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International Review of Electrical Engineering - June 2007 - Papers







International Review of Electrical Engineering - Papers

go to top    Security Assessment of Power Systems Using Contingencies Ranked by QV Modal Aggregated Participation Factors
        by M. A. Ríos, H. Amaranto

        Vol. 2. n. 3, pp. 293-300


Abstract - The continuation power flow (CPF) has been used as a tool for computing a voltage stability margin called the maximum loadability of the system for an operational point. An exhaustive N-1 contingency criterion is used to compute the CPF loadability margin under emergency conditions; however, this procedure spends a high computational time and makes so difficult its application in power system operational planning. Firstly, this paper proposes a voltage instability contingency ranking criterion based on Q-V modal sensibility analysis, which allows the selection of a short list of critical contingencies for voltage stability. So, the loadability margin is computed only for the short list of contingencies that reduces the computation time consumption making feasible its utilization for operational planning purposes. The contingency ranking criterion is based on a definition of an aggregated participation branch that measures both the impact of branch contingencies in the overall set of eigenvalues of the Q-V sensibility matrix and the relative importance of the modal QV sensibilities. Then, this paper proposes the application of statistical stratification of populations in order to compute the average loadability under contingencies and a statistical critical low bound loadability margin.

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Keywords: Voltage Instability Contingency Ranking, Modal QV Sensibility Analysis, Power System Security Assessment, Voltage Stability.



go to top    Multi Objectives Optimization of the Active/Reactive/Environmental Dispatch of an Electrical Network
        by S. Brini, H. Ben Aribia, H. Hadj Abdallah, A. Ouali

       Vol. 2. n. 3, pp. 301-309


Abstract - The technological development contributed to an increase of the energy consumption. Consequently, a growth of the powers to generate and to transport and new constraints are imposed. The electric networks become more and more big and complicated. The conduct centers of the electric networks are before non-linear problems, multi objectives, having a lot of variables and of constraints. To avoid the complexity of the problems formulation, one uses the Evolutionary Algorithms for their resolution.
This paper presents one of the electric network problems; it's the Active, reactive and Environmental dispatch. It consists in distributing the active productions between the power stations of the most economic way, to reduce the emissions of the polluting gases and to maintain an appropriate voltage profile under constraints bound to the reactive productions of the compensation devices, to the active production of generators, to the active losses and to the energizing balance. The resolution is done by the SPEA method and the simulations have been made on an IEEE test network (10 buses, 5 machines and 13 lines).

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Keywords: Dispatch, Fuel cost, Polluting gases emission, Compensation devices, Active losses, Multi objectives optimization, Evolutionary algorithms, SPEA.



go to top    Wind Generator Output Power Smoothing by Using Pitch Controller

        by S. M. Muyeen, M. H. Ali, R. Takahashi, T. Murata, J. Tamura

       Vol. 2. n. 3, pp. 310-321


Abstract - It is well known that pitch controller can maintain output power of wind generator at rated level when wind speed is above the rated speed. Moreover, it can also enhance the transient stability of wind generator when severe network disturbance occurs in power system. In this paper, another new feature of pitch controller is analyzed. As wind speed varies randomly the output power of wind generator fluctuates continuously. This fluctuation can be minimized significantly by changing the blade pitch angle of wind turbine. Our proposed pitch controller can do this well. The wind generator output power loss and smoothness level are analyzed when the proposed pitch controller is used with wind turbine. Comparative studies are carried on using three types of input command power of the controller. Some technical points of mechanical servo system of wind turbine are emphasized to reduce the load of wind turbine. Moreover, different types of wind speed patterns are used to validate the effectiveness of the proposed controller. Simulation results show that the wind power fluctuation can be reduced significantly by using the proposed fuzzy logic based pitch controller.

