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Home>Products>Journal and Reviews>I.RE.Mo.S.>Latest issue
International Review on Modelling and Simulations - June 2010 - Papers
International Review on Modelling and Simulations - Papers
Abstract - This
paper presents a new numerical method for the resolution of initial
value problems for fractional orders differential equations. The method
is based on the generalized Taylor's formula, it calculates the solution
of the equation and overcomes the shortcoming and, in addition, it's
independent from the point in which the fractional derivative is
defined. Two numerical examples are detailed to show the effectiveness
of the proposed method in the simulation of a dynamic fractional order
linear system described with a state space representation.
Keywords: Caputo fractional derivative, generalized Taylor's formula, fractional order differential equations, initial value problems, state space representation, simulation.
Abstract - The
energy of traditional continuous Hopfield neural networks (CHNN) only
decreases with time, so it cannot jump out of local minima. By adding an
extra self-feedback to every neuron of CHNN, the energy of CHNN will not
always decrease, but can increase or maintain. The energy increasing may
lead to avoiding the local optimal values. The conditions under which
the CHNN energy increases, decreases or maintains are given,
respectively. An adding decaying self-feedback CHNN (ADSCHNN) is
presented and approved. Furthermore, the ADSCHNN is applied to the
solution of the traveling salesman problem (TSP) and a comparison
between chaotic simulated annealing (CSA) and ADSCHNN in the same energy
function is conducted. ADSCHNN also is compared with other methods.
Simulations results show that the ADSCHNN outperformed other methods and
obtained the local optimal solution or the global optimal solution.
Keywords: Continuous Hopfield Neural Networks, Adding Decaying Self-feedback CHNN, Combinatorial Optimization Problem, Traveling Salesman Problem, Global Optimization .
Abstract - In this
paper transmission network planning will be presented in which the
competition ability associated with minimum investment costs is
considered. This type of transmission expansion can be addressed as an
open access transmission expansion planning. Such open access
transmission planning is modeled regarding extreme and feasible
generating scenarios. A mathematical modeling of transmission expansion
problem, considering generation scenarios is solved via a constructive
heuristic algorithm using an iterative technique. In this paper a
constructive heuristic algorithm solves several non-linear programming
in order to identify the most important transmission line that should be
constructed. The proposed methodology is implemented to the Garver as
well as IEEE 24-bus test systems to show its significant performance.
Keywords: Transmission expansion planning, Constructive heuristic algorithm, Open access, Multiple generating scenarios.
Abstract - In this contribution, we investigate the possibility of eliminating the crowbar circuit which is normally used to protect the auxiliary railway supply system in case of a catenary transient overvoltage. The idea is to act at the control level by suspending the operation of the auxiliary inverter when the input voltage reaches some given threshold. Experimental results are firstly presented for an inertial-type load in order to get an insight into the ensuing phenomena. Then, a theoretical analysis is carried on to explain the experimental observations, with emphasis on the freewheeling sequence of the inverter output currents. The subsequent voltage oscillations across the inverter switches are also justified. Considering a numerical example with realistic parameters values, it is shown that the freewheeling stage is not dangerous for the power devices of the auxiliary inverter. The switch voltages oscillations could however be destructive, depending on the value of the inverter dc input voltage at the time these oscillations start (rather than their peak value itself). Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Auxiliary Railway Supply, Soft Crowbar, Transient Overvoltage.
Abstract - This paper investigates the capabilities of a proposed control strategy designed to enhance phase current profile in switched reluctance machine (SRM) drives. The new developed control concept can significantly accomplish the performance of the SRM in terms of efficiency, torque ripple and power quality when compared to standard PWM current control. This control consists of feeding each phase with a constant volt per hertz (V/f) law for low speed range. The suggested V/f method is simple and is easy for practical implementation. Principle of this mode of control and analytical expressions for current calculation are provided and discussed. Obtained simulation results demonstrate the effectiveness of the proposed control strategy. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: PWM Current Control, Single Pulse, Switched Reluctance Machine, Torque Ripple, V/F Control.
Abstract - According to important role of induction motors in power industry and systems, and so much of produced energy in the world are consumed by these motors, therefore, analyzing performance and efficiency increase and paying attention to consider reduction of energy consumption, can be evaluated. In order to this purpose, different approaches like changing structure to reduce losses have been presented to increase efficiency of induction motors in previous researches. In this paper, new kind of induction motor with two internal and external rotors has been introduced. This new kind of induction motor is Double Rotor Induction Motor (DRIM). Besides, electrical and mathematical equations related to voltage, torque, current and other features of motor in dq axis has been presented for calculation and simulation in Matlab/Simulink software package. The results of simulation and comparing it to traditional induction motor (IM) express validity of equations, and also increase of efficiency, improvement of power quality and optimization of other features in DRIM. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Double Rotor Induction Motor (DRIM), Efficiency, Induction Motor (IM), Matlab/Simulink Software Package, Modeling, Power Factor.
