compared in between Genetic Algorithm and Particle Swarm Optimization, which are used in selecting the optimal location and operating requirements of FACTS devices like SVC,TCSC and UPFC. Loss minimization and voltage stability enhancement are the two different objective functions to be evaluated in this proposed approach. IEEE 14 bus, IEEE 30 bus and IEEE 57 bus systems are being taken as test systems to demonstrate the applicability and efficiency of the proposed system. Results from GA and PSO are compared with the test results showing that PSO is more effective than GA.
Keywords: FACTS controllers, Stability margin, Voltage collapse, Genetic Algorithm, Particle Swarm Optimization.
A Review of UPFC and a Novel FACTS Controller for Voltage Stability Enhancements
in Power Systems Vol. 5. n. 4, pp. 1612-1619
Abstract - FLEXIBLE
AC transmission systems (FACTS) have been developed for better control
of electric power flow through the efficient utilization of existing
transmission lines. In its most exotic form, the unified power-flow
controller (UPFC) is a FACTS controller consisting of power-electronic
components that can be employed for controlling the magnitude and phase
angle of the line voltage and the line impedance simultaneously.
However, excessive installation and operating costs do not justify
widespread use of such a controller. To address this issue, the
designing of converter-less FACTS device has been introduced. This
converter less FACTS device has been designed using the traditional
technology of transformer and taps, commonly known as “SEN” Transformer.
The ST uses time-tested components, such as transformers and tap
changers, and injects a voltage of variable magnitude and phase angle,
such as a UPFC, in series with the transmission line, thereby regulating
the active and reactive power flow in the line independently. A three
bus 230kv transmission line is taken as reference for the digital
simulation.
Keywords: FACTS (Flexible AC Transmission Systems), Converter-Less FACTS Controller, UPFC (Unified Power Flow Controller), ST (SEN Transformer), Voltage Stability.
Optimal Allocation of Machines and Buffers in Transfer Line-Flow Systems under
Reliability-Space and Cost Constraints Vol. 5. n. 4, pp. 1620-1627
Abstract - The
problem of the optimal performance design of manufacturing system where
redundant machines and buffers are included in order to achieve desired
levels of performance rate is considered. A procedure which determines
the maximum performance configuration subject to reliability, cost and
space of buffer constraints is proposed. In this procedure, system
machines and specific buffers are chosen from a list of available
product and a number of machines are determined for each system
component with their buffers spaces allocation. Machines are
characterized by their cost, failure rate, repaired rate and processing
time. Buffers are characterized by their cost and space or (size). To
estimate production line transfer performance, a decomposition-type
method is used. A list of available product on the market characterizes
specific space buffers and machines with their characteristics are
available. The optimal design problem is formulated as a combinatorial
optimization where the decision variables are size or space buffers
allocations and kind of machine as redundant components. A universal
generating function technique is applied to evaluate system
availability.
Keywords: Manufacturing System, Performance Evaluation, Optimal Performance Design, Space Buffers Allocation, Universal Generating Function.
Fuzzy Controller Based Design to Improve Transient Stability for STATCOM Vol. 5. n. 4, pp. 1628-1633
Abstract - This
paper presents a fuzzy controller for static synchronous static Time
critical error and better damping system oscillations after a short
circuit fault is presented. To achieve this idea, a controller is
designed based on energy function lyapunov, to overcome the system and
due complexity of computing a fuzzy neural controller is recommended.
Here a membership function identifies the fuzzy system. Fuzzy control is
employed to the system for enhancing transient stability. The
performance is analyzed using digital simulation with single machine
infinite bus (SMIB).
Keywords: Lyapunov Energy Function, Fuzzy, STATCOM, Transient Stability.
Probability of Transition to Ageing Failure Based on Usage History of
Distribution Transformers Vol. 5. n. 4, pp. 1634-1639
Abstract - The
methods of asset management have been traditionally based on average
historical data about the expected life time and ageing failure
probability of typical types of power system components. However, such
data cannot reflect the impact that usage history of the components,
such as their historical loading profile, may have on their ageing
failure probability and their expected life time. This paper presents a
methodology to investigate the impact that historical loading profile of
distribution transformers may have on their ageing failure probability.
Extensive research data has been used to obtain quantitative results for
realistic test cases of distribution transformers serving residential,
commercial and office building consumers. The obtained results can
provide useful information for distribution network operators to
understand possible risk of component ageing failure in real-time
operation and to make important asset management decisions.
Keywords: Distribution Transformer, Power Distribution, Power System Ageing.