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Keywords: Exponential moving average, fuzzy logic controller, mechanical dead zone, simple moving average, pitch controller, wind generator, power smoothing.



go to top    Analysis and Two-Dimensional Modelling of the Doping Effect on the Leakage Current in Polysilicon Transistors

        by Y. Bourezig, B. Bouabdallah, B. Benichou, F. Gaffiot

     Vol. 2. n. 3, pp. 322-326


Abstract - Recently, there has been a growing interest in polysilicon thin film transistors. The greatest motivation for this is their application to flat- panel displays. The purpose of this work is to study the effect of the polysilicon doping on the leakage current, observed when the structure is in depletion mode. The study consists of an analysis of the experiment transfer characteristics for different doping concentrations of polysilicon, which reveals that the leakage current is the sum of two different components: the residual current observed in flat band regime, and the generation current for VGS>=0. In order to explain the variation of these ones as a function of doping concentration, a two-dimensional simulation program is presented. It is based on the resolution of Poisson’s equation. The results show that, the evolution of the residual current versus layer doping, can be explained by Baccarani’s model. The generation current is field assisted, its variation according to the gate voltage is related to POOLE –FRENKEL effect. The predominance of one of the both results from the physical and conduction properties of the polycrystalline layer.

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Keywords: leakage current, Modelling, polysilicon, Poole-Frenkel effect.



go to top    Enhanced Micro Modeling Technique for Semiconductor devices to Study Faulty Mode in Power Converters

        by F. Charfi, M. B. Messaoud, B. François, K. Al-Haddad, F. Sellami

     Vol. 2. n. 3, pp. 327-336


Abstract - The paper deals with the use of simulation to effectively model and analyse the electric power system, from a high level of abstraction through a detailed analysis of inner characteristics. A particular model has been developed to simulate a typical induction motor drive to estimate performances in case of semiconductor faults. This model includes models of the power devices and the control stage. Detailed analyses of the inverter drive are shown to illustrate how the inverter and its components can also be simulated to a very high degree of accuracy. Analysis of the IGBT thermal and diode reverse recovery transient effects are also discussed. Advanced techniques such as behavioral modeling are used to accurately and quickly model components of the power system drive and controller. Simulation results have been compared successfully with measurements in steady state and transients. This work is described at a first step in a research project about reliability evaluation of power system embedded in electric vehicles.

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Keywords: IGBT, Power Inverter, Power Diode, Fault.



go to top    Shunt Active Power Filters and PWM Rectifiers in Three-Phase Three Wire Systems: a Survey
        by E. Bárcenas, V. Cárdenas, J. Arau

     Vol. 2. n. 3, pp. 337-345


Abstract - This paper presents a survey of recent approaches which addresses solutions for current harmonic reduction in three phase three wire systems. The analyzed works are the most representative solutions to obtain unity power factor in the mains and to fulfill the corresponding regulations; the comparison is done between shunt active power filters and PWM rectifiers. The revised solutions are diverse and a classification according to their operating principle, input currents and output power is done. The main objective is to identify the areas of industrial application for each particular solution.

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Keywords: Power factor correction, PWM rectifier, Shunt active power filter.



go to top    Voltage-Source Active Power Filter with a Current Sensorless Control

        by M. Routimo, M. Salo, H. Tuusa

     Vol. 2. n. 3, pp. 346-358


Abstract - The harmonic filtering characteristic of a conventional shunt active filter is heavily dependent on the accuracy of the current sensing and control algorithms. These issues have been widely studied in the literature. This paper presents a space-vector control method for a voltage-source active power filter that does not require any information on the currents to compensate the harmonics. The operating principle of the active filter is to act as a voltage-source supplying the load to be compensated. Consequently the load current harmonics circulate through the filter and the mains current contains only the fundamental component.
In the paper, the operating principles and space-vector control of the system are presented and analyzed. The effects of the parameter mismatches of the proposed open-loop control are moreover examined. The filtering performance and power losses are examined through laboratory measurements and the results are compared to a conventional shunt active filter. The results show that the proposed system has wide harmonic filtering bandwidth. However, it is also noted that the pulse width modulated voltage produced sets restrictions for the load to be compensated. The efficiency measurements show that the losses in the active filter bridge and in the supply filter coil are lower than the losses in the conventional shunt active filters.

