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Home>Products>Journal and Reviews>I.R.E.E.>Latest issue
International Review of Electrical Engineering - April 2008 - Papers
International Review of Electrical Engineering - Papers
by A. Geranmayeh Vol. 3. n. 2, pp. 218-224
Abstract - An efficient and simple explicit solution of the electric field integral equation describing the transient radiation of nonlinearly loaded thin-wire antennas is presented for fast and versatile modeling of the lightning return stroke channels above prefect conducting ground. An adaptive marching-on-in-time scheme is proposed in which the time step size as well as the spatial resolution of pulse bases expansion along the large-scale channel is moderated at each time step based on the Haar decomposition of the former stage results. This yields to a considerable reduction in the number of spatio-temporal unknowns needed to accurately approximate the transient propagating current along the channel, especially the smoothly varying tail of the response. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Thin-wire EFIE, Marching-on-in-time scheme, Lightning return stroke, Wavelet transform.
Vol. 3. n. 2, pp. 225-232
Abstract - This paper presents an algorithm for the efficiency assessment of LPS (Lightning Protection System) of buildings and high voltage switchyards. Lightning strikes are simulated by means of the Monte Carlo method, with the application of electrogeometric model. The peak value of the lightning current, in each case, is also stochastically chosen from the logarithmic normal distribution. In the stochastic model, LPS and structure or switchyard can be approximated by a number of straight segments, triangles and plane quadrangles. Origin of the lightning strikes is located on the imaginary plane above the structure. Each lightning strike starts its descend on this plane and follows a stochastic path toward the protected structure or earth surface. Minimal distance from the lightning stroke stepped leader head to elements of LPS, structure and earth surface is computed after the each jump. If this distance is smaller then the striking distance, lightning will strike its nearest point belonging to the LPS, structure or the earth surface. Efficiency of the LPS is seen as quotient between the total number of lightning strikes ending up on LPS itself and the total number of lightning strikes. Lightning strikes hitting the earth surface are not counted. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electrogeometric Model, Lightning Protection System, Monte Carlo Method, Stochastic Efficiency Assessment.
Vol. 3. n. 2, pp. 233-241
Abstract - The worldwide trend for the restructuring of electric industry has caused dramatic changes in operation and planning procedures of the power system. Under the restructured electricity market environment, identifying a minimum-cost plan under particular constraints is not sufficient anymore and other aspects such as market efficiency and environmental concerns are of equal importance. In this context, network augmentation plays a vital role in providing a full competitive environment for market players. This paper presents a novel forward heuristic algorithm to select the most effective expansion options based on a set of market–based and reliability-based sensitivity indices. These indices are used for multi-evaluation of each transmission option from the view point of electricity market and reliability criteria. The proposed method has been applied on a 6-bus test system for verifying its effectiveness. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Heuristic Optimization Technique, Transmission Expansion Planning, Electricity Market.
Vol. 3. n. 2, pp. 242-247
Abstract - The fast development of reduced size local systems destined to electric energy production poses the problem of their integration in the existing networks so much point of view of present norms power quality (PQ) as the usufruct discounted of advantages that ensue some. To the inverse, disorganized and non controlled introduction of these systems would lead to stroke on verse deterioration more and more increased from PQ. In this work, it is intended to introduce a simplified method as according to existing topology and space-temporal distribution of loads, it would allow the energy system operator to know active and reactive powers potential margins to inject at the network in order to reduce losses and to improve the level voltage. The gait adopted in this work is based on insertion of production distributed generation (DG) in various positions with application and verification on the east Algerian zone electrical network. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Distributed generation, power losses, voltage stability, optimization, power quality.
Vol. 3. n. 2, pp. 248-252
Abstract - Optimal network configurations are solved to achieve balanced loading, among the feeders by operating switches using appropriate system topologies with respect to load patterns. This paper presents a method for determining optimal switching in distribution system to minimize the number of switching that in turn results the increase of the life of switches and reduction of switching losses. Using daily load curves of different load customers, critical switches of the system are identified by optimal operating load pattern for peak and OFF peak duration. It results minimizing the number of switching operations that in turn increases switch life span, reduces the crew requirement and the switching losses. The algorithm used is based on the concept of optimum flow pattern of the network. For different test cases with load levels, this method is computationally attractive for loss reduction and minimizing the switching operations. Line data of feeders of two substations in Vizianagaram (City in Andhra Pradesh, India) is taken for computations. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Reconfiguration, Switching operations, Loss minimization.
