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International Review of Electrical Engineering - October 2007 - Papers





International Review of Electrical Engineering - Papers


go to top    Permittivity and Conductivity Evaluation of Cylindrically Shaped Homogeneous Bodies: Basic Principles and Quadrupole System Measurement Method
        by J. A. Brandão Faria

       Vol. 2. n. 5, pp. 638-647


Abstract - This paper presents the theoretical foundations and basic measurement principles concerning the evaluation of the permittivity of a cylindrical dielectric rod and the conductivity of a circular conducting disk in the framework of stationary regimes. The novelty resides in the fact that both measurement methods exploit the same theoretical substrate — the well-known electrostatic field distribution of two symmetrically charged filaments. The simplicity of the proposed methods, together with the fact that only basic equipment is required to carry out the necessary measurements, makes this contribution significant.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Permittivity Measurement, Conductivity Measurement, Stationary Regimes, Electromagnetic Field Equations.



go to top    Fuzzy Control Approach for Monomachine Power Systems
        by A. Kahouli, T. Guesmi, H. Hadj Abdallah, O. Abderrazak

       Vol. 2. n. 5, pp. 648-654


Abstract - Electrical power system angle stability can be improved by a wide variety of controls. Some methods have been used effectively for many years, both at generating plants and in transmission network. In this paper, a fuzzy control strategy for stabilization of the transient faulted power system is presented. The first step is to find the critical clearing time (CCT) by equal area stability criterion and numerical integration. The second interests to fuzzy logic controller. For this last step, we present the nonlinear model with a Takagi-Sugeno fuzzy model (TS). Then, a model-based in fuzzy controller design utilizing the concept of the so-called “Parallel Distributed Compensation” (PDC) is employed. Stability analysis and control design problems can be reduced to linear matrix inequality (LMI) problems. Therefore, they can be solved efficiently in practice by convex programming techniques for LMI’s. A single machine infinite bus system is analysed with the proposed methods.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Power system, transient stability, critical clearing time, T-S fuzzy model, PDC, Lyapunov stability, LMI’s techniques.



go to top    Methodology Based in Practical Fuzzy Rules Coordinated with Asymetric Dynamic Compensation Applied in Unbalanced Distribution Network

        by B. Mahdad, T. Bouktir, K. Srairi

     Vol. 2. n. 5, pp. 655-664


Abstract - This paper presents a dynamic approach that coordinate the expertise of power system engineer with asymetric distribution reactive power compensation for shunt FACTS technology to reduce the asymmetrical voltage and enhance the system loadability in unbalanced distribution network. Static Var Compensator (SVC) is one of the key elements in power system that provides the opportunity to improve power quality. The main idea is to determine the optimal reactive power injected or absorbed by Multi SVC on the nodes for each phase that the real power losses and voltage deviation will be minimized for a given load profile. The proposed approach has been tested in a variety of distribution network. Testing results indicate clearly that the proposed approach based in asymmetrical compensation reduce the effect of asymmetrical voltage in distribution power system and improve the index of power quality.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Asymetric voltage, FACTS, SVC, STATCOM, Unbalanced network, System loadability, Reactive index sensitivity.



go to top    Energy-efficient Innovative Lighting and Energy Supply Solutions in Developing Countries

        by P. Bhusal, A. Zahnd, M. Eloholma, L. Halonen

     Vol. 2. n. 5, pp. 665-670


Abstract - The vast majority of the rural population in the developing countries is out of reach of electricity and hence has to depend on the traditional fuels to fulfil the daily energy needs. Providing grid electricity to the rural areas of many developing countries is a very difficult task due to the geographical complexity and lack of financial resources. The paper explains the use of different renewable energy sources in combination with efficient lighting technology as a realistic option to provide clean lighting services to developing countries. The application of Light Emitting Diodes and renewable energy sources has been a sustainable solution to the basic lighting needs of rural people. The paper also presents a comparison of costs between available renewable energy technologies.