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Keywords: Harmonic compensation, open-loop control, voltage-source active power filter.



go to top    A New Topology of Three-Phase Five Level Inverter Applied to Static VAR Generation Schemes

        by T. H. Abdelhamid, N. H. Abbasy

     Vol. 2. n. 3, pp. 359-368


Abstract - The fast growing development of ultra rapid power switching devices and the desire to reduce harmonics have led to the increase in use of converters for large-scale reactive power compensation capable of generating or absorbing reactive current components with a time response faster than the fundamental power cycle. In this paper, a new topology of three-phase 5-level inverter, having a least number of components, is developed. It can also be adapted to any desired number of levels, where the percentage reduction in switching devices increases by the increase of the number of levels. The developed inverter is applied for static VAR generation/compensation through a multi-carrier PWM technique. A full dynamic analysis to the compensator performance is presented in this paper. Control rules of the compensator parameters are addressed and implemented. Simulation results are presented to prove the validity of the compensator performance.

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Keywords: Multilevel inverters, static VAR generation (SVG), multi-carrier PWM.



go to top    Discrete Adaptive Speed Sensorless Drive of Induction Motors
        by A. Oualha, M. Ben Messaoud

   Vol. 2. n. 3, pp. 369-377


Abstract - The use of mechanical speed sensor in the field of control of induction motors can cause some problems. Recently, many software are developed to estimate the speed by using only electrical measurements and machine parameters. This paper presents a new speed sensorless drive of induction motors for field oriented control. The proposed speed estimator is based on the Model Reference Adaptive Scheme (MRAS) and uses based the comparison of estimated and measured stator current. The reduction error is achieved by an appropriate unity transfer function as reference model. The estimator formulation is defined and developed in the discrete case. The proposed algorithm requires neither matrix calculation nor approximation on Taylor series of matrix exponential. To establish the stability of the discrete estimator, the hyperstability concept introduced by Popov in the discrete case is used. The influence of the sampling period on the algorithm stability of is studied. Some simulation results are presented, in order to valid the theoretical development.

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Keywords: Sensorless drives, Induction motors, Field-oriented control, Model Reference Adaptive Scheme, hyperstability.



go to top    Comparative Study of Nonlinear Speed Observers for Induction Motors
        by M. A. Gallegos-Lara, R. Alvarez-Salas, C. A. Nuñez-Gutierrez

   Vol. 2. n. 3, pp. 378-385


Abstract - This paper deals with the speed estimation problem of induction motors. Performance comparison of two speed estimation methods used in speed sensorless vector controllers is presented. Both Kalman Filter (KF) and Model Reference Adaptive System (MRAS) are the estimation algorithms discussed and compared in the same operating conditions. The comparative study is done by taking into account the convergence velocity, sensitivity to parametric variations and behavior in the low speed region. Experimental tests have been carried out in identical conditions in order to obtain a reliable comparison.

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Keywords: Induction motor, speed observers, Kalman Filter, Model Reference Adaptive System.



go to top    Sensorless Control of a Linearized Induction Motor Drive
        by K. B. Mohanty

        Vol. 2. n. 3, pp. 386-397


Abstract - This paper presents an input-output linearizing and decoupling control scheme for speed control of an induction motor drive. In this scheme, the motor model is linearized, and torque and flux are decoupled by use of nonlinear control. Proportional-cum-integral controllers are used for the linear electrical and mechanical subsystems. A reduced order rotor flux observer is designed, eliminating the need of flux sensor for control purpose. A stator flux based algorithm is used to estimate the synchronous speed and then rotor speed, leading to sensorless control. Also, rotor flux and speed are estimated using Kalman filter. The control scheme is implemented and tested in laboratory.

