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International Review on Modelling and Simulations - August 2009 - Papers

Mode Identification and Fault Detection of Hybrid Dynamical Systems Using Behavior Graphs
Available Transfer Capability (ATC): A Review
Evaluation of Distribution Reliability Improvement with Distributed Generators using Monte Carlo Simulation
Analysis of the Nigerian 330 kV Electric Power Network Using an Extended Heffron-Phillips Model Technique
Optimal Reactive Power Planning Technique Using Multi-Agent System
Modelling and Control of Grid-Connected PV/Fuel Cell/Battery Hybrid Power System
Fault Location in High Voltage Transmission Line with Current Traveling Wave
Low Power (Low Energy) FPGAs: A Survey
Improving RF Characteristics of MEMS Capacitive Shunt Switches
Analysis of a ZVS Converter with High Conversion Ratio
Four-/Five-Element Planar Log-Periodic Dipole Antennas for Medical Telemetry Applications
Fed an Induction Motor Drive Using an Advanced Current Source Inverter
Three-Dimensional Finite Element Analysis of GaPO4/Pt Surface Acoustic Wave Resonator Based on Cell Model
Accurate Modeling of the Eddy Current Effects in Helical Flux Compression Generators Using 2-Dimensional Filamentary Method in Frequency Domain
Mitigating Ferroresonance in Capacitive and Inductive Voltage Transformers With Ferroresonance Suppressing Methods
Modeling of a DC-Arc Furnace Used for Smelting of Ferronickel Ore Fines
Application of Homotopy-Perturbation Method to the Estimation of Electric Potential in 2D Plate with Infinite Length
Mathematical Model for the Kinematics of a Continuous Ship Unloader
CFD Simulation and Experimental Verification of the Flow Field in a Centrifugal Separator
Nonlinear Multiphysic Transitory Analysis of Reinforced Concrete Columns with Respect to the Fire Resistance
Improvements on Data Acquisition Systems Performances

International Review on Modelling and Simulations - Papers

Mode Identification and Fault Detection of Hybrid Dynamical Systems Using Behavior Graphs
by A. Takrouni, V. Cocquempot, N. Zanzouri, M. Ksouri

Vol. 2. n. 4, pp. 346-350

Abstract - The general principle of model-based Fault Detection and Isolation (FDI) algorithms is to compare the expected behavior of the system, given by a model, with its actual behavior, known through on-line observations. Hybrid Dynamical Systems (HDS) constitute a wide class of common industrial applications, where the behavior is determined by the interaction between continuous and discrete dynamics, i.e. behavioral modes succession. Faults in HDS may corrupt the two dynamics. As a consequence, FDI in HDS consists in three main activities : 1) to identify the current behavioral mode, i.e. to estimate the discrete state; 2) to check if the current mode is coherent with the expected one and 3) to check if the continuous behavior is normal or not. Classical approaches use exhaustive algorithms in order to solve the monitoring of the mode (activities 1-2). In fact, using the known inputs and outputs that may be either continuous or discrete information, each mode of the system is considered as an actual mode candidate. These approaches raise their limits when the number of modes is growing. In that paper, we propose to limit the set of possible mode candidates by using a priori information on the discrete evolution under normal and faulty hypothesis. Two kinds of graphs are derived from the initial hybrid model, namely Normal Behavior Graphs (NBG), Faulty Behavior Graphs (FBG). Using these graphs allows us not only to identify efficiently the actual mode but also to directly interpret (diagnose) the discrete faulty evolution in terms of faults.
Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Hybrid dynamical systems, Fault detection and isolation, Behaviors graphs, Similarity.

Available Transfer Capability (ATC): A Review
by Mojgan Hojabri , Hashim Hizam , Norman Mariun , Senan Mahmood Abdullah

Vol. 2. n. 4, pp. 351-355

Abstract - With the advanced development of electrical power markets, large amount of electric power is consumed and transacted which require, accurate determination of Available Transfer Capability (ATC) and broadcasting the ATC information to prevent and relieve transmission congestion effectively. In this paper existing deterministic and probabilistic methods for calculating ATC, are reviewed. Some suggestions for dealing with the technique challenges are given for the future research.

Keywords: Available transfer capability (ATC), Transmission capability margins, Power market.

