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International Review of Electrical Engineering  Vol. 6 N. 4-- Part A

International Review of Electrical Engineering  Vol. 6 N. 4-- Part B


go to top     International Review of Electrical Engineering - August 2011 (Vol. 6 N. 4) - Papers Part A



go to top     International Review of Electrical Engineering - August 2011 (Vol. 6 N. 4) - Papers Part B






International Review of Electrical Engineering - Papers- Part A


go to top   Analysis and Implementation of Single-Stage Interleaved Double Buck-Boost Converter with High Power Factor
         by Bor-Ren Lin, Chia-Hung Chao and Ming-Hung Yu

         Vol. 6. n. 4, pp. 1523-1530


Abstract - This paper presents a single-stage interleaved double buck-boost topology to achieve the functions of high power factor, low current harmonics, reactive power compensation and output voltage regulation. Double buck-boost topology with only one MOSFET is adopted to reduce the DC bus voltage stress and achieve a high voltage step-up/down feature between the output and input sides. Thus the low voltage stress of power switches can be used in the converter. Since the discontinuous conduction mode (DCM) is adopted to control the buck-boost converter, the input line current is automatically following the mains voltage and the line current is a sinusoidal waveform and in phase with mains voltage. Compared to a conventional buck-boost converter, the proposed converter has wide duty ratio such that the lower or higher output voltage can be achieved. Experimental results, taken from a laboratory prototype rated at 200W, AC source voltage of 110Vrms, output voltage of 48V, and switching frequency of 100kHz, are presented to demonstrate the converter performance.

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Keywords: Double Buck-Boost, High Conversion Ratio, PFC.


go to top   Voltage Control Techniques in Uninterruptible Power Supply Inverters: A Review
         by Ghazanfar Shahgholian, Jawad Faiz, Masoud Jabbari

         Vol. 6. n. 4, pp. 1531-1542


Abstract - Uninterruptible power supply (UPS) systems are required for supplying sinusoidal output voltage for linear and nonlinear loads. They must be highly reliable and fast in dynamic response. Many control strategies have been applied to UPS inverters. The basic objectives of UPS control systems are tracking ability and robustness. Generally, the tasks of output voltage control for UPS inverters are providing fast dynamic responses and maintaining a perfect sinusoidal voltage waveform even with nonlinear or changing loads. To achieve these aims, many controllers have been proposed in the literature. In this paper a comprehensive review of the control techniques of UPS systems with advantages and disadvantages of each is carried out.

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Keywords: Inverter, Uninterruptible Power Supply, Control Techniques.


go to top   Effect of Temperature Variation on LCC Resonant DC-DC Converter
         by M. Prabhakar, V. Kamaraj

         Vol. 6. n. 4, pp. 1543-1548


Abstract - DC-DC converters used in automotive applications are subjected to high temperatures. In this paper, the output voltage of a LCC resonant tank based DC-DC converter is studied under various temperatures. Simulation model of the power semiconductor switches and components at various temperatures have been developed. Based on the simulation results, it is found that the voltage regulation of the chosen converter is well within acceptable limits. Experimental results show that the converter operates satisfactorily at about 90% efficiency.

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Keywords: DC-DC Power Conversion, Temperature Effects, Voltage Regulation.


go to top  Bridgeless Buck-Boost AC/DC Converter with Voltage Doubler Output and BCM Operation
         by Bor-Ren Lin and Po-Jen Cheng

         Vol. 6. n. 4, pp. 1549-1555


Abstract - A Bridgeless double buck-boost AC/DC converter with low conduction losses and no reverse recovery loss on rectifier diodes is proposed to achieve high power factor, low current harmonics and a sinusoidal line current from utility side. The boundary conduction mode (BCM) operation is adopted to control active switches such that the diode reverse recovery problem is overcome and the diodes are turned off at zero current switching (ZCS). The AC source current can automatically follow the utility voltage with nearly unity power factor and active switch is turned on at ZCS. Compared to a conventional boost type AC/DC converter, there is only one diode conduction loss in the proposed circuit. Thus the proposed converter has high circuit efficiency. The voltage doubler topology can double its output voltage to extend the useable energy of capacitor when the line voltage is off. The circuit configuration, principle operation, system analysis, and design consideration of the proposed converter are presented. Finally, experiments for a 250 W prototype are presented to show the performance of the proposed converter.

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Keywords: Buck-Boost Converter, Bridgeless Rectification, Power Factor Correction, Boundary Conduction Mode, Voltage Doubler, Reverse Recovery Loss.



go to top   Analysis and Implementation of a Zero-voltage-switching Synchronous Buck Converter with a Coupled Inductor
         by Hyun-Lark Do

         Vol. 6. n. 4, pp. 1556-1563


Abstract - This paper presents a zero-voltage-switching (ZVS) synchronous buck converter. It utilizes an auxiliary circuit to provide ZVS of the power switches. The reverse recovery problem of the anti-parallel body diode of the synchronous switch is solved due to ZVS characteristic. Moreover, it provides a ripple-free filter inductor current. The auxiliary circuit cancels out the current ripple. Then, the output filter stage can be simplified. Theoretical analysis of the proposed buck converter is provided and the experimental results obtained on 110W prototype are discussed.

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Keywords: Buck Converter, Zero-Voltage-Switching, Coupled Inductor.


go to top   High Power Factor AC/DC Converter with High Step-Down Conversion Ratio
         by B. R. Lin, L. A. Lin

         Vol. 6. n. 4, pp. 1564-1569


Abstract - This paper presents high step-down AC/DC converter with discontinuous conduction mode (DCM) to achieve power factor correction, low harmonic AC current and output voltage regulation. Buck-boost type topology is adopted to reduce the DC bus voltage stress and achieve a high voltage step-down conversion ratio between the output and input sides. Since the input inductor is operated in DCM mode, the input line current can automatically follow the line voltage and the line current is a sinusoidal waveform with a DC offset and in phase with AC mains. Compared to a conventional buck converter, the proposed converter has wide duty ratio such that the conduction loss on power switches can be reduced. Finally, the experimental results based on a 200W prototype are provided to verify the effectiveness of the proposed converter.

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Keywords: High Step-Down Conversion Ratio, Power Factor Correction, Discontinuous Conduction Mode, Continuous Conduction Mode.



go to top   DSP Controlled Isolated DC-DC Converter for Distributed Generation System
         by M.A.A. Younis, N.A. Rahim, S. Mekhilef

         Vol. 6. n. 4, pp. 1570-1580


Abstract - This paper presents the analysis and design of Isolated DC-DC converter suitable for distributed generation system. The DC-DC converter consist H-bridge inverter, High frequency transformer, full bridge rectifier, and low pass filter. Phase shift PWM with Zero voltage and zero current switching used to minimize the switching power dissipation. Digital Signal Processing (DSP) board is used to implement the control algorithm. The control algorithm includes phase-shift PWM and PID close loop control, are designed using SIMULINK Embedded Target Library which are used to represent algorithms and peripherals specific DSP family. The converter is simulated using SIMULINK software to verify the operation of the converter. Fuel cell model is prepared to act as unstable voltage source in the simulation of the converter. Experimental results and simulation results are shown to validate the proposed DC-DC converter.

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Keywords: DC/DC Converter, Distributed Generation, Fuel Cell Model, Phase-shift PWM DSP Implementation, PID Controller, Zero Voltage and Zero Current Switching.


go to top   Study on Inverter’s IGBT Fault Behavior with Permanent Magnet Synchronous Motor’s Drive
         by  A. Khlaief, K. Jemli, M. Boussak, M. Gossa

         Vol. 6. n. 4, pp.1581-1589


Abstract - This paper deals with condition monitoring of electrical failures in variable speed synchronous motor drives by stator current analysis. The aim of this paper is the presentation of a method of knowledge electrical fault which can present itself at the time of variable speed controllers Permanent Magnet Synchronous Motor (PMSM) drives and practical implementation of a novel fault diagnosis and protection scheme for the Interior Permanent-Magnet (IPM) synchronous motors using vector forms (VF). In the proposed technique, the line currents of different faulted and normal conditions of the IPM motor are preprocessed by the (VF). The current waveform patterns for various modes of open IGBT fault are investigated. Two types of fault conditions—transistor at the OFF state (transistor always open) and single-phase open circuit fault. The Texas Instrument 32-bit floating-point digital signal processor TMS 320F240 (20 MHz) is used for the real-time implementation of the proposed protection algorithm. The mathematical model of PMSM in a stationary α–β reference frame are adopted, the results is presented and applied using a 1.1 kW - 230V/400V- 6 poles three-phase Permanent Magnet Synchronous Machine.

