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International Review of Electrical Engineering  Vol. 5 N. 4-- Part A

International Review of Electrical Engineering  Vol. 5 N. 4-- Part B

 

 

International Review of Electrical Engineering - August 2010 - Papers Part A

 

 

go to top     International Review of Electrical Engineering - August 2010 - Papers Part B

 

 

 

 

International Review of Electrical Engineering - Papers- Part A

 

go to top   A New Bidirectional Soft-Switching Multi-Input DC-DC Converter for Automotive Applications
         by F. Esposito, G. Gentile, V. Isastia, S. Meo

         Vol. 5. n. 4, pp. 1336-1346

 

Abstract - In the next future, hybrid electric vehicles and electric vehicles will be more and more hybridized using different electrical storage devices. Traditionally in a vehicle having many energy storage systems, several independent power electronic converters were utilized. Due to their reduced part count, control simplicity and better efficiency, multi-input dc-dc converters seem to be a promising choice in hybridizing energy systems, therefore in literature many solutions have been proposed. In the paper, a new bidirectional soft-switching multi-input dc-dc converter for automotive applications is proposed. Such configuration is obtained as combination of two individual half-bridge dc-dc converters feeding a common dc bus. The soft-switch capability is achieved adding a simple auxiliary active clamping circuit for each leg. Such auxiliary circuit is operational regardless of boost or buck mode operation. The configuration guarantees fixed switching frequency, active clamped zero voltage switching operations of the main switches and bidirectional power flow. ZVS operations are guaranteed with wide load range. Reverse recovery effects are minimized and the drop voltage occurred over the switches is significantly reduced. In the paper the operating principle, soft-switching conditions and steady state analysis are presented. A 500 W prototype has been built and experimental results to verify the theoretical analysis are provided.

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Keywords: Multi-Input Dc-Dc Converter, Bidirectional Dc-Dc converter, Electric Power System, ZVS, Active Clamped.

 


 

go to top   Design and Implementation of Static Synchronous Series Compensator with a Soft-Switching H-bridge Inverter with DSP-Based Synchronization Control
         by T. S. Ustun, S. Mekhilef

         Vol. 5. n. 4, pp. 1347-1353

 

Abstract - The implementation of an H-bridge inverter which is aimed to be a building block for Flexible AC Transmission Systems, namely Static Synchronous Series Compensator, is explained in detail. The inverter is implemented with the ready-made module from Mitsubishi PS21997. A quasi-resonant topology that is comprised of a clamping circuit and a resonant circuit, is also implemented in order to achieve soft switching and thus increase the overall efficiency of the inverter by decreasing switching losses that reach considerable values with the abundant number of switches and a switching frequency of the order of kHz. The control loop is realized by means of a Digital Signal Processor in order to achieve synchronization with the power line and power flow control. The overall system is characterized by a 6-pulse inverter the input voltage of which is not a pure DC but a waveform that occasionally reaches zero level with the help of a quasi-resonant circuit at the source side, and which can keep detect the power line current and inject a voltage which is in full quadrature (90 degree phase difference) with it. This system is aimed to be a building block for FACTS devices such as Static Synchronous Series Compensator (SSSC). The motivation of designing a more efficient and dynamic inverter with high power quality is to construct more efficient and effective FACTS devices.

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Keywords: FACTS, H-Bridge Inverter Implementation, Quasi-Resonant, Mitsubishi Module PS21997, Synchronization, Voltage Injection.

 


 

go to top   Multiobjective Optimal Design of Medium Frequency Transformers for Full-Bridge DC-DC Converters
         by Christophe Versèle, Olivier Deblecker, Jacques Lobry

         Vol. 5. n. 4, pp. 1354-1363

 

Abstract - This paper deals with the multiobjective optimal design of medium frequency (MF) transformers for full-bridge dc-dc converters. The design problem requires minimizing the weight and the loss of the transformer while ensuring the satisfaction of a number of constraints. These constraints include appropriate limits on efficiency, temperature rise and winding dimensions. The optimization variables are, as for them, the operating frequency, the maximum flux density, the current density in windings as well as the core dimensions. If the first three variables are commonly used as design variables, it is rarer to treat the core dimensions as design variables. It should be noticed that the MF transformer model used in the design procedure takes full account of the currents and voltages waveforms. In this contribution, a design procedure of MF transformers based on multiobjective genetic algorithms is proposed. Finally, some typical results are shown and discussed.

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Keywords: Full-bridge dc-dc converter, Medium frequency transformer, Multiobjective optimization.

 


 

go to top   Design and Realization of a Three Phase Cascaded Multilevel Inverter for Industrial Drives with Reduced Power Quality Issues
         by V. Kumar Chinnaiyan, Dr. Jovithajerome, J. Karpagam

         Vol. 5. n. 4, pp. 1364-1369

 

Abstract -  The main objective of the proposed work is to design a power electronic converter to reduce the power quality issues. Due to the increased usage of power electronic converters for processing the power, the power quality issues become the hot research topic in the recent past. As the power level increases, the voltage level is increased accordingly to obtain satisfactory efficiency. During the last decades, the voltage rating of fast switching high voltage semiconductors such as the Insulated Gate Bipolar Transistor (IGBT) has increased. Still, there is a need for series connection of switching devices. In this area of applications, the multilevel power converter has shown growing popularity. The fundamental advantages of the multilevel converter topologies are low distorted output waveforms and limited voltage stress on the switching devices and hence the reduced electromagnetic interferences on the output waveforms. The main disadvantages are higher complexity and more difficult control but it can be overcome by using modern digital controllers. In this paper, the performance parameters are analyzed with the prototype of a three phase cascaded multilevel inverter is designed with digital controller for reduced power quality issues with induction motor drive with the options to use for harnessing the renewable energy too. The main focus has been on the quality of output waveform and the result obtained with the developed experimental hardware setup proves the same.

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Keywords: Power Converters, Power Quality, Cascaded Multilevel Inverter, FPGA, Space Vector Pulse Width Modulation, Loses, Total Harmonic Distortion, Electromagnetic Interferences.

 


 

go to top   Interleaved SEPIC Converter with Low Turn-on Switching Loss
         by Bor-Ren Lin, Po-Li Chen, Jyun-Ji Chen

         Vol. 5. n. 4, pp. 1370-1380

 

Abstract - An interleaved Single Ended Primary Inductor Converter (SEPIC) with low turn-on switching loss is presented in this paper. Power switches can be turned on with zero-voltage-switching (ZVS) feature when it is operated at duty cycle greater than 0.5. Although, the proposed converter is operated at hard switching when the duty cycle is less than 0.5, the smooth current by the resonant inductance can reduce the turn-on switching loss. Thus the total switching losses can be reduced compared to the hard switching converter. The interleaved PWM scheme can also reduce the current ripple at the input and output capacitors. Thus the size of inductor and capacitor can be reduced. The circuit configuration, operational principles and design considerations of the proposed converter are discussed in detail. Finally, simulations and experiments from a 120W laboratory prototype are provided to confirm the theoretical analysis and the advantages of the proposed converter.

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Keywords: Zero voltage switching (ZVS), converters, interleaved PWM.

 


 

go to top   Analysis, Design and Implementation of a New ZVS Interleaved Asymmetrical Half-bridge Converter Using Synchronous Rectifier
         by M. Taheri, J. Milimonfared, M. Daryabak

         Vol. 5. n. 4, pp. 1381-1389

 

Abstract - This paper presents an interleaved asymmetrical half-bridge zero-voltage-switching (ZVS) converter using synchronous rectifier. The presented topology is composed of an asymmetrical half-bridge forward converter parallel with an asymmetrical half-bridge flyback converter. Only two power switches are used in the primary side of transformers, and Operate asymmetrically under zero voltage switching to achieve high efficiency and low switch voltage stress in comparison with conventional and active clamp converters. Because of interleaved operation of the converter, the output current ripple will be reduced. The proposed converter can approximately share the total load current between two secondaries. Therefore, the copper loss of the transformers can be decreased. The synchronous rectifier switches are used at the secondaries to further reduce the conduction loss of the rectifier diodes. The synchronous rectifier switches of the proposed converter also conduct under zero voltage switching condition with a continuous conduction mode. Detailed analysis and design of this new converter are described. A prototype converter has been implemented and experimental results have been recorded with an ac input voltage ranging from 85 to 135Vrms, an output voltage of 12V and an output current of 15A.

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Keywords: Active-Clamping Circuit, Interleaved Converter, Synchronous Rectifier, Zero-Voltage Switching, Asymmetrical Half-Bridge Converter.

 


 

go to top   Interleaved Series-Parallel Flyback Converter with High Power Factor
         by Bor-Ren Lin, Ming-Hung Yu, Jyun-Ji Chen

         Vol. 5. n. 4, pp. 1390-1397

 

Abstract - An interleaved discontinuous-conduction-mode (DCM) flyback converter is presented for power-factor- correction. Four flyback converters are divided into two modules which are driven in the interleaved fashion. The current ripples in input capacitor and output capacitor are partially cancelled and the current stresses of semiconductors can be reduced. Based on a steady-state time-domain analysis of each equivalent switching mode, an average model is derived. After applying small-signal perturbations, the ac transfer functions are obtained. Then the closed loop control of the proposed converter is made. Finally, the experimental results from a 250W prototype are presented to verify the effectiveness of the proposed converter.