Evaluation of Distribution Reliability Improvement with Distributed Generators using Monte Carlo Simulation
by Fangxing Li, Nura Sabir

Vol. 2. n. 4, pp. 356-361

Abstract - This paper models the impact of distributed generation to distribution system reliability using a comprehensive, sequential Monte Carlo simulation model. Since utility-connected distributed generation is typically installed close to the consumers, it can reduce the current at the main feeder. Consequently, it increases the chance that a stressed feeder can be reconfigured under a fault at a neighboring feeder. As a comparison, it may be impossible to reconfigure feeder connection because reconfiguration will lead to line overflow without distributed generators to supply part of the load. Test results from a system modified from the IEEE 34-bus system are presented. It is shown that installation of distributed generators can improve the distribution system reliability considerably.

Keywords: Distributed Generation, Distribution Reliability, Monte Carlo Simulation, Reconfiguration.

Analysis of the Nigerian 330 kV Electric Power Network Using an Extended Heffron-Phillips Model Technique
by Michael O. Omoigui, Olorunfemi Ojo

Vol. 2. n. 4, pp. 362-375

Abstract - Research on the dynamics of electric power systems are generally focused on inter-connected systems and little attention has been given to understand the unique characteristics of longitudinal power systems which are very common in developing countries of the world especially in Africa and South America. This paper therefore investigates the dynamics of the longitudinal Nigerian power system with the use of an extended Heffron-Phillips Model technique to provide insights into possible small and large signal dynamic trends. Based on the small signal analysis, the reduced model of the Nigerian power system provides a clear and practical basis for examination of the causes of small-disturbance instability phenomena. Investigation shows that critical eigenvalues which corresponds to oscillatory modes of 1.05 Hz, 1.14 Hz and 1.16 Hz for 80% load; 0.99 Hz, 1.40 Hz and 1.10 Hz for 90% load; and 0.93 Hz, 1.72 Hz and 1.025 Hz for 100% load; and 0.533 Hz, 2.38 Hz and 0.66 Hz for 110% load respectively. These are undamped natural oscillation frequencies corresponding to rotor angle modes of the machines in the network. They suggest the possible use of FACTS devices to stiffen longitudinal power systems to improve both the dynamic and transient stability of the system to which such systems are susceptible to.

Keywords: Modeling, Dynamic stability, Power balances, Longitudinal network, Eigenvalues.

Optimal Reactive Power Planning Technique Using Multi-Agent System
by N. Benalia, R. Diabi, J. C. Maun, A. Moussaoui

Vol. 2. n. 4, pp. 376-380

Abstract - Lack of reactive power support may cause undesirable voltage decay leading to total system instability. Thus, appropriate reactive power support scheme should be arranged in order to maintain system stability. This paper presents enhancement of voltage stability system through Optimal reactive power planning technique using a multi-agent system, the proposed method consists of several Bus agents (BAGs) and compensator agents (CAGs). A BAG corresponds to the bus in the substation, while a CAG supervise and control the compensator. From the simulation results, it can be seen the proposed multi-agent system could reach the right solution by making use of only local information.
This means that the proposed multi-agent system is a promising approach to more large-scale power system networks.

Keywords: Reactive Power Planning, Voltage stability, Multi-agent system, Compensation.

Modelling and Control of Grid-Connected PV/Fuel Cell/Battery Hybrid Power System
by S. G. Tesfahunegn, A. Hajizadeh, T.M. Undeland,O.Ulleberg, P. J. S. Vie

Vol. 2. n. 4, pp. 381-388

Abstract - This paper presents modeling and control of a DC coupled PV/FC/Battery distributed generation system which provides both real and reactive power support to a utility grid. Components are modeled and validated with measured data. An effective control strategy is developed to control the power flow both on the DC and AC (grid) sides. Simulation results are presented to demonstrate the effectiveness of the control strategy.

Keywords: Battery, Fuel Cell, Hybrid power system, sliding mode control, PV.

Fault Location in High Voltage Transmission Line with Current Traveling Wave
by I. Moosaviyan, S. Gh. Seifossadat, R. Kianinezhad

Vol. 2. n. 4, pp. 389-394

Abstract - This paper presents a new fault location method for high-speed transmission line protection using wavelet technique. Traveling wave theory is utilized in capturing the travel time of the transients along the monitored lines between the fault point and the relay. This knowledge is related to the travel time of the signals which have already been decomposed into their modal components. The voltage signals are analyzed with db4 wavelet to obtain detail coefficients of signal decomposition. Fault location are calculated on the base of sum of local end detail coefficients, and compared with threshold values to detect and locate the faults. Validation of the method is carried out by simulation for typical 400 kV power system transmission line.

Keywords: Fault location, Traveling wave, Wavelet transform, Multiresolution analysis.

