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Home>Products>Journal and Reviews>I.RE.Mo.S.>Latest issue
International Review on Modelling and Simulations - December 2008 - Papers
International Review on Modelling and Simulations - Papers
by M. B. B. Sharifian, M. Farrokhifar, F. Rahimi, S. Kanmohammadi and R. Mohammadi
Abstract - With
great progress in fuzzy set theory and its success and compatibility in
such dread applications, there has been also several efforts in using
this theory in network planning methods such as PERT and CPM to make
more realistic usage of them and better dealing with uncertainties that
is intrinsic in estimating duration of activities. Although these
efforts are essential and basic in operation research and specially its
network planning branch, the problem, which appears in application of
these methods especially in projects with great number of nodes and
activities, is insufficiency of graphical methods. In this paper, using
non-interactive fuzzy subtraction, an algorithm is proposed that reads
fuzzy numbers as activity durations along with their initial and final
node numbers; then constructs network and computes earliest expected
time, latest allowable time, and slack time for each node. At the end,
critical path, or paths for different
α-cuts are calculated.
Keywords: : Defuzzification, Refuzzification, Network planning, initial shape.
Abstract - This paper deals with the development of recursive parametric estimation algorithms for large-scale stochastic systems on the basis of the maximum likelihood method and by using the prediction error method. We consider the large-scale systems operating in stochastic environment, which can be decomposed into several single-input single-output interconnected systems. We suppose that each interconnected system is described by discrete-time input-output mathematical model with unknown slowly time-varying parameters. The parametric estimation problem of the considered large-scale stochastic systems is studied by using an approximation of the maximum likelihood method, in order to obtain recursive algorithms. Thus, recursive parametric estimation algorithms are proposed, by including a forgetting factor in the computation of the adaptation gain matrix. The convergence conditions and the techniques of the practical implementation of these algorithms are given. Numerical simulations were elaborated concerning the on-line estimate of a large-scale stochastic system with unknown slowly time-varying parameters, which is constituted by two interconnected systems, in order to validate the developed analytical results. The obtained simulation results are very satisfactory. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Large-scale stochastic systems, Interconnected systems, Input-output mathematical models, Recursive parametric estimation, RAML parametric estimation algorithms.
Abstract - Two different high order time series models represent a parametric estimate that is exactly equal to the biased non-parametric lagged- product autocovariance estimate. Hence, the raw information is the same for parametric and for non-parametric spectral and autocorrelation analysis. In non-parametric estimation, the periodogram is smoothed with a window to diminish or to remove insignificant details. That gives a distortion to the details of all modified non-parametric estimates, defined by the shape and by the width of the window. In contrast, parametric time series models can eliminate higher order details without distorting the remaining lower order details. Firstly, many candidate models are estimated, with different type and order. From those candidates, a single time series model is selected automatically with statistical criteria, without user interaction. The selection of model order and model type with the ARMAsel algorithm lets the data speak and decide. Interesting alternative models are suggested by looking at the estimated accuracies of all other candidates. Those accuracies can be considered as the language that is used by random data for the communication of their information. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: ARMA model, autocorrelation function, autocovariance, order selection, parametric model, spectral estimation, time series.
Abstract - Based on a thermal lumped element model and on experimental results concerning the active region heating as a function of several injected current values, a very simple model involving Rollover effects has been implemented. The temperature rise in the active region of the laser with nanostructure due to current injection of magnitude current (I) was calculated according to ΔT=aI+bI2-cL where a, b and c are coefficients which depend on the thermal resistance of the device and on the laser diode series resistance and turn-on voltage. L is the laser output power. We were able to analyze separately the effect of the diode thermal resistance, series resistance, turn-on voltage and characteristic temperature on the L–I curves. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Quantum well Laser, Rollover Effect, Temperature, L–I Characteristic.
Abstract - This paper proposes a new and non-traditional approach for time-harmonic and transient linear electrical circuit analysis. The numerical algorithm proposed in this paper is based on a finite element technique (FET). According to FET terminology, each branch of the electric circuit is treated as a single finite element with own local system of algebraic equations. Global system of equations is obtained by assembling local system of equations of each finite element according to FET procedure. In order to validate presented procedure, a MATLAB program was developed and applied for the transient linear circuit analysis on the linear electrical circuit example. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Numerical analysis, Finite Element Technique, Circuit analysis.
Abstract - A low leakage power 1-bit full-adder circuit suitable for implementation in deep submicron CMOS (nano-scale CMOS) technologies is proposed. In this circuit, two adder subcomponents have been designed for reduced static leakage current. HSPICE simulations in 90nm, 65nm and 45nm PTM (Predictive Technology Model) technologies show great improvements of the proposed adder with respect to other structures in term of static power consumption. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Adder Modules, Deep Submicron Technology, Static Power Consumption.