Vol. 3. n. 2, pp. 253-264
Abstract - This paper proposes a method to allocate transmission usage for simultaneous bilateral transactions using artificial neural network (ANN). The basic idea is to use supervised learning paradigm to train the ANN, utilising a conventional circuit theory method as the trainer. Based on solved load flow and followed by a procedure to decouple the line usage on the basis of transaction pairs, the description of inputs and outputs of the training data for the ANN is obtained. The structure of artificial neural network is designed to assess the extent of line usage by each generator while supplying to their respective customer. Most commonly used feed forward architecture has been chosen for the proposed ANN based transmission usage allocation technique. Almost all the system variables obtained from load flow solutions are utilized as an input to the neural network. Moreover, tan-sigmoid activation functions are incorporated in the hidden layer to realize the non linear nature of the transmission usage allocation. The proposed ANN provides promising results in terms of accuracy and computation time. A 6-bus and also the modified IEEE 14-bus network is utilized as test systems to illustrate the effectiveness of the ANN output compared to that of conventional methods. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Artificial neural network (ANN), bilateral transactions, circuit theory, and transmission usage allocation.
Vol. 3. n. 2, pp. 265-272
Abstract - This paper presents the power angle stability studies of a large utility system based on North American Electric Reliability Corporation (NERC) requirements. We carry out nine types of contingencies and find out that the most severe contingency causing stability problem is the stuck-breaker faults. The impact of substation configuration and speed of protection system on stability of the system is also discussed. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Power system angle stability, Contingency analysis, Short circuit analysis, Power system simulation for engineering.
Vol. 3. n. 2, pp. 273-280
Abstract - This paper is concerned with predicting the electrical behaviour of metallization patterns printed onto dielectric substrates using the Finite Element Method (FEM). The method described was initially aimed at the modelling of Printed Circuit Boards (PCB) layouts, but is just as applicable to VLSI layouts. It involves the generation of an equivalent circuit to model the electrical properties of the layout. This can be obtained efficiently and provided directly to a circuit simulation program. Predictions can then be made of how the performance of a circuit implemented on a PCB is modified by its physical layout, or of the performance of printed components such as spiral inductors. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Induction Finite Element Method, Modelling, Printed Circuit Boards, Prediction, Simulation.
Vol. 3. n. 2, pp. 281-288
Abstract - This paper presents a methodology to design and prototype FPGA-based fully digital controller for power electronics systems. A Top-down design methodology is used to study step by step the digital adaptation and the fully digital implementation of the control algorithm. Finally, “FPGA in the loop” prototyping is achieved, based on MATLAB/SimPower Systems and Altera DSP Builder computer aided design tools. Modeling, simulation and FPGA in the loop prototyping are achieved in a unique design environment. An application using the proposed methodology is studied: a fully digital controller for a three-phase parallel active power filter. The fully digital controller implementation is described and the hardware digital controller experimentally validated by FPGA in the loop prototyping. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Aperture, Field Programmable Gate Array (FPGA), Design methodology, fully digital controller, industrial power control system.
Vol. 3. n. 2, pp. 289-299
Abstract - Enormous amounts of power electronics drives are being used in the industry nowadays. Authors find wide applications of Switched Reluctance Motor (SRM) drives in industry, office automation and appliances. This paper deals with the literature survey on the converter topologies of switched reluctance motor drives. The switched reluctance motor is famous for its fault tolerance and good dynamic response. One of the main aspects of the research in switched reluctance motor drives is the converter design. The performance and the cost of the SRM drive are highly affected by performance of the converters. Although a number of converters have emerged over the years for Switched Reluctance Motor drives. There has always been a trade-off between gaining some of the advantages and losing some with each new topology. The selection of a converter, in most of the cases, depends upon the application. Attempt is made to provide a guidance and quick reference for the researchers and practicing engineers, those are working in the area of converter topologies for Switched Reluctance Motor drives . Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Moments Switched reluctance motor, converter topology, hard-switching, soft-switching, resonant converter, performance, efficiency.
by S. Guizani, F. B. Ammar Vol. 3. n. 2, pp. 300-311
Abstract - The authors propose the mathematical model in Park reference frame of squirrel cage induction machine with double star stator windings. Each star is supplied by its own voltage source inverter. The redundancy operating mode of the two inverters improves reliability, availability, since the loss of one inverter does not stop the machine. Moreover, the multiphase stator winding is of a major interest to reduce the space harmonics content. A special attention is paid to analyze the stability by examining the root-locus in complex plan of six order flux model in full speed range. Simulation results are carried out to analyze the influence of the magnetic coupling between two star stator windings on the stability of the motor drive. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Double star asynchronous machine – eigenvalues– Root-locus– magnetic coupling.