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Keywords: Renewable Energy, Rural Lighting, Energy Efficiency, Light Up The World.



go to top    Dynamical Modeling and Control of Current-Output Converters

        by M. Hankaniemi, T. Suntio

       Vol. 2. n. 5, pp. 671-680


Abstract - A switched-mode converter operates usually as a constant-voltage-controlled or voltage-output converter with well-known characteristics. In the applications, where the converters have to recharge a storage battery or supercapacitor, they have to be provided with overcurrent limiting in order to protect them from damage due to the extremely low internal impedance of those energy storage devices. The change from the voltage-output mode to the current-output mode would also change the dynamics of the associated converter profoundly, which is not really understood. The type of load may, however, recover the properties of the voltage-output converter making the control design challenging. The paper provides consistent methods to develop the dynamical models of the current-output converter from the models of the corresponding voltage-output converter. Experimental evidence is provided validating the theoretical findings.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Current-output converter, dynamical model, control design.



go to top    A Comparative Study of Robust Control for an ASVC-Based Var Flow Compensation
        by M. Benyamina, B. Mazari, A. Tahri

       Vol. 2. n. 5, pp. 681-686


Abstract - Var compensators should be properly controlled to provide fast and continuous reactive power to meet a certain load demand. This ensures improved transmission performance and enhances the transient stability of the power system. This paper deals with the application of the internal model control technique to an advanced static var compensator. The controller is evaluated under a variety of operating conditions and the simulations results demonstrate instantaneous and robust var flow with the ac transmission system and superior performance as compared to a conventional proportional-integral controller.

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Keywords: ASVC Compensator, Robust Control, IMC, Stat feedback.



go to top    A Sliding Mode Controller for a Three Level Resonant Single Stage PFC AC/DC Converter

        by M. S. Agamy, P. K. Jain

         Vol. 2. n. 5, pp. 687-694


Abstract - This paper presents a variable structure control method for a single stage three level resonant AC/DC converter. An Observer with adaptive parameter estimation is also introduced to achieve current sensorless operation of the controller, thus returning the number of feedback measurements to two (both of which are voltage measurements) instead of three. Two integrated control loops are used: one to regulate the output voltage and the other switching function is to regulate both the input current and dc-bus voltage. This controller also makes the system response less sensitive to load variations, supply voltage changes and resonant tank parameter variations.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Single Stage PFC; Three-Level Resonant Converters; Sliding Mode Control; Adaptive Estimation.



go to top    Non Integer Order I-P Pole Placement Controller Design: Application to Induction Motor Control

        by R. Mansouri, M. Bettayeb, S. Djennoune

      Vol. 2. n. 5, pp. 695-703


Abstract - Fractional calculus can provide novel and higher performance for the classical integer order controllers thanks to the fractional order derivative or integral. However, the difficulties of designing fractional order controllers increase, in particular when using the pole placement principle. This paper deals with an induction motor control using non integer order I-P controllers. The main contribution of this paper is the development of a method to find the controller’s parameters using the pole placement method and the choice of the reference fractional model of the closed loop. The model is selected such that its step response will be equivalent to that of a dumped second order model. The parameters of the reference model are determined using the genetic algorithm in order to optimize thus equivalence. The application of these controllers to the induction motor shows its interest, particularly its robustness with respect to the mechanical parameters variations.

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Keywords: Induction Motor, Genetic Algorithm, Non Integer Controller, Poles Placement, Robust Control.



go to top    Torque and Inductances of Concentrated Wound Permanent Magnet Machines
        by H. Jussila, P. Salminen, M. Niemelä, A. Parviainen, J. Pyrhönen

        Vol. 2. n. 5, pp. 704-710


Abstract - The study addresses concentrated wound permanent magnet motors and their ability to produce torque. The inductances and the maximum available torque of a concentrated wound PM machine are examined as the pole pair number and the number of slots per pole and per phase q are varied within compatible constraints. The machines under study have a 45 kW output power and a speed of 400 rpm. Several concentrated wound PM machines are computed applying an analytical method and a finite-element-method-based analysis tool. The results show that as q increases from 0.25 to 0.5, the pull-out torque of the concentrated wound machine increases, obtaining the highest values as q equals to 0.5. However, as q increases further and integral slot windings (q = 1, q = 2) are used the torque development will be bigger when the same rotor main dimensions are maintained. This indicates that selecting a concentrated wound construction must have other relevant reasons than maximizing the rotor torque per volume ratio.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Permanent magnet motor, inductance, maximum torque, concentrated winding.



go to top    Analytical Study, Modeling and Detection of Inter-Turn Short-Circuits in Stator Windings of Induction Motors
        by M. Sahraoui, A. Ghoggal, S. E. Zouzou, A. Aboubou, H. Razik

