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International Review of Electrical Engineering  Vol. 6 N. 5-- Part A

International Review of Electrical Engineering  Vol. 6 N. 5-- Part B

 

go to top     International Review of Electrical Engineering - October 2011 (Vol. 6 N. 5) - Papers Part A

 

 

go to top      International Review of Electrical Engineering - October 2011 (Vol. 6 N. 5) - Papers Part B

 

 

 


 

 

International Review of Electrical Engineering - Papers- Part A

 

go to top   High Power Factor Interleaved Buck AC/DC Converter with Boundary Conduction Mode
         by B. R. Lin, S. C. Huang

         Vol. 6. n. 5, pp. 2079-2087

 

Abstract - This paper presents the system analysis and circuit implementation of high power factor interleaved buck AC/DC converter with boundary conduction mode (BCM) to achieve power factor correction (PFC) and regulate DC bus voltage. Two buck converter cells are driven in the interleaved fashion. The current ripples at input and output sides are partially cancelled and the current stresses of semiconductors can be reduced. The BCM operation is adopted to control switches such that the input current is followed the AC source voltage with a nearly unity power factor. The buck AC/DC converter improves the circuit efficiency across the wide line ranges and load conditions compared to the efficiency of boost PFC circuit. The low output voltage can also reduce the voltage stress of semiconductors in the second DC/DC converter. Finally, experiments taken from a 500W prototype are presented to verify the effectiveness of the proposed converter.

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Keywords: Buck AC/DC Converter, Power Factor Correction (PFC), Boundary Conduction Mode (BCM)..

 


 

go to top   A New Zero Voltage Switching PWM Dual-Switch Forward Converter
         by E. Adib, A. Shirzadi, F. Saghaee

         Vol. 6. n. 5, pp. 2088-2093

 

Abstract - In this paper a new dual switch forward converter is introduced which uses a simple auxiliary circuit. In the proposed converter zero voltage switching condition is achieved for main switches while the auxiliary switch is soft switched. The proposed converter is analyzed and various operating modes are presented. Also, design considerations are discussed. Experimental results are presented which verifies the validity of theoretical analysis.

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Keywords: Dual Switch Forward Converter, Zero Voltage Switching (ZVS).
 


 

go to top   Generalized Space Vector PWM Algorithm for Minimizing THD in Hybrid Multilevel Inverters
         by  R.Karthikeyan, Dr.S.Chenthur Pandian

         Vol. 6. n. 5, pp. 2094-2099

 

Abstract - This paper proposes a generalized space vector pulse width modulation (SVPWM) technique for hybrid multilevel inverters for minimizing total harmonic distortion (THD). The proposed method easily determines the actual location of the instantaneous reference space vector and the corresponding switching sequence of a multilevel inverter. The proposed algorithm offers a novel method for minimizing the total harmonic distortion (THD) of the output voltage of the inverter and uses simple arithmetic for determining the sector and does not require lookup tables. The proposed method can be extended to any n-level inverter, and a generalized algorithm is also proposed. Finally, the algorithm was implemented on a Digital Signal Processor (DSP) and the scheme is explained for a five level inverter, and experimental results are presented for a five level inverter.

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Keywords: Hybrid Multilevel Inverter, Space Vector Pulse Width Modulation (SVPWM), Total Harmonic Distortion (THD).

 


 

go to top   Comparison of Five Level Active Neutral Point Clamped Derived Converters
         by L. Parvulescu, D. Floricau, M. Covrig

         Vol. 6. n. 5, pp. 2100-2105

 

Abstract - This paper presents a comparative study between two five-level converters. Control strategies and simulation results are presented in order to show the principles that led to the development of these converters. Advantages and disadvantages are presented in view of the power losses in the semiconductor devices and the power conversion efficiency. Experimental results are presented to prove the operation mode of the most recent converter.

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Keywords: Coupled Inductor, Flying Capacitor, Multilevel Converters, Power Losses.
 