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Keywords: Zero current switching (ZVS), flyback converters, interleaved PWM, power factor correcton.

 


 

go to top   Three-phase Shunt Active Power Filter Control with Line Current Sensing Only, Under Unbalanced Loading Conditions

         by B. Hekimoglu, M. Cakir, N. Abut

         Vol. 5. n. 4, pp. 1398-1404

 

Abstract - A three-phase shunt active power filter (APF) control strategy, which only employs line current sensing, is proposed. Since there is no harmonic calculation, the controller design is very simple and gives satisfactory current harmonics compensation even under unbalanced loading conditions. An analysis of the system and experimental results on a low cost microcontroller based laboratory prototype are reported. The shunt APF control strategy has been shown to be effective even under unbalanced loading conditions.

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Keywords: Harmonic Compensation, Line Current Sensing, Shunt Active Power Filter, Unbalanced Load.

 


 

go to top   Soft Switched Four Wire Inverter for UPS Applications

         by R. Senthil Kumar, Dr. Jovitha Jerome, P. Prem, T. Alex Stanley Raja

         Vol. 5. n. 4, pp. 1405-1412

 

Abstract - This paper presents a method for controlling the output voltage of a three phase four leg inverter based Uninterrupted Power Supply (UPS). The use of a four wire inverter increases the quality of the output whereas the soft switching technique employed helps to increases the overall efficiency of the inverter. Furthermore, in order to improve the system response to load variations, a PI control strategy is proposed. The 4 leg three phase inverters handles the neutral current caused by non-linear loads in a better manner. The main feature of a 4 leg inverter is its ability to deal with load unbalance in a system. The additional leg maintains a desired sinusoidal output voltage waveform for all loading conditions and transients. The neutral connection is present to handle the ground current due to unbalanced loads. The feasibility of the proposed modulation technique is verified by MATLAB simulation. It also discusses the experimental analysis of the 4 wire inverter.

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Keywords: Four wire inverter, MATLAB, PI, Soft Switching, UPS.

 


 

go to top   A Device for Improving the Voltage Sag Ride Through Capability of PCs
         by H. Shareef, A. Mohamed, K. Mohamed
         Vol. 5. n. 4, pp. 1413-1417

 

Abstract - Voltage sags have emerged as one of the most serious power quality problem. Voltage sag disturbances which sometimes last less than a fraction of second, can cause sensitive equipment such as personal computers (PCs) to shut down and interrupt PC controlled systems and processes for considerable periods of time, which leads to loss of production and high costs. In order to overcome this problem, an electronic device to enhance the ride through capability of PCs during voltage sag is developed. The proposed device can be connected to the power supply unit of PC to add a new operational state to the PC’s power supply, in which PC is supplied for one second by a capacitor bank in the events of voltage sags. It consists of sag detection circuit, control circuit, switching circuit and capacitor bank. The device is easy to use and can be built from cheap, commercially available components. Some of the salient features of the proposed device are that it does not require additional uninterruptible power supply for its operation, and it does not draw high levels of inrush currents from the mains. Furthermore, the proposed device can be adapted to other voltage sensitive devices such as lamps and ac contactors.

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Keywords: Voltage Sag, Ride Through Capability, Switch Mode Power Supply, PC, Voltage Tolerance Curves.

 


 

go to top   A New Isolated Bidirectional Buck-Boost DC-DC Converter
         by B. Fani, M. Delshad
         Vol. 5. n. 4, pp. 1418-1423

 

Abstract - In this paper, a new isolated dc-dc bidirectional converter is introduced. This converter consists of flyback and forward transformers and only one switch in primary side and one switch in secondary side of transformers. In this converter energy transfers to the output in both on and off switch states and controlled by PWM signal. Therefore implementation of control circuits is easy. Also this converter operates over a wide input voltage range. Theoretical analysis is presented and computer simulation and experimental results verify the converter analysis.

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Keywords: Bidirectional, Dc-Dc Converter, Buck-Boost, PWM, Flyback, Forward.

 


 

go to top   Design and Implementation of a Widened ZVS Range Active Clamping Two- Transformer Flyback Converter
         by A. Rahnamaee, J. Milimonfared

         Vol. 5. n. 4, pp. 1424-1429

 

Abstract - In this paper, a double transformer flyback converter using an auxiliary circuit to achieve soft switching condition for two main switches is presented. A new active clamp topology consists of an additional inductor and a capacitor is proposed to yield zero voltage switching over a wide load range. Employing two transformers, load current is shared between secondary sides of the transformers, hence; copper and output diode conductive losses are significantly decreased. As a result, efficiency of the converter does not drop in the lower out powers due to the loss of ZVS operation. Not only the design procedure but also detailed performance of the converter is thoroughly explained. Finally, the experimental results based on a prototype 24V/8A converter are given to validate the proposed topology.

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Keywords: Active clamping, soft switching, two transformer flyback switched mode power supplies, zero-voltage-switching.
 


 

go to top   High Voltage Driving Circuit with Negative Pulse Feature for Tubular Field Emission Lamp
         by C.-H. Lin, C.-M. Wang, M.-H. Hung

         Vol. 5. n. 4, pp. 1430-1435

 

Abstract - A high voltage driving circuit having pulse mode is proposed for driving tubular field emission lamp (FEL). The employed main circuit topology, which is a flyback converter operated in discontinuous conduction mode (DCM), will not only provide a low cost negative pulse feature, but also eliminate the arcing phenomenon caused by the traditional DC driving so as to improve the system efficiency and to prolong the lamp lifespan. In this paper, an equivalent model of the FEL is constructed to exhibit its capacitive characteristics. Moreover, each operation mode in a switching cycle is also described. And then a complete design considerations and mathematical model are detailed. All the experimental results agree with the computer simulations to verify the theoretical predictions.

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Keywords: Flyback converter, pulse power, field emission lamp, arcing.

 


 

go to top   Fault Detection of Power Transformer Windings Using Variations of Symmetrical Sequence Components of Line Currents
         by M. Yazdani-Asrami, E. Samadaei, S. Darvishi, M. Taghipour

         Vol. 5. n. 4, pp. 1436-1443

 

Abstract - One of the problems that may occur during utilization of power transformer is short circuit fault in windings. During the time of short circuit fault in winding, fault current changes according to intensity of short circuit. In this paper, a new approach to simulate and diagnostic of internal fault of transformer’s winding has been presented. According to happened variation in line current and evaluation of symmetrical component (positive, negative and zero sequences), easy and precise algorithm has been obtained that can be used for simulation of internal fault of transformer’s winding. On the other hand, to determine the percentage of damage inside winding, the obtained data from simulation has been used. The algorithm has been accomplished for both light and severe faults and has been simulated by Matlab/Simulink software package so that, in which index of light fault depends on electrical variations and index of severe fault relates to magnetic variations arising from fault in transformer winding. According to simplicity of this approach contrary to other previous approaches, the value of short circuit current of damaged winding, and also current variations, rate and intensity of damage inside winding can be easily obtained.

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Keywords: Internal Fault, Line Current, Short Circuit, Symmetrical Component, Power Transformer, Matlab/Simulink Software Package.

 


 

go to top   Effects of Harmonic Current Content and Ambient Temperature on Load Ability and Life Time of Distribution Transformers

         by S. B. Sadati, M. Yazdani-Asrami, M. Taghipour

         Vol. 5. n. 4, pp. 1444-1451

 

Abstract - Transformers are the main components in distribution systems that failure of them has many disadvantages for the system. The reason of most of these failures is increase of transformer's loss due to increase of harmonics particularly, current harmonics and environment or Ambient temperature. Increasing the amount of harmonic contents of load current create extra loss in windings and thus, leads to increase their hot spot temperature, increase of stress on their insulations, reduction of useful life of insulation and ultimately, reducing capacity of transformer.
These losses cause increase of temperature in different parts of transformer especially, its hot spot and increase of this temperature can reduce useful life time of transformer’s insulations. Therefore, be aware of harmonics values and contents, reduction of loading capacity of transformer and also, calculation of transformer's hot spot led to approximate remained life time of transformer seems essential. In this paper, additional to evaluation of equations related to loss and estimation of life time of transformer, measuring and sampling of some transformer's current and voltage belonged to Mazandaran Electric Power Distribution Company (EPDC of Mazandaran Province, Sari, IRAN) has been done. Then losses and remained life time and load ability of them have been estimated and evaluated under these situations according to equations and written program in MATLAB/SIMULINK software package.

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Keywords: Distribution Transformer, Harmonic Currents, Harmonic Loss Factor, Hot Spot Temperature, Maximum Load Ability, Measurement or Experimental Setup, Useful Life.

 


 

go to top   Identifying the Location of Disk to Disk Short-Circuit in Power Transformer by Means of Double-2d Finite Element Analysis
         by M. R. Barzegaran, M. Mirzaie, M. Yazdani-Asrami, R. Ahmadi Kordkheili

         Vol. 5. n. 4, pp. 1452-1459

 

Abstract - Short-circuit is known as one of the most important basis of the damages in power transformers, weakness of insulation, and many other reasons which would cause these minor faults. To prevent these minor faults to be a major fault, a sensitive and accurate technique in fault detection is used in this paper. Frequency response analysis as a well-known and sensitive method of fault detection is coupled with Finite element analysis that is one of the most accurate methods of simulation. A sensitive transfer function has been noticed in the winding of a three phase power transformer and the response is analyzed in wide band frequency in healthy state and also some faulty states. Results of the simulation in these states are compared for better and faster identification of minor faults. In order to enhance accuracy, double-2d simulation instead of 2d simulation is used and also magnetic and electric analyses are performed simultaneously which is new in these kinds of analyses.