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Keywords: Linearizing control, Decoupling control, Sensorless control, Kalman filter.



go to top    Speed Sensorless Vector Control of Induction Motors Using Singularly Perturbed Sliding Mode Observer
        by A. Mezouar, M. K. Fellah, S. Hadjeri

         Vol. 2. n. 3, pp. 398-405


Abstract - In this paper, a new design of a sliding mode observer is presented using two-time scale approach for sensorless induction motor drives. This approach, based on the singular perturbation theory, decomposes the observer error dynamics on two parts; fast part, associated to the stator current observer, and slow part, associated to the rotor flux observer. Using this decomposition, the rotor flux observer accuracy is guaranteed through the stator current observer. In addition, the rotor speed is estimated by an adaptive law based on the measured and estimated stator currents and estimated rotor fluxes. The effectiveness of this new observer design has been successfully verified through computer simulation, where the control algorithm is based on the indirect-field-oriented sliding mode control.

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Keywords: Induction motor, speed estimation, sliding mode control and observer, singular perturbation.



go to top    Three Phase Induction Motor Incipient Rotor’s Faults Detection Based on Improved Root-MUSIC Approach
        by A. H. Boudinar, A. Bendiabdellah, N. Benouzza, N. Boughanmi

   Vol. 2. n. 3, pp. 406-413


Abstract - Induction motor plays a very important role in industrial applications. Early fault detection is one of the main problems. So, in order to detect an incipient fault, we must pay a special attention to the spectral analysis of stator current. Several frequency estimation techniques have been developed and used to help induction motor fault detection and diagnosis. In this paper, a new application of the Root-MUSIC method to improve the diagnosis is proposed. This method is a variant of the well known MUSIC (MUltiple SIgnal Classification) method. This is a powerful tool for extracting meaningful frequencies from the signal, which is in our case the stator current. Unfortunately, the Root-MUSIC method takes a long computation time to find more frequencies by increasing the order of the frequency signal dimension. To solve this problem, this method will not be applied to the totality of the signal spectrum but only to a bandwidth of specified frequency. An algorithm RMIF (Root-MUSIC Improved by Filtering) based on a digital band-pass filter within a specific frequency range is proposed with Root-MUSIC in order to improve the diagnosis performances. The proposed technique has been applied to detect incipient broken bar rotor faults in a three-phase squirrel-cage induction motor. Experimental results were presented to show the various merits of this RMIF technique compared to the classical PSD technique.

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Keywords: Broken bars, fault detection, induction motors, stator current, spectral estimation techniques, PSD, Root-MUSIC, band-pass filter.



go to top    Design, Modelling and Control of a Linear Induction Motor
        by M. A. Nasr Khoidja, B. Ben Salah

         Vol. 2. n. 3, pp. 414-424


Abstract - Developments presented in this paper are devoted to the design, the realization and the control of a linear induction motor. In this order, a first modelling approach exploiting an analytical analysis technique articulated on the layers method was developed. To validate the previous results, a second modelling approach, exploiting numerical techniques was elaborated around a discretization by finite elements. The exploitation of these two modelling approaches permitted to propose a non conventional control strategy in order to improve the robustness of the realized machine control. The results of the numerical simulations for the considered linear induction motor are presented and discussed.

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Keywords: Linear induction motor (LIM), layers method, finite element, design, modelling, fuzzy logic control.



go to top    Exact Analytical Model of the No-Load Flux Density in the Air-gap, the Permanent Magnets and the Rotor Yoke for the Surface Mounted Permanent Magnet Motors
        by F. Dubas, C. Espanet

        Vol. 2. n. 3, pp. 425-437


Abstract - In this paper, the authors present a general computation of the magnetic flux density at the no-load operation of surface mounted permanent magnet (PM) motors (SMPMM) having both external and internal rotor topologies with either an iron-cored or air-cored stator. It deals with an analytical model (AM) which is based on a two-dimensional (2-D) analysis in polar coordinate which includes both radial and parallel magnetization and solves the governing Laplacian/Poissonian field equation in the air-gap/PMs/rotor yoke regions. The analytical results are compared with the ones obtained by a numerical analysis using the finite-element method (FEM) and it show good agreement.