by C. B. Jabeur-Seddik, F. Fnaiech Vol. 3. n. 2, pp. 312-325
Abstract - In this paper, four controllers are designed for a direct torque control of an induction machine and validated on a voltage-source pulse width modulation inverter-fed induction motor drive. Basically, it is a task of replacing the classical Direct Torque Control strategy (DTC) by a Direct Torque Neural Control strategy (DTNC), a Direct Torque Fuzzy Control strategy (DTFC), a Direct Torque Neuro-Fuzzy Control strategy (DTNFC) and a Direct Torque Genetic-Neuro-Fuzzy Control strategy (DTGNFC), based respectively on a neural controller, a fuzzy controller, a neuro-fuzzy controller and a genetic-neuro-fuzzy controller. The purpose of this work is to reduce the torque and the flux ripples caused by the hysteresis controllers and the selection table in the classical DTC and to require low current in the start-up by fluxing the machine when the torque is maintained equal to zero. Following, the proposed methods are incorporated in the classical DTC scheme in order to replace both hysteresis controllers and the selection table. In this context, a simulation experiments have been carried out to demonstrate the robustness of these controllers in the transients and at the machine start-up. Other settings are considered such as changing the rotary direction and the behavior of the flux response when the torque is zero. The superiority of such controllers is then highlighted. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Direct torque control, Induction motor control, Neural control, Fuzzy control, Genetic algorithms, Voltage-source pulse width modulation inverter.
Vol. 3. n. 2, pp. 326-336
Abstract - The purpose of this paper is to provide a numerical method for identification of the mutual inductance and leakage inductances of an induction motor operating either in open-loop or closed-loop drives. This paper presents a numerical method for computing steady-state and dynamic performances of a saturated induction motor. Input parameters of this method are unsaturated inductances and corresponding saturation curves. Computation of steady-state performance is based on an iterative numerical procedure. Computing dynamic states assumes that leakage inductance and mutual inductance depend on the values of the motor currents. This paper also presents a conventional indirect rotor field oriented (RFO) control system, where mutual inductance is identified in two ways. The first way identifies the mutual inductance depending on the rotor flux reference. The second way identifies the mutual inductance upon the value of the magnetizing current. These results ensure utilization of the indirect RFO control system at variable magnetizing levels. A comparison of these two methods is presented. The effectiveness of the proposed method is verified through simulation and experimentation. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electrical drives, Induction motor, Iterative method, Rotor field control.
Vol. 3. n. 2, pp. 337-343
Abstract - A method for induction motor speed sensorless control in the system with voltage inverter and output filter is presented. It is almost impossible or extremely difficult to get precise control of this motor in such condition because the filter introduces voltage drop and additional phase shift. In this paper, a nonlinear control method is used in the control process and additional controllers are introduced to control filter state variables. To obtain well running sensorless drive of the system, a structure of the state observer will be extended to estimate motor currents and stator voltage. This trend is to avoid the necessity of using additional sensors. The presented system was realized in simulation and tested experimentally. The desired high system performance is confirmed by simulation and experimentally. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Inverter output filter, sensorless control, speed observer, induction motor.
Vol. 3. n. 2, pp. 344-354
Abstract - Neural networks and fuzzy controllers are both capable of controlling nonlinear dynamical systems and it is well known that they are able to ensure robustness towards parameter variations of the controlled system, so, in this paper, these two emerged systems are used in order to improve the performances of induction motor drives. As a first step, an approach of linguistic fuzzy modeling proposed by Ben-Ghalia is applied to induction motor. Thus, a classical model is first given with feedback linearization. After more, in order to minimize the dependence of the system to parameter variations and external perturbations, and reduce the number of variable states, a new model of the original system is proposed. This model is too simple and is suitable to cognitive approach such as fuzzy modeling. On the other hand, to improve the performances especially the robustness towards parameter variations and external perturbations, of the overall system based on the new proposed fuzzy model, a speed Gaussian Radial Basis Function Neural Network controller is used. Finally, Simulation study is carried out and the results revealed very interesting features. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Feedback linearization control, fuzzy modeling approach, nonlinear feedback based on modeling, neuro-fuzzy system, Gaussian Radial Basis Function Neural Network controller, induction motor.