Abstract - This paper presents a torque control approach of a sensorless induction motor in the indirect vector-controlled drive using artificial neural networks. The presented approach is based on adaptive observer which makes it possible to reconstruct precisely not only the rotor flux but also angular velocity, load torque, and decoupled voltages to obtain an accurate estimated motor torque while taking account of the induction machine parameters variations. The error between the rotor flux linkages based on a neural network model and a voltage model is back propagated to adjust the weights of the observer neural network model. Considering the enormous algorithmic resources which request the neural networks integration, the number of neurons employed by studying different neural network structures, have been optimized. The neural observer is then employed, together with an enhanced control design obtained by optimizing torque and flux transient responses to improve the vector control algorithm performance. To test the integrity of the electric motors propelling an electric vehicle (EV), a thermal and a mechanical model for the EV is introduced. Simulations results (MATLAB–SIMILINK) are used to highlight the effectiveness of this design method. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electric Vehicle, Decoupling Mechanism, Indirect Rotor Field-Oriented (IRFO), Induction Motor (IM), Recurrent Neural Network, Speed Sensorless Induction Motor Drive.
Abstract - This paper present a new method for estimating rotor speed with the application of fuzzy logic to Model Reference Adaptive System (MRAS) in an indirect vector-controlled induction motor drive with adaptive stator resistance. The proposed fuzzy logic adaptive controller constituted by fuzzy IF-Then rules is a new application technique of MRAS, even when the motor parameters variation in conventional MRAS. The MRAS based on the rotor flux has the immediate advantage in that the model is simple, presents the theory, modelling and this method because eliminates the produced error in the adaptation by fuzzy logic controller, is more stable and robust. Simulation results show high performance. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Sensorless Speed, Field Oriented, Fuzzy Logic, Model Reference Adaptive, Induction Motor.
Abstract - The aims of this paper is to develop an electromagnetic-mechanical model to study the dynamic performances of tubular linear stepping motors. The studied tubular linear stepping motors are, the classical tubular Linear Switched Reluctance Stepping Motor (LSRSM) and its hybrid version with incorporating a Permanent Magnet (PM) on the stator giving the (PMLSM). The governing magnetic field nonlinear equations expressed in terms of magnetic vector potential are solved using the nodal-based finite element method while incorporating the Newton-Raphson algorithm for the magnetic nonlinearity treatment. The sequential coupling between the electromagnetic and mechanical equations is carried out, firstly through the magnetic force, and secondly by the modified flux distribution due to the moving parts displacement simulated by the Macro-element method. The validity of the model is checked by comparing the computed and the measured displacement. Finally, the predicted dynamic performances of the PMLSM are compared to those obtained for the LSRSM. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Linear stepping motor, Finite Elements, Dynamic performances, Macro -Element, Saturation.
Abstract - This paper describes the simulation of flux distribution on 100kVA 3 phase distribution transformer assembled with 60°-45° T-joint and mitred lap corner joint with stagger yoke and limb. The core that being used is 3% Silicon Iron Cold Rolled Grain Oriented (CRGO) material. The flux distributions have been simulated using 2 Dimensions Finite Element Method (2DFEM) based on a vector potential formulation. The loss of transformer core lamination is calculated using the hysteresis curve. The simulation shows that 1.78 T flux density was maximum at the centre limb of transformer core, hence produced the losses of 2.54 W/kg. The transformer core assembled with 60°-45° T-joint is more efficient than the transformer core assembled with 90° T-joint. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Finite Element, Hysteresis, Flux Distribution, Core Loss.
Abstract - An electricity-producing system using a Photovoltaic system, a project initiated by Thailand’s King, his majesty King Bhumibol Adulyadej, has been established across Thailand where schools, public health centers, and a wide range of other end users are located. The 798 PV Cell stations (1-5kWp) are currently installed around the country; ten of which were selected for evaluation in this study. The evaluation included analyses of the station’s present performance levels and an assessment of the potential for expansion of the overall system. The PV Cell system includes PV stand alone stations, PV grid connection stations and PV water pumping stations. All stations use Mono Silicon (Si), Poly Si, Hybrid and Amorphous type PV cells. The evaluation of the PV cell system’s potential for future expansion was based on the International Agency Photovoltaic Power Systems TASK 2 – Performance, Reliability, and Analysis of Photovoltaic Systems (IEA PVPS Task 2). The results show that these three stations of systems are performing as designed, exceed the performance levels of similar systems in other countries, and can be further developed. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: PV Stand alone System (PVSAS), PV Gird Connection System (PVGCS), PV Water Pumping System (PVWPS), Performance Ratio (PR), Production Factor (PF).