 

go to top   Zero-Voltage-Switching Resonant SEPIC Converter
         by Hyun-Lark Do

         Vol. 6. n. 5, pp. 2106-2113

 

Abstract - A zero-voltage-switching (ZVS) resonant single-ended primary inductor converter (SEPIC) is presented in this paper. The voltage multiplier technique and active clamp technique are applied to the conventional SEPIC converter to increase the voltage gain, reduce the voltage stresses of the power switches and diode, and obtain ZVS of power switches. Moreover, by utilizing the resonance between the additional inductor and the capacitor in the voltage multiplier circuit, the zero-current-switching (ZCS) operation of the output diode is achieved and its reverse-recovery loss is significantly reduced. The proposed converter achieves high efficiency due to soft-switching characteristics of the power switches and output diode. The operation principle and steady-state analysis of the proposed converter are provided in detail. A prototype of the proposed converter is developed, and its experimental results are presented for validation.

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Keywords: SEPIC Converter, Voltage Multiplier, Zero-Voltage-Switching, Zero-Current- Switching.

 


 

go to top  Three-Phase Switched Capacitor Active Power Filter with Modified Artificial Neural Network and Flexible-Band Hysteresis
         by Mohd Amran Mohd Radzi, Nasrudin Abd. Rahim

         Vol. 6. n. 5, pp. 2114-2121

 

Abstract - This paper presents design and development of a three-phase switched capacitor active power filter (APF) to reduce line-current harmonics and operate in-phase with line voltage. Its control design combines a modified artificial neural network (ANN) harmonic detection technique and flexible-band hysteresis current control. The modified ANN with a suitable learning rate produces good and fast harmonic reference current for use in the switching algorithm, which performs flexible-band through embedded with band and without band hysteresis current control. MATLAB Simulink software verified the proposed APF’s topology and controller. A laboratory-built three-phase switched capacitor APF tested its feasibility. Simulation and experimental results verified its performance. It compensated harmonic current well, and the source current waveform became almost sinusoidal with near unity power factor. The results show that the three-phase switched capacitor APF with the modified ANN and the digital flexible-band hysteresis current algorithms could reduce THD and could increase power factor of the system.

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Keywords: Active Power Filter, Artificial Neural Network, Hysteresis, Harmonic, Power Factor.

 


 

go to top   Design and Study of Flexible LCCL Series Resonant Inverter for Induction Heating
         by Zhijuan Zhang, Neil W. Bergmann, Heming Li

         Vol. 6. n. 5, pp. 2122-2128

 

Abstract - A flexible LCCL load matching electrostatic coupling approach for SRI (series resonant inverters) of induction heating is proposed. It enables more flexible and convenient load matching through the multiple configurations of the matching series capacitors in the LCCL circuit. The LCCL resonant circuit topology and electrical characteristics are analyzed. The LCCL multiple capacitor configurations principle is given. The single phase full-bridge SRI for induction heating power supply prototype and SRI with output transformer are designed and tested by using an FPGA as the main controller. The experimental results validate the proposed approach and confirmed that the proposed approach can reach higher efficiency in contrast with the SRI with output transformer.

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Keywords: LCCL Circuit, Series Resonant Inverter, Induction Heating, Output Transformer.

 


 

go to top   Zero-Voltage-Switching Cuk Converter with Low Input Current Ripple
         by Hyun-Lark Do

         Vol. 6. n. 5, pp. 2129-2134

 

Abstract - A zero-voltage-switching (ZVS) Cuk converter with low input current ripple is proposed in this paper. This converter consists of a coupled inductor, an auxiliary serial inductor, a capacitor, and two power switches. Two separate inductors in the conventional Cuk converter are replaced with a coupled inductor. The coupled inductor in the proposed converter provides not only an input current with very low current ripple but also ZVS operation for both main and auxiliary switches. Due to ZVS operation of power switches, switching losses are significantly reduced and the efficiency is improved. The operation principle and steady-state analysis of the proposed converter are provided in detail. A prototype of the proposed converter is developed, and its experimental results are presented for validation.

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Keywords: Cuk Converter, Coupled Inductors, Zero-Voltage-Switching, Input Current Ripple.