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Keywords: Diagnosis, Permanent Magnet Synchronous Motor (PMSM), Artificial Neural Network (NN), Vector Forms (VF), Open Circuit Fault.



go to top   Utilization of Wavelet Transform to Detect the Internal Incipient Faults of Power Transformers
         by Mehdi Salaynaderi, J. Beiza , N. Taghizadegan, A. A. Dadjouyan, J. Rabbaani

         Vol. 6. n. 4, pp. 1590-1597


Abstract - In the case of a fault occurrence, the pattern of the fault currents obtained by the standard impulse tests contains a typical signature of the nature and the location of the insulation failure involved. This paper presents a new approach to classify the pattern of the arc discharge location as one of the important types of internal incipient faults in transformer windings. The Continuous Wavelet Transform (CWT) has been used to calculate the most predominant frequency of each fault and its time of occurrence. The data obtained from the field tests of a 66kV/25MVA interleaved transformer winding and the computer simulations have been used for the classification.

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Keywords: Wavelet Transform, Windings Internal Incipient Faults, Arc Discharge, Power Transformers, Impulse Voltage.


go to top   Influence of Ferromagnetic Materials on Torque Production in Switched Reluctance Motors
         by Marcel Torrent

         Vol. 6. n. 4, pp. 1598-1606


Abstract - This paper presents an analysis of the influence of ferromagnetic materials on switched reluctance motor (SRM) torque production. Construction and basic operation of SRMs depends on the material core. The type of control used must also be considered, as it dictates the dynamic torque. Torque production was calculated via finite element method analysis, from the energy conversion loop obtained with the magnetization curves and from the dynamic simulation. An SRM model to determine the magnetization curves whose only previous knowledge of the aligned and unaligned positions was developed to simplify the simulations. The model was evaluated in two motors that were designed and tested in the laboratory.

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Keywords: Ferromagnetic Materials, Torque, Magnetization Curves, Switched Reluctance Motor (SRM).


go to top  Advanced Digital Control of a Six-Phase Series-Connected Two-induction Machine Drive
         by Rijaniaina Njakasoa Andriamalala, Lotfi Baghli, Jean Nirinarison Razafinjaka, Hubert Razik, François-Michel Sargos

         Vol. 6. n. 4, pp. 1607-1619


Abstract - This paper deals with a decoupled vector control of two induction motors connected in series using mainly RST controller. This kind of controller offers further degrees of freedom to set the dynamic of the system. The first step is to fixe a reference model of the current and speed loops. A method of pole placement is detailed. Then, the three polynomial elements R, S, T of each controller will be synthesized by utilizing algebraic approaches and by solving the Diophante equation. In a first time, performance of RST controller is proven by simulation and experiment on the current and speed controls. Nonetheless, it is also possible to obtain better tracking, disturbance rejection and settling time by combining RST and IP controllers in practice. A special case is therefore treated where RST regulator is used for currents and IP controller is considered for speeds. This case will be experimentally demonstrated.

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Keywords: RST Controller, IP Controller, Decoupling Control, Series-Connection, Vector Control, Tracking.



go to top   Current Regulated PWM Based Control For Four-Switch Three-Phase Brushless DC Motor Drives
         by V M Varatharaju, B L Mathur, K Udhayakumar

         Vol. 6. n. 4, pp. 1620-1626


Abstract - Permanent magnet brushless dc motor (PMBLDCM) drives are continually gaining popularity in motion control applications. This paper investigates the performance of direct current controlled pulse width modulation (DCC-PWM) based control of four-switch three-phase (FSTP) inverter feeding permanent magnet brushless dc (PMBLDC) motor. A MATLAB/Simulink model for the FSTP fed PMBLDC motor is developed and tested with direct current controlled PWM method. The triumph of the DCC-PWM in obtaining desired speed-torque characteristics is validated with help of simulation results. The DCC-PWM is also implemented with proportional-integral controller using TMS320LF2407 digital signal processor.

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Keywords: PMBLDC Motor, Four-Switch Three-Phase Inverter, Direct Current Controlled PWM .



go to top   A Comparative Analysis of the Effects of Rotor Molding Clinches on Torque Ripple of Mutually Coupled SRMS
         by C. Sahin, A. E. Amac, M. Karacor, A. Emadi

         Vol. 6. n. 4, pp. 1627-1635


Abstract - In this study, the mitigation of torque ripples at mutually coupled switched reluctance motor (MCSRM) is investigated experimentally. Although, MCSRMs have higher performance than classical switched reluctance machines (SRMs), they are not attractive enough due to their high torque ripples. There are many different methods to solve this problem. One of the methods is to change the geometric structure of the machine. The analyses of previous studies show that despite there being favorable results in applications, the molding pins of the machines are neglected in those works. A motor that gives positive results may get affected negatively by its random molding during generation. In this research, a 3-phase average 100 watt MCSRM is chosen for analysis and effects on torque of the geometric point of molding pins in the machine are studied comparatively. Maxwell 2D program is used for analyses and two different models are compared with each other. The obtained results show that torque ripple of the machine is lower when molding pins are closer to the rotor post, and it is reduced by 12% at 6 Amps in the proposed MCSRM.
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Keywords: Short Pitched, Full Pitched, SRM, Torque Ripple, MCSRM.


go to top   Real Time Implementation of Fuzzy Adaption Mechanism for MRAS Sensorless Indirect vector control of Induction Motor
         by Z. Boulghasoul, A. Elbacha, E. Elwarraki

         Vol. 6. n. 4, pp. 1636-1653


Abstract - This paper describes a real time implementation of sensorless control of Induction motor using MRAS observer with fuzzy logic adaptation mechanism under indirect field oriented control (IFOC). This mechanism is used to drive a signal tuning into zero in order to ensure high estimation stability and better tracking of the real speed in comparison with the classical PI mechanism under several test of speed control. In order to improve the sensorless drive, several strategies of speed control are presented and tested such as Classical Proportional Integral (PI), PI Limited and PI anti-windup with its various forms including the fuzzy anti-windup form. The results presented in this work regarding this sensorless approach has been performed by simulation using MATLAB/SIMULINK® software and experimentally using a dSPACE 1104 board. The results obtained in both open loop speed control and sensorless control in high and low speed establish the superiority of the fuzzy adaptation mechanism in both steady state and transient response.

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Keywords: Induction Motor, MRAS Speed Sensorless, Fuzzy Logic Adaptation Mechanism, IFOC, PI Controller, PI Anti-Windup Controller, PI Fuzzy Anti-Windup Controller, Dspace 1104.


go to top   Optimal Current Assignment Strategy for Maximum Torque Control of Induction Machines
         by Yun Zhao, Yesong Li, Yang Liu

         Vol. 6. n. 4, pp. 1654-1663


Abstract - A novel current optimization strategy which ensures maximum torque capability over the whole speed range for induction machines is presented in this paper. Considering the voltage ratings of the power inverter, the current constraint of the induction machine and the limit of the maximum slip frequency adequately, the trajectory of the optimal current vector for maximum torque operation is investigated by finding the extremum of the torque function, and the guidelines for the implementation of the current assignment strategy is summarized. Following the guidelines, an alternative approach that effectively combines the best attributes of the conventional flux-weakening method with modified voltage controller is proposed to realize the optimal current control. Finally, a complete solution of induction machine drive system including the proposed algorithm is fully implemented to evaluate the validity of the algorithm, which can achieve maximum torque operation and good dynamic response over a wide speed range.

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Keywords: Flux-Weakening Control, Induction Machine, Indirect Rotor Flux Orientation, Maximum Torque Control.



go to top   High Speed Shaft Sensorless DFOC Induction Motor Drive with Field Angle Correction
         by Vlado B. Porobić, Evgenije M. Adžić, Darko P. Marčetić

         Vol. 6. n. 4, pp. 1664-1674


Abstract - This paper presents a contribution to the study of shaft sensorless vector control of low cost induction motor drive in high speed region, where drive stability is seriously jeopardized. Novel control solution with field angle correction is proposed, which overcomes limitations of existing rotor field oriented vector control methods in high speed region due to rotor leakage inductance variance. Additionally, critical influence of model discretization and time discrete nature of PWM voltage source inverter (VSI) in such situation is also considered. A detailed analysis of the field angle correction method through the developed numerical steady state model, and its evaluation through simulation and experiments, using a fixed-point DSP based low cost industrial drive are given.