A Reliability Based Multi-Objective Formulation for Optimal PMU Placement Vol. 5. n. 4, pp. 1640-1644
Abstract - This
paper presents a method to simultaneously maximize reliability while minimizing
the cost of Phasor Measurement Units (PMUs) for full Observability in power
systems. The formulation incorporates the reliability of individual PMUs and
finds a placement that is optimal cost-wise while exceeding a specified level of
system-wide reliability. This multi-objective problem is formulated as a
nonlinear programming model and solved for the IEEE 14, 30, 57 and 118 bus test
systems. The results show that traditional optimal cost only PMU placement
formulations achieve a system reliability of ~0.5 which is improved to 0.9 with
the proposed formulation.
Keywords: Multi-Objective Optimization, Nonlinear Programming, Phasor Measurement Units, Power System Observability, Reliability Modeling.
Electromagnetic Force in Vertical and Horizontal Arrangement of Busbar System
under Short-Circuit Current Vol. 5. n. 4, pp. 1645-1651
Abstract - Each
conductor busbar is subjected to an electromagnetic force exerted by
short-circuit currents. In this paper, the electromagnetic forces
affected by the short-circuit current in rigid bare conductor busbars
are calculated in the vertical and horizontal arrangement. Short-circuit
current values are calculated mathematically by assuming that the peak
value of steady-state AC current is equal to the peak value of the
short-circuit current. The equation introduced by IEC Standard 865/1993
is applied to calculate short-circuit electromagnetic forces. The force
generated in the vertical arrangement is compared with that generated in
the horizontal arrangement. Results show that the busbar in the vertical
arrangement has an electromagnetic force that is two times higher than
that of the busbar in the horizontal arrangement. The calculation result
is compared with the simulation result, which is obtained by applying
Maxwell stress method in Opera-2D. The dimensional configuration of the
busbar system visibly influences the strength of the electromagnetic
force given the short-circuit current. Maximum electromagnetic force
decreases about 4%–7% because of the increasing configuration of the
busbar arrangement in the thickness or central distance between the
conductors. Furthermore, the electromagnetic force determined by finite
element simulation agrees with that derived using IEC Standard 865/1993.
Keywords: Busbar, Maximum Electromagnetic Forces, Short-circuit Current.
Performance Comparison of a New Compensator Based on Magnetically Controlled
Reactor and Static Var Compensator (SVC) Vol. 5. n. 4, pp. 1652-1663
Abstract - With the
need for the transmission of large amount of power over long distances,
there has been a greatly increased demand for reactive power
compensators to regulate and stabilize transmission voltage. Static Var
Compensators (SVC), are compensators capable of absorbing and injecting
reactive power from/to a network. But, they produce harmonic currents,
which cause poor power quality. Also, they have higher maintenance costs
and need to have more space for installation. A new type of reactive
power compensator based on Magnetically Controlled Reactor (MCR) which
has a high saturation in the magnetic circuit with optimal magnetic and
electrical circuit parameters that ensures less than 2-3% of total
harmonic distortion even without special filters installation. The
response of a SVC in voltage regulation to the voltage variations in a
transmission line is faster than that of an MCR-based compensator.
Although, an MCR-based compensator can be designed to respond like a SVC
in as short as 0.02 sec, the price of MCR-based compensator depends on
its response time. In high voltage transmission lines, voltage
variations are not sudden, so the slow response of the MCR-based
compensator with respect to the SVC is not important. The main objective
of this article is to compare an MCR-based compensator and Static Var
Compensator (SVC) from a transient behavior point of view, and a
detailed model of a magnetically controlled reactor and capacitor banks
installations is used to illustrate the ideas presented throughout the
article.
Keywords: Magnetically Controlled Reactor, Static Var Compensator, MCR-Based Compensator.
Power Quality in Practice, Analysis of Power Quality and Available Solutions Vol. 5. n. 4, pp. 1664-1671
Abstract - Nowadays
we are often confronted with the declined quality of electricity.
Problem of the power factor compensation with increased incidence of
harmonic currents is discussed in this article. Article contains a
recommendation for application of unprotected compensation device,
protected compensation device or filtering-compensation device according
to total harmonic distortion at the connecting point. Also a practical
measurement and simulation experiment verifying analyzed problem are
mentioned.
Keywords: Power Quality, Power Factor, Unprotected Compensation Device, Filtering-Compensation Device.
Comparison of FACTS Device Installation in Power Transmission System Vol. 5. n. 4, pp. 1672-1678
Abstract - Mechanism
of power system operations become more complex due to the increasing
load demand and which lead to increased pressure and high risk to the
transmission line. Therefore power system operation and stability become
less safe due to unexpected congestion and voltage violations. In
additional, new transmission line is considered one of the solutions to
provide a stable operation it is more secure to the power system.