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Keywords: Analytical model, no-load magnetic flux density, parallel and radial magnetization, synchronous PM machines.



go to top    High Performance Torque Control of Brushless DC Motor Drive Based on TMS320LF2407 DSP Controller
        by A. Vahedi, H. Moghbeli, A. Halvaei Niasar

         Vol. 2. n. 3, pp. 438-447


Abstract - Brushless DC (BLDC) motor is attracting much interest due to its high efficiency, good performance and ease of control for many applications. This paper presents the design and implementation of a torque controller for a Brushless DC motor drive using the TMS320LF2407A digital signal processor (DSP) produced by Texas Instruments. Firstly, a theoretical analysis of a BLDC motor drive is presented and the validity of the proposed analysis is verified by simulation. The torque is controlled via current regulation directly. Then, hardware and software details of the system are explored. Finally, an experimental system included by a BLDC motor, DSP control board, inverters, rectifier is set up to validate the theoretical ones.

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Keywords: Linear Tubular Switched Reluctance Stepping Motor; sinusoidal model; advanced model; artificial neural networks.



go to top    Incorporation of Vector Preisach Hysteresis Model in Transient Finite Element Analysis for a SMPM
        by A. Mansouri, H. Trabelsi

   Vol. 2. n. 3, pp. 448-454


Abstract - In this paper, a numerical algorithm is developed to predict the magnetic field distribution in a surface-mounted permanent magnet motor (SMPM). The developed algorithm consists of the vector Preisach model coupled with 2-D transient finite element analysis (FEA). In this study, the hysteresis vector is modeled by means of angularly distributed scalar Preisach models. The link between the hysteresis model and the FEA is given by the non linear iterative scheme: Fixed point technique in its H-version, which is capable of handling the hysteresis features. The classical Preisach model was created to compute B as a function of H, but in FEA the output result is B. Hence, an inversion of the model is needed to obtain the value of H. This can be found only by non linear iteration. Moreover, it is vectoriel iteration with pure convergence. A special attention is given to the parametric definition of the developed hysteresis model and the convergence of the algorithm. A comparison between experimental data provided by the material manufacture and the simulated ones is presented.

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Keywords: vector hysteresis model, Preisach model, fixed point, convergence, distribution function.



go to top    Digital Step Motor Drive with EKF Estimation of Speed and Rotor Position
        by M. Bendjedia, Y. Aït-Amirat, B. Walther, A. Berthon

       Vol. 2. n. 3, pp. 455-565


Abstract - This paper will present experimental results and theoretical study of sensorless control of hybrid step motor. The rotor position is estimated by steady state extended Kalman filter. With this method the computing time is reduced. At standstill, the initial rotor position is estimated by the pulse current method. We describe the design of a robust RST controller to control rotor position. Experimental results obtained are better than those obtained by a classical PID approach. All algorithms are implemented with the powerful DS1103 board from dSPACE. The use of DSP let us to combine an estimator and a rotor position control without mechanical sensor.

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Keywords: Hybrid Step Motor, Modeling, Sensorless control, Kalman Filter, Position Control, RST Controller, DSP Implementation.



go to top    Numerical Simulation of Seawater Flow Produced by Conduction MHD Pump
        by N. Bennecib, S. Drid, R. Abdessemed

         Vol. 2. n. 3, pp. 566-472


Abstract - In order to circumvent the corrosion and mechanical wear encountered on the mechanical parts, non-mechanical pumping systems have been developed to supplement the conventional mechanical ones. Early numerical studies of magnetohydrodynamic (MHD) pump have been presented using the Galerkin type finite element method and control volume (CV) techniques. This paper, therefore, presents a simplified MHD flow model based upon steady state, incompressible and laminar flow theory to investigate the characteristics of a DC pump MHD; finite volume method to solve both electromagnetic and hydrodynamic model under code DCPMHD. A transformation from the physical space (r, z) to the computational space (ω, ξ) was introduced. A detailed picture of the electric and hydrodynamic fields encountered in DC pumps is presented.

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Keywords: Finite volume method, Magnetohydrodynamic pumps, Navier-stokes equations, Non-mechanical pumps.





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