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Keywords: Induction Motor, High Speed Drive, Sensorless Control, Digital Signal Processor.



go to top   Global Optimization of Reshaped Shaded Pole Induction Motors Based on Genetic Algorithm Method
         by Sadegh Shamlou, Mojtaba Mirsalim

         Vol. 6. n. 4, pp. 1675-1682


Abstract - Statistical reports show that more than half of the shipments of fractional horsepower motors to US are single-phase shaded pole motors. In this paper, a new reshaped stator of shaded pole motors is proposed. A genetic algorithm optimization method based on transient 2-D finite element analysis is applied to the motor to reach a global optimum design including the factors of raw material cost, operating cost, efficiency, and third harmonic dip in torque. Two different criteria are implemented in optimization of the motors. In the first, by keeping the rotor the same as the base model, the optimum design reaches a 25% lower use in iron while, in the second criterion with approximately 5% lower iron use, significant improvement in performance characteristics, for instance seven percent increase in efficiency is reached. In addition, the authors will illustrate that the proposed structures have lower cost and more simple structure to manufacture in comparison to conventional shaded pole induction motors. Finally, by experimenting on two prototyped motors the validity of the optimum models are verified.

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Keywords: Finite Element Analysis, Genetic Algorithm, Optimization, Shaded Pole Induction Motor.



go to top   A Swappable Single Phase Switched Reluctance Motor with Bifilar Drive Converter
         by M. Asgar, E. Afjei, A. Siadatan

         Vol. 6. n. 4, pp. 1683-1691


Abstract - Single phase switched reluctance motors (SRM) has special place in high volume, low-cost and low-performance applications as well as high-speed, low-power motor drives in different industrial applications. Single phase SRMs have some disadvantages such as low power density and lack of the self-starting ability. In order to overcome these problems a few methods have been presented. For example utilization of permanent magnet or special rotor configuration or additional mechanisms are some of this approaches. Have been adoped by different researchers Many of these methods are expensive or make the manufacturing process more difficult. This paper proposes a new method which overcomes these problems. The proposed approach focuses on a new single phase SR motor topology which will address a procedure for reliable starting, The single phase motor utilizing a new converter topology for this motor and the corresponding control methodology. The new configuration enables the motor for self-starting without the use of permanent magnet or any other starting device. The prototype was simulated, fabricated, and tested in laboratory. Simulation and experimental results of the proposed SRM drive system are presented.

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Keywords: Single-Phase Switched Reluctance Motor, Bifilar Drive, Swapable Switch.


go to top  An Extended PNGV Battery Model for Electric and Hybrid Vehicles
         by Mohamed Daowd, Noshin Omar, Joeri Van Mierlo, Peter Van Den Bossche

         Vol. 6. n. 4, pp. 1692-1706


Abstract - Battery performances at different operating conditions, temperature, loading … etc, have a great influence on the performance of the electrical vehicles (EVs) and hybrid electric vehicles (HEVs). Therefore, an accurate and efficient battery model is needful to predict and optimize the battery performance. This paper presents a battery model with a series of innovative aspects into the partnership for a new generation of vehicles (PNGV), which also known as FreedomCAR battery model. The proposed battery model, extended PNGV (EPNGV), proposes some modification in the parameters estimation and modeling techniques as well the PNGV battery model itself. In addition, the EPNGV model includes the influence of the state of charge, temperature, current rates (c-rates) and cycle number on the model parameters, as well the Peukert constant, self-discharging, energy efficiency and state of health prediction. Experimental results of lithium-polymer 12Ah 3.7V batteries are used for the battery models parameters estimation and validation. The EPNGV battery model has been compared with other battery models: the Thevenin and the traditional PNGV battery models at different operating conditions based on experimental and simulation results. The battery parameters estimation as well the battery modeling are implemented using MATLAB/Simulink.

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Keywords: Cell Testing, Freedomcar Battery Model, MATLAB/Simulink, Parameter Estimation, PNGV Electrical Battery Model.



go to top   Interior Permanent Magnet Motors for Traction Application with non-Overlapping Concentrated Windings and with Integer Slot Windings
         by P. Lindh, M. Rilla, H. Jussila, J. Nerg, J. A. Tapia, J. Pyrhönen

         Vol. 6. n. 4, pp. 1707-1714


Abstract - In this paper, interior permanent magnet machines using either integer slot windings or non-overlapping concentrated windings are designed and analyzed for traction applications. Nowadays, Permanent Magnet (PM) synchronous reluctance motors are often used in traction applications because of their ability to control the stator flux in the field weakening operation. Reluctance torque is produced due to the inductance difference between the direct and quadrature axes' inductances and the stator current linkage. Power density can be increased by adding interior permanent magnets to the machine. The authors were interested in studying whether the reluctance torque can also be beneficial when using non-overlapping concentrated windings. Two 25 kW motors were designed in the same frame. Both motors should give at least 2 p.u. torques at low speed and approximately 0.6 p.u. at double speed as the rated speed is fixed to 1000 rpm. Analytical computations are verified by finite element analysis utilizing Cedrat’s Flux2D. It was noticed that a non-overlapping concentrated winding machine can also be used as traction motor and can further be designed to produce reluctance torque. The integer slot motor has been built and measured and thereby the theoretical computations are verified by real measurements.

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Keywords: Interior Permanent Magnet Machines, Concentrated Winding, Reluctance Torque, Field Weakening.



go to top   Effect of Noise Factors in Energy Management of Series Plug-in Hybrid Electric Vehicles
         by Mojtaba Shams-Zahraei, Abbas Z. Kouzani, Behnam Ganji

         Vol. 6. n. 4, pp. 1715-1726


Abstract - It has been demonstrated that charge depletion (CD) energy management strategies are more efficient choices for energy management of plug-in hybrid electric vehicles (PHEVs). The knowledge of drive cycle as a priori can improve the performance of CD energy management in PHEVs. However, there are many noise factors which affect both drivetrain power demand and vehicle performance even in identical drive cycles. In this research, the effect of each noise factor is investigated by introducing the concept of power cycle instead of drive cycle for a journey. Based on the nature of the noise factors, a practical solution for developing a power-cycle library is introduced. Investigating the predicted power cycle, an energy management strategy is developed which considers the influence of temperature noise factor on engine performance. The effect of different environmental and geographic conditions, driver behavior, aging of battery and other components are considered. Simulation results for a modelled series PHEV similar to GM Volt show that the suggested energy management strategy based on the driver power cycle library improves both vehicle fuel economy and battery health by reducing battery load and temperature.

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Keywords: Energy Management, Plug-in Hybrid Electric Vehicles, Noise Factors, Power Cycle Prediction.



go to top   Design Optimization and Optimal Power Control of Fuel Cell Hybrid Electric Vehicles Based on Swarm Intelligence
         by Omar Hegazy, Joeri Van Mierlo, Philippe Lataire

         Vol. 6. n. 4, pp. 1727-1738


Abstract - The fuel consumption of fuel cell hybrid vehicles depends significantly on the energy control strategy and the component sizing. Therefore, it is necessary to determine the optimal design and power sharing between the sources in order to minimize the fuel consumption and components cost of the vehicle for a given driving cycle. This paper proposes a control strategy based on Particle Swarm Optimization (PSO) in order to achieve the optimal design and minimum fuel consumption for Fuel Cell/Supercapacitor hybrid electric vehicles (FC/SC HEVs). PSO algorithm is a member of the wide category of Swarm Intelligence Methods (SI). To evaluate the performance of the proposed methodology for FC/SC HEVs, a modified PSO algorithm will be compared with Genetic Algorithm (GA) while satisfying the operational constraints. In this research, three control strategies based on the knowledge of the fuel cell efficiency map are implemented and compared with the aim to minimize the hydrogen consumption for the FC/SC HEV. These control strategies are control strategy based on Efficiency Map (CSEM), control strategy based on Particle Swarm Optimization (CSPSO) and control strategy based on Genetic Algorithm (CSGA). To demonstrate the effectiveness of the proposed methodology, simulation studies are performed using Matlab/ Simulink by integrating the detailed mathematical and electrical models of the FC/SC hybrid vehicular system.