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Keywords: Power Transformer, Fault Detection, Double 2d Finite Element Analysis, Transfer Function, Quasi Static, Frequency Response Analysis.

 


 

go to top   Diagnosis of Broken Bar Fault in Induction Machines Using Advanced Digital Signal Processing
         by A. Braham, Z. Lachiri

         Vol. 5. n. 4, pp. 1460-1468

 

Abstract - In induction machines, motor current signature analysis has been tested in many industrial cases with good results. However, this method does not always achieve successfully results to detect broken-rotor-bar under variable load torque. Recent advances on signal processing techniques have provided more powerful tools for faults diagnosis. This paper proposes a novel approach based on Power Spectrum Density estimation (PSD) to diagnose and detect broken-rotor-bar faults in induction motor under different levels of load. This paper also analyses three different spectral decomposition methods applied to induction machine stator current, namely Welch, Burg and Multiple Signal Classification (MUSIC). Based on different power spectral estimation concepts, the frequency resolution, variance and detection capability are different from each other according to the set of parameters used. The proposed methodology aims to determine which spectral estimate method best suited for implementation in an automated system for fault detection. Also, the PSD estimate is used for feature extraction and aims at identifying the descriptors that show high variability between different classes and thus would help distinguishing between them. Various scenarios are examined using data sets of stator current signals from experiments under different load, and the results are compared to obtain the best performance for automated process.

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Keywords: Induction Motor, Broken-Rotor-Bar, Fault Diagnosis, Power Spectrum Density Estimation.

 


 

go to top   A New Direct Torque Control for Reduced Energy Consumption in Induction Motors
         by G. Calzada-Lara, F. Pazos-Flores, R. Alvarez-Salas

         Vol. 5. n. 4, pp. 1469-1476

 

Abstract - This document proposes an energetic output improvement of electric drives for induction motors. This modification pointing toward a better energetic output (improving the efficiency) according to the application, and can be made in the most common control algorithms as the FOC (Flux Oriented Control) and the DTC (Direct Torque Control). The simulation results show that the proposed controller ensures both, a good speed control and smooth torque response with current shapes with low THD, when these are compared with the conventional DTC scheme. Experimental results for a 1.1 kW induction motor are presented and analyzed using a dSpace system with DS1103 controller board based on digital processor Texas Instruments TMS320F240. Obtained results demonstrated that the proposed control scheme is able to obtain a high performance. The increase in drive’s efficiency supposes on the one hand, a considerable economic saving and, on the other hand, a reduction in the environment pollution.

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Keywords: Direct Torque Control (DTC), Efficiency Improvement, Energetic Output, Induction Motor.

 


 

go to top   The Modelling of the E-Core Transverse Flux Machine Based on Neural Network
         by Çiğdem Gündoğan Türker, Feriha Erfan Kuyumcu

         Vol. 5. n. 4, pp. 1477-1487

 

Abstract - The E-core Transverse Flux Machine (ETFM) that has a different and a new structure, is combined of the principle of transverse flux machine and conventional Switched Reluctance Machine. This paper is focused about the modelling and the imlementation of the ETFM for an application. An accurate ETFM model needs a good knowledge of the magnetic characteristics of the machine to determine its electrical and mechanical behaviors. This paper investigates the use of Artificial Neural Networks (ANNs) for the modelling of the magnetic nonlinearity of the SRM. The data for the training of the ANN is obtained experimentally methods. To validate the accuracy of the NN model, the comparison between experimental results is also given. The ETFM is applied for an exercise bike. The control structure of the system is presented in this paper. The complete modelling and the simulation of the whole system, considering the nonlinear characteristic of the drive, are implemented by Matlab/Simulink and verified the waveforms with the real system results under different conditions.

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Keywords: E-Core Transverse Flux Machine, Artificial Neural Network.

 


 

go to top   Design and Analysis of a Hybrid Stepper Motor for Actuating the Gimbal of Control Moment Gyroscope
         by Praveen R. P., Ravichandran M. H., Sadasivan Achari V. T., Dr. Jagathy Raj V. P., Dr. Madhu G., Dr. Bindu G. R.

         Vol. 5. n. 4, pp. 1488-1495

 

Abstract - This paper presents the design, analysis and development of a 400-step hybrid stepper motor for actuating the gimbal of a Control Moment Gyroscope (CMG). The design of the hybrid stepper motor for achieving a specific performance requires the choice of appropriate tooth geometry. In this paper, a detailed account of the results of two-dimensional finite-element (FE) analysis conducted with different tooth width/tooth pitch ratios (t/λ) and also with different tooth/slot shapes such as square and trapezoidal, is presented. The use of equal t/λ ratio on stator and rotor provides nearly 10% more torque than the case with unequal t/λ ratio, but with corresponding increase in detent torque and distorted static torque profile. The hybrid stepper motor for actuating the gimbal of a CMG requires maximum torque density, less-detent torque or cogging torque, better positional accuracy and smooth static torque profile. For the said requirements different pitch slotting with equal tooth width has to be provided. The magnitude of the cogging torque has almost been reduced to 50% from what it was while employing equal t/λ configuration. From the various FE models subjected to analysis, trapezoidal teeth configuration with unequal tooth pitch on the stator and rotor is found to be the best configuration and is selected for fabrication. The designed motor is fabricated and the experimental results are compared with the FE results.

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Keywords: Hybrid stepper motor, cogging torque, FEA, space application.

 


 

go to top   DTC Based Control Strategy of a Twin AC Drive Used for a Cement Kiln
         by I. X. Bogiatzidis, E. D. Mitronikas, A. N. Safacas

         Vol. 5. n. 4, pp. 1496-1503

 

Abstract - An analysis of the basic principles which determines the control strategy of a twin AC drive used for a cement kiln taking into account the stringent industrial requirements and unexpected abnormalities, has been investigated in this paper. A model of the whole electromechanical drive will be presented using Matlab / Simulink software and simulation results will be shown. Finally, a laboratory simulating system appropriately designed and constructed to emulate the operation of the real kiln drive will be described and some experimental results will also be presented.

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Keywords: Backlash, Cement kiln, Twin AC Drive, DTC, Laboratory kiln .

 


 

go to top   Performances Evaluation of Two-Motor Drive with Matrix Converter Supply and Series Connection of Stator Windings
         by A. Djahbar, B. Mazari

         Vol. 5. n. 4, pp. 1504-1511

 

Abstract - Recent research has shown that is possible to connect in series stator windings of multi-phase machines and control all the machines in the group independently, although the complete multi-drive system is supplied from a single multi-phase voltage source converter (VSI inverter or matrix converter).
This paper analyzes a six-phase two-motor, consisting of a direct AC-AC six-phase matrix converter, a six-phase induction machine, and a three-phase induction machine. Stator windings of the two machines are connected in series in an appropriate manner.
After a theoretical introduction of the six-phase matrix converter, a scalar modulation scheme with three intervals which ensures high performance and meets desired requirements is used for the control of matrix converter. Verification of the proposed system is provided by simulation and the results are given in the paper.

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Keywords: Six-phase matrix converter, scalar modulation, Six-phase induction machine and three-phase induction machine.

 


 

go to top   Theoretical and Experimental Investigation of the Effect of Eccentricity Faults on Noise Generation in Brushless DC Permanent Magnet Motors
         by A. Rezig, M. R Mekideche, A. Djerdir

         Vol. 5. n. 4, pp. 1512-1518

 

Abstract - Vibrations and noise in electrical machines are directly related to the characteristics of the radial forces on one hand, and mechanical behavior on the other. The characteristics of these forces depend on the air gap flux density, and they are influenced by other factors such as stator slots and poles, saturation level, winding type and certain faults. The aim of this work is to investigate the effect of eccentricity faults on electromagnetic noise generated by the external surface of PM synchronous machine (PMSM). For this purpose an analytical electromagnetic vibroacoustic model is developed. The results confirm the effect of eccentricity fault in generating some low modes radial forces. An experimental device is being installed to validate the results of the analytical model.

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Keywords: Noise and vibration, radial forces, eccentricity, analytical model, FEM simulation, natural frequency. Noise components.

 


 

go to top   Real Time Implementation of Fuzzy Logic Based MRAS Observer for Speed Sensorless Vector Control of Induction Motor
         by K. Negadi, A. Mansouri, B. Khatemi

         Vol. 5. n. 4, pp. 1519-1528

 

Abstract - Of the different methods for sensorless control of induction motor drive Model Reference Adaptive system (MRAS) finds lot of attention due to its good performance. Usually the sensorless speed control performance of induction motor drive deteriorates at low speeds nearing zero speed range. Due to this interest has been diverted to improve the performance of the induction motor drive at low speeds. In this paper a novel adaptation mechanism is proposed which replaces normally used PI controller in MRAS adaptation mechanism by a fuzzy logic controller. Implementation hardware of MRAS based sensorless control of induction motor drive where the speed signal obtained is tuned by using a fuzzy logic controller are presented. In this paper the effectiveness of the proposed control scheme is demonstrated by experimental results.