Low Power (Low Energy) FPGAs: A Survey
by A. Hassanzadeh

Vol. 2. n. 4, pp. 395-400

Abstract - In this paper a survey of various techniques that have been used for design of a low power (low energy) Field Programmable Gate Array is presented. Recent low power configurable designs such as software radios or mobile applications require battery operated FPGAs. Furthermore, low power FPGA design is a new challenge rather than speed and area in FPGA design that has been past problems. Low power design techniques include not only process considerations but also hardware and software implementation methods. Different methods are reviewed, advantages and disadvantages of each method have been mentioned and their experimental results are provided.

Keywords: Low power/energy FPGA, Low power logic and switch, Power aware CAD.

Improving RF Characteristics of MEMS Capacitive Shunt Switches
by Yasser Mafinejad, Khalil Mafinezhad, Abbas Z. Kouzani

Vol. 2. n. 4, pp. 401-406

Abstract - This paper presents a new RF MEMS electrostatic switch with low actuation voltage. Usually, electrostatic switches with low pull-down voltage have large up-state capacitance deteriorating their RF characteristics. The proposed switch enjoys good RF characteristics for a frequency band of larger than one octave, and a low actuation voltage of 9 volts. Low actuation voltage could be achieved by decreasing the gap or increasing the area of the beam. In both cases, the up-state capacitance enlarges deteriorating the RF characteristics. In this work, regardless of the value of Cu, the height of the gap is chosen by considering the reliability and life cycle of the switch. Then, the area is calculated for the chosen gap and the desired actuation voltage. The switch is a π circuit consisting of two shunt switches and a short transmission line in between them. The key aspect of this design is the optimization of the length and the characteristic impedance of the line to suit fabrication constraints and desired frequency band. The switch is simulated and its RF characteristics evaluated. An excellent improvement of the RF characteristics of the up-state position is observed. For the down-state position, a superb isolation is observed.

Keywords: Micro Electro Mechanical Systems (MEMS), Radio Frequency Characteristics (RFCh), RF MEMS switch, π Match Circuit (πMC), Actuation Voltage (AV), High Impedance Short Transmission Line (HISTL).

Analysis of a ZVS Converter with High Conversion Ratio
by Bor-Ren Lin, Chien-Lan Hunag

Vol. 2. n. 4, pp. 407-413

Abstract - This paper presents the system analysis and circuit implementation of a zero voltage switching (ZVS) converter based on double flyback circuits to have a high voltage step-up/down feature between the output and input sides. Compared with the conventional flyback converter, the proposed converter has wide duty ratio so that the lower or higher output voltage can be achieved. An active snubber circuit is connected in parallel with the main switch to achieve ZVS turn-on. The resonance is based on the output capacitance of power switch and resonant inductance at the transition interval between the main and auxiliary switches. Therefore, the turn-on switching losses of power switch are reduced. The circuit configuration, system analysis, and design consideration of the proposed converter are presented in detail. Finally, experimental results based on a 200W prototype are provided to verify the effectiveness of the proposed converter.

Keywords: Zero-voltage switching (ZVS), High conversion ratio.

   Four-/Five-Element Planar Log-Periodic Dipole Antennas for Medical Telemetry Applications
         by Mohamed Salah Karoui, Hamadi Ghariani, Mounir Samet, Mohamed Ramdani, Richard Perdriau
            Vol. 2. n. 4, pp. 414-418

Abstract - This paper presents the different characteristics of 4- and 5-element multi-band planar Log-Periodic Dipole Antennas (LPDAs) particularly suitable for medical telemetry applications using industrial, scientific and medical (ISM) frequency bands. The designed antennas are printed on FR4 substrates, the sizes of which are 200 * 132 * 1.6 mm and 191 * 171 * 1.6 mm, respectively for the four- and five-element antennas, and are fed by a 50 Ω coplanar line. Measurement and simulation results are detailed and discussed for both antennas.

Keywords: Log-periodic antennas, Frequency independent antennas, ISM band.

   Fed an Induction Motor Drive Using an Advanced Current Source Inverter
         by S.M. Shirvani Boroujeni
            Vol. 2. n. 4, pp. 419-425

Abstract - The thyristor-based current source inverter (CSI) fed ac machine drives are often employed in high power applications. However, the thyristor-based CSI has intrinsic drawbacks because the thyristors cannot be turned off by the gating signals. Therefore, external circuits are required to turn the thyristors off by using reverse-biased voltages, as well as transfer reactive energies of inductive loads after turning off the thyristors. This paper presents a hysteresis modulated CSI drive which overcomes all these drawbacks and results in sinusoidal motor voltage and current even with CSI switching at fundamental frequency. The proposed CSI drive uses a voltage source inverter as an auxiliary circuit replacing the bulky ac capacitors used in the conventional drive. Then an indirect field oriented controlled CSI drive based on proposed configuration is developed. The simulation results are presented. Simulation results show that the proposed drive has stable operation even at low speeds.