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Keywords: Fuel cell Hybrid Electric Vehicle (FCHEV), Powertrain Modeling; Dynamic Model of Fuel Cell, Dynamic Model of Supercapacitor, PSO Algorithm, Genetic Algorithm, Power Management Control Strategies (PMCS).



go to top   Analysis, Control and Implementation of a High-Power Interleaved Boost Converter for Fuel Cell Hybrid Electric Vehicles
         by Omar Hegazy, Joeri Van Mierlo, Philippe Lataire

         Vol. 6. n. 4, pp. 1739-1747


Abstract - Multi-channel DC/DC converters have received an increasing attention in recent years for high power applications. This paper presents an analysis, design and implementation of a high-power multileg interleaved DC/DC boost converter with a digital signal processor (DSP) based controller. This research focuses on non-isolated DC/DC converter that interfaces the fuel cell to the powertrain of the hybrid electric vehicles. In this paper, two-phase interleaved boost converter (IBC) with digital phase-shift control scheme is proposed in order to reduce the input/output ripples and to reduce the size of the passive components with high efficiency for high power applications. On the other hand, the digital control based on DSP is more convenient than other methods to achieve the synchronization and phase shifted operation for interleaved converters. To realize the proposed control in DSP, a real time workshop (RTW) is used for automatic real-time code generation. The proposed converter, IBC, is compared with other topologies, such as conventional boost converter (BC) and multi-device boost converter (MDBC) in order to examine its performance. Moreover, a generalized small-signal model with complete parameters of these DC/DC converters is derived, which has not been discussed earlier. The PWM DC/DC converter topologies and their control are designed and investigated by using Matlab/Simulink. A 30 kW two-phase interleaved boost converter has been realized and successfully tested in our laboratory. Experimentally, a dual-loop average current control implemented in TMS320F2808 DSP is employed to achieve the fast transient response. Furthermore, the simulation and experimental results are provided.

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Keywords: Fuel cell Hybrid Electric Vehicle (FCHEV), DC/DC Boost Converters, Generalized Small-Signal Model, Loss Model, Closed-loop Control Strategy, Direct Digital Control, Digital Signal Processor (DSP).



go to top   New Interface for Coordinated Maintenance Scheduling of Generating Units in Neighbor Countries Applying Genetic Algorithm and Monte-Carlo Simulation
         by M. Manbachi, F. Mahdloo, A. Ataei, M. R. Haghifam

         Vol. 6. n. 4, pp. 1748-1756


Abstract - The aim of this study is to present a new comprehensive solution for maintenance scheduling of power generating units by applying a market interface between neighbor countries. The solution was obtained by using a Genetic Algorithm (GA) and a Monte-Carlo Simulation (MCS). In general, there are two points of view which can create serious problems in maintenance scheduling of power systems. Each Generation Company (GenCo) desires to maximize its payoffs, whereas the system operator has system reliability solicitudes in peak seasons. Thus, the optimum solution can be gained through having various generations in different seasons. Therefore, we propose a cooperated framework between neighbor countries based on GA. In this method, generation companies of neighbor countries set their strategies to participate in a Cooperative Maintenance Market (CMM) by considering load and fuel uncertainties. On the other hand, the Joint System Operator (JSO) manages CMM based on reliability indices and offers incentives/ penalties for companies relying on common policies of neighbor countries through MCS technique. To evaluate the accuracy and the adequacy of our solution for maintenance scheduling of power generation units in neighbor countries, a modified IEEE Reliability Test System (RTS) was studied as an applicable case study.

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Keywords: Cooperative Maintenance Market, Genetic Algorithm, Maintenance Scheduling, Monte-Carlo Simulation, Reliability.



go to top   Portable Measurement System for Detecting the Condition of Non-ceramic Insulator Based on Pulse Current Method
         by Shengchang Ji, Yuanyuan Wang

         Vol. 6. n. 4, pp. 1757-1767


Abstract - Presently, more and more non-ceramic insulators are being used on the power transmission lines. With the in-service year′s increase, organic material degradation or aging comes into being more and more. In order to keep the running safety of power system, it is important to detect the aging condition of non-ceramic insulators. In this paper, a portable measurement system for detecting pulse current of non-ceramic insulator is set up. The wideband current transducer, extraction circuit of pulse current and the circuit of reference signal are designed and realized. Based on the experimental system set up in the laboratory, the characteristics of corona pulse current are studied. Moreover, the portable measurement system based on pulse current method is also used to diagnose the condition of non-ceramic insulators in the field, the results show that the quantity of corona pulse, the phase distribution and the pulse current amplitude of long time running insulator have obvious difference from that of short time running insulators, which verifies that pulse current method is an excellent way to detect the faulty insulators on ground. Such work provides direction for detecting the aging condition of non-ceramic insulators based on pulse current method.

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Keywords:  Non-ceramic Insulator, Corona Pulse Current, Portable Measurement System, Aging.



go to top   A New Statistical Ranking of Tree Inception Voltage Distribution of Silicone Rubber and Epoxy Resin under AC Voltage Excitation
         by M. H. Ahmad, H. Ahmad, N. Bashir, Y. Z. Arief, R. Kurnianto, F. Yusof, Z. Abdul-Malek, A. Darus

         Vol. 6. n. 4, pp. 1768-1775


Abstract - Electrical treeing is a common insulation pre-breakdown phenomenon. Due to prolonged stresses, polymeric insulating material cannot withstand the aging and degradation from voltage application, environmental factors and from several influenced factors. Therefore, this phenomenon needs to be explored from the initial stage for better understanding of its early inception. However, previous studies have shown that some initial parameters were analysed by using still-can-improved statistical techniques. Thus, in this paper, a more accurate statistical technique was performed in order to determine the value, the distribution and distribution statistical rank of tree inception voltage of silicone rubber and epoxy resin by fitting method. The electrical tree inception voltage was measured and recorded by applying a sequential of AC voltage between the point-to-plane electrodes via a camera-equipped online monitoring system. The experiment was performed based on IEC 1072:1991 “Methods of Test for Evaluating the Resistance of Insulating Materials Against the Initiation of Electrical Trees”. The experimental results were analysed satistically and comparison was made between the best fitted distribution and Weibull distribution. Obtained results have shown that tree inception voltage depends on the material composition since other factors were kept constant. Based on the statistical analysis, the tree inception voltage of silicone rubber and epoxy resin were best fitted with Johnson SB distribution rather than Weibull distribution which showed higher fitting error. Based on the fitted distribution, the values of tree inception voltage of silicone rubber and epoxy resin were calculated and found to be 3.1529 kV and 4.6528 kV respectively. The results of fitting using Anderson-Darling goodness-of-fit test and Kolmogorov-Smirnov goodness-of-fit were compared. It was found that the Johnson SB statistical distribution holds good for silicone rubber and epoxy resin for electrical treeing initiation. Therefore, it has been proved that Johnson SB distribution is better than Weibull distribution in representing the tree inception voltage distribution.

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Keywords: – Electrical Treeing, Tree Inception Voltage, Johnson SB distribution, Weibull Distribution, Anderson-Darling Goodness-of-Fit Test, Kolmogorov-Smirnov Goodness-of-Fit Test.


International Review of Electrical Engineering - Papers- Part B


go to top   Critical Lines Identification for ATC Assessment in Power System Planning
         by Mojgan Hojabri, Hashim Hizam, Norman Mariun, Ishak Aris, Mudathir Funsho Akorede

         Vol. 6. n. 4, pp. 1776-1782


Abstract - Ability to evaluate the accurate available transfer capability (ATC) has important impact on the trade of energy in power marketing. The impact of the transmission element status of transmission path has a possibility to severely change the statistics of the ATC. The impact of the line outage is more significant among the other component outages. The ATC assessment requires N-1 security assessment under line outages scenarios. Moreover, an efficient contingency ranking method to determine critical lines has significant impact on the ATC computational time. In this paper, MW loss, MVAR loss and Load Margin Index are described to find the critical lines for computing the ATC under contingencies. These methods are tested on IEEE 118 bus system and the ATC based on Krylov algebraic method are calculated for each critical line. Based on ATC results calculated from these contingency ranking methods, the efficiency of these methods compare together.

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Keywords: Contingency Evaluation, Available Transfer Capability (ATC), Critical Line Ranking, Line Outage, Load Margin Index, MW Loss, MVAR Loss.


go to top  Optimal Capacitor Placement in Three-Phase Distribution Systems Using Improved Harmony Search Algorithm
         by Reza Sirjani, Azah Mohamed, Hussain Shareef

         Vol. 6. n. 4, pp. 1783-1793


Abstract - Capacitors in power systems are used to supply reactive power for the purpose of loss minimization and voltage profile improvement. Besides, appropriate placement of capacitors is also important so as to ensure that system power loss and total capacitor costs is reduced. Most of the capacitor placement techniques assume that the system is balanced and ignore the effect of harmonics. In this paper, an improved harmony search (IHS) algorithm is applied to solve the optimal capacitor placement problem. The performance of the proposed HS algorithm is validated on a three-phase 9-bus distribution system by considering mutual coupling, load unbalancing and harmonics. The obtained capacitor placement results using IHS are compared with particle swarm optimization to demonstrate its effectiveness.