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Keywords: Induction motor drives, sensorless control, fuzzy logic controller, MRAS, modeling, field oriented control, Dspace.

 


 

go to top   Determination of Induction Motor Double-Cage Model Parameters Based on Bacterial Foraging Optimization Algorithm
         by V. P. Sakthivel, S. Subramanian

         Vol. 5. n. 4, pp. 1529-1537

 

Abstract - A newly developed technique, called Bacterial Foraging Optimization (BFO) algorithm, is proposed for the parameter determination of induction motor double-cage model from standard manufacture data such as rated output power, starting torque, breakdown torque, full load torque, efficiency and power factor at rated output power. Using the squared error between the determined and the manufacture data as the objective function, the parameter determination problem is transferred into an optimization process where the double cage model parameters are determined that minimize the defined objective function. The objective function is iteratively minimized using the BFO algorithm.
The method has been tested with two sample motors. The performance of the BFO algorithm is compared with classical parameter determination (CPD) method and other optimization methods including Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Immune Algorithm (IA). Simulation results exhibit the potential of the proposed technique to capture the true values of the machine parameters and the superiority of the results obtained using the BFO over other parameter determination techniques.

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Keywords: Double-cage model, Manufacturer data, Optimization techniques, Parameter determination.

 


 

go to top   Constant Flux Control Based Single-phase Induction Motor Drive
         by K. Samidurai, K. Thanushkodi

         Vol. 5. n. 4, pp. 1538-1542

 

Abstract - At present the speed control of a capacitor-run single phase induction motor is being achieved by using triac based voltage regulators. This paper proposes a new scheme, in which the motor is supplied by a 90 degree phase shifted sinusoidal variable voltage, variable frequency source with the constant flux control (i.e volt/hertz control). Performance comparison is made between these two schemes in this paper. The proposed scheme eliminates the capacitor connected in series with the auxiliary winding. Experimental results show that an appreciable amount of energy saving and improved efficiency are obtained in the proposed scheme.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Capacitor-run induction motor, Energy saving, Inverter, Sinusoidal pulse width modulation (SPWM), Volt/hertz speed control.

 


 

go to top   Sensitivity Analysis of Hysteresis Motor Through a Circuit Coupled 3D FEM Model
         by M. R. Ghazanchaei, A. Vahedi, M. Mirimani, A. Baktash

         Vol. 5. n. 4, pp. 1543-1549

 

Abstract - Hysteresis motor is a synchronous motor that uses the hysteresis characteristics of magnetic materials. It is known that the magnetic characteristics of the motor could be easily affected by variation on hysteresis material, structural dimensions and winding distributions. Variation on constructional parameters plays an important role in flux distribution in hysteresis ring and influences the output torque, terminal current and efficiency. Regarding this issue, in this study effect of different parameters variation on performance characteristics of circumferential flux hysteresis motor is investigated. Simulation of prototype motor in order to extract the output values of motor and sensitivity analysis is done using 3D Finite Element Model. Based on output results of sensitivity analysis a new motor is produced with optimal parameters and the output quantities of this motor is compared with original motor. There is a great improvement in performance of new motor.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Conventional hysteresis motor, Finite Element Model, Complex Permeability, Sensitivity analysis.

 


 

go to top   Entropy Transferred by Aging Process in Electric Motors
         by S. Seker, E. Onal

         Vol. 5. n. 4, pp. 1550-1554

 

Abstract - In this study, motor bearing degradation is formed under the accelerated aging processes. Normal and aged motor cases are compared through the vibration measurements. These vibration signals are analyzed to extract the aging features by the statistical parameters. Hence, probability values of the healthy and faulty motor cases are defined and then, entropy value, which is transferred from the healthy (initial) case to faulty (aged) case, is calculated in the sense of the Shannon’s Entropy.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Vibration, Statistical parameters, Aging, Entropy, Motor Diagnostic.

 


 

go to top   Novel MPPT Controller for Wind Turbine Driven Permanent Magnet Generator with Power Converters
         by R. Bharanikumar, A. Nirmal Kumar, Maheswari K. T.

         Vol. 5. n. 4, pp. 1555-1562

 

Abstract - A novel maximum power point tracking (MPPT) control for the operation of permanent magnet generator (PMG) based variable speed wind turbine is presented in this paper. The maximum power point tracking is required to get high efficiency for wind energy conversion system. The maximum power point for each wind speed is traced using a new method of Maximum Power Point Tracking algorithm. The rotating speed of permanent-magnet generator should be adjusted in the real time to capture maximum power from the wind. The proposed system consist of wind turbine, permanent-magnet generator, three-phase rectifier, boost chopper, inverter. The duty cycle of the boost chopper is the control parameter. To enhance the performance, PMG is operated at variable speed condition. The proposed system is simulated in MATLAB / SIMULINK and the results are compared with laboratory experimental setup.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: PMG, rectifier, boost chopper, inverter, wind turbine, MPPT.

 


 

go to top   Adaptive Inverse Control Schemes Based on Fuzzy Neural Networks for Induction Motor Drives
         by Tsao-Tsung Ma

         Vol. 5. n. 4, pp. 1563-1570

 

Abstract - This paper describes the design of adaptive inverse controllers for the speed tracking control of induction motors (IM). The proposed adaptive inverse control scheme uses an open-loop control scheme to concur the instability problem caused by conventional feedback control systems and utilizes an on-line compensator to achieve improved dynamic performances. In this paper, two fuzzy neural networks (FNN) are utilized to respectively perform the tasks of on-line identification of IM dynamics and the main speed tracking controller. In the control scheme, a fuzzy controller is properly designed to real-time compensate the changes of operating conditions and possible disturbances. All of the controllers used in this design are optimized by using the particle swarm optimization techniques. Comprehensive simulation and hardware tests are carried out to verify the performance of the proposed controller.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Adaptive inverse controller, Fuzzy neural network, Induction motor drive.

 


 

go to top   Magnetic Circuit Optimization for a Switched Reluctance Generator
         by V. Hrabovcová, M. Lipták, P. Rafajdus

         Vol. 5. n. 4, pp. 1571-1579

 

Abstract - This paper deals with an optimization of a Switched Reluctance Generator magnetic circuit for a given speed and outer dimensions from the point of view of maximum efficiency by means of FEM analysis. Basic principles of the SRG operation and energy conversion are explained, an equivalent circuit and mathematical model is created and simulation outputs are presented.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Switched Reluctance Generator, optimization, electrical machines.

 


 

go to top   A Solar Powered Autonomous Mobile Vehicle for Monitoring and Surveillance Missions of Long Duration
         by Antonio Guerrero-González, Francisco García-Córdova, Francisco de Asis Ruz-Vila

         Vol. 5. n. 4, pp. 1580-1587

 

Abstract - In this paper, an autonomous vehicle capable of operating during large periods of time for observation and monitoring is proposed. The vehicle integrates photovoltaic panels and a methanol fuel cell, together with a neurobiological inspired control architecture for intelligent navigation. In this work, the autonomy of the vehicle is evaluated in several scenarios, when the vehicle is moving in mission and when the vehicle is not moving. The energetical management module generates recharge missions with a variable priority level depending on the batteries level to the mission planner. The biologically inspired neural network architecture proposed for nonholonomic mobile robots makes the integration of a kinematic adaptive neuro-controller for trajectory tracking and an obstacle avoidance adaptive neuro- controller possible.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Solar Powered Autonomous Vehicles, Neuro-controller, Fuel Cell, Power Management.

 


 

go to top   Investigation of the Reactions Exhibited by the System in Relation to Different Loads in a Sample House Powered with a Hybrid Photovoltaic- Hydrogen/Fuel Cell
         by Y. Oner, E. Cetin

         Vol. 5. n. 4, pp. 1588-1594

 

Abstract - In today’s world where energy resources are rapidly depleted and great importance is attached to clean, environmental friendly, modular and fossil fuel-independent energy sources, “photovoltaic-hydrogen fuel cell hybrid energy production systems” come into prominence. In our university, there is a Clean Energy House and here, there is already a 5kWP photovoltaic and 2.4kWP hydrogen fuel cell power system established. Here, electric energy is produced through photovoltaic panels mounted on sun tracking half of which are fixed and the other half is liquid-based, the energy produced is stored in batteries with 28.8kWh storage capacity and some of the stored energy is consumed to meet the internal energy needs of the clean energy house through 5kW-220V/50Hz thoroughly sinus inverter, the rest is used to power a hydrogen generator. Hydrogen generated from the city water through the hydrogen generator is converted into DC energy through 2.4kW power cells. With this study, electrical energy analysis of the clean energy house was carried out. Within the framework of the study, harmonics, voltage changes, voltage and current sags, voltage and current swells, transients, power-cuts, frequency changes, in short, power quality of the whole system was analyzed.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Photovoltaic, Hydrogen Power Cell, Electrical Analysis.

 


 

go to top   Experimental Analysis and Electrical Modeling of PEM Fuel Cell’s MEA
         by Erkan Dursun, Gülsah Yegen Ozalp, Osman Kilic

         Vol. 5. n. 4, pp. 1595-1599

 

Abstract - The proton exchange membrane fuel cell (PEMFC) which has low operating temperature, high power density and zero emission is the most suitable one for energy applications. In this study, two different PEMFCs membrane electrode assemblies (MEA) are tested in terms of electrical characteristics in different temperatures and humidity. Then these results are compared with improved PEMFCs electrical circuit model. This model is developed in MATLAB/Simulink®.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Experimental analysis, modeling, fuel cell, membrane electrode assembly.