Keywords: Commutation, Current-source inverter (CSI), Hysteresis modulation (HM), Space vector control, Supervision real-codec genetic algorithm (RCGA), Voltage-source inverter (VSI).

   Three-Dimensional Finite Element Analysis of GaPO4/Pt Surface Acoustic Wave Resonator Based on Cell Model
         by S. A. Mousavi, M. N. Hamidon, R. M. Sidek, M. Bayat, M. R. Khabbazi, M. Rahimi
            Vol. 2. n. 4, pp. 426-432

Abstract - This paper present a three-dimensional finite element method for the one-port surface acoustic wave resonator base on GaPO4 with 5° cut for high frequency application. Interdigital transducer is assumed a thin film platinum with chromium as an under-layer material. The simulated frequency response and wave propagation are obtained under base cell model at 433.92 MHz centre frequency under ISM band. Frequency responses versus impedance are compared and verify with the known result in literature. The results show that the total displacements are vanished at a distance of about 2 to 3 wavelength from the surface. As expected, the X and Y displacement are 90°out-of-phase with each other. It is observed that the mass loading effect is suitable for prediction of resonant frequency. It is Q found that the factor value is larger than 1000 and the mode shapes for resonant and anti-resonant condition are different at two edges of stop-band.

Keywords: Three-dimensional FEM, SAW, Wave propagation, Mass loading effect, Frequency response, Gallium orthophosphate, Resonator.

Accurate Modeling of the Eddy Current Effects in Helical Flux Compression Generators Using 2-Dimensional Filamentary Method in Frequency Domain
by M. H. Khanzade, Y. Alinejad-Beromi, A.Shoulaie

Vol. 2. n. 4, pp. 433-437

Abstract - This paper presents an approach to modeling the eddy current effects in helical flux compression generators accurately. This approach based on the 2-dimensional filamentary method in frequency domain. Using matrix representation in frequency domain, the equivalent resistance and inductance of a helical coil which is used in the helical flux compression generators are calculated directly and without calculating the filaments currents. The validation of the presented method has been verified by measurement.

Keywords: Eddy current, Helical Flux compression generator, Proximity effect, skin effect.

Mitigating Ferroresonance in Capacitive and Inductive Voltage Transformers With Ferroresonance Suppressing Methods
by Saeed Shahabi, Ahmad Gholami, Mohammad Mirzaie

Vol. 2. n. 4, pp. 438-445

Abstract - In order to restrain ferroresonance in coupling capacitor voltage transformers (CCVT), three kinds of ferroresonance suppression circuits (FSCs) have been presented. The resonant type, the fast-saturation reactor type and electronic type which are connected to secondary side of CCVTs, are proposed in this paper. Frequency domain analyses, for voltage ratio magnitude, are carried out for CCVTs to obtain preferable FSC. Furthermore, using surge suppressors such as metal oxide varistors (MOV) to improve the performance of the FSCs is investigated. Time domain simulations demonstrate that ferroresonance can be cleared in few cycles in presence of FSCs. In addition, to mitigate ferroresonanse in inductive transformers (VTs), we connect the damping resistor to the open-delta-arranged auxiliary winding.

Keywords: CCVT, VT, Ferroresonance, FSC, Frequency Response Characteristic.

Modeling of a DC-Arc Furnace Used for Smelting of Ferronickel Ore Fines

by O. Zavalani

Vol. 2. n. 4, pp. 446-451

Abstract - The use of DC arc furnace is considered today an attractive alternative for smelting of ores of many varieties. In this paper we present an approach for a thermal and electrical model of a DC arc furnace used for smelting of ore fines, experimental verification of model in a pilot furnace used for smelting of ferronickel ores, results obtained and conclusions. The principal goal of this project is to offer to the engineers of ferronickel smelting industry and students an important tool for understanding the modeling techniques and the use of simulation software in designing of DC arc furnaces used for smelting of ferronickel ore fines.
In the near future we shall present dedicated software for designing of DC arc furnaces for smelting of ferronickel ore fines which is under development and is based on thermal and electrical models and results presented here.

Keywords: DC arc furnace, Modeling, FEM, Thermal, Electrical, Smelting, Ferronickel ore fines.