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Keywords: Capacitor Placement, Load Unbalancing, Harmonics, Harmony Search Algorithm.



go to top   Multi Objective Optimal Power Flow with FACTS Devices Using Shuffled Frog Leaping Algorithm
         by M. Sedighizadeh, M. Sarvi, E. Naderi

         Vol. 6. n. 4, pp. 1794-1801

Abstract - In this study, Shuffled Frog Leaping Algorithm (SFLA) for optimizing generators fuel cost, active power transmission losses and voltage deviation of system buses simultaneously and with FACTS devices in power system have been used. In this suggested approach, optimal power flow has been formulized as a multi-purpose optimal problem. Applied FACTS devices include Thyristor Controlled Series Capacitor (TCSC) and Unified Power Flow Controller (UPFC). Proposed method have been examined on 5 buses and 30 buses IEEE standard test systems and obtained results of suggested algorithm have been compared with obtained results of Improvement Particle Swarm Optimization method.

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Keywords: Optimal, Power Flow, FACTS, Shuffled Frog Leaping Algorithm (SFLA).


go to topThe Optimisation of Stand-Alone Hybrid Renewable Energy Systems Using HOMER
         by M. B. M. Rozlan, A. F. Zobaa, S. H. E. Abdel Aleem

         Vol. 6. n. 4, pp. 1802-1810


Abstract - The aim of this paper is to determine the possibility of the stand-alone hybrid renewable energy system which able to satisfy the electric load demand by using HOMER Software. Besides, it is always desirable to have an environmental friendly energy system in order to maintain its natural beauty and prevent the effect of global warming. As the project economics is concerned, it is necessary to indentify the system life cycle cost or Total Net Present Cost, TNPC, of the optimal hybrid energy system, where this also can be analysing by optimization in HOMER. For observing the realistic effect has on power system designed and it economics, it is also important to assess the effect of uncertainty or a change in sensitivity variable such wind speed and fuel price which this can be done by performing sensitivity analysis.

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Keywords: Renewable Energy, Stand-Alone Systems, Optimisation, HOMER.



go to top   Inter-Area Oscillation Damping by Optimal and Coordinated Design of PSS and SVC Using an Improved Differential Evolution Algorithm
         by M. Joorabian, B. Noshad, B. Mohammadi, M. S. Javadi

         Vol. 6. n. 4, pp. 1811-1821


Abstract - In large scale power systems, PSS is not sufficient to damp inter-area oscillations; therefore, FACTS devices, such as SVC, which is one of the most important these devices, are typically used with PSSs. In this paper, the parameters of a power system stabiliser (PSS) and static VAR compensator (SVC) with help of a combination of a Differential Evolution algorithm (DE) and Local Search Algorithm (called the DELSA (Memetic DE algorithm)) are introduced, which are designed independently, converge to the correct and optimal solution in a small number of iterations and are attuned to damping low frequency oscillations, such as local mode oscillations, inter-area mode oscillations, other controllers modes, and modes of the generator excitation system. Suppose that the DE algorithm searches in a wide-ranging area, whereas the local search focuses on the attraction area, which probably has the optimal solution. We studied the three-area power system that was simulated in the time domain by MATLAB.

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Keywords: Differential Evolution Algorithm (DE), Inter-Area Oscillations, Local Search (LS), Memetic DE Algorithm, PSS, SVC.


go to top   The Effect of Thyristor Controlled Series Compensator on Power System Oscillation Damping Control
         by Ghazanfar Shahgholian, Afshin Etesami

         Vol. 6. n. 4, pp. 1822-1830


Abstract - The variable series compensation is highly effective in both controlling power flow in the line and in improving stability. Thyristor controlled series compensator (TCSC) is one of the most important and known series flexible ac transmission system (FACTS) controllers. This paper investigates the effects of the TCSC on small-signal power system stability. The power sensitivity model is used to the representation of the electric power system. Both IEEE type-ST1 and IEEE type-ST3 excitation sys¬t¬e¬m model are used. The proposed controller and technique are employed single-machine infinite-bus (SMIB) system under different cases. To validate the effectiveness of the TCSC on enhancing system stability, eigenvalues analysis and a time-domain simulation implemented on SMIB equipped with TCSC. Finally, the simulation results verify the validity of the proposed approach.

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Keywords: FACTS Device, TCSC, Linear and Nonlinear Model, Modal Analysis, Damping Controller.



go to top   Vulnerability Assessment of Cascade Contingencies in Power Systems
         by John A. Sanchez, Mario A. Ríos

         Vol. 6. n. 4, pp. 1831-1838


Abstract - The post-mortem analysis of several blackouts has shown that cascade phenomena are involved in many of them. So, it is important to evaluate the power system vulnerability in the scope of this kind of events. This paper proposes a methodology to classify cascade events based on both interrupted load under a blackout and the time required by the system operator to restore the power supply, as a vulnerability assessment. At the same time, the cascade contingencies’ vulnerability of the system is based on Monte Carlo simulations and a probabilistic representation of the cascade behavior that includes generator and branches failures, unnecessary operation and hidden failures in protection devices, branch’s sympathetic tripping, operator reaction and operative under frequency load shedding scheme. The proposed algorithm has been tested on the IEEE 118 nodes system.

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Keywords: Cascade Failures, Hidden Failures, Load Shedding, Monte Carlo Simulation, Power System Restoration, Security of Power Systems.



go to top   CHP Optimized Selection Methodology for a Multi-Carrier Energy System
         by Aras Sheikhi, Mehdi S. Naderi, Ali Mohammad Ranjbar,G. B. Gharehpetian, Farahbakhsh Safe

         Vol. 6. n. 4, pp. 1839-1846

Abstract - Today, the interest on distributed generation has been increasing, especially due to technical development on generation systems that meet environmental and energy policy concerns. One of the most important distributed energy technologies is Combined Heat and Power (CHP). CHP is small and self-contained electric generation plan that can provide power for household applications, commercial or industrial facilities and hence its applications are overtly increasing. It can reduce power loss and enhance service reliability in distribution systems. One of the influential factors for the users is the purchasing cost of CHP which is largely dependent on its type, capacity and efficiency. Therefore among all exciting of the commercial CHP technologies certain economic choices are to be taken into account. Cost-Benefit analysis is one of the famous approaches aiming at maximization of benefit-to-cost ratio. The proposed method in this paper determine the optimized size of CHP for users by considering an integrated view of electricity and natural gas network based on the novel concept of energy hubs. The benefits of CHP placement equipped with a heat storage device described in this paper include power cost saving, power loss reduction, reliability enhancement and environmental considerations. At last to confirm the proposed method the best size of CHP is determined for a hotel as a case study.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Combined Heat and Power, Benefit to Cost Analysis, Energy Hub, Optimal Operation, CO2 Emission.



go to top   Optimal Power Flow Based on Imperialist Competitive Algorithm
         by A.J. Ghanizadeh, G. Mokhtari1, M. Abedi, G.B. Gharehpetian

         Vol. 6. n. 4, pp. 1847-1852


Abstract - This paper presents a new method, which is based on evolutionary algorithm called Imperialist Competitive Algorithm (ICA) in order to solve the Optimal Power Flow problem. The objective is to minimize the total fuel cost of thermal generating units satisfying equality and inequality constraints. The proposed method has been applied to IEEE 30-bus test system. The results have been compared with other evolutionary methods. It is shown that proposed method leads to lower generation cost and its convergence is faster than other method.

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Keywords: Imperialist Competitive Algorithm (ICA), Optimal Power Flow, Equality and Inequality Constraints, Constraint Handling.



go to top   Tracking the Voltage Sag Source Location using Multivariable Regression Model
         by VA. Kazemi, A. Mohamed, H. Shareef

         Vol. 6. n. 4, pp. 1853-1861


Abstract - This paper presents a new method to identify the location of the voltage sag source using the multivariable regression model and the regression coefficients at all buses in a distribution system. If a fault occurs in a bus, the voltage of unmonitored buses is estimated by using the proposed model and the voltage deviation is calculated using the voltage magnitude before and after the fault. Then the maximum voltage deviation is selected to calculate the standard deviation from the maximum voltage deviations. The bus with minimum standard deviation is considered as the location of the voltage sag source. To demonstrate the applicability of the method, the IEEE 30 bus test system is used to identify the accurate location of voltage sag source. The branch current deviation model is considered to verify the accuracy of the multivariable regression model. The results showed that the multivariable regression model gives better accuracy than the branch current deviation model in locating the source of voltage sag.