Abstract - In transient analysis of wave propagation in underground cables in lossy ground, the earth-return path impedance plays a major role. Formula which determines this integral consists of an oscillatory and complex integral. This paper proposes adaptive Simpson method as a numerical integration method to solve this integral. As it will be shown this method is fast and very simple in comparison with the other proposed methods. The comparison between the values of earth return path impedance which is obtained by the proposed method and the results which is obtained by finite element method (FEM) shows the accuracy of this method. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Underground cables, Eearth-return path impedance, Aadaptive Simpson method, Finite element method (FEM), Transient analysis.
Abstract - This research work concerns a mixed ASIC (Application Specific Integrated Circuit) integrating both analogical and digital functions. The development of this type of integrated circuit is receiving a great deal of interest. In order to solve the difficulties related to the absence of common basic structure necessary to the conception of both types of function, we propose a simple technique based on the use of an inverter NMOS, configured for the analogical treatment. This approach is applied to a mixed circuit, which is a PLL. The comparison of the results obtained through behavioral and structural simulations confirm the interest and the efficiency of such a technique. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Mixed circuit, Design, Modeling, Behavioral, Structural, VHDL, SPICE.
Abstract - In this paper, a novel intelligent method is applied to the problem of sizing in a hybrid power system such that the demand of residential area is met and two hybrid systems are considered and the results are analyzed from the viewpoint of meeting the demand and total costs. Finally, the best system is selected. This study is performed for Ganje area in north-western Iran. The systems consist of fuel cells, some wind units, some electrolyzers, a reformer, a compressor, an anaerobic reactor and some hydrogen tanks. The system is assumed to be stand-alone and uses the biomass as an available energy resource. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: : Wind turbine, fuel cell, hybrid power system, renewable energy, optimal sizing, particle swarm optimization.
Abstract - This paper presents new explorations into the use of multi-agent technology applied to coordinated secondary voltage control of FACTS devices in power systems. Each agent is integrated with an electric component in power systems. In the proposed approach, agent development and communication simulation have been carried out on the Java agent Development (JADE) framework. The power system also has been implemented in Java. For validating the proposed method the multi-agent system is applied to IEEE 39-buses New England power system and many contingencies and test cases studied. Results show that an adaptive coordination can be achieved. For improving the ability, autonomy and response time of proposed decentralized control system, decision making of agents equipped with Reinforcement Learning (RL) algorithm. The SARSA and Q-learning which are two well known algorithms in RL used and tested successfully in this application. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Multi-agent systems, Coordinated voltage control, Reinforcement Learning, Java Agent DEvelopment (JADE) platform.
Abstract - - In competitive electricity markets, price forecasting is becoming increasingly relevant to power producers and consumers. Price forecasts provide crucial information for power producers and consumers to develop bidding strategies in order to maximize benefit. This paper provides a method for predicting day-ahead electricity prices in the PJM market using General Regression Neural Network (GRNN) computing technique. Publicly available data acquired from the PJM electricity market were used for training and testing the ANN. The results obtained through the simulation show that the proposed algorithm is efficient, accurate and produce better results. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: : Generaizedl Regression Neural Network, Radial basis function network, day-ahead electricity market, price forecasting.
by L. Boumediene, M. Khiat, M.Rahli, A. Chaker
Abstract - The main objective of this paper is to present, the advanced load flow models for the distribution static VAR compensator (D-SVC). The models are incorporated into existing load flow (LF). The harmonic load flow technique is described which solves the network at fundamental and harmonic frequencies in the presence of nonlinear elements. It is based on the harmonic iteration, The D-SVC state variables are combined the nodal voltage magnitudes and angles of the network, Iterative solution through Newton methods .Discussions and comments for applications of these harmonic sources in harmonic modeling and simulation also will be described. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: : Load flow, Harmonic power flow, D-SVC.
by Kimmo Kivikko, Jouni Pylvänäinen, Pertti Järventausta, Antti Mäkinen, Pekka Verho, Tero Kaipia, Jukka Lassila, Jarmo Partanen
Abstract - Electricity supply reliability and interruption costs are nowadays of great interest. Large blackouts around the world have also aroused the customers’ interest in the reliability of distribution networks. In addition to this, reliability worth values are widely used in the regulation of distribution companies. For distribution network companies, the reliability-based network analysis offers an excellent tool for focusing the network investments on the most critical areas in the network, and thus use the assets in the best way to increase the level of reliability.In order to find the optimal network structures and lowest life-cycle cost, several network enhancement alternatives, including optimizing different reliability indices like SAIDI and SAIFI as well as interruption costs, were evaluated with reliability analysis software. The results show that the use of one individual optimization parameter does not necessarily lead to an optimal network. Several reliability parameters should be analyzed simultaneously to assure reasonable network solution. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electricity distribution, Reliability worth, Interruption costs.