 


 

go to top   A Low Cost Implementation of a Single-Phase Shunt Active Filter
         by B. Hekimoglu, M. Cakir, N. Abut

         Vol. 6. n. 5, pp. 2135-2143
 

Abstract - A low cost single-phase active filter with power factor correction and harmonic compensation capability for solving power quality problem is proposed. Adaline neural networks based reference current extraction with PI voltage regulation is presented for the control of the shunt active filter. Harmonic reductions and power factor correction will both be carried out by the proposed filter. The design of the current extraction with reduced number of sensors and the voltage control loop are explained. Experimental results are included to demonstrate the effectiveness of the proposed design scheme.

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Keywords: Shunt Active Filter, Power Factor Correction, Harmonic Compensation, Line Current Sensing, Adaline Neural Networks, Adaptive Noise Cancellation.
 


 

go to top   Integrated Zero-Voltage-Switching Boost Flyback Converter
         by Hyun-Lark Do

         Vol. 6. n. 5, pp. 2144-2151

 

Abstract - This paper proposes an integrated zero-voltage-switching (ZVS) boost flyback converter. Specifically, in the proposed converter, a boost inductor with an auxiliary winding is used to obtain ZVS of power switches and maintain a continuous input current. A half-bridge flyback is integrated in the proposed converter to provide a regulated output and obtain zero-current-switching (ZCS) of the output rectifier. The proposed converter achieves high efficiency due to soft-switching of all semiconductor devices. The operation principle and steady-state analysis of the proposed converter are provided in detail. A prototype of the proposed converter is developed, and its experimental results are presented for validation.

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Keywords: Boost Converter, Flyback Converter, Zero-Voltage-Switching, Zero- Current- Switching.

 


 

go to top  Interleaved Single-Stage PFC Converter with ZVS Turn-On
         by Bor-Ren Lin, Jhen-Yang Pan

         Vol. 6. n. 5, pp. 2152-2159

 

Abstract - This paper presents an interleaved single-stage power factor correction (PFC) converter. The circuit topology of the adopted single-stage AC/DC converter is based on a boost converter and an asymmetrical half-bridge flyback to achieve high power factor, zero voltage switching (ZVS) and load voltage regulation. Since the power switches are turned on and off with asymmetric pulse-width modulation (APWM) scheme, the resonant behavior by the leakage inductance and output capacitance of active switches at the transition interval can help active switches to be turned on at ZVS. In order to increase output power and reduce ripple current at input and output sides, two ZVS half-bridge converters with interleaved PWM scheme are connected in parallel in the proposed circuit. The boost converter is operated in discontinuous conduction mode (DCM) to automatically draw a sinusoidal line current from AC mains with high power factor and low current distortion. Finally, a laboratory prototype with 240W rated power has been implemented to verify the performance and feasibility of the proposed converter.

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Keywords: PFC, Interleaved PWM, DCM, APWM.

 


 

go to top   Three-Phase Cascaded Multilevel Inverter Based on Transistor-Clamped H-Bridge Power Cell
         by N. A. Rahim, M. F. M. Elias, H. W. Ping

         Vol. 6. n. 5, pp. 2160-2167

 

Abstract - This paper presents a new cascaded multilevel inverter based on five-level transistor-clamped H-Bridge power cell. With the proposed configuration, higher quality output is produced as compared to the conventional H-bridge (CHB) inverter with the same number of cells. Multicarrier phase-shifted pulse-width modulation technique is used to achieve balance power distribution between the cells. Analysis of line voltage harmonics and power losses are performed and compared with that of CHB. The effectiveness of the proposed inverter is verified through simulation and experimental tests on an induction motor.

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Keywords: Cascaded H-Bridge Inverter (CHB), Five-Level Inverter, Multilevel Inverter, Multicarrier Phase-Shifted Pulse-Width Modulation (PWM), Transistor-Clamped Inverter.