Application of Homotopy-Perturbation Method to the Estimation of Electric Potential in 2D Plate with Infinite Length

by Saeed Rastegar, S.Asghar Gholamian, S. Esmaeili Jafarabadi, Mohammad Yosefi

Vol. 2. n. 4, pp. 452-457

Abstract - Estimation of electric potential due to dependent of many electrical components to this parameter is one of the most significant issues in electrical engineering. In this work, a powerful analytical method, called homotopy-perturbation method (HPM) is investigated to analyze the electrical potential in 2D plate with infinite length. Comparison of this new method with finite element method (FEM) is applied to assure us about the accuracy of solution.

Keywords: Electric potential, 2D plate, Homotopy-perturbation method (HPM) and finite element method (FEM).

Mathematical Model for the Kinematics of a Continuous Ship Unloader

by Filip Van den Abeele, Any Noca, Marc Van Steelant.

Vol. 2. n. 4, pp. 465-471

Abstract - Unlike traditional portal cranes, a Continuous Ship Unloader (CSU) is not hampered by an intermittent offloading mechanism. The digging foot, consisting of an endless chain with offloading buckets, allows reaching very high capacities when unloading large Panamax vessels carrying iron ore or coal. However, severe problems were reported with the hydraulic control system of the CSU during service. Measurements of cylinder displacements and hydraulic pressures revealed that the digging foot fails to follow the imposed positions. A profound kinematic analysis, presented in this paper, sheds a brighter light on the evolution of the chain length during the transition from idle state to bypass. The aberrations in the calculated chain sag can explain why some imposed positions cannot be obtained by the hydraulic control system.

Keywords: Kinematics, Continuous Ship Unloader, Digging Foot, Chain Length.

CFD Simulation and Experimental Verification of the Flow Field in a Centrifugal Separator

by Panagiotis I. Kefalas, Dionissios P. Margaris

Vol. 2. n. 4, pp. 472-478

Abstract - The performance of a newly developed Centrifugal Phase Separator (CPS) is investigated using RANS-based two-phase computational fluid dynamics (CFD) and experimental model studies. The cyclone separator consists of two volutes (inlet and outlet) connected with a cylindrical tower; recirculation of the flow within the tower ensures adequate centrifugal forces for phase separation. Numerical calculations are performed using the commercial CFD code FLUENT for different mesh types, turbulence models, advection schemes, and mesh resolution. Results of the simulation are compared with data from experimental model studies. The RNG k-ε turbulence model with hexahedral mesh gives satisfactory results. A significant improvement in CFD prediction is obtained when using a second order accurate advection scheme. Useful predictions of the phase separation efficiency, across the cyclone separator were produced with an error of approximately 10-15%.

Keywords: Centrifugal Separator, Numerical Simulation, Computational Fluid Dynamics, Experiments, Performance.

Nonlinear Multiphysic Transitory Analysis of Reinforced Concrete Columns with Respect to the Fire Resistance

by N. Otmani (Benmehidi), M. Guenfoud

Vol. 2. n. 4, pp. 479-484

Abstract - This paper is devoted to nonlinear numerical modeling of reinforced concrete columns subjected to fire. Today, it is possible to assess the fire behavior of structures by numerical simulation. During a fire, the structure of a building loses its mechanical strength following the increase in temperature, leading to the ruin of the building. In this work we use the software SAFIR to analyze columns under fire. Because the columns have an extremely important role in building, the verification of fire resistance of these elements is particularly crucial. The results show a thermal calculation and a structural calculation which is based on the temperatures obtained the latter has allowed us to know the different variations of different parameters such as bending moment, fiber stresses, displacements and tangent modulus.

Keywords: Column, Concrete, Fire, Resistance, Steel.

Improvements on Data Acquisition Systems Performances

by Constantin-Daniel Oancea, Melania Naumof, Adrian Nedelcu, Leonas Ciulinaru

Vol. 2. n. 4, pp. 485-489

Abstract - Although data acquisition is a very usual technique, there are several aspects not always considered, like synchronization of acquired measures and evaluation of the errors that derive from this fact. The paper hereby aims to point this thing out, by mathematical determination of the necessary correction and implementation of the software meant to evaluate the performances of the acquisition system. As an example, a three-phased acquisition system has been developed in order to monitor the currents and voltages on the three phases. Also other measures have been calculated, such as power and phase. Errors that affect the above mentioned, due to the different moments of time when samples are acquired, are analyzed and brought to the minimum value.

Keywords: Error, Accuracy, Data Acquisition, Improving Performance.