Abstract - Microgrids can be defined as distribution systems with DG units, energy storages and controllable loads i.e. Smart Grids. Most of the time microgrids will be operated normally connected to utility grid with the same management principles as other parts of the Smart Grids. In addition to this microgrids have a special capability of working in islanded mode, e.g., during the utility grid outages. In this paper effect of distributed generation (DG) unit converter's fault behavior to low voltage (LV) microgrid protection during island operation is studied in some specific cases through simulation studies with PSCAD simulation software. When protection of islanded microgrid is designed one of the most important questions is how converter based DG units will contribute to the fault current feeding. In the simulations different control strategies of converter connected DG units during faults are investigated with various DG unit configurations and also the role of energy storages is examined to find out their effect to microgrid voltages and currents that are measured by the protective devices. In overall the protection of LV microgrid needs to be very fast to both minimize duration of voltage dips to customers and maintain stability in island operated microgrid. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Microgrid, Distributed Generation, Energy Storage, Protection, Islanding, Low Voltage Network, Fault Behavior, Stability.
Abstract - Wind energy is the most significant renewable energy resource in power system generation. Conventional energy resources are dwindling and public concern are rapidly increasing, hence wind power is known as a proper alternative to solve this problem in the last decade. Reliability assessment of power system integrated with wind energy is an intricate process. The evaluation process requires historical wind speed data collected over many years for the particular site to determine the needed parameters of wind speed model. In this paper statistical test is used to generate wind speed probability distribution at different location. The wind speed model combined with the wind turbine generator characteristics to obtain wind farm power output. This paper also presents an analytical method which is applied to a large test system to illustrate impact of wind power on reliability indices. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Reliability Evaluation, Wind Power, Analytical Method, Power System Reliability.
Abstract - With large sources of biomass available in rural areas, biomass based electricity generation can be a dependable source of power that can complement the main power supply. Gasification being the cleanest and the most efficient combustion method known, biomass generation systems using gasification technology can provide clean energy. With different sources of power generation available and have different costs of generation, electricity price fixation has an important role in the power market. A generalized pricing method should take care of the demand variations and the market conditions. Peak and off peak period demand, quality of supply and reliability of service influence the electricity price. This paper proposes a model for determining the price of electrical energy from biomass based power plants considering operating constraints and the economic components that influence the electricity price. It incorporates CDM benefit, income from by-product and penalty factors in addition to the economic components. The model developed is applied to a typical biomass gasifier generating unit in India for determining the optimal electricity price. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Biomass gasifier, CDM benefit, Penalty, Energy price, Capital cost.
Abstract - This paper presents a study of the feasibility of using artificial neural networks (ANNs) in transient stability assessment for power systems. Critical Clearing Time (CCT) is used as an index to evaluate transient stability, Critical Clearing Time values were obtained by the Runge-Kutta method and used for training. The proposed approach has been tested on 3-generators power system in the case of three-phase short circuit on one transmission line. Two applications of artificial neural networks are presented in this article. The first uses a structure with an output boolean characterizing the state of system stability, it is equal to 1 if the system is stable and 0 if the system is unstable. The second application shows the effectiveness of ANN to calculate the Critical Clearing Time CCT. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Artificial Neural Networks, Critical Clearing Time, Power System, Transient Stability.
Abstract - This article analysis the unavailability and the performance of the safety instrumented systems (SIS) by taking into account the uncertainty and the imprecision on the parameters characteristic of the components. Two evaluation methods are applied to an example. The first evaluation method uses the faults trees; the second method is based on the use of the Markov chains. Parameters characteristic of the SIS, such as such as the common cause failure factor…, are replaced by fuzzy numbers allowing the reliability experts to express their uncertainty in the statement of the values of the probability of failures and other system performances. We show how the imprecision on the characteristic parameter values, such as the common cause failure factor, induces significant changes on the safety integrity level of a Safety Instrumented System. This work shows how it interests the decision maker knowing the uncertainty on the performance parameter. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Safety Instrumented Systems, Safety Integrity Level, Fault Tree, Markov Chains, Fuzzy Numbers, Uncertainty, Imprecision.
Abstract - In order to understand the discharge characteristics in an alternating current plasma display panel (ac PDP) and optimize it further, a three-dimensional fluid code has been developed. Using three-dimensional simulation code, we have given different parameters of the particle transport and we calculated the ion incident angle and energy distributions on the dielectric surface of the cathode region in PDP cell. The angle distribution of ions impinging on the cathode surface is one of the important factors for accurate experimental measurement of the secondary electron emission coefficient and for estimation of MgO sputtering. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Monte Carlo, Discharge, Hybrid-fluid, Cold Plasma, Plasma Panel Display.