Vol. 3. n. 2, pp. 355-360
Abstract - This paper presents sensorless volts per hertz (v/f) control algorithm to control the speed of an induction motor. First, a flux estimator was employed to estimate the stator flux using stator voltage and current. Then, based on the mathematical model of the induction motor, the speed of the motor was calculated, and the frequency of the voltage command was compensated. To improve the integration problem, a low pass filter was used in the stator flux estimator. In this filter, the cut-off frequency is proportional to the voltage frequency; therefore, the phase shift and amplitude degradation of the estimated flux can be corrected easily. Finally, to illustrate the proposed control algorithm performance, a PC-based experimental system was constructed. Experimental results are presented to validate the effectiveness of our design. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Speed sensorless, scalar control, induction motor drives.
Vol. 3. n. 2, pp. 361-370
Abstract - This paper describes a novel inverse fuzzy model based rotor flux oriented vector control approach of the induction motor. In order to obtain high performance speed response, rotor flux oriented vector control techniques are usually used to control the torque and flux separately as in direct current machines. The application of fuzzy logic in modeling of uncertainly dynamical systems is in progress; however fuzzy modeling is one of the major topics in the field of modeling of dynamical systems. The authors has made an effort to develop an inverse fuzzy model of the vector control block applied to the induction motor to successfully improve the classical approach of the vector control. For the simulations results, it is shown that the proposed algorithm can successfully find the inverse fuzzy model that approximate the rotor flux oriented vector control block, with a compact number of fuzzy rules and membership's functions. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Inverse Fuzzy Model, Fuzzy Modeling, Vector Control, Induction Motor.
Vol. 3. n. 2, pp. 371-377
Abstract - Synchronous generators subjected to LOF (Loss of Field or Excitation) may sustain severe damage in the generator resulting from high current and pulsating torques. In this research, a new scheme is proposed by taking the saturation in main flux into account to design a LOF impedance relay. A computer model for synchronous generator is developed using its flux and current differential equations. Governor control loop is considered in the machine modeling. Transient performance is also focus of investigation. The relay characteristic circle proposed is smaller than the conventional one, which aids to avoidance of nuisance tripping of the relay under stable system swings. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: LOF (Loss of Field or Excitation), LOF Relay, Saturation, Seen Impedance Characteristics.
Vol. 3. n. 2, pp. 378-385
Abstract - In this paper, a concise approach is proposed to control non linear systems by a systematic gain scheduling approach. Non linear systems are first approached by a set of affine models using High-level canonical piecewise affine (HL-CPWA) approach. Such models are not appropriate for analysis or for control because of absolute functions appearing in their structure. A novel approach is then proposed to transform the affine models on a bank of standard linear models. In this investigation, criterion approximation errors are optimised. The main contribution of such approach is to constraint the state variables on a predefined trajectory. This idea avoids instable dynamics when the system tries to switch between two consecutive linear models. State feedback controllers are finally computed on off line using Linear Matrix Inequalities (LMIs) and convex programming tools and scheduled on sub-linear models under quadratic stability constraint. The performances and the limitations of the proposed approach are pointed and illustrated by means of simulation results of a non linear system. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Gain scheduling control, Linear Matrix Inequality (LMI), Nonlinear systems, Piecewise affine (PWA) canonical form.
Vol. 3. n. 2, pp. 386-394
Abstract - The present paper has as objective the modeling of an electronic differential system for an electric vehicle that will offer the best stability of vehicle in the curved road. The electronic differential proposed in the traction system for an electric vehicle driven directly by two wheel motor is based on direct torque fuzzy control for each wheel-motor. Differents simulations have been carried out : driving vehicle on straight road and driving vehicle in curved road right and left. The result obtained by simulations is very satisfied due to the good stability of vehicle in curved road. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electric vehicle, direct torque control, electronic differential, multimachine control.
Vol. 3. n. 2, pp. 395-400
Abstract - A novel multiplexing technique based on absolute polar return-to zero (RZ) duty cycle division is proposed, under the name: Absolute Polar Duty Cycle Division Multiplexing (APDCDM). Theoretical and simulation studies have been carried out to evaluate the performance of this technique based on the signal energy and Symbol Error Rate (SER). The new technique allows for more efficient use of time slots as well as the spectrum, taking the advantage of both the conventional Time Division Multiplexing (TDM) and Frequency Division Multiplexing (FDM). The simulation has been set for wireless transmission based on free space propagation model with Adaptive White Gaussian Noise (AWGN). Phase Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM) are used as modulation schemes to evaluate these techniques against data rates and number of users. The performance of APDCDM is compared with multilevel M-ary as well as with the TDM techniques. The study shows that by increasing the number of users, the energy per bit in APDCDM has better performance than that of TDM technique. The simulation result correspond with the theoretical study shows that APDCDM, has better SER than TDM. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Multiplexing technique, Duty cycle, Communication networks.
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