However it is more expensive and time consuming which also need to
address the political and environmental issues. One of the alternatives
which can be employed is the use of Flexible AC Transmission System
(FACTS). This paper presents a study on optimal location and sizing of
FACTS device based on Particle Swarm Optimization for minimization of
transmission losses, voltage profile improvement which takes into
account cost of installation. In this study, Static Var Compensator
(SVC) and Thyristor Controlled Series Compensator (TCSC) are chosen as
the compensation device. Validation through the implementation on the
IEEE 30-bus system indicated that PSO is feasible to achieve the task.
In simulation results are compared with those obtained from Evolutionary
Programming (EP) and Artificial Immune System (AIS) technique in the
attempt to highlight its merit.
Keywords:
FACTS Devices, Particle Swarm Optimization, Transmission
Loss, Minimization, Static Var Compensator, Optimal Location, Optimal
Sizing.
Effect of Static and Dynamic Load model on Dynamic Stability of Distribution
Network with Fixed and Variable Speed Wind Farm: A Bifurcation Analysis Vol. 5. n. 4, pp. 1679-1689
Abstract - Load representation has a significant impact on power system analysis and control results. In this paper, the interaction between static load, motor load and wind farm connected to a distribution network is described in the context of bifurcation analysis. The wind farm is represented considers both constant speed and variable speed inductions generators. Motor loads are assessed with respect to their mechanical loads. The network is represented by three models: a differential equations model (ODE), a differential-algebraic equations model (DAE) with a voltage dependent static load, and a DAE model with a fully dynamic load. A differential algebraic representation is developed; and the study is based on the determination of bifurcation points. The bifurcation analysis has indicated the occurrence of saddle-node and Hopf bifurcations. The bifurcation points indicated the load-generator dynamic interaction and the network permissible wind power penetration. Bifurcation analysis has shown the effect of the dynamic load on the dynamic stability of the network.
Keywords: Dynamic Stability, Bifurcation, Fixed Speed Induction Generator, Variable Speed Induction Generator, Static Load, Dynamic Load, Distribution Network.
Development of MATLAB/SIMULINK Models for PV and Wind Systems and Review on
Control Strategies for Hybrid Energy Systems Vol. 5. n. 4, pp. 1690-1700
Abstract -
Depletion of fossil fuel resources and environmental pollution caused by
them necessitates alternate energy sources for electricity production.
In the recent past renewable energy sources are considered as
alternative for the fossil fuel energy sources. Photovoltaic and Wind
are the more promising renewable energy sources and are widely used in
many countries for standalone applications or connected to Utility Grid.
The unpredictable pattern of natural resources requires combined
utilization of these sources for providing uninterrupted and reliable
power supply to the consumers. A MATLAB/SIMULINK model for 10 kW Solar
PV system has been developed and its characteristics are presented. The
characteristics of Wind turbine is also simulated and results are
presented. Further this paper presents the review of current state of
control strategies for hybrid energy system in standalone mode and grid
connected mode. Also the future developments of such system and their
recognition by the industrial and home users are discussed.
Keywords: Energy Management, Hybrid Power Systems, MPPT, Power Conversion, Solar Energy, Wind Energy.
Enhancement of Transient Stability Limit Using Fuzzy Controlled TCSC Vol. 5. n. 4, pp. 1701-1709
Abstract - Accurate
analysis of the transient stability requires the detailed modeling of
generating units and other equipment. At present, the most practical
available method of transientstability analysis is time-domain
simulation in which the nonlinear differential equations are solved by
R.K. fourth order method or network reduction techniques. In general
rotor angle stability is taken as index, but the concept of transient
stability, which is the function of operating condition and disturbances
deals with the ability of the system to remain intact after
beingsubjected to abnormal deviations. In this paper, the transient
stability assessment of WSCC-9 bus system is carried out for three phase
fault of self clearing type at different fault locations. TCSC
controller has been modeled and implemented on the WSCC-9 bus system at
the optimal location. The effective location of TCSC for different
faults locations is obtained by performing trajectory sensitivity
analysis with respect to clearing time. The case studies depict the
optimal location of fixed compensation in the WSCC- 9 bus system, based
on the stability index (ETA). Further, a fuzzy controlled TCSC has been
implemented on WSCC-9 bus system to improve stability of system. The
fuzzy controlled TCSC is observed to perform better, compared to
conventional PI controller.
Keywords: Transient Stability, Trajectory Sensitivity Analysis, Stability Index, Fuzzy Controller, TCSC.