 


 

go to top   Analysis of a Photovoltaic-Fuel Cell Hybrid Energy System In Terms of Electromagnetic Pollution
         by Eylem Yilmaz Ulu, Engin Cetin, O. Onder Karakilinc, Ahmet Yilanci, H. Kemal Ozturk

         Vol. 5. n. 4, pp. 1600-1608

 

Abstract - In the modern life, extensive use of electrical energy has some harmful effects on nature. Fossil based energy production systems as well as nuclear power plants cause a lot of damage risks for environment and human health. In addition, using of fossil fuels contributes to global warming and the other significant subject, electromagnetic pollution. Strong electromagnetic fields (EMFs) and the related electromagnetic radiation (EMR) are harmful to us. Long-term exposure may aggravate any existing health problems or diseases and may cause or intensify especially lack of energy or fatigue, irritability, aggression, hyperactivity, sleep disorders and emotional instability. In any energy system, the components which disperse high electromagnetic pollution should be determined to take some actions against their effects. In this study, an electromagnetic pollution analysis of a hybrid photovoltaic-fuel cell system installed at Pamukkale University in Denizli, Turkey is performed. Electromagnetic pollution intensities of the components of the installed hybrid energy system are measured under different loads. In addition, results of measurements are compared with worldwide standards.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Fuel cell, photovoltaic, electromagnetic pollution, environment.

 


 

 

International Review of Electrical Engineering - Papers- Part B

 

 

go to top   Power System Stability Enhancement using Bio Inspired Genetic and PSO Algorithm implementation

         by R. Shivakumar, Dr. R. Lakshmipathi, M. Panneerselvam

         Vol. 5. n. 4, pp. 1609-1615

 

Abstract - Improvement of Power System Stability is the most important issue in Modern Interconnected Power Systems. With the increasing Complexity of Power System, Electromechanical Oscillations are becoming one of the major problem affecting the System Stability. This paper provides a systematic approach to design an Optimal Controller to damp the Electromechanical Oscillations based on Bio Inspired Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) Techniques. The Proposed Controller design is based on Power System Damping Factor based Objective function formulation to compute the optimal controller parameters, which aid in enhancing System Stability.To validate the Robustness and effectiveness of the Optimal Controller, Non linear Time domain Simulations has been carried out under various system loading conditions and also implementing dynamic Parameter variations of the system model considered. A detailed Comparative study is also done to show the superiority of the Bio Inspired algorithms based controller over the Conventional Lead lag controller.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Electromechanical Oscillations, Genetic Algorithm, Particle Swarm Optimization, Power System Stabilizer.

 


 

go to top   A Fuzzy Multi-Objective Multi-Case Genetic-Based Optimization for Allocation of FACTS Devices to Improve System Static Security, Power Loss and Transmission Line Voltage Profiles
         by A. Deihimi, H. Javaheri

         Vol. 5. n. 4, pp. 1616-1626

 

Abstract - This paper presents a multi-objective multi-case problem of optimal allocation of flexible AC transmission system (FACTS) devices to be solved by an approach based on fuzzy decision making and genetic algorithm. Three main features of this study over previous works are: a) in addition to real power transmission loss and static security indices, the reactive power absorbed by transmission lines is considered as another objective so as to correct voltage profiles on lines of high series reactance, b) bus voltage deviations and line overloads are individually avoided as much as possible by imposing stringent constraints through defining appropriate membership functions, and c) in addition to system base case, a number of critical contingency cases obtained from a contingency analysis/ranking method are included directly in the optimization process. The installation cost is taken into account before optimization process by selecting number of devices. The variables to be optimized consist of location and type of FACTS devices, their settings for base case and regarded contingency cases. Three generic types of FACTS devices namely TCSC, SVC and STATCOM are used and modeled for steady-state studies. Simulations are performed on the standard IEEE 30-bus and 57-bus systems and the results are discussed.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Fuzzy Decision Making, Genetic Algorithm, Optimal Allocation of FACTS Devices, Static Power System Security, Transmission Line Voltage Profile.

 


 

go to top   A Primal-Dual Interior Point Method to Minimize Total Active Power Loss in Electric Power Systems
         by M. Khiat, A. Marano

         Vol. 5. n. 4, pp. 1627-1632

 

Abstract - In this paper aims at the study of an Interior Point Method (IPM) based on the logarithmic-Barrier Primal-Dual Algorithm (LB-PDA), for Nonlinear Programming (NLP). The total active power loss minimization is formulated as an Optimal Reactive Power Flow (ORPF), including equality and inequality constraints which represent the power system security conditions. It is shown that this optimization method has very attractive features to solve the Var/voltage problems. Finally, some results obtained with various simulations for a real transmission power system are presented.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Active power loss minimization, primal-dual interior point method.

 


 

go to top   Economic Effects of FACTS on the Transient Stability of Power Plants
         by Iraj Rahimi Pordanjani, Hooman Efranian Mazin, Gevorg B. Gharehpetian

         Vol. 5. n. 4, pp. 1633-1640

 

Abstract - With the increased demand for electrical power, power systems currently need to be operated close to their stability limits, increasing the transient instability probability at power plants. In this situation, FACTS devices can be used effectively because of their capability to improve transient stability. Several studies have been made to assess the effect of FACTS on transient stability. However, these studies have not considered this effect from the economic point of view. Therefore, the aim of this paper is to analyze the economic effects of FACTS on the transient stability of power plants. This will be done by evaluating the effect of the FACTS on the transient instability risk of the power plant. A generic procedure is proposed for this evaluation in this paper. The procedure is then applied to a real case study, Tehran transmission system and the economic effect of a TCSC on the transient stability of a power plant in this system is investigated.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Flexible AC Transmission Systems (FACTS), Reliability, Thyristor Controlled Series Capacitor (TCSC), Transient instability risk, Transient stability.

 


 

go to top   A Robust Static Voltage Stability Index for Distribution Networks
         by Ulas Eminoglu

         Vol. 5. n. 4, pp. 1641-1647

 

Abstract - In this paper, a new static voltage stability index is proposed for identifying the line or its corresponding bus on the verge of voltage collapse of distribution networks. The index is developed by using the distribution line receiving end bus voltage formulation, and its adequacy is evaluated on a modern distribution test system which has voltage controlled bus (PV-bus). From analyses, it is observed that the proposed stability index correctly predict the critical line and its corresponding bus as well, and can provide useful information for the most sensitive line at any operating point of distribution networks. On the other hand, most of the existing voltage stability indices do not correctly estimate the critical bus or its corresponding line for this particular distribution network. In addition, the estimation about the most critical bus or line by using these stability indices for the any operation point of radial systems may cause utilities a wrong conclusion on the critical bus or its corresponding line because they would be inadequate for assessing the most sensitive bus or line in such distribution networks.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Critical Line, Distribution Networks, Voltage Stability Indices, Voltage Collapse.

 


 

go to top   Novel Adaptive Control Schemes Based on Online-Trained Fuzzy Neural Networks for the STATCOM
         by Tsao-Tsung Ma

         Vol. 5. n. 4, pp. 1648-1654

 

Abstract - This paper presents the design of fuzzy neural networks (FNN) based controllers for the STATCOM to provide better control features in performing various reactive power flow control functions during steady-state and transient operations of power systems. The STATCOM with different hardware structures may have different operating modes and system dynamics which require advanced controllers to achieve satisfactory performances. In this paper, two separate FNN tuned PI controllers are used for controlling the STATCOM, one for the reactive power control and the other for the internal dc voltage regulation. Simulation and experimental studies carried out in the Matlab/Simulink environment is described and results of various power flow control examples show the successful control of the STATCOM and the effectiveness of the new control algorithm.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Flexible ac transmission systems (FACTS), Static synchronous compensator (STATCOM), FNN controller.

 


 

go to top   Sub-transmission System Expansion Planning Including Distributed Generation and Considering the Losses by Genetic Algorithm
         by Amir Bagheri, Seyed Hadi Hosseini, Saeid Jalilzadeh, Abolfazl Jalilvand, Mohsen Parsa Moghaddam

         Vol. 5. n. 4, pp. 1655-1663

 

Abstract - Nowadays, small generators called Distributed Generation (DG) has provided new options in the design of electric networks. In this paper, the presence of distributed generation is regarded as an alternative for supplying the load of sub-transmission system. The effects of DG on expansion planning of sub-transmission system such as costs and losses have been mathematically modeled. Fixed and variable costs of the plan are formulated in the model. The solution of this problem gives the optimal capacity of substations, optimal location and capacity of DGs as well as optimal configuration of sub-transmission lines satisfying the reliability and system operational constraints and considering the losses. The proposed objective function and its constraints compose an optimization problem which is solved using Genetic Algorithm (GA) and Linear Programming (LP). To confirm the effectiveness of the proposed method, it is applied to a typical sub-transmission system and the simulated results are compared with the expansion planning of the same sub-transmission system without the use of distributed generation. The results show that the use of distributed generation in the expansion planning of sub-transmission system provides more economical plans and imposes less loss to the system.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Expansion planning, distributed generation, sub-transmission, Genetic Algorithm.