 


 

go to top   Control of ZCS-SR Inverter-Fed High Voltage DC-DC Converter by Digitally Tuning Tank Capacitance and Slightly Varying Pulse Frequency in Dual-Mode Operation
         by Sze Sing Lee, Shahid Iqbal, Mohamad Kamarol

         Vol. 6. n. 5, pp. 2168-2177

 

Abstract - Essentially, output voltage of an X-ray power supply for medical imaging application is required to stabilize very quickly without overshoot. In conventional pulse-frequency-modulated (PFM) zero current switching (ZCS) series resonant (SR) inverter-fed high voltage dc (HVDC) power supplies, the transient response is slow at low switching frequency. To address this problem, this paper proposes a new control scheme in dual-mode operation. In the proposed control scheme, the steady-state output voltage is controlled by digitally tuning tank capacitance and slightly varying pulse frequency of series resonant inverter. Quick rise of output voltage is achieved by operating the series resonant inverter in dual-mode frequency control. In this control strategy, the series resonant inverter is started with high switching frequency. As the output voltage reaches 90% of target value, the switching frequency is reduced to a value which corresponds to the target output voltage. This can effectively reduce the rise time of output voltage and prevent overshoot. To verify the performance of the proposed control scheme, a scale down laboratory prototype is built and tested. The experimental results reveal the excellent performance of the proposed control scheme.
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Keywords: HVDC Power Supply, Series Resonant Inverter.

 


 

go to top   Two Types of Voltage-Boosting Converters Based on PWM Control Strategy
         by K. I. Hwu, W. C. Tu, C. F. Chuang

         Vol. 6. n. 5, pp. 2178-2187

 

Abstract - Two simple voltage-boosting converters, based on charge pumps with one inductor inserted, are presented herein. Above all, by only changing the turn-on types for switches, without changing the circuit structure, there are two voltage conversion ratios to be generated easily. The proposed converters have individual simple operating analyses—if each converter operates in the continuous conduction mode (CCM), only two operating modes exist. Furthermore, the power switches used in each converter are easy to drive—only two half-bridge gate drivers and one low-side gate driver are needed and the voltage stress on the output diode can be reduced as compared to the traditional boost converter. In this paper, a brief illustration of basic operating principles of the proposed converters is firstly given, and secondly some experimental results are provided to demonstrate their effectiveness.

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Keywords: Charge Pump, Voltage-Boosting Converter, Voltage Stress.

 


 

go to top   Interleaved ZVS Active-Clamped Bidirectional DC-DC Converter for Hybrid-Electric Vehicles
         by G. Gatto, V. Isastia, I. Marongiu, S. Meo, A. Perfetto

         Vol. 6. n. 5, pp. 2188-2197

         DOI: http://dx.doi.org/10.15866/iree.v6i5.8483

 

Abstract - In the paper an interleaved soft switching dc-dc converter for applications in electric vehicle is proposed. The used topology raises the efficiency and the power density of the dc/dc converter minimizing switching losses by adopting a simple auxiliary active clamping circuit. Such auxiliary circuit is operational regardless of boost or buck mode of operation. The configuration guarantees fixed switching frequency, active clamped zero voltage switching operations of the main switches and bidirectional power flow. ZVS operations are guaranteed with wide load range. In the paper the operating principle, soft-switching conditions and steady state analysis are presented. A 27 kW prototype is designed and simulation results to verify the theoretical analysis are provided.

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Keywords: Interleaved, Bidirectional Dc-Dc converter, ZVS, Active Clamped.

 


 

go to top   Artificial Intelligence Based Techniques for Distinguishing Inrush Current from Faults in Large Power Transformers
         by A. R. Moradi, M. Ebadian, M. Yazdani-Asrami, M. Taghipour

         Vol. 6. n. 5, pp. 2198-2206

 

Abstract - The magnetizing inrush current phenomenon is a large transient condition, which occurs when a transformer is energized. The inrush current magnitude may be as high as ten times of transformer rated current that causes mal-operation of protection systems. Indeed, the similarity between signatures of inrush current and internal fault condition make this failure. So, for safe running of a transformer, it is necessary to distinguish inrush current from fault currents. It should be mentioned that, transformers outage may result in costly and time-consuming repair or replacement. In this paper, an Artificial Neural Network (ANN) which is trained by two different swarm based algorithms; Gravitational Search Algorithm (GSA) and Particle Swarm Optimization (PSO) have been used to discriminate between inrush current and fault currents in power transformers. In fact, GSA operates based on gravity law and in opposite of other swarm based algorithms, particles have identity and PSO is based on behaviors of bird flocking. Proposed approach has two general stages. In first step, obtained data from simulation have been processed and applied to an ANN, and then in second step, using training data considered ANN has been trained by GSA & PSO. Proposed technique has been compared with one of the common training approach which is called Back Propagation (BP) and finally, results show that proposed technique is so quick and can do discrimination very accurate and without any computational burdens.

