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Home>Products>Journal and Reviews>I.RE.Mo.S.>Latest issue
International Review on Modelling and Simulations - April 2010 - Papers
International Review on Modelling and Simulations - Papers
Vol. 3. n. 2, pp. 129-139
Abstract - This
paper presents the development of an efficiency maximum power point
tracking (MPPT) controller for a standalone photovoltaic (PV) system. An
important component in the MPPT controller is the boost converter. The
main objective of the study is to develop an efficient boost converter
so as to achieve a cost effective MPPT controller. In the proposed boost
converter design, a passive regenerative snubber circuit is included to
absorb the energy of stray inductance so as to reduce the IGBT switching
losses. The simulation results show that the proposed boost converter
design gives an efficiency of 93% which is better than the conventional
converter. A computer simulation model of the PV system based on MATLAB
codes has been developed to evaluate the performance of the MPPT
controller. The proposed MPPT controller is found to be better than the
conventional MPPT controller in which it gives efficiencies of 94% for
temperatures lower than 29 oC and 89% for temperatures higher than 29 oC.
Keywords: Photovoltaic Systems, MPPT, Simulation of PV Systems, Boost Converter.
Vol. 3. n. 2, pp. 140-145
Abstract - Inrush
current is created duo to saturation of core during period of
energization of transformer. The main feature of this current is its
high amplitude and 2nd harmonic content. This current has undesirable
effect considering shortage of electricity quality, extra loss, and
reduction of useful life of transformer and fault in operation of
protection relays. In this paper, effect of presence and absence of
fourth wire on the peak value of inrush current in three-piece
three-phase transformer with star-star connection has been evaluated.
Its result will be extendable for three-phase power reactors with star
connection. Results show that four-wire system from a probability point
of lower inrush current peak and also from a chance point of become
unsaturated of single, two or three-phase has more proper situation than
three-wire system in same condition from viewpoint of switching angle
and hysteresis or remnant flux.
Keywords: Transformer, Inrush Current, Remnant Flux, Switching Angle, Fourth or Null Wire.
Vol. 3. n. 2, pp. 146-157
Abstract - In high
voltage application (rolling mill, traction, micro-grid, aircraft
......) it’s advantageous to combine several low power multilevel
inverter to replace one high power multilevel inverter . However for a
given application, there are many possible multilevel inverter
topologies which differ by the nature of the series and/ or parallel
connections of the elementary modules. The selection is therefore
particularly sensitive. In this paper, the authors apply the PROMETHEE
II (Preference Ranking Organization Method for Enrichment Evaluations)
tool for Multi-Criteria Decision Making (MCDM) to compare and rank the
different topologies considering several and sometimes conflicting
criteria cost, reliability, efficiency and components sizing.
Keywords: Multi-Criteria Analysis, Multilevel Converter Topologies, Selection, Multi-Criteria Decision Making (MCDM), PROMETHEE II.
Vol. 3. n. 2, pp. 158-167
Abstract - Many industrial applications require new control techniques in order to obtain fast response and to improve the dynamic performances. One of the techniques users, sliding mode, fuzzy logic and fuzzy sliding mode control which are characterizes by robustness and insensitivity to the parameters variation. In this paper, we present a comparative study of a direct stator flux orientation control of doubly fed induction motor by three regulators: sliding mode, fuzzy logic and fuzzy sliding mode. The three regulators are applies in speed regulation of doubly fed induction motor (DFIM). The robustness between these three regulators was tested and validated under simulations with the presence of variations of the parameters of the motor, in particular the face of disturbances of load torque. The results show that the three regulators are robust against external perturbations, but the fuzzy sliding mode controller has good performance than the fuzzy logic and sliding mode controllers. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Doubly Fed Induction Motor, Direct Stator Flux Orientation Control, Sliding Mode Controller, Fuzzy Logic Controller, Fuzzy Sliding Mode Controller.
Vol. 3. n. 2, pp. 168-177
Abstract - The aim of this paper seeks to optimize the characteristics of an hybrid linear tubular stepping motor. First, the existing of electromagnetic, thermal, mechanical and dynamic phenomena in the studied complex system orients us to elaborate several models. Second, the formulation of the optimization problem required initially the choice of the optimization criteria specific to the considered application which coincide with global mass and losses. The tests of the influences of electrical and geometric parameters on the weight and losses of the machine entailed the best selection of the optimization variables. After that, a definition of thermal, mechanical and magnetic constraints is achieved limiting the objective function minimization. The analytic model coupled with Genetic Algorithm and using the efficient weighted sum method has entailed conclusive results. The contribution of the machine optimization application is principally a clutter reduction permitting its integration in small systems; leakage flux lines attenuation and a temperature decrease limiting the machine overheat. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Force, Multi-Objective Optimization, Criteria Selection, Optimization Variables, Constraints, Genetic Algorithm, Hybrid Structure.