 


 

go to top   Dynamic Economic Dispatch Solution Using Composite Cost Function
         by S. Subramanian, R. Anandhakumar

         Vol. 5. n. 4, pp. 1664-1669

 

Abstract - This paper proposes using the composite cost function to solve the dynamic economic dispatch problem in power system operation. The dynamic economic dispatch must not only satisfy the system load demand and the spinning reserve capacity, but some practical operation constraints of generators, such as ramp rate limits are also considered in practical generator operation. The feasibility of the proposed composite cost function solution method is demonstrated on sample power system and it is compared with other stochastic methods in terms of solution quality and computation efficiency. The numerical simulation results showed that the proposed method was indeed capable of obtaining the higher quality solutions efficiently in dynamic economic dispatch problems.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Composite cost function, Dynamic economic dispatch, Ramping rate limits.

 


 

go to top   Improving Contribution of DFIG-based Wind Farms in Short-Term Frequency Regulation of Power Systems
         by M. Akbari, Seyed M. Madani

         Vol. 5. n. 4, pp. 1670-1677

 

Abstract - This paper investigates the impacts and contribution of doubly-fed induction generator (DFIG) based wind farms in power system frequency regulation. First, the negative impacts of increasing penetration of DFIG-based wind farms on power system frequency regulation are studied. Then, DFIGs’ useful capabilities and control methods to contribute in system frequency control are presented. Considering the problems of conventional control methods, a new method for participation of DFIG-based wind farms in short term frequency control is proposed. The method uses “average frequency” to estimate power imbalance, quickly and precisely. Then, the kinetic energy stored in the wind farm inertia is exploited to compensate this power imbalance. Several simulations using a nine-bus test system are performed to demonstrate the effectiveness of the proposed method.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords:  Doubly-fed induction generator, Frequency control Kinetic energy Power imbalance estimation.

 


 

go to top   Electromagnetic Transients Analysis of Lightning Overvoltages on Wind Power Plants
         by R. B. Rodrigues, V. M. F. Mendes, J. P. S. Catalão

         Vol. 5. n. 4, pp. 1678-1684

 

Abstract - As wind power generation undergoes rapid growth, lightning and overvoltage incidents involving wind power plants have come to be regarded as a serious problem. Firstly, lightning location systems are discussed, as well as important parameters regarding lightning protection. Also, this paper presents a case study, based on a wind turbine with an interconnecting transformer, for the study of adequate lightning and overvoltage protection measures. The electromagnetic transients circuit under study is described, and computational results are presented.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Electromagnetic transients, lightning, overvoltages, protection, wind power plants.

 


 

go to top   Multiobjective Augmented Eps-constraint Optimization for Economic/Environmental Stochastic Unit Commitment in Power Systems with High Penetration of Wind Power
         by M. A. Khorsand , H. Heydari

         Vol. 5. n. 4, pp. 1685-1694

 

Abstract - To regard environmental protection renewable energy sources especially wind, has been applied to achieve emission reduction goals. While wind generation does not directly produce air pollutants emission, it causes some changes on thermal power generation scheduling which may lead them to produce more air pollutants emission especially during low and medium energy demand periods. So it seems necessary to consider air pollutants emission level in wind-thermal scheduling problems. This paper proposes a methodology for wind-thermal scheduling in a power system with high penetration of wind power subject to consider air pollutants emission reduction. Because of simultaneous minimizing total operating cost and air pollutants emission, a Multiobjective Mathematical Programming (MMP) is introduced. The computation of the required reserve levels and their costs is attained through a stochastic programming market-clearing model. Also, the network constraints and the costs of both the load shedding and the wind spillage are considered. The MMP approach based on Augmented Eps-constraint algorithm has been suggested for generating Pareto-optimal solutions of wind-thermal units scheduling problem. Additionally, Fuzzy decision making process is employed to choose one of the Pareto-optimal solutions as the best compromise nondominated solution. The usefulness of the proposed approach were demonstrated through an IEEE 30-bus test system.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Air Pollutants Emission, Multiobjective Mathematical Programming, Stochastic Programming, Unit Commitment, Wind Power.

 


 

go to top   Reliability Based Unit Commitment of a Distribution Company with Integrations of Probabilistic Wind Farm and Spinning Reserve Based on Benders Decomposition Method
         by M. Baghdadi, S. S. Mortazavi, A. Saidian

         Vol. 5. n. 4, pp. 1695-1706

 

Abstract - A comprehensive framework model of a reliability based unit commitment of a distribution company with security and reliability considerations is presented in this paper. A probabilistic wind farm, which is a renewable energy resource, is modeled in this work. The requirement energy of Distribution Company can be either provided by Distribution Company’s own distributed generations or purchased from power market. Since allocating proper spinning reserve improves reliability level, the amount of spinning reserve will be calculated iteratively in way to improves reliability of the system. In this work, all equations are expressed in a linear fashion in which unit commitment formulation depends on binary variables associated with only on/off of units. The Benders decomposition method is used to solve security based unit commitment. Two test system with real data of wind farm is implemented to confirm the efficiency of proposed method.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Benders Decomposition, DISCO, Probabilistic Spinning Reserve, Reliability, SCUC, Wind Farm.

 


 

go to top   Self Scheduling Program for VRB Energy Storage System in Competitive Electricity Market
         by I. Gerami Moghaddam, F. Fallahi

         Vol. 5. n. 4, pp. 1707-1714

 

Abstract - Recent developments and advances in energy storage technologies are making the application of energy storage technologies a viable solution to power system applications. This paper addresses the economical aspects of VRB plant participation in competitive electricity markets as a power producer. The costs including installation, Operation & Maintenance and the revenues containing energy price arbitrage, reducing transmission access cost and deferring facility investment are among economic parameters considered here. In order to achieve this goal, an appropriate Self-Scheduling approach must be developed to determine its maximum potential of expected profit among multi-markets such as energy and ancillary services markets. The profit maximization problem faced by the VRB is therefore an optimal scheduling problem that is formulated as a mixed-integer non-linear programming (MINLP) problem. Also numerical studies have been conducted to evaluation premium on feed-in model for a VRB power plant to ensure profitable operation is guaranteed.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: VRB plant, feed-in tariff, Self-Scheduling problem, MINLP, Renewable Energy Support Schemes.

 


 

go to top   Redundancy Allocation Problem of Multi State Power Systems Using Ant Colony System

         by O. Bendjeghaba, D. Ouahdi

         Vol. 5. n. 4, pp. 1715-1720

 

Abstract - This paper considers the redundancy allocation problem (RAP) in which both the type of components and the corresponding number of redundancy of each component in each subsystem are to be decided simultaneously so as to minimize the system cost subject to reliability constraint. The problem has been studied in the literature for decades, usually using mathematical programming or heuristic/metaheuristic optimization approaches where they consider only the homogeneous redundancy. A metaheuristic approach based on the ant colony system combined with the universal moment generating function is presented for solving both the ordinary and the heterogeneous RAP. It can efficiently search to find the feasible optimal or near optimal solution. The obtained computational results using the approach, demonstrate that this one is a promising tool for solving this class of redundancy allocation problem especially at the design stage.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Ant colony system (ACS), Heterogeneous redundancy allocation problem (HRAP), Metaheuristic, Multi state power systems (MSPS), Universal moment generating function (UMGF).

 


 

go to top   Energy Saving and Environmental Benefits and CO2 Reduction From a Combined Heat and Power System

         by I. Gerami Moghaddam, H. Moradi, A. Saidian

         Vol. 5. n. 4, pp. 1721-1727

 

Abstract - High efficiency of cogeneration systems is one of the major factors that make them attractive for investors. The utilization of these systems is possible by using different strategies such as electrical dispatch, thermal dispatch and a combination of these two methods which is known as hybrid dispatch. In this paper, the efficiency of cogeneration systems is evaluated by some indices such as overall energy saving, thermal efficiency and Energy-Chargeable-to-Power (ECP). Also, the amount of CO2 production has been calculated by using above operational strategies and in a case of without CHP. Then, all of the operational modes are applied to a local customer having predefined electrical and thermal loads and the results are analyzed. A CHP operator can choose the proper strategy by using the results of this investigation and considering the goal of applying cogeneration technology which fulfills the expectations from such system.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Cogeneration, emission reduction ,fuel energy saving, greenhouse gases, micro Turbinem ,trigeneration.

 


 

go to top   Synchronization Method for Three Phase Applications

         by Sebastián Maestri, Patricio Donato, Roberto Petrocelli, Ignacio Carugati, Daniel Carrica, Mario Benedetti

         Vol. 5. n. 4, pp. 1728-1735

 

Abstract - Grid synchronization is critical for a large number of systems, being difficult to achieve in variable frequency or polluted environments. This article presents a simple and fast response digital signal processing method designed to obtain utility grid synchronism. This method is based on varying the sampling frequency so as to generate sampling pulses at a frequency multiple of the main frequency and in phase with it. Even though it operates with a variable sampling frequency, a model in z-transform space is developed, which simplifies the design of the system controller. This feature makes it suitable for measuring harmonics in the utility grid and for obtaining the phase reference for applications such as on-line power converters. Design equations for a closed loop controller producing a critically damped response are also developed herein. The method has been verified conducting experimental tests under different disturbance conditions.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Synchronism, three phase systems, variable sampling rate, space vector.