by R. Rodríguez, M.A. Ríos
Abstract - The classical application of optimal power flow OPF uses as voltage security constraint that the node voltages are into a specific range. However, it is not enough to keep the buses into the regular ranges considered acceptable to ensure the voltage stability. This paper describes the option to include voltage security constraints in the OPF. The proposed constraint is related to a proximity index to the instability called FVSI Index. So, the first part of this paper describes the theoretical argues focused to stability voltage index study, conceptual basis and OPF formulation, with an objective function of minimum cost. Then, the methodological use of the FVSI Index into the OPF formulation is described. Finally, applications in the IEEE 6 Buses and IEEE 24 Buses are shown, concluding that dispatch security has a cost associated in the total dispatch cost. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Voltage stability, Index FVSI, Optimal power flow, VSCOPF, Voltage Stability Index.
by Mohd Z. A. Ab Kadir, Mohd. H. Mohamad Ariff, Junainah Sardi
Abstract - This paper presents the application of transient modelling technique in representing the substation and performing the analysis on the prediction of the transformer damage. Modelling parameters and the substation layout design are based and adapted from 132/11 kV Simpang Renggam – Ayer Hitam substation in Johor Baharu, Malaysia, courtesy of the Tenaga Nasional Berhad (TNB). The model is based on single phase line model as it was suggested by the IEEE to represent the substation in transient analysis simulation. Extensive analyses on the placement of the surge arresters at the substation and prediction of the transformer damage are also presented. The results obtained from this analysis are then compared with the suggested Basic Lightning Insulation Level (BIL) by the TNB, according to the standards, for assessing the percentage of transformer damage and optimizing the substation performance in terms of its reliability and cost effectiveness. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Insulation coordination, Lightning, Basic Lightning Insulation Level (BIL), Surge arrester.
by C. Deslot, P. Kulisa, F. Bario
Abstract - A three-dimensional Navier-Stokes code is used to numerically investigate the rotor-stator interaction in a large scale turbine inlet guide vane (IGV) placed upstream of a moving circular cylinder system. Potential counterflow interactions are more especially discussed. Steady and unsteady simulations are performed and show that the potential effect generates significant pressure fluctuations on both the pressure and suction sides. A detailed analysis of the pressure field shows that these cylinder-induced disturbances propagate upstream as a nearly sinusoidal acoustic wave. The initial amplitude and form of the wave is connected to the stagnation pressure and the location of the stagnation point on the cylinder in the rotating frame. In addition, a numerical comparison with viscous wake interactions by positioning a cylinder upstream of the IGV shows that disturbances induced by potential effect have the same order of magnitude. To corroborate the numerical results, experimental measurements are carried out in a low speed large scale cascade facility placed upstream of a specially designed circular-cylinder rotating system. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Rotor-stator Interaction, Potential effect, Numerical simulations, Turbine, Low-speed preconditioning.
Abstract - Gas insulated sub-stations are high voltage substations that are compact, requiring little maintenance when compared to air-insulated conventional sub-stations. The compactness is with the use of SF6 gas, which has higher dielectric strength. Free conducting particles, depending upon their shape, size and location, may lead to serious deterioration of the dielectric strength of the system and also one of the major factors causing breakdown of the system and leading to power disruption. The aim of this paper is to simulate the particle movement in a single phase Gas Insulated Bus duct (GIB). To obtain the particle trajectories, the equations describing the motion of the particle due to Image charge effect has been developed in this paper. The mathematical modeling for the movement of particle is carried out by considering the charge acquired by the particle, the macroscopic electric field at the particle location, the drag coefficient, Reynolds’s number and the coefficient of restitution. Present work analyses the movement of free-conducting particles inside a single phase gas insulated system. Simulation considers with and without Image charge effect for analyzing the particle trajectories at various voltages of Aluminum and copper particles is presented. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Metallic particles, Image charge effect, Gas insulated substations, Gas Insulated Transmission Line.
Abstract - In this article, we are interested in the equation of a solid particle trained in a Poiseuille flow type. The model used in the literature includes integro-differential equations which were treated numerically. It is noticed that the difficulty in these equations comes from the force of history which is expressed like a kernel integral, type of Abel. While using an expression of the integral equation of Abel, we solve the equation of the sphere analytically. The final result is that the exact solution can be substituted for the approximate solution obtained previously by other authors. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Particle, fluid, integral of Abel.
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