SVM based Hysteresis Current Controller for DSTATCOM using Instantaneous
Reactive Power Theory Vol. 5. n. 4, pp. 1710-1716
Abstract - A
Distribution STATCOM (DSTATCOM) is a shunt compensation device used for
reactive power compensation. It can be used either in the power factor
correction mode or in the voltage regulation mode. In this paper, a
vector based hysteresis current controller (HCC) for DSTATCOM, operated
in the power factor correction mode, is implemented. The control law is
derived based on generalized instantaneous reactive power theory. The
controller uses errors in current represented in stationary α-β frame,
multi-level hysteresis comparators and an associated lookup table to
produce a switching pattern, which restricts the errors in currents to
lie within a region. Extensive use of zero vectors has been made to
reduce the switching frequency and switching losses. The control
technique implemented does not require phase locked loop (PLL) to track
the line frequency. The use of HCC makes the system robust, and hence
independent of load parameter variation, with fast transient response.
The performance of vector based HCC is studied in MATLAB/SIMULINK
environment and results obtained are satisfactory.
Keywords: DSTATCOM, Hysteresis Current Controller, Instantaneous Reactive Power Theory, Voltage Source Converter.
Security-Constrained Unit Commitment with Considering Demand Response with High
Penetration of Wind Power Vol. 5. n. 4, pp. 1717-1724
Abstract - In recent
years, restructuring vertical integration mechanism into free market
system in most countries has growing trend. With restructuring in
electricity industry, the philosophy of the system operation is changed.
In new philosophy, for reliable operation of electricity systems, it is
necessary to balance supply and demand. In restructured environment,
Independent System Operator (ISO) for the balance, in addition to the
use of energy resources, from cheap sources such as Demand Response (DR)
uses. In this paper, the method of mitigate violations of demand and
wind power is demand response programs. Because ISO runs constrained
unit commitment (SCUC) for day-ahead market scheduling, so DR programs
should be considered in SCUC problem. First, SCUC problem decomposed
into the master unit commitment problem and subproblems using Bender
Decomposition technique. The UC problem is solved in the master problem
with the forecasted demand and wind power generation and this solving is
checked for satisfying hourly network constraints. Next, net demand is
used for considering wind power and demand uncertainties simultaneously.
Scenarios of net demand are simulated with using Monte Carlo simulation
technique. The scenario reduction technique is employed for the purpose
of decreasing of computational requirement. The initial dispatch is
checked in the feasibility check subproblem and generation redispatch
and DR program are used for satisfying the early volatility of wind
power and demand. If the redispatch and DR program failed to mitigate
violations, Benders cuts are created and add to the master problem. The
iterative process between the master problem and feasibility check
subproblem will continue until optimal solution obtain. A six-bus system
is used for testing the proposed algorithm and the associated results
are analyzed.
Keywords: Security Constrained Unit Commitment, Wind Power and Demand Uncertainties, Demand Response.
Modeling and Simulation of PHEV As a Virtual UPQC Based on Vehicle to Grid
Technology Vol. 5. n. 4, pp. 1725-1732
Abstract -
Power electronic-based FACTS devices like Unified Power Quality
Conditioner (UPQC) can fulfil multiple power quality control objectives
such as needs of reactive power compensation, voltage flicker and
harmonics current compensation. Although the main disadvantage of UPQCs
are their excessive price. Therefore UPQCs are not widely used. In this
paper a method proposed to analyze the reactive and active power
transaction capabilities of a practical vehicle battery in the Plug-in
Hybrid Electric Vehicles (PHEV) in a Vehicles to Grids (V2G) mode of
operation, which gives a low-cost solution for designing a virtual UPQC
using PHEV charging station. A third order dynamic battery model is used
to represent the PHEV and substitute to dc link of UPQC. Simulations
have been executed in MATLAB SIMULINK and demonstrated that PHEVs have
able to work as a virtual UPQC to improve power quality.
Keywords: V2G, UPQC, PHEV, Battery Model, Smart Grid.
Revenue Maximization for Capacitor Placement in Distribution Networks Using
Differential Evolution and Pattern Search Vol. 5. n. 4, pp. 1733-1740
Abstract - This
article studies the implementation of meta-heuristic algorithm based for
solving the capacitor placement optimization problem with maximum net
savings. Differential Evolution and Pattern Search are used as
meta-heuristic optimization tools to solve optimal Capacitor Placement (OCP)
problem. The Objective function is formulated and aims to enhance bus
voltage profiles effectively within the specified voltage constraints
and reduce line active energy losses while maximizing the benefits of
installing reactive compensators. To tackle and reduce the search space
process and computational CPU time, the potential buses candidate for
capacitor allocation are pre-identified. The identification of potential
locations is obtained based on the calculations of Power Loss Indices (PLI)
and/or loss Sensitivity factors (LSF) with weak voltage buses. At that
moment, Hybrid Differential Evolution-Pattern Search approach is used
for estimation of required optimum level/size of shunt capacitive
compensations. Both PLI and LSF indicators for bus nominations are
tested, and analyzed with comparisons. The overall accuracy and
reliability of the developed approach were validated and tested on
10-bus, 22-bus, 28-bus, 33-bus, 34-bus and 69-bus radial distribution
systems. Computational results obtained showed that the proposed
approach capable of producing high-quality solutions, and demonstrated
its viability. The results are compared with ones of previous studies
using recent heuristic methods and the same network tests.