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Keywords: Voltage Sag, Multivariable Regression, Voltage Deviation, Standard Deviation, Current Deviation


go to top   Study the Effects of STATCOM on the Static Voltage Stability Improvement and Reduction of Active and Reactive Losses
         by M. Shaygan, S. Gh. Seifossadat, Morteza Razaz

         Vol. 6. n. 4, pp. 1862-1869


Abstract - In this paper, the effects of STATCOM on improving the static voltage stability and reduction of the losses in a power system are investigated. In the first step, to analyze the static voltage stability, STATCOM is modeled for inserting in Newton-Raphson Power flow equations. Then the static voltage stability study is performed by modal analysis. By using this method critical areas and the best location for STATCOM are determined. Case studies are carried out on a EHV practical 24-bus system .To confirm the effects of STATCOM on voltage stability improvement and reduction of the active and reactive losses, three cases (with STATCOM and without STATCOM) consist of: 1) base case, 2) case of increasing load at critical buses and 3) case of line outage are carried out.

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Keywords: STATCOM, Static Voltage Stability, Modal Analysis, Bus Participation Factor.


go to top   Optimal Power Flow Solution Using Artificial Bees Colony Algorithms
         by Umaporn Kwannetr, Uthen Leeton, Thanatchai Kulworawanichpong

         Vol. 6. n. 4, pp. 1870-1882


Abstract - This paper illustrates an application of Artificial Bees Colony (ABC) algorithms to optimal power flow (OPF) problems in comparative with some effective mathematical and evolutionary optimization methods. The ABC is one of swarm intelligences, which was just developed since 2005. This algorithm is to simulate the intelligent behaviour of honey bee swarms. It is a population-based search method and simply employs only common control parameters such as colony size and maximum generation number. The artificial bees are created to discover places of food sources with high amount of nectar. At the end of ABC searching procedure, the food source with the highest nectar is found to represent the global optimum. The proposed algorithm was tested with four mathematical test functions (simple quadratic function, Rosenbrock’s function, circle function and Bohachevski’s function) and five standard IEEE test power systems (6-bus, 14-bus, 30-bus, 57-bus and 118-bus test systems). The test power systems were divided into two cases. The first test case was given by applying a quadratic function to generators’ fuel-cost curve whereas a non-smooth fuel-cost function was assigned to the second. The comparisons among solutions obtained by sequential quadratic programming (SQP), genetic algorithms (GA) and artificial bees colony (ABC) were carried out. As revealed from the simulated results, the effectiveness of the ABC algorithm for solving OPF problems was confirmed.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Optimal Power Flow, Artificial Bees Colony, Genetic Algorithms, Quasi-Newton Search Method.


go to top  Optimal Design of Damping Controllers for Multi-machine Power Systems Using Metaheuristic Techniques
         by E. Bijami, R. Abshari, J. Askari, S. Hosseinnia, M. M. Farsangi

         Vol. 6. n. 4, pp. 1883-1894


Abstract - This paper presents three metaheuristic approaches for simultaneous coordinated tuning of damping controllers, an Imperialist Competitive Algorithm (ICA), a Shuffled Frog Leaping Algorithm (SFLA) and a Harmony Search Algorithm (HSA) to damp the power system low frequency oscillations. A conventional lead-lag structure is considered for controllers. The aim of the proposed control strategy is to choose the best controller parameters in such a manner that the dominant eigenvalues of the closed-loop system are shifted to the left-hand side of s-plane as far as possible. In order to verify the effectiveness and ability of the proposed algorithms in designing the damping controllers, one small and one large power systems are considered. Two power system stabilizers (PSSs) are designed simultaneously for the small power system and one PSS for a generator and one supplementary controller for a Static Var Compensator (SVC) are designed simultaneously for the large power system. The simulation studies show that proposed approaches have good capability in solving the problem but the controllers designed by ICA perform better than those by HSA and SFLA in damping the power system low frequency oscillations.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Low Frequency Oscillations, Imperialist Competitive Algorithm, Shuffled Frog Leaping Algorithm, Harmony Search Algorithm, Stability, PSS, SVC.



go to top  Switching Phenomenon in Six-Phase Transmission System
         by H. Ahmad, M. I. Jambak, K. Y. Lau, M. K. N. Mohd Sarmin, S. S. Ahmed, M. A. B. Sidik

         Vol. 6. n. 4, pp. 1895-1904


Abstract - Converting a three-phase transmission line into a six-phase one is one of the feasible approaches to increase the power transfer capability of existing three phase double circuit transmission networks. However, this will impact the existing tower insulation. One of the main concerns is switching overvoltages that occur in transmission lines due to the opening and closing of circuit breakers. This paper aims to investigate into the switching phenomenon that would occur in a six-phase transmission system. Till now such an investigation using a laboratory replica of a practical transmission network is yet to be reported. In this work one of the transmission lines belonging to the Malaysian national utility i.e., Tenaga Nasional Berhad’s (TNB) has been investigated as a six phase line through simulations as well as an experimental prototype. It is the 113.1 km long 132 kV three-phase double circuit transmission line between Gua Musang and Kuala Krai in Kelantan, Malaysia. A comparison between simulation and experimental results is also given. The work is expected to enhance the understanding of the changes in switching overvoltages due to conversion of a three phase transmission line into a six-phase line.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Switching Phenomenon, Six-Phase Transmission, High Phase Order Transmission Line, Power Delivery.



go to top   Application of Bacterial Foraging Algorithm for Optimal Location of FACTS Devices with Multi-Objective Functions
         by Senthil Kumar.M, Renuga.P

         Vol. 6. n. 4, pp. 1905-1915


Abstract - The continuous demand in electric power system network has caused the system to be heavily loaded leading to voltage instability. Voltage instability condition in a stressed power system could be improved by controlling the reactive power dispatch, reactive power injection on the load bus and controlling the tap changing of on- load-tap-changer (OLTC) transformer. This paper presents an application of Bacterial Foraging (BF) Algorithm to find optimal location of Flexible AC Transmission System (FACTS) devices to achieve voltage stability improvement in power system with minimum cost of installation of FACTS devices. While finding the optimal location, thermal limit for the lines and voltage limit for the buses are taken as constraints. Three types of FACTS devices, Thyristor Controlled Series Compensator (TCSC), Static VAR Compensator (SVC) and Unified Power Flow Controller (UPFC) are considered. The proposed approach has been evaluated with four different objective functions namely, loss minimization, voltage profile improvement, voltage stability enhancement and total cost minimization. Voltage stability level of the system is defined based on the L-index of load buses. The IEEE 14 and IEEE 30- bus systems were used as test systems to demonstrate the applicability and efficiency of the proposed method. The results are encouraging and will be useful in voltage stability improvement.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Static Var Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC), Unified Power Flow Controller (UPFC), Bacterial Foraging (BF) Algorithm, Voltage Stability Index (L-index), Voltage Stability.



go to top   A Comprehensive Review on Methods for Solving FACTS Optimization Problem in Power Systems
         by A. Rezaeejordehi, J. Jasni

         Vol. 6. n. 4, pp. 1916-1926

Abstract - This paper presents a comprehensive review of various methods for solution of flexible AC transmission systems (FACTS) optimization problem in power systems. First, it explains the requirements of an ideal solution for FACTS optimization problem, then classifies the methods used by researchers in four main groups as classical methods, technical methods, heuristics and mixed methods, and discusses thoroughly about characteristics, advantages and disadvantages of each group of methods. Finally, according to the pros and cons of these methods, heuristic methods are determined as the most effective group of optimizers and also some hints are offered for future researches on this area.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved





go to top   Optimal PMU Placement Considering Contingencies by Using a Hybrid Discrete Particle Swarm Optimization Technique
         by Y. Alinejad-Beromi, A. Ahmadi, H. Rezai Soleymanpour