 


 

go to top   The Impact of Transmission Loss Component on Transmission Cost Recovery in Pool Electricity Markets
         by M. Y. Hassan, M. A. Almaktar, M. P. Abdullah, F. Hussin, M. S. Majid, H. A. Rahman

         Vol. 5. n. 4, pp. 1736-1746

 

Abstract - This paper proposes a DC based pricing scheme for transmission cost recovery for pool electricity markets. The scheme uses Generalized Generation Distribution factors (GGDFs) for allocating the utilization of the grid by different transmission users. The same factors are utilized for allocating transmission losses among the market’s participants. The proposed pricing scheme is tested on 5-bus and IEEE 14-bus systems and compared with Ireland’s pricing scheme that has adopted the DC lossless Transmission Use of System Charge (TUoSC). The proposed DC approach is validated with AC Z-bus Distribution Factors (ZBDF). Results show that the proposed scheme provides sensible signals for transmission system users relieving the transmission network. The merit of the proposed scheme over the Irish one lies on rewarding users for reducing the transmission system losses.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Generalized generation distribution factors, Locational and non-locational charges, Loss allocation, Z-bus distribution factors.

 


 

go to top   Development of Voltage Acceptability Curves for Fluorescent Lighting Systems
         by H. Shareef, A. Mohamed, K. Mohamed

         Vol. 5. n. 4, pp. 1747-1753

 

Abstract - This paper presents the design and construction of voltage acceptability curves for fluorescent lighting systems. It is derived from mathematical representation of actual light output variations of fluorescent lamps (FLs) during voltage sags and a predefined malfunction criterion called the light standard. Light standard may be thought of a standard based on a minimum acceptable light output, below which the operation of the lighting system is unacceptable. The effect of voltage sag on the light intensity is obtained by extensive tests conducted for three 18 Watt FLs with different ballast types. The experiments are conducted on the basis of recent testing standards and utilization of a modern industrial power corrupter. The experimental results of tested FLs show that the lamp with electromagnetic ballast is more sensitive to voltage sags than that of the lamps equipped with electronic ballasts. Hence, the design of voltage acceptability curves for FL with electromagnetic ballast is shown to have more restrictive criterion in accepting the supply voltage disturbances such as voltage sag.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Fluorescent Lamps, Voltage Sags, Voltage Tolerance Curves, Power Quality, Ballast, CFL.

 


 

go to top   Evaluation of AC Contactor Ride through Capability during Voltage Sag with Point-in-Wave of Initiation
         by M. A. Hannan, N. A. Nordin, A. Mohamed

         Vol. 5. n. 4, pp. 1754-1759

 

Abstract - This paper presents the performance evaluation of AC contactor ride through capability and behavior during voltage sag with point-in-wave of initiation by simulation and experimental setup. The experimental result of the ride through capability curve is constructed and identified the sensitivity level and its failure area. Simulation results were compared well with the curve obtained experimentally to validate the ride through capability and the sensitivity of the AC contactor for any type of voltage sag with point-in-wave of initiation.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: AC contactor, ride through capability, voltage sag, point-in-wave.

 


 

go to top   Generalized Equations for Fault Voltages and Currents in Neutral Conductors of Underground Multi-Cable Power Lines
with Earthing Wires Laid Alongside

         by I. Medic, D. Bajs, E. Sutlovic

         Vol. 5. n. 4, pp. 1760-1768

 

Abstract - An analytical method for calculating the low-frequency fault currents and related voltages, at any point along neutral conductors (i.e., metallic screens and adjacent earthing wires) of multi-cable power lines, is presented in this paper. The earthing system under consideration consists of two substation earthings, which are interconnected by insulated metallic screens/sheaths of modern XLPE cables and also by bare earthing wires laid in parallel in the same cable trench. The analytical expressions, derived by solving a set of differential equations, are based on the assumption of uniformly distributed self and mutual conductances to ground (“leakances”) of earthing wires. The proposed mathematical model also takes into account mutual inductive couplings between all conductors (phases, cable screens/sheaths and bare earthing wires). In addition, the values of related substation grounding impedances at the power line terminals are not neglected and are now taken into account as known input values. Particularly, in the case of a double-circuit cable line with two earthing conductors in trench, a set of generalized equations for currents and voltages along the related neutral conductors are derived in detail. As an illustrative example, the derived mathematical expressions are applied to three-phase double-circuit power cable line, consisting of six single-core power cables and two earthing conductors laid alongside.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords:  Earthing, Fault -Current Distribution, Double-Circuit Line, Power Cables.

 


 

go to top   A Li-ion Battery Discharge Model
         by Liang-Rui Chen, Chuan-Sheng Liu

         Vol. 5. n. 4, pp. 1769-1774

 

Abstract - In this paper, a Simulink model for describing the Li-ion battery discharge behaviors is proposed. This model describes the response of the open-circuit voltage and closed-circuit voltage to time in the discharge process of the Li-ion battery. The Li-ion battery discharge behavior is divided into three parts: initial transient state part, steady state part, and tail transient state part. The initial transient state and the steady state parts are described by using a RC circuit respectively while a nonlinear voltage source is used to describe the tail transient state part. In addition, this model has an equivalent series resistance, used to make the electrical resistance value of the electrodes and the guard circuit equivalent. Finally, a Panasonic 18650 Li-ion battery Simulink model is implemented to verify the feasibility of the proposed method. The results of experiments and simulations show that the Li-ion battery Simulink model can accurately describe the response of the open-circuit voltage and closed-circuit voltage to time in the discharge process.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Li-ion battery, initial transient state part, steady state part, tail transient state part, Simulink model.

 


 

go to top   A Novel Approach for Distance Relays Setting in Presence of IPFC
         by Iraj Ahmadi, Ali Yazdian Varjani, Mojtaba Khederzadeh

         Vol. 5. n. 4, pp. 1775-1783

 

Abstract - In this paper, a novel approch is presented to mitigate the impact of Inter line Power Flow controller (IPFC) on distance relays first zone operation. Impacts of IPFC on line distance relays have been evaluated analytically and by simulation. These impacts have been formulated based on mathematical mapping theory. It has been shown that the main impact of IPFC on distance relays is to deviate impedance region seen by distance relays from relays tripping characteristic. The pre-fault injected active and reactive power of IPFC convertors have been used to determine the displacement of distance relays characteristic. Then using the setting groups facility of commercial distance relays, a mapping method has been used to achieve maximum overlapping of relay characteristic with impedance region of protected line, in order to mitigate IPFC impacts on distance relay. Simulation results done using PSCAD/EMTDC software have been used to demonstrate the efficiency of proposed approach.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Distance Relay, Inter Line Power Flow Controller, Mapping Theory, Setting Group.

 


 

go to top   A New Diagnostic Test for Power Cables Based on Frequency Analysis
         by H. Vahedi, M. Yazdani-Asrami

         Vol. 5. n. 4, pp. 1784-1788

 

Abstract - Electric power cables are considered as one of the essential elements in electric transmission and distribution systems. Any failure in these equipments directly reduces system reliability and increases maintenance costs. Consequently, the preventive maintenance techniques and also fault diagnosis methods are increasingly developed. In this regard, frequency response analysis (FRA) can be taken to be account an appropriate method in order to diagnose any change which occurs in cables physical construction. This contribution has concentrated on the application of frequency analysis measurements as a new kind of diagnostic test to investigate its ability for diagnosing a few numbers of common faults which are occurred in power cables. Experimental measurements have been performed on a power cable using FRA analyzer instrument in two healthy and faulty situations. All intentional faults have been experimentally applied on geometry of cables and the FRA results have been measured and compared. The obtained results are very interesting and applicable for maintenance aims to find the happened fault, quickly.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Condition Monitoring, Diagnostic Test, Experimental Measurement, Frequency Response Analysis, XLPE insulated Cable.

 


 

go to top   De-noising Technique Based on Wavelet Decomposition for Impulse Voltage Measurements and Noise Analysis
         by E. Onal, O. Kalenderli, S. Seker

         Vol. 5. n. 4, pp. 1789-1797

 

Abstract - This paper describes a novel approach to estimate the mean-curve of impulse voltage waveforms that are recorded during impulse voltage tests. The waveforms measured in practice contain oscillations and overshoots due to contribution of different noise sources. In this sense, usage of automated signal analysis tools that determine the important parameters of the impulse waveform such as peak value, front time, tail time etc. is very useful. This paper presents a noise analysis approach that is based on multi-resolution signal decomposition and statistical analysis for high-voltage impulse measurements. As the results of this analysis, the effective noise peaks are shown at approximately frequencies of 2.3, 17, 30 and 35 MHz. Also the effect of electromagnetic disturbance is observed around 2 MHz and noise components which are higher than 10 MHz are related to digitizers in the test hall. In this study, these noise parts are separated from the mean curve using the multi-resolution wavelet analysis and then, the noise spectra are given to define the characteristic peaks. Consequently, common properties of the spectra, which are independent from the electrode system, reflect the similar peak values at the specific frequency values. Hence, this research presents a new possibility for de-noising of the measurements.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Impulse voltage measurement, Noise analysis, Multi-resolution wavelet analysis, De-noising technique.