Keywords: Cost Minimization, Distribution Power Flow, Evolutionary Techniques, Reactive Power Support.
On Plant Modeling for the Plant-Input Mapping (PIM) Digital Redesign of a Power
System Stabilizer Vol. 5. n. 4, pp. 1741-1749
Abstract - This
paper is concerned with the plant modeling for the digital redesign of a
continuous-time power system stabilizer PSS for a single machine power
system using Plant–Input-Mapping PIM method. The traditional approach
has been to use the bilinear transform (Tustin’s method), but this needs
small sampling intervals which gives some difficulties with modern
control. The presented technique guarantees the stability for any
sampling rate as well as it takes closed-loop characteristics into
consideration. The proposed technique is successfully applied to the
discretization of the conventional continuous time PSS for
single-machine power system. For comparison studies the proposed
technique is compared with conventional continuous-time PSS and Tustin’s
PSS. The simulation results show that the states of the proposed digital
redesign technique closely match those of the conventional
continuous-time PSS. The proposed digital redesign technique guarantees
stability even with relatively slow sampling rates while Tustin’s method
falls when sampling interval becomes larger.
Keywords: Digital Redesign, Discretization, Dynamic Stability, Power Systems, Sampled-Data System.
Modelling, Analysis and Design of Fuel Cell based Distributed Generation System
with Active and Reactive Power Flow Control Vol. 5. n. 4, pp. 1750-1757
Abstract - This
paper deals with the modelling, power flow control and load following
analysis of fuel cell based distributed generation system. The modelled
fuel cell is interfaced to the grid through the power conditioning unit
with desired active and reactive power flow control. The output of the
fuel cell stack is given to the dc-side of the voltage source inverter
for interfacing to the grid. The active power transfer is based on the
phase angle difference between dc-ac converter output voltage and grid
voltage. The reactive power management is based on difference in
magnitude of converter output and grid voltages. The entire system is
modelled in MATLAB/Simulink environment and simulations carried out to
verify the operation and the control principle and then co-simulated in
digital signal processor TMS320F2812 through processor-in-loop.
Keywords: Fuel Cell, Distributed Generation, Active And Reactive Power, Processor-In-Loop Simulation.
Generalized Approach for Calculation of Reduction Factor of a Cable Line
Consisting of Three Single-Core Cables Vol. 5. n. 4, pp. 1758-1764
Abstract - This
paper presents a generalized approach for calculation of reduction
factor of cable line consisting of three arbitrary arranged single-core
cables. First, a general solution of the corresponding equation system
written for six inductively coupled electrical circuits with an earth
return path is presented and discussed. Afterwards, generalized
analytical relations for calculation of reduction factor are derived and
illustrated on a practical example. The influence of the cable screen
temperature on calculated value of reduction factor is analyzed, as well
as the influence of earth resistivity and distances between the
single-core cables. The paper gives the expression for reduction factor
of three single-core cables with cross-bonded metal screens which is not
documented in the existing literature.
Keywords: Power Cable, Reduction Factor, Ground Fault Current, Safety Conditions.
A Method for Ground Fault Distance Computation in Unearthed Medium Voltage
Distribution Network Vol. 5. n. 4, pp. 1765-1772
Abstract - In
networks with unearthed or compensated neutral, earth fault signals consist of
different frequency components, which result from charging and discharging of
the network capacitances. The charge transient which usually is of higher
amplitude and lower frequency than the discharge transient is most suitable for
fault location. This paper discusses a method for estimating a single phase to
ground fault location in radially operated unearthed distribution network. The
proposed method is based on correlation of undamped charge transient frequency
with the fault distance. The undamped complex frequency is defined from the
development of single phase to ground fault bus impedance matrix of the circuit
network in complex frequency domain. The accuracy of the method was tested using
a simulation model and the network example with overhead lines. The analysis was
performed using the EMTP-ATP software.
Keywords: Fault Location, Unearthed Network, Charge Transient, Impedance Matrix.