Vol. 3. n. 2, pp. 178-186
Abstract - This paper puts forward an analytical and practical analysis of the global stability dedicated to a low rating LC filter on a DC link for a rapid cycling synchronous drive. The first part describes the regenerative AC/DC front stage through an original bidirectional and self-commutated rectifier. The second part deals with the modelling of the AC/DC front stage, the DC link and the output synchronous drive. The last part analyzes the DC link stability taking into account the analytical correlation between the LC rating, the synchronous drive parameters and finally the feed-back control parameters of the PWM feeding. This contribution offers to designer a possible solution for on-board / embedded applications where sizing reduction and safety are simultaneously required. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electrical Stability, DC link, DC/AC Converter, Permanent Magnet Synchronous Drive, Power Flow, AC/DC Synchronous Rectifier, Self-Switching.
Vol. 3. n. 2, pp. 187-193
Abstract - In this paper, in order to a modeling study of proton exchange membrane fuel cell (PEMFC) performance, an artificial neural network (ANN) model based on a new learning algorithm is developed. PEMFC is a nonlinear, multi-input and multi-output, time-varying, and strongly coupled system that is hard to model via conventional methods. A suitable model is needed for PEMFC to predict how a PEMFC will behave under various operating conditions. ANNs as efficient tools for identification of unknown systems have proved themselves in many investigations due to handle complex input-output mapping without detailed analytical model of the system. Consequently, an ANN-based model is built and a new learning algorithm is used to tune ANN parameters, then the model is tested with the experimental data. In order to study the efficiency of the proposed algorithm, a comparison of the results is made through the PSO-based ANN model. Results are quite satisfactory and manifest that proposed technique can successfully adjust ANN parameters and model predict the PEMFC performance with high degree of accuracy. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Proton Exchange Membrane Fuel Cell, Modeling, Artificial Neural Network, Learning Algorithm, Particle Swarm Optimization.
Vol. 3. n. 2, pp. 194-201
Abstract - Collapsible soils are defined as unsaturated soils, which are particularized by a metastable structure, and undergo a rapid collapse when they are inundated (with or without loading), which might causes significant damage. Because of the structural composition of these soils, reconstituted samples, made up of various proportions of sand and fine particles were tested. The first phase of the present investigation concerns the experimental determination of the geotechnical characteristics. A comprehensive testing program using the ultrasonic apparatus and the cone penetrometer was carried out, in order to identify the factors which control the collapse mechanism. The results obtained clearly show the influence of certain parameters such as; initial moisture content, the energy of compaction and the quantity of fine particles, on the collapse potential, limit penetration and the ultrasonic speed. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Collapse Potential, Cone Penetrometer, Compaction, Kaolin and Ultrasonic Speed.
Vol. 3. n. 2, pp. 202-205
Abstract - In this paper, an electrokinetic flow of an electrolyte in a nano-channel will be studied. This study will be with existence of the Electric Double Layer (EDL) and fully analytical. Governing equation for the EDL is Poisson-Boltzmann. In addition, Navier-Stokes equations for electrolyte flow, Species and mass conservation equations are in use. Induced electric potential force the electrolyte ions and decrease the mass flow rate. In this paper, it is assumed that, zeta potential has small quantity. In this paper, after getting the equations set from the literature and transforming it into curvilinear coordinates, the set will be simplified and be solved analytically for small zeta potentials in a nano-channel. In addition, numerical method has been employed to compare the agreement of each method to the traditional rectilinear ones. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electrokinetics, Electric Double Layer (EDL), Zeta Potential, Nano-Channel, Curvilinear Coordinates.
Vol. 3. n. 2, pp. 206-211
Abstract - Recent studies have shown the use of electromagnetic vector sensors in an array system can significantly enhance the array’s overall performance. The fact that the entire electromagnetic field components can be measured allows the observability of the direction-finding to maximize. However, the main drawback that often prevents the use of vector sensors in practical systems is due to the high computational complexity. To compromise the array performance with the complexity reduction, “distributed” vector sensors are introduced, where only certain components of the field are measured. In this paper, a novel selection criterion for evaluating distributed vector sensors is proposed. The method is derived according to optimizing of the array’s ultimate detection capability. The theoretical framework is supported by computer simulation studies, where it is shown that this proposed selection criterion may be used as a figure of merit in array design applications. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electromagnetic Vector Sensor, Distributed Vector Sensor, Array Detection, Array Design.
Vol. 3. n. 2, pp. 212-218
Abstract - In this paper, a fuzzy approach based on residual processing is proposed for on-line fault detection and isolation in case of faults affecting sensors and actuators of systems with parameter uncertainties. The membership functions parameters of the fuzzy system are optimized by the use of genetic algorithms and simulated annealing. The proposed approaches are illustrated and compared through a reel hydraulic example. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fault Detection and Isolation, Uncertain Parameter Systems, Fuzzy Logic, Genetic Algorithms, Simulated Annealing.
Vol. 3. n. 2, pp. 219-226
Abstract - In this paper, we develop a new control technique based on the formalism of the exact input-output linearization. The very performed developments largely rely on Hauser's approximation and Lyapunov's theory of stability. The framework of the study that we present employs the nonlinear non-minimum phase model of the "ball and beam" system and aims at ensuring the tracking of the output trajectory. A clear improvement of the dynamic behavior of the tracking error is then guaranteed through the fast attenuation of its amplitude. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Exact Input-Output Linearization, Robust Relative Degree, Lyapunov Function, Trajectory Tracking.