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Keywords: Artificial Neural Network, Gravitational Search Algorithm, Inrush Current, Internal Faults, Particle Swarm Optimization, Power Transformers.

 


 

go to top   Impacts of Non-Sinusoidal Load Currents on Distribution Transformer Losses-Part I: Theoretical Aspects and Finite Element Based Simulation
         by M. Mirzaie, M. Yazdani-Asrami, S. B. Sadati, A. Shayegani Akmal

         Vol. 6. n. 5, pp. 2207-2214

 

Abstract - Power quality problems have negative effects on the energy system components. These problems such as voltage sags, voltage harmonics and especially current harmonics can severely impact the loads in electrical systems. Many transformers which installed to supply linear loads with sinusoidal currents have had their loads to be gradually replaced with non-linear loads that inject non-sinusoidal currents into power or distribution networks. These non-sinusoidal currents will increase losses and hence cause abnormal winding temperature rise which will decrease the expected lifetime of transformers. Such conditions require transformer load reduction or upgrading of component with a larger and more economical unit. The transformer loss is a critical problem because with the continuous increase in global electrical energy consumption, there is a necessity to improve the efficiency of transformers. Small reductions in transformer losses produce significant energy savings, since the number of transformers in power and distribution systems is high. Therefore, in today’s competitive environment, reduction of transformer losses will give a competitive advantage.
Finite Element Analysis consists of a computer model of a material or design that is stressed and analyzed for specific results. It is used in new product design and also, existing product refinement. Especially, this method is using in new electrical machine design procedures, now.
In this paper, as a first part of distribution transformer loss study, effects of non-sinusoidal current on distribution transformer have been evaluated and the transformer losses under non-sinusoidal load currents have been investigated using transformer model under non-linear loads. This model has been established and analyzed in PSCAD/EMTDC software package. Then, for validity check of results, the losses have been compared with results of finite element analysis in MAXWELL software.

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Keywords: : Current Harmonics, Derating, Finite Element Analysis, MAXWELL Software, Non-Sinusoidal Current, PSCAD/EMTDC Software, Transformer.

 


 

go to top   Impacts of Non-Sinusoidal Load Currents on Distribution Transformer Losses-Part II: Standard Aspects and Experimental Measurement
         by M. Mirzaie, M. Yazdani-Asrami, S. B. Sadati, A. Shayegani Akmal

         Vol. 6. n. 5, pp. 2215-2220

 

Abstract - Nowadays, reliability is an inevitable part of power system studies and operation, due to significant increase in the number of industrial electrical consumers. Transformer is one of the major and critical components in power system and distribution network in the area of reliability issue, since their outage may result in costly and time-consuming repair or replacement. Nowadays, loads of transformers are widely perturbed with harmonics. Harmonic components cause the transformer losses to increase and thus, transformer may fail to operate. In this paper, as a Part II of our study, effects of non-sinusoidal load currents on distribution transformer losses have been studied by means of IEEE standard and experimental measurement. For this purpose, the losses of a typical distribution transformer under non-sinusoidal loads have been measured. Afterwards, by considering harmonic spectrum of the used non-linear loads, transformer losses have been calculated using IEEE C 57.110 standard. Finally, obtained results have been compared. It should be mentioned that in Part I of this study, distribution transformer losses under non-sinusoidal load currents have been evaluated and calculated using Finite Element Method and a circuit based method by means of a transient software.

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Keywords: Compact Fluorescent Lamps, Derating, Distribution Transformers, Experimental Measurement, Harmonics, Losses, Non-Linear Loads.