UPQC with two Current Control Strategies under unbalanced Load Conditions Vol. 5. n. 4, pp. 1773-1779
Abstract - This
paper presents comparison of control strategy of a three-phase; three
wire Unified Power Quality Conditioner (UPQC) .It is used to improve
power quality in distribution system. The UPQC is realized by the
integration of series and shunt active power filters (APF) sharing a
common dc bus capacitor. The realization of shunt and series APF is
carried out by using a three-phase, three legs Voltage Source Inverter (VSI).
In series active filter, the fundamental source voltages are extracted
by synchronous reference frame technique. In Shunt active filter, the
fundamental current is derived by two different techniques (i.e.)
synchronous detection method and unit vector template method. The
performance of the applied two control algorithm of shunt active filter
with series active filter is evaluated in terms of power-factor
correction, load balancing, and mitigation of voltage and current
harmonics in a three-phase, three-wire distribution system for
non-linear load and unbalanced load conditions. In both APF the
reference signals and sensed signals are compared by a hysteresis curent
controller and to generate switching pulses. The comparison between two
control algorithms is made by use of MATLAB / Simulink-based simulations
environment.
Keywords: Unified power quality conditioner, Synchronous reference frame theory, Unit vector template , Power synchronous detection, current Harmonics, and Voltage Harmonics.
Modeling Hydro Power Plants and Tuning Hydro Governors as an Educational
Guideline Vol. 5. n. 4, pp. 1780-1790
Abstract -
Appropriate modeling of components and related controllers are very
significant in studying dynamic performance of power systems. In this
paper, an educational procedure for modeling, simulation, and governor
tuning of hydro power plants is presented. Different existing dynamic
models of hydro plant components are reviewed. The procedure for
calculating the required parameters from real plant data is also
presented. Application and performance of reviewed models is discussed
as well. In addition, appropriate methods for tuning different types of
hydro governors are studied and a classical method is used for PID
governors. Inclusion of the nonlinearity and elasticity of the detailed
turbine-penstock model, and studying the effect of the servo transfer
functions are the main aspects of the proposed tuning method. The paper
is written in a way to be useful for an electrical engineering student
or a novice engineer to model, simulate, and analyze a hydro power plant
dynamic behavior, and finally tune its governor. This work can be used
as a primitive guideline for educational and practical purposes.
Keywords: Power Plant Dynamics, Hydraulic Turbines, Governor Tuning, Power System Education, PID Controller.
Robust Tuning of
PSSs in a Multi-Machine Area Vol. 5. n. 4, pp. 1791-1797
Abstract - It is the
purpose of this paper to multi-objective design of multi-machine power
system stabilizers (PSSs) using Imperialist competition algorithm (ICA).
The ability of the proposed approach for optimal setting of the widely
used CPSSs has been attended. The PSSs parameters designing problem is
converted to an optimization problem with the multi-objective function
including the desired damping factor and the desired damping ratio of
the power system modes, which is solved by a ICA algorithm. The
capability of the proposed approach is confirmed on a multi-machine
power system under different operating conditions and disturbances. The
results of the proposed approach are compared with the genetic algorithm
(GA) based tuned PSS through some performance indices to reveal its
strong performance.
Keywords: PSS Design, Imperialist Competition Algorithm (ICA), Genetic Algorithm (GA), Multi-Objective Optimization.
Conventional MPPT System of Wind Generation: Comparative Study Vol. 5. n. 4, pp. 1798-1804
Abstract - The wind
turbines used for power generation should enable to produce maximum
power, making best use of available energy in the wind. A specific known
terminology: Maximum Power Point Tracking (MPPT) must be introduced to
obtain maximum energy efficiency. The strategy from this command is to
control the electromagnetic torque to adjust the speed mechanics to
maximize the electrical power generated. There are two families from
control structures, the strategy from maximizing the power with and
without velocity control. The aim of this paper is to evaluate the
performances of two types of MPPT controllers mentioned on an 7.5kW test
bench containing a DFIG and we interested to compare this two strategies
from maximizing the power extracted for a wind generation system with a
horizontal axis. The corresponding simulation model are described in
section III. The studied MPPT controllers are presented results are
given, analyzed and discussed in part IV. Finally, in last part,
extracts some conclusions on this paper.
Keywords: Wind, MPPT, Modeling, DFIG, Speed Control, Control Strategy, Power.