Abstract - This paper presents the analysis and optimization for conventional Comparator-Based Switched-Capacitor (CBSC) gain-stage, and proposes a solution to modify the tight trade-off between accuracy, speed, and input swing by interposing a middle-phase in charge-transfer mode. The required digital controller for current sources and comparators in the modified CBSC gain-stage are described, and its performance is compared to that of conventional CBSC gain-stage. Simulation, using a TSMC 0.13-µm CMOS-technology with 1V power-supply, shows that the modified structure improves the accuracy by typically 1.5bits, and lowers the settling time by 15% without extra power dissipation. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Current Source, Comparator-based SC, Scaled-CMOS, Low-voltage.
Abstract - The usage of embedded systems in different applications is prevalent in recent years. These systems include a wide range of equipment from cell phones to medical instruments, which consist of hardware and software. In many examples of embedded systems, fault occurrence can lead to serious dangers in system behavior (for example in rackets). Therefore, we should try to increase the fault tolerance feature in these systems. Consequently, we need some mechanisms that increase the robustness and reliability of such systems. These objectives cause the On-Line test to be a great concern. It is not important that in which level (Hardware level, Software level or Firmware) these mechanisms work. The major concern is that how well these systems can provide debugging, testing and verification features for the user regardless of their implementation levels. Background Debug Module is a real time tool for these features. In this paper we apply an innovative way to use the Background Debug Module tool for fault injection in an embedded system. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Embedded Systems, Fault Tolerance, Real-Time Debugging, Background Debug Module.
Abstract - Pulsing characterization of RF power amplifier operating in linear and non-linear modes has been performed using a generic RF power amplifier platform. RF power amplifier for this purpose is designed, simulated, built and measured. The pulsing characteristics of the amplifier operating in two modes are measured for different pulse frequency, duty cycle, and pulse repetition rates. The transient responses of the amplifier in two modes are then compared. The performance table illustrating pulsing characteristics of amplifier operating in linear and nonlinear modes is presented. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Rf Power Amplifiers, Pulsing, Linear, Nonlinear, Class Ab, Class C.
Abstract - Minimum shift keying (MSK) is a prominent data transmission technique in digital communications. It is a special case of continuous phase frequency shift keying but it can also be derived from offset quadrature phase shift keying. In this paper, we simulate MSK modulation using the VisSim/Comm software package. Two transceiver implementations are presented. Their detailed description accompanied by representative examples show the merits of the proposal. Performance evaluation of the simulators verifies their accuracy. The proposed models offer a strong virtual laboratory environment for studying and evaluating MSK modulation. Their major advantages are their accuracy and the detailed and realistic simulation of the transceivers. The last enables users to intervene, change model parameters and gain information in time and spectral domain at each point in the structure, in a way that is not allowed by the MSK building blocks of the simulation libraries. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Simulation, Minimum Shift Keying, VisSim/Comm, Transceiver, Digital Transmission.
Abstract - In this paper a new approach has been used for design of a folded cascode amplifier that minimizes total thermal and flicker noise. A numerical method has been employed to select all transistor sizes and currents to minimize the total input referred noise at a specific frequency. Two cases of power constraint and area constraint have been studied for the amplifier design. This research shows that area is much more important than current in low frequency low noise amplifier design. Simulation results confirm the methodology used. by IREE. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Folded Cascode Amplifier, Low Noise Amplifier, Nonlinear Minimization.
Abstract - This paper presents the analysis and simulation of a multiband first and second iterations wire fractal antenna based on plusses fractal geometry. The proposed antenna design, analysis and characterization had been performed using the method of moments (MoM) technique. The radiation characteristics, VSWR, gain, and reflection coefficient of the proposed antennas were described and simulated using 4nec2 software package. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fractal Plusses Geometry, Method of Moments, Multiband Antenna.
Abstract - The Tunisian SAHEL railway supply system of 68 km length track is fed by one electrical substation ESS 150 kV/25 kV. The frequency and train location dependant impedance of overhead line is modelled as distributed circuit using Telegrapher’s model. Furthermore, the simulation results obtained with the lumped element equivalent circuits are compared with those obtained by Telegrapher’s model. The impedance seen from the locomotive is simulated as a function of the position along the line for frequencies up to 7 kHz, under different assumptions of the impedance load. The authors show that the parallel resonance frequencies have a significant influence on the harmonic current amplification seen from substation. The harmonic amplifications are determined by the ratio of current in substation, and current injected in each of the nine sectioning post. In addition a special attention is paid to give new analytic expressions of parallel resonances locations. On the other hand, a second ESS is introduced in supply system to overcome the voltage drop. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Telegrapher’s model, railway system, line impedance, harmonic amplification, parallel resonance.
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