 


 

go to top   On the Frequency Resolution of Improved Empirical Mode Decomposition Method
         by A. Öztürk, S. Şeker

         Vol. 5. n. 4, pp. 1798-1805

 

Abstract - Empirical Mode Decomposition, which constitutes the core of Hilbert Huang Transform, is an efficient method in analysis of non-stationary and non-linear signals due to its data-driven nature. Nevertheless, the original method imposes a limitation on the frequency resolution and also suffers due to end effects. In this paper, through analyses of synthetic and actual vibration data, it is shown that better frequency resolution beyond the limitation imposed by the original method can be achieved by modifying the local mean approximation and boundary values of the original algorithm.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Empirical Mode Decomposition, End Effects, Frequency Resolution, Local Mean Approximation, Vibration Data.

 


 

go to top   Pulsed Power Magnification Using Multiple Wound Transmission Lines
         by Arvin Nikjamal, Abolfazl Vahedi

         Vol. 5. n. 4, pp. 1806-1811

 

Abstract - In this paper, a method for energy compression is described in which regular storage elements are replaced by segments of transmission lines. The fundamental of this method is the direct proportion of the appearance time of a traveling voltage pulse on a channel to the electrical length of it. According to this fact, if power pulses are fed into a group of transmission lines of different lengths at proportional different times, they will reach the end points simultaneously and generate a higher output peak power, as a result of a rise either in voltage, current or a combination of both. This magnification is achieved by a suitable connection mode at the end points of the transmission lines. Main goal of this approach rather than its capability of operation in extremely high frequencies with short rise and fall times of rectangular pulses, is that the switching elements in the system need to tolerate a much lower peak power than the compressed power reached to the load. Another main aspect that is taken into consideration is the presence of the shield cable impedance contributing to the lines power loss. The very well known method used for minimizing these losses is winding the transmission lines to increase the line shielding inductance if coaxial cables are used. Therefore, herein, circuit models are presented to assess theoretically the temporal response of the wound coaxial pulsers by using SPICE circuit simulator.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Energy Compression, Pulse Generation, Pulsed Power, Wound Transmission Lines.

 


 

go to top   Enhanced Procedure for Double Knife-Edge Diffraction Path-Loss Assessment
         by Ivan Marinovic, Igor Zanchi, Zoran Blazevic

         Vol. 5. n. 4, pp. 1812-1816

 

Abstract - Deygout method still remains one of the most frequently used approximate methods for path-loss assessment, but generally, yields overestimated loss in most cases. This is especially obvious when two obstacles stand relatively close to each other with relatively equal heights. In this paper we propose a method to eliminate this deviation. In that aim, several combinations of double diffraction scenarios are presented in order to compare our results with Deygout’s, taking the Vogler’s numerical results as a reference.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Diffraction Path-Loss, Knife-Edge Model, Deygout Method.

 


 

go to top   New Generation of Radar Waveforms Based Chaos Theory With Loss Detection to Targets
         by T. Sedghi , M. Fakheri, H. Shirzad, J. Pourahmadazar

         Vol. 5. n. 4, pp. 1817-1823

 

Abstract - This paper is a preliminary investigation of a class of radar signals generated by recursively defined functions. Signals are of fundamental importance in radar, since a radar system uses transmitted and returned signals from the environment to decide on the presence of targets, as well as their range, bearing and speed. The issue of an appropriate choice of signal is complex, and application dependent. This paper is a brief simulation of a new class of signals, known as chaotic signals. Such signals may be of importance in radar for a number of reasons. The first is that they are generated from a deterministic map, but can be made to appear as noise. This would be useful from an electronic protection point of view. Secondly, since these signals can be generated from a single dynamical system, with different control parameters and initial conditions, it may be possible to reduce the need for a comprehensive library of signals in a radar system. The generation of such signals, as a discrete time dynamical system, will be outlined. We investigate the stability of such signals, using the Lyapunov spectrum. The radar ambiguity function is used to decide whether this signal is practical use in radar.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Radar, Radar Cross Section, Chaos, Ambiguity Function, Lyapunov spectrum.

 


 

go to top   Application of Meta-Evolutionary Programming in ANN-based Lightning Prediction System
         by D. Johari, T. K. A. Rahman, I. Musirin, N. Aminudin

         Vol. 5. n. 4, pp. 1824-1432

 

Abstract - This paper presents the development of hybrid Meta-Evolutionary Programming and Artificial Neural Network lightning prediction system based on historical lightning and meteorological data in Malaysia. It involved the development of the ANN design and optimization of the system using EP optimization technique. ANN is employed as it has the ability to learn by example and do tasks based on training experience, making it profoundly suitable for pattern recognition and forecasting tasks. However, due to its heuristic nature, the process of finding suitable network architectures could be burdensome and time-consuming. There is also no systematic way to design the optimal architecture for a given task automatically. For that reason, an efficient optimization technique such as Meta EP is employed to find the best ANN architectures systematically. Comparative studies conducted with respect to heuristic search indicated that hybrid-meta-EP-ANN is more accurate in its prediction capability. The most significant advantage of using EP optimization technique is that it provides a structured and automatic way for obtaining optimal values of the ANN parameters. As a result, the developed lightning prediction system is able to generalize well when presented with new sets of input data.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Artificial neural network, Cross validation, Early stopping, Evolutionary programming, Lightning prediction.

 


 

go to top   Novel Coaxial High Pass Filter Design for RF Applications
         by Abdullah Eroglu

         Vol. 5. n. 4, pp. 1833-1837

 

Abstract - The complete design of a novel coaxial high pass filter is given analytically and numerically for high power RF applications. The coaxial structure consists of two hollow concentric cylinders with a septum located between them at a single azimuthal angle. This septum provides a good high pass filter characteristics and mechanically holds two hollow cylinders together. The attenuation slope in the stop band with this structure is much sharper than the existing filter configurations. This gives faster transition time from stop band to pass band. One end of the coaxial structure is closed and the other end is used as an output port. Excitation port is placed on the side walls of the outside cylinder. The design procedure proposed in this paper has been implemented to obtain a filter configuration at the lower end of the UHF range. The new filter is simulated using 3D electromagnetic simulator, HFSS. It is then constructed and measured. Simulation results are compared with the measured results. Good agreement between simulated and measured results has been observed.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Coaxial filter, cavity, high pass, resonance, RF, UHF.

 


 

go to top   Design Analysis of a Dual Frequency RFID Reader Antenna
         by Ahmed Toaha Mobashsher, Mohammad Tariqul Islam, Norbahiah Misran

         Vol. 5. n. 4, pp. 1838-1847

 

Abstract - In this paper, the analysis of design, fabrication and measurement of a high gain dual frequency RFID reader antenna, proposed for ISM bands of 2.45GHz and 5.8GHz, is discussed with overall explanations. The antenna is composed of a U-shaped copper strip with unequal arm, a printed rectangular ring and the ground plane. The antenna operates over 2.37GHz to 2.49GHz, of 120MHz for the lower band; while the upper band exhibits good impedance bandwidth of 420MHz (from 5.55GHz to 5.97GHz), where return loss of -10dB is taken as the reference for both bands. The U-shaped feeding strip excites the rectangular ring effectively by providing a good impedance matching with over 98% of efficiency in both the frequency bands and also 9.56 and 10.17dBi gain in the lower and higher frequency band, respectively. Furthermore, the analytical parametric study facilitates more elaboration of the design and optimization processes for the antenna researchers.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Dual frequency, RFID reader, microstrip antenna.

 


 

go to top   A Planar Monopole Antenna for UWB Applications
         by Rezaul Azim, Mohammad Tariqul Islam, Norbahiah Misran

         Vol. 5. n. 4, pp. 1848-1852

 

Abstract - In this paper, a planar monopole antenna fed by a microstrip line has been proposed. The proposed compact antenna is consists of a circular ring patch and a partial ground plane with a rectangular slot. The measured -10 dB return loss bandwidth of the proposed antenna ranges from 3.4 GHz to 16.76 GHz (132.54%) which almost cover the entire UWB band. The nearly stable radiation pattern with a maximum gain of 5.4 dBi makes the proposed antenna suitable for being used in wireless communication and microwave imaging system for medical application. Details of the proposed antenna design are presented and discussed.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Monopole Antenna, Microstrip line, Planar antenna, Ultrawideband antenna.

 


 

go to top   A Matrix Factorization Based Channel Estimation Technique for FPGA Implementation of Multiple Antenna System
         by Mostafa W. Numan, Mohammad T. Islam, Norbahiah Misran, Mohd Alauddin M. Ali

         Vol. 5. n. 4, pp. 1853-1861

 

Abstract - In this paper, a proficient channel estimation technique is proposed to carry out performance improvement and complexity reduction of multiple antenna system. Matrix factorization is applied on training based least squares (LS) estimation to reduce a full rank matrix into a simpler form in order to eliminate matrix inversion. Performance evaluation of the proposed method is validated through MATLAB simulations which indicate 2dB improvement in terms of SNR compared to LS estimation. Moreover complexity comparison is performed in terms of mathematical operations, which shows that proposed approach appreciably outperforms LS estimation at a lower complexity and represents a good solution for channel estimation technique. The paper also provides design and implementation of a multiple antenna system on Xilinx Virtex™-4 XC4VLX60 FPGA that provides reconfigurability, resource utilization and less power consumption. The encoder design is straight forward; however, the decoder design is little tricky as it requires resource optimization. The hardware, presented in this paper, utilizes the resources by adopting the technique of parallelism. The system is developed based on modular design which simplifies system design, eases hardware update and facilitates testing the various modules in an independent manner.

Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Multiple antenna system, channel state information, channel estimation, matrix factorization, FPGA, hardware implementation.

 

 


 
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