         Vol. 6. n. 4, pp. 1927-1938


Abstract - This paper presents a Hybrid Discrete Particle Swarm Optimization Technique (HDPSO) for the solution of optimal placement of Phasor Measurement Unit (PMU) in smart grids. In this paper, the optimal PMU placement (OPP) is considered as an integer valued optimization problem which is hard to solve due to considering various conditions of power network including the base case state, effects of conventional measurements and contingencies such as single measurement loss or single branch outage. The proposed HDPSO is based on the quantum particle swarm optimization algorithm which has a good convergence behavior. To increase the efficiency of the proposed HDPSO the concepts of time varying coefficients are incorporated to the proposed algorithm. Besides, a new neighborhood topology namely Stochastic Based String (SBS) topology is introduced. The proposed SBS topology prevents the particles to rush toward obtained local best solutions at the beginning of the search process. The efficiency of the proposed method is verified by the simulation results of IEEE 14-bus, 30-bus, New England 39-bus, 57-bus and 118 bus systems, respectively. The results are also compared with some newly methods in the area which verify our proposed method as a novel solution method to obtain reliable measurement system with the least number of PMUs.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Measurement Unit, Particle Swarm Optimization, Optimal PMU Placemen, Smart Grid.


go to top   Wind Power Penetration Limit Calculation Based on Stochastic Optimal Power Flow
         by Wei Gu, Rui Wang, Rong Sun, Qun Li

         Vol. 6. n. 4, pp. 1939-1945


Abstract - This paper presents a calculation method of wind power penetration limit based on stochastic optimal flow. Aiming to maximize wind power integrated into the system while taking power flow equation and security constraints into consideration, a mixed integer nonlinear programming model with multi-variables including random ones and multi-constraints is proposed utilizing chance constrained programming due to the random feature of wind speed. A particle swarm optimization algorithm based on stochastic simulation technique is employed to solve this model. Simulation of the IEEE 30-bus test system validates the feasibility and correctness of the proposed model and some limiting factors which impact wind power penetration limit are also analyzed to put forward suggestions on the planning of wind farm.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Wind Power Penetration Limit; Stochastic Optimal Power Flow; Chance Constrained Programming; Particle Swarm Optimization; Stochastic Simulation.


go to top   New Formulation Technique for Generation Tracing via Evolutionary Programming
         by Z. Hamid, I. Musirin, M. M. Othman, M. N. A. Rahim

         Vol. 6. n. 4, pp. 1946-1959


Abstract - In deregulated power system, the only way to provide fair and non-discriminatory transmission service pricing is by performing electricity tracing. The transaction based allocation, which was quite attractive among transmission service providers, does not take account of physical power flow results, whereas the conventional power tracing techniques which majorly rely on proportional sharing principle and matrix operation are powerless to obtain the tracing results when the matrix to be inversed is singular. In virtue of that, this paper proposed a new formulation of power tracing algorithm via Artificial Intelligence (AI) based optimization approach, namely Evolutionary Programming (EP) with only simple steps and easy implementation. The proposed method is free from any assumptions, matrix operation, and can perform the tracing process based on the actual power flow results. Validation on IEEE 30 bus and 57 bus power system proves the capability of the proposed technique for real system application.

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Keywords: EP, Generation Tracing, Losses Allocation, Matrix Singularity, Proportional Sharing.



go to top   Optimal Sizing of Distributed Energy Resources in MicroGrid Solved by Mixed-Integer Non Linear Programming
         by S. M. M. Tafreshi, H. A. Zamani, S. M. Ezzati, H. Vahedi, E. Dahri

         Vol. 6. n. 4, pp. 1960-1970


Abstract - In this paper, a methodology to perform the optimal unit sizing for Distributed Energy Resources (DER) in MicroGird (MG), has been developed. Based on a Mixed-Integer Non Linear Programming (MINLP), a new optimal unit sizing method was developed to calculate the optimum system configuration that can achieve the customers required Loss of Power Supply Probability (LPSP) with a minimum Cost of Energy (COE). The proposed method results are validated for single source DG and hybrid DG with results obtained from HOMER and Genetic Algorithm (GA) for the same test systems.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Optimal Unit Sizing, Cost of Energy, Hybrid Renewable Energy System, Mixed-Integer Non Linear Programming, Genetic Algorithm.



go to top   A Novel Mixed-Integer Linear Algorithm to Generate Unit Commitment and Dispatching Scenarios for Reliability Test Grids
         by M. Giuntoli, D. Poli

         Vol. 6. n. 4, pp. 1971-1983


Abstract - Reliability test grids are often used by the analysts to simulate the effect of new possible operational procedures regarding the power system. One of the main problems affecting the use of test grids for reliability studies is that the result of the simulations is strongly dependent not only on the new procedure under investigation, but also on the working point preselected for the simulated grid, in particular in terms of dispatching scenario. In this paper, the use of a sensitivity analysis to separate the two effects is discussed; hence a novel Mixed-Integer Linear Programming (MILP) method is proposed and implemented for providing, with a single Optimal Power Flow, the Unit Commitment and the day-ahead production schedules of a hydro-thermal generating park, as a first stage to perform reliability studies on a given test grid. Operational requirements, like reserve margins and transmission constraints, can be easily tuned to perform sensitivity analyses. The dispatching scenarios are generated assuming a deregulated framework and implementing inside the OPF the rules of day-ahead markets for energy and ancillary services. A mixed deterministic-probabilistic tool for generating bidding strategies is used to simulate the behavior of market players.

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Keywords: Unit Commitment, Generation Scheduling, Reliability Test Grid, Mixed-Integer Linear Programming.



go to top   Optimization and Coordination of Damping Controls for Optimal Oscillations Damping in Multi-Machine Power System
         by Mahdiyeh Eslami, Hussain Shareef, Azah Mohamed

         Vol. 6. n. 4, pp. 1984-1993


Abstract - This paper proposes a novel optimization technique for simultaneous coordinated designing of power system stabilizer (PSS) and static VAR compensator (SVC) as a damping controller in the multi-machine power system. PSO and chaos theory is hybridized to form a chaotic PSO (CPSO), which reasonably combines the population-based evolutionary searching ability of PSO and chaotic searching behavior. The coordinated design problem of PSS and SVC controllers over a wide range of loading conditions are formulated as a multi-objective optimization problem which is the aggregation of the two objectives related to the damping ratio and damping factor. The proposed damping controllers are tested on a weakly connected power system. The effectiveness of the proposed controllers is demonstrated through the eigenvalue analysis and nonlinear time-domain simulation. The results of these studies show that the proposed coordinated controllers have an excellent capability in damping power system inter-area oscillations and enhance greatly the dynamic stability of the power system. Moreover, it is superior to both the manually coordinated stabilizers of the PSS and the SVC damping controller.

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Keywords: Chaotic, PSO, PSS, SVC, Coordinated Design.



go to top   Design of Robust Output Feedback Damping Controller for STATCOM Using PSO Technique
         by Amin Safari, Hossein Shayeghi, Akram Asghari Govar

         Vol. 6. n. 4, pp. 1994-2001


Abstract - – A novel approach based Particle Swarm Optimization (PSO) is proposed for optimal selection of the output feedback damping controller parameters for static synchronous compensator (STATCOM) in order to improve the damping for power system oscillations. The problem of robustly STATCOM based damping controller is formulated as an optimization problem according to the time domain-based objective function which is solved by PSO. To ensure the robustness of the proposed damping controller, the design process takes into account a wide range of operating conditions and system configurations. The damping provided by the proposed controller was compared with a genetic algorithm (GA) based controller. The effectiveness of the proposed controller for damping low frequency oscillations is tested and demonstrated through nonlinear time-domain simulation and some performance indices studies. The robust output feedback controller design has been demonstrated to provide extremely good damping characteristics over a range of operating conditions.

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Keywords: Output Feedback Damping Controller, Particle Swarm Optimization, Power Oscillation Damping, STATCOM.



go to top   Voltage and Frequency Control of an Islanded Power System Based on Wind-Battery Generation
         by Simin Peng, Gang Shi, Yunfeng Cao, Xu Cai

         Vol. 6. n. 4, pp. 2002-2012


Abstract - This paper focuses on voltage and frequency control of an islanded power system based on wind-battery generation with a double fed induction generator (DFIG), a power conditioning system (PCS), and a battery energy storage system (BESS). The PCS along with the BESS is used to supply the power demand for the DFIG and loads to form a virtual grid, behaving as a sole free-slack for the isolated system, and is adequately coordinated with the generated power of the DFIG, the energy of the BESS to keep the voltage and frequency at point of common coupling (PCC) to an acceptable level. The proposed control scheme, using only a voltage close-loop, has the capability of load balance and voltage regulation via regulating automatically the active/reactive power output of the PCS. And an efficient power balance mode is theoretically presented to make the system operate in the most effective way. The main components of the islanded system are modeled based on PSCAD/EMTDC and a 50-kW experimental platform is developed using the DSP processor. Simulation and experimental results show that the generation system can keep the voltage and frequency stability at desired level during different dynamic conditions like varying in loads and wind speed.
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Keywords: Islanded Power System, Voltage and Frequency Control; Battery Energy Storage System, Power Conditioning System.