Mitigation of System Disturbances in an Interconnected Power Grid Vol. 5. n. 4, pp. 1805-1815
Abstract - Southern
Africa Power Pool (SAPP) operates a large interconnected power grid of
national electric power utilities and independent power players in 12
countries in Southern Africa. The paper presents recommendations,
implemented mitigation measures to overcome major power system
disturbances in SAPP system following system disturbances and outcome of
investigations during 2008. Power system consultants and specialists
from SAPP power utility members conducted steady state, dynamic and
small signal power system studies to determine the root causes of the
disturbances. The causes were traced to poor damping of power system
oscillations; risks and vulnerability of SAPP system to transient
stability; and unsafe transfer limits through transmission corridors.
Measures implemented to mitigate system disturbances involved fitting or
tuning PSS (Power Systems Stabilizers) and governors to identified
generators. For mitigating against future disturbances it was
recommended that Static Voltage Compensators (SVCs) and Flexible AC
transmission Systems (FACTS) devices and equipment should be installed
in transmission locations recommended from the study. The paper offers
three significant contributions: understanding the root causes of system
disturbances in large grids; methods of improving operation of large
scale power grids; improving system performance through redesign by
deploying FACTS or PSS to improve system damping or transfer capability.
Keywords: Damping, Interconnected Power Grid, Small Signal Stability, System Disturbance; Transfer Capability, Transient Stability.
An Alternative Voltage Sag Source Identification Method Utilizing Radial Basis
Function Network Vol. 5. n. 4, pp. 1816-1823
Abstract - Power
quality monitors (PQM) are required to be installed in a power supply
network in order to assess power quality (PQ) disturbances such as
voltage sags. However, with few PQMs installation, it is difficult to
pinpoint the exact location of voltage sag. This paper proposes a new
method for identifying the voltage sag source location by using the
artificial neural network (ANN). Radial basis function networks are
initially trained to estimate the unmonitored bus voltages during
various sags caused by faults. Then voltage deviation of system buses is
calculated to pinpoint voltage sag location. The validation of the
proposed methodology is demonstrated by using an IEEE 30 Bus test
system. The results shows that the proposed method can correctly locate
the voltage sag source based on highest voltage deviation obtained
through estimated unmonitored bus voltages.
Keywords: Voltage Sag, Voltage Deviation, Radial Basis Function Network, Estimated Bus Voltage, Power Quality.
Distributed Maintenance Concept; Application: Scheduling Maintenance Tasks Using
Dynamic Programming Method Vol. 5. n. 4, pp. 1824-1827
Abstract - This
paper describes the approach based on dynamic programing used to
schedule maintenance tasks in a distributed context; the implementation
of this concept (distributed maintenance) involves the construction of a
plan based on the analysis of processes and processors, to accelerate
the process of equipment maintenance. In general, the manager of the
company responsible for managing the human resources has to solve the
following problem: assign for each task to maintain the best skills at
the right time. The scheduling of maintenance tasks takes into account
the competence and the availability of human resources. Dynamic
programming approach used to solve that kind of problem is an
optimization method proceeding by implicit enumeration of solutions.
This approach can effectively solve problems of sequential decisions.
More generally, it is to address problems with an optimization strategy
to decompose the problem into a sequence of problems, and then establish
a recurrence relation between the optimal solutions.
Keywords: Distributed Maintenance, Human Resources, Scheduling, Ability, Availability, Dynamic Programming.
A Literature Review on Strategic Bidding in an Open Access Electricity Market Vol. 5. n. 4, pp. 1828-1837
Abstract - In
competitive electricity markets also called as open access, formation of
supply bid is one of the concerns, where suppliers have to maximize
their profit under incomplete information of other competing generators.
This initiated a significant research effort by the researchers and
practitioners in electricity market throughout the world. As a part of
this, many authors have presented different methodologies and tools to
solve the bidding strategy problem in a competitive electricity market.
The purpose of this paper is to provide an over view of different types
of electricity markets, auction mechanism and a procedure for bidding in
power pools. This paper also presents a literature survey based on
different bidding methodologies applied so far in the area of power
system deregulation.
Keywords: Electricity Market, Bidding Strategy, Market Clearing Price (MCP), Auctions.
Cost
Assessment of Offshore Wind Generation for Australia Vol. 5. n. 4, pp. 1838-1846
Abstract - Wind
energy generation has experienced a significant growth over the past
decade due the advantage of carbon neutral generation. Compared with the
onshore wind energy, offshore wind energy generation has higher
availability and fewer constraints, leading to the foundation of
offshore wind farm in Europe where the lands are limited. However, due
to the remarkable investment requirement of offshore wind farm, the cost
assessment of an offshore wind farm should be carried out for verifying
its feasibility. The aim of this work is to build the cost model
ofoffshore wind generation for Australia. Suitable cost models are
developed to calculate the actual cost of energy for the offshore wind
farm, based on the real-industrial price. This study also provides cost
expression for each component and therefore, the final total investment
can be readily estimated.