Vol. 3. n. 2, pp. 227-234
Abstract - In this paper we propose a new approach to control on-off systems usually controlled by the classical schema of on-off regulation. The aim of this control is to keep the output into a defined range, and in the same time reduce consumption and optimize the switching number of the control. Firstly we propose to hybridize non linear on-off system presented in the multimodel form into the Mixed Logical Dynamical representation; the control law elaborated is an extension of the Model predictive controller to hybrid models. Two approaches have been developed in this work, providing the best combination of weight values of the cost function and the prediction horizons. The first one is suitable for systems with a large sampling time. For the second approach, by setting the value of the prediction horizon N the smallest we can apply this control for fast systems. These propositions are applied on the case study of an experimental greenhouse. Simulations with the two proposed approaches are presented and compared to the existing on-off regulation; the results indicate a global reduction of consumption around twenty percent, the correspondent switching number remains in acceptable margins. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Agricultural Greenhouse, hybrid system, MLD Modeling, On-off regulation, Predictive control.
Vol. 3. n. 2, pp. 235-240
Abstract - PENCEL Pressuremeter and Cone Penetrometer tests were performed at two sites chosen in Florida. One of the sites was predominately clays and the second was sands. The study goal was to reveal that pushed-in PENCEL tests would produce reliable engineering parameters. The PENCEL was pushed to the preferred test depth using the cone penetrometer equipment. Correlations were developed within the engineering parameters obtained from PENCEL pressuremeter data and between the PENCEL and cone penetrometer engineering parameters. All correlations matched published values. From the PENCEL data excellent correlations were created between the initial elastic modulus and limit pressures. Excellent correlations were also produced between the initial elastic modulus and the limit pressure as well as the initial elastic modulus and the elastic reload modulus. From the comparisons between pressuremeter and cone penetrometer data, promising correlations were developed between the pressuremeter initial elastic moduli and Cone Penetrometer tip resistances. Promising correlations were also developed between pressuremeter limit pressure and Cone Penetrometer tip resistances. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Cone Penetrometer, Pressuremeter, Reload Moduli, Limit Pressure, Tip Resistance.
Vol. 3. n. 2, pp. 241-249
Abstract - Epoxy resin and mica sheets are essential for the insulation of rotating machines stator bars. Although such insulation is resistant to partial discharges and mechanically strong, it may also suffer from electrical trees, which in the long run may cause ultimate failure. Electrical tree is a phenomenon which is intimately related to insulation breakdown and the deterioration of the insulating capability of the materials. An attempt to simulate the electrical tree propagation in epoxy resin with a mica sheet barrier is presented with various combinations of structures. A comparison with experimental results obtained elsewhere, is also attempted. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Rotating Machine Insulation, Electrical Tree, Stator Bars, Insulation Breakdown, Electrical Tree Propagation.
Vol. 3. n. 2, pp. 250-254
Abstract - In the piezoresistive pressure sensor, we need to study the stress repartition on the Silicon membrane surface. This study is very important because it allows us to determinate where the stress is maximal and to place there the four piezoresistors, which provide a maximal sensitivity to the pressure. Because of the anisotropy of the Silicon, we have to study too its mechanical parameters (Young Modulus and Poisson Coefficient) and piezoresistive (piezoresistive coefficients) parameters in the different crystallographic directions. These studies will allow us to optimize the sensor characteristics (Sensitivity, Linearity …). Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Anisotropy, Piezoresistivity, Poisson Coefficient, Silicon, Sensitivity, Sensor, Stress, Theory of Plates, Young Modulus.
Vol. 3. n. 2, pp. 255-264
Abstract - An innovative configuration for reducing voltage harmonics on the DC side and current total harmonic distortion on the AC side of twelve-pulse series connected AC/DC rectifiers for HVDC transmission system is proposed in this paper. The principle of the method is to modify the current waveforms on the DC side of the converter by using self-commutated switches to reduce current harmonics, and voltage harmonics on the DC side of the converter can be reduced by means of direct voltage ripple injection method in HVDC transmission system. An averaging inductor is added to the series connected converters and thus simplifies the pulse multiplication significantly. This method can make a 12-pulse double bridge converter to operate at 24, 36 and 48 pulses. A reinjection transformer is also used in series-connected converters to reinject a current to the main rectifier. Minimum value for the total harmonic distortion of AC current can be achieved by selecting an appropriate value for turn ratio of reinjection transformer. Genetic Algorithm (GA) has been used to calculate the optimal value for turn ratio of reinjection transformer. The total harmonic distortion of AC current has been calculated for different values of the turn ratio of reinjection transformer, and the minimum value of THD is obtained at turn ratio of reinjection transformer calculated by GA for 24, 36 and 48-pulse operation modes. By direct voltage ripple reinjection on the DC side, voltage harmonics can be reduced on the DC side of HVDC converters. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: HVDC Transmission Systems, Reinjection Transformer, Harmonic Optimization, Genetic Algorithm (GA.
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