go to top   Optimal Allocation and Sizing of Capacitors to Minimize the Distribution Line Loss and to Improve the Voltage Profile Using Big Bang-Big Crunch Optimization
         by M. Sedighizadeh, D. Arzaghi-haris

         Vol. 6. n. 4, pp. 2013-2019


Abstract - In this paper, the Big Bang-Big Crunch (BB-BC) optimization is presented to find the optimal placement and size of capacitors in a distribution system. The BB-BC method is inspired by one of the theories of the evolution of universe. The potentialities of BB-BC are its inherent numerical simplicity, high convergence speed, and easy implementation. The objective function is composed of the line loss and the capacitors investment cost. The bus voltage and the feeder current as constraints are included in the objective function by a constraint penalty factor.
To validate the proposed method, the 18-bus IEEE distribution system is used. The proposed method is applied to the problem and its speed and accuracy are studied. The results are compared with pure Binary Particle Swarm Optimization (BPSO), genetic algorithm, and nonlinear programming. It is illustrated in the example that the proposed optimization method is more accurate and particularly more robust than others for the planning of capacitors
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Capacitor Placement; Big Bang-Big Crunch (BB-BC) Optimization, Binary Particle Swarm Optimization (BPSO), Genetic Algorithms (GA).



go to top  Stochastic Based Reactive Power Market in Deregulated Environment
         by Roozbeh Kamali

         Vol. 6. n. 4, pp. 2020-2028


Abstract - This paper presents a stochastic reactive power market in deregulated power systems in which the uncertainties of load forecast, generating units as well as transmission lines are taken into account. At first, Lattice Monte Carlo Simulation (LMCS) is used to generate random scenarios. The roulette while mechanism is implemented to generate the load of each scenario. In order to reduce computation burden, the scenario reduction technique is implemented to select only the most probable scenario and discard the similar ones and those with low probability. After scenario reduction, the stochastic reactive power market is cleared in the form of a series of deterministic optimization problems, including the non-contingent scenario and different post-contingency states. The objective function is to minimize the expected value of total payment function (TPF) of generators in dollars paid to the generators for their reactive power compensation. The proposed stochastic reactive power market is studied based on the IEEE 24-bus Reliability Test System.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Lattice Monte Carlo Simulation (LMCS), Stochastic Reactive Power Market, Load Forecast Error, Total Payment Function (TPF).



go to top   A Novel Power Distribution System Planning by Installing DG Units in a Competitive Electricity Market
         by M. Hosseinpour, M. Najafi, R. Ebrahimi, M. Davoodi

         Vol. 6. n. 4, pp. 2029-2035


Abstract - The long-term planning problem for improving the distribution system faces with lots of complexities due to its large number of decision variables. The optimum allocation of distributed generation (DG) sources and finding out their capacity in the restructured power environment is a new way to expand the capacity of the distribution firm covered network. In this paper, a new method is proposed for finding out the optimum location and capacity of DG sources in the restructured environment through the net present value analysis using an optimization model. This model aims to minimize the investment cost of the distribution firm, utility cost and the losses cost considering the anticipated load peak value. Considering the power market price anticipation to be indefinite, the proposed method is based on laying out the genetic algorithm and a fuzzy model to the power market price and the capacity expansion design of the distribution system during different time intervals is proposed along with two static and semi-dynamic methods. The efficiency of the proposed approach is well shown applying it to a sample network.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Net Present Value Analysis, Power Market, Distributed Generation Source, Optimum Allocation, Fuzzy Model.


go to top   A Multi-Objective Framework for Transmission Expansion Planning in Electricity Market
         by Mohammad Taghi Ameli, Mojtaba Shivaie

         Vol. 6. n. 4, pp. 2036-2047


Abstract - The restructuring of the power system has changed the traditional planning objectives and introduced challenges in the field of Transmission Expansion Planning (TEP). Due to these changes, new approaches are needed for transmission planning in the deregulated environment. Therefore, in this paper, a new framework is presented for Multi-Objective Transmission Expansion Planning. This framework is based on a multiple criteria decision making whose fundamental elements are REliability and MARKet (REMARK). Investment cost, congestion cost, Users' Benefit (UB) and Expected Customer Interruption Cost (ECOST) are considered in the optimization as objectives. The proposed model is a complicated non-linear mixed-integer optimization problem. A hybrid Genetic Algorithm (GA) and Quadratic Programming (QP) is used followed by a Fuzzy Sets Theory (FST) to obtain the final optimal solution. The planning methodology has been demonstrated on the 6 machine 8 bus test system to show the feasibility and capabilities of the proposed algorithm. Also, in order to compare the historical expansion plan and the expansion plan developed by the proposed methodology, it was applied to the part of a real life 400-kV transmission grid.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Electricity Market, Genetic Algorithm (GA), Multi-Objective Transmission Expansion Planning (MOTEP), Quadratic Programming (QP), Reliability.



go to top   Electric Substation Ancillary Services Power Consumption and Quality Monitoring and Analysis
         by Constantin Barbulescu, Stefan Kilyeni, Nicolae Chiosa, Dan Jigoria-Oprea

         Vol. 6. n. 4, pp. 2048-2058


Abstract - Power quality is the study of the sources, effects and control of disturbances which propagate via the electric power supply. The disturbances change the supply RMS voltage or its waveform (or very occasionally the frequency) and may originate from various sources. Within the paper, the authors are focusing on power quality monitoring. The presented approach refers to substation ancillary services power supply from the autotransformer tertiary winding. The voltage is the main qualitative element, influencing the proper operation of the consumers. That is why its quality practically defines the power quality. A real case study is discussed. Various electric quantities have been monitored. The results are discussed and the appropriate conclusions are highlighted.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Substations, Ancillary Services, Data Acquisition, Load Curve, Spline Functions, Forecasting, Neural Network, Power Quality, Power System Monitoring, Substations, Software Tool.



go to top   A Bi-Level Voltage Control Scheme of Power Systems via Automatic Zone Partitioning
         by Mohamed Shaaban

         Vol. 6. n. 4, pp. 2059-2067


Abstract - Future power systems should effectively provide a continuous and rapid closed-loop control of system voltage over a broad range of temporal and spatial horizons, and for large deviations from the normal operation. A two-stage voltage control strategy is presented in this paper to reset the reference voltage values of AVRs of synchronous generators, in a coordinated manner, to enhance the voltage profile on a system-wide basis. The power system is partitioned, automatically, into distinct voltage zones of closely coupled buses based on the concept of electrical distance. A pilot bus is then identified in each voltage zone that represents the most sensitive bus, in that zone, for the change of system operating conditions. A distributed control law is developed to control the voltage magnitudes at these pilot buses. The main feature of the developed control is that it abrogates the need for tertiary higher control level, allowing direct interaction between the zone controller and the AVRs in their respective zones. The proposed voltage control scheme is implemented on the IEEE 118 bus under practical system conditions and results are presented.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Power System Voltage Control, Reactive Power, Electrical Distance.



go to top   A Multi-Regional Model for Generation Expansion Planning after Restructuring in Developing Countries
         by Amir H. Fakehi, Mohammad B. Ghofrani, Yadollah Saboohi

         Vol. 6. n. 4, pp. 2068- 2078


Abstract - In many developing countries, restructuring is usually started by dividing vertically integrated power systems into regional companies. Analysis of the procedure of restructuring requires appropriate analytical tools for modeling interactive behavior of the regional companies in a competitive energy market. The problem of generation expansion planning in the competitive environment becomes more complex where the new generation units are constructed on the basis of decentralized decisions. Recent studies of long term expansion planning show that market equilibrium modeling is an effective technique to analyze the long-term optimum development of the generation systems. In the present paper, a Nash-Cournot Market Equilibrium model has been developed to predict the long-term expansion of generation system. Similar to some previous works, the conventional model has some shortcomings in practical applications and is complex due to large number of parameters and variables. Thus, to find an approximate solution for the proposed model, an algorithm based on a bi-level equilibrium method has been developed. Discounted net profit of market players has been considered as the objective function for each generation company which is to be maximized during the long term horizon. Implementation of the algorithm and its application in a case study over the southeastern power generation system of Iran has been presented. Results of case study show that the efficiency of the method in finding the equilibrium is higher than solving a complicated planning problem in competitive situation.

Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved


Keywords: Generation Expansion Planning, Linear Complementary Problem, Nash-Cournot Equilibrium, Restructuring in Developing Countries.



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