       Vol. 2. n. 5, pp. 711-722


Abstract - In this paper an analytical approach is presented to study in a more efficient way, the spectral contents of the stator line current of three-phase squirrel cage induction motors under healthy conditions and with inter-turn short-circuit. This study is based on analytical expressions for the stator and the cage rotor magnetomotive forces (MMF) which are derived using the winding function approach. Also, an accuracy mathematical model of the induction motor operating under stator inter-turns short-circuits is established. This model is based on the multiplied coupled circuit approach. The inductances calculations are performed thanks to an extension in 2-D of the modified winding function approach (eMWFA), which is able to take into account the space harmonics in addition to the effects of rotor bar skewing and the linear rise of MMF across the slots. It is found that inter-turn short circuit does not induce any new frequency components in the stator current spectrum; but, it increases only the magnitudes of the rotor slot harmonics. Experimental tests which are carried out on a special three-phase induction motor validate the theoretical analysis.

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Keywords: Diagnosis, Induction Motors, Inter-Turns Short-Circuit, Stator Faults.



go to top    Microstepping Approach Developed for Linear Switched Reluctance Step Actuators Presenting Edge Effects
        by L. El Amraoui Ouni, M. Benrejeb

       Vol. 2. n. 5, pp. 723-729


Abstract - A microstep control strategy, developed for linear switched reluctance step actuators, is proposed in this paper. The design of the studied actuator using finite element simulations has allowed to put, especially, in evidence the important dissymmetries observed on electromagnetic force characteristics developed by the different actuator phases. From this observation, an adapted control strategy, exploiting the obtained finite element results is used for punctual evaluation of the electromagnetic force. Hence, response surfaces of electromagnetic force according to plunger positions and phase supply currents are built and inversed in order to determine the supply current configurations required for accurate microstepping. Practical tests have validated the elaborated control strategy.

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Keywords: microstepping, linear actuator, edge effects, Finite Elements, force response surface.



go to top    Stability in the Passivity Based Control with Robust Non Linear Observer of the Induction Motor
        by A. Mansouri, M. Chenafa, A. Bouhenna, E. Etien, A. Belaidi

       Vol. 2. n. 5, pp. 730-737


Abstract - This paper mainly deals with the design of passivity control with an observer for a special class of nonlinear systems. In this work, we present the design of an observer for a special class of nonlinear systems satisfying some regularity assumptions. The solution to the output feedback torque and rotor flux tracking problem for an induction motor model given in the natural frame was proposed. In this approach the design of controller and observer is interlaced and global stability results for the total system is proved. It must be pointed out that the existing observer in the literature is simple, with only updating from current error terms in the rotor equations. The control algorithm is studied through simulations and applied in many configurations (various set point, flux and speed profiles and torque disturbances), and is shown to be very efficient.

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Keywords: Induction Motor, Lyapunov Stability, Non linear Observer, Passivity Control.



go to top    Backstepping Control Design of Sensorless Speed Induction Motor Based on MRAS Technique
        by S. Chaouch, M.S. Nait Said, A. Makoof

       Vol. 2. n. 5, pp. 738-744


Abstract - This paper deals with sensorless induction motor drive controlled by a new design combining backstepping theory and field oriented method. Backstepping control is proposed for replacing the existing PI controller to obtain high performance motion control systems, for the speed, flux and currents control loops. Stability analysis based on Lyapunov theory is also performed to guarantee the convergence of the speed tracking error from all possible initials conditions. This last model needs to obtain accurate information about rotor flux and rotor speed, which are estimated by model reference adaptive system (MRAS) technique. The aim advantage of this scheme is that the machine control becomes more stable with an improvement of low speed performances where the torques capabilities are sufficiently developed. The simulation results show the improved drive characteristics and performances.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Induction motor, Backstepping Control, Sensorless, MRAS Technique, Field oriented Control.



go to top    A New Approach for Combining Neural Networks During Training for Time Series Modeling
        by Z. H. Ashour, S. R. Hashem, H. A. Fayed

         Vol. 2. n. 5, pp. 745-750


Abstract -  A great deal of data in business, economics, engineering and the nature science occur in the form of time series. Linear models have been frequently used for time series modeling. Recently, neural networks (NN’s) have been used as nonlinear models. Many researchers have performed a combination of several NN’s in order to attain a better accuracy model. In this paper, we propose a new approach for combining NN’s. We develop a number of combination models during the training of the NN’s and then select the best performer among them on a validation set as the eventual combination model. Experimental results show the significant improvements of the proposed method compared to the apparent best NN, and combination of the trained NN’s.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Neural Networks Combination, Non Linear Models, Time Series Modeling.


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