Keywords: Offshore Wind Farm, Levelised Cost Of Energy, Cost Assessment, Cost Model, Australia.
Investigate the Impressionability of the Reliability Level on Unit Commitment Vol. 5. n. 4, pp. 1847-1853
Abstract - In this paper, the problems of the Unit Commitment (UC) and Dynamic Economic Dispatch (DED) have been thoroughly investigated by employing the Simulated Annealing (SA) Algorithm. On the other hand, the effect of the ramp rate constrain is surveyed to solve the UC problem and to achieve the desired reliability level. Because of this, the spinning reserve capacity is essential to design the optimization problem. The evaluation of the required spinning reserve capacity is performed by implementing the reliability constraints based on the expected unserved energy and loss of load probability index. The obtained results of simulation have suggested our excellent approach in cost enhancement.
Keywords: UC, DED, SA Algorithm, Ramp Rate, Expected Unserved Energy, Uncertainty Load Forecast.
Correlation Evaluation of Unsynchronized Multi-End Windows for Locating Partial
Discharge Sources in Covered-Conductor Overhead Lines Vol. 5. n. 4, pp. 1854-1857
Abstract - A
correlation of unsynchronized multi-end windows technique is used for
locating partial discharge (PD) source on covered-conductor (CC)
overhead lines. The maximum correlation factor between signal arrivals
at two-end measuring points is used in order to find the ratio of
correlation. Then the ratio of correlation signals is ploted against its
ratio of difference distance. The graph is plotted using LAB Fit
software. The algorithm is developed and tested by the means of
simulation. Electromagnetic Transient Program-Alternating Transient
Program (EMTP-ATP) is used to implement and analyze a PD monitoring
system. The proposed algorithm performance is evaluated by extracting
the high frequency features using windowed-standard deviation (STD). The
simulated evaluation proves that an accurate PD source location can be
achieved using the proposed algorithm technique.
Keywords: Partial Discharge, Rogowski Coil, Overhead Covered-Conductor, Distribution Network, PD Sensors.
Mathematical Modeling and Harmonics Optimization of a Multi-Level Magnetically
Controlled Reactor with Harmony Search Algorithm Vol. 5. n. 4, pp. 1858-1866
Abstract -
Proposed a new structure based on the multi-level saturation
controllable reactor (MLMCR), can effectively reduce the MLMCR output
harmonic contained in the current. Having a different length and area of
the core portion of the apparatus by a plurality of MLMCR, Levels
magnetic is generated due to the magnetic saturation in the work process
the harmonic current of the different phases, to generate harmonic
currents through the magnetic valve can achieve the purpose of reducing
the output current contained in the harmonic. In this paper, based on
the characteristics of the device on the core structure, the
establishment of Mathematical model MLMCR harmonic characteristics, and
the following conclusions: There are three main factors to affect the
size of the MLMCR output harmonic, Respectively, for the the core
classification number and the length of the cross-section and area, of
which the latter two of MLMCR output harmonic greatest impact. By The HS
parameters to optimize the design can makes MLMCR output total harmonic
current maximum does not exceed the amount 1.8% of the rated output
current.
Keywords: Magnetically Controlled Reactor, Harmonic Analysis, Magnetic Curve, Mathematical Model, Harmony Search Algoritm.
Significance of Fault Diagnosis and Reduced Shock Module in Rotating Machinery
by Data Collectors Using Trending Software and Modal Analysis Vol. 5. n. 4, pp. 1867-1875
Abstract - Vibration
diagnosis is the most reliable method for identifying machine damage at
an early stage. Imbalance and misalignment defects can be detected
accurately, as well as rolling bearing damage and gear tooth defects.
Satisfactory operation of any machine is always important for tools
safety, increased productivity, and low downtime and maintenance
overhead. Such requirements could usually be fulfilled by proper design
and installation of machines at site. Design part is perhaps more
matured in most cases; however installation may play a significant role
in the dynamic behaviour even for properly designed machines. Vibration
based condition monitoring and codes are well known and widely followed
for most of the conventional rotating machines like Pumps, Motors,
Turbines, etc., as well as improve or decay shock module in rotor system
has been done in this study. The experimental technique used thus far is
called Modal Testing, a well known and widely used technique in research
and industry to obtain the Modal and Dynamic response properties of
structures. The objective of this research using measuring devices to
detect incipient damage to rotating components at an early stage. As a
result, unplanned downtime can be prevented and maintenance costs can be
reduced.
Keywords: Data Collectors, Shock Module, Trending Software, Vibration Diagnosis.
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