 


 

go to top   Experimental Attempts and Field Experiences to Fault Diagnosis of Power Transformers using FRA Technique
         by H. Firoozi, S. Karami

         Vol. 6. n. 5, pp. 2221-2228

 

Abstract - Power transformer are considered as one of the essential elements in electrical networks. Any failure in these equipments directly reduces network reliability and increases maintenance costs. Consequently, the preventive maintenance techniques are increasingly developed. In this regard, Frequency Response Analysis (FRA) is an appropriate method in order to diagnose any change which occurs in transformer physical construction.
This contribution has concentrated on some challenging aspects through several experimental studies to achieve a better understanding of transformer frequency response variations. The sensitivity of FRA measurements due to some test conditions and set up arrangements is investigated which is determinable to achieve reliable measurements. Also, some practical measurements performed on some faulty power transformers which have led to quick fault diagnosing are represented. The obtained results are ultimately interesting and applicable for maintenance and fault diagnosis engineers to quickly fault diagnosis on the scene.

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Keywords: Power Transformer, Frequency Response Analysis (FRA), Fault Diagnosis.

 


 

go to top   High Thrust Density Transverse Flux Linear Motor: Thrust Analysis and Driving Method
         by M. R. Zare, M. Norhisam, N. Mariun, I. Aris, H. Wakiwaka, M. Nirei

         Vol. 6. n. 5, pp. 2229-2236

 

Abstract - This paper present characteristic model of a novel High thrust Density Transverse Flux Linear Motor (HDTFLM). The analytical method is explained, and its results are compared with the simulation. The simulation results for the thrust and cogging force of HDTFLM are validated with the measurement results. In this research a single-phase model was used that has the advantage of having independent magnetic circuit on each phase of the proposed HDTFLM. Moreover, a single-phase model consumes less time of simulation rather than a three-phase model. The simulation results of thrust are achieved using 3D-FEA. Finally, the prototype HDTFLM is derived with Permanent Magnet Stepper motor (PMST) configuration.

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Keywords: Linear Motor, High Thrust Density, Transverse Flux, Permeance, Finite Element Analysis (FEA).
 


 

go to top   Neural Network Speed Sensorless Direct Vector Control of Induction Motor using Fuzzy Logic in Speed Control Loop
         by Ben Hamed Mouna, Abid Aicha, Sbita Lassaad

         Vol. 6. n. 5, pp. 2237-2246

 

Abstract - This paper deals with performance analysis and implementation of a robust sensorless speed controller associated with a new direct rotor flux oriented control (DRFOC) for induction motor (IM) drives. The robustness s is guaranted by the use of a fuzzy logic controller. Due to the drawbacks of speed sensor, an intelligent algorithm is evolved to eliminate it. It is based on neural network theory. Besides, a new DRFOC scheme is investigated. It is based on the rotor flux components regulation. Experimental results for one kw IM are pesented and analyzed using a dSpace system with DS1104 controller board based on digital signal processor (DSP) TMS320F240. Simulation and experimental results are presented to show the validity and usefulness of the proposed algorithms.

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Keywords: IM, Speed Sensorless, Neural Network, DRFOC and Fuzzy Logic.

 


 

go to top   Flux Linkage Approach Used for Phase Inductance Computation of a Three Phase Tubular Linear PM Synchronous Actuator
         byI. Bensalem, L. El Amraoui Ouni, M. Benrejeb, F. Gillon, P. Brochet

         Vol. 6. n. 5, pp. 2247-2252

 

Abstract - The modeling of electrical machines by equivalent circuits requires an appropriate calculation of inductance values. The energy-perturbation and flux-linkage methods are extremely used to determine inductance values of electrical machines from two-dimensional finite element solutions. Both methods are numerically equivalent and give approximately the same values of inductance for axi-symmetric structures. However, the flux-linkage method requires less computation resources and is numerically more robust than the energy perturbation method. Hence, the flux linkage approach is chosen, for two-dimensional inductance calculation of a three phase tubular linear PM synchronous actuator. In this paper, the total flux in the (a,b,c) frame work are obtained from FE method and therefore include saturation and cross-couplings. The resulting inductance values are computed for different current densities and over one pole pitch and then stored on 3D Matlab functions to be used in the dynamical actuator modeling.

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Keywords: Flux-Linkage Approach, Inductance Computation, Magnetic Saturation, PM Linear Synchronous Actuator.
 


 

go to top   Optimization of Pole Numbers and Rotor Size for a Single Phase Slot-less Permanent Magnet Generator
         by M. Norhisam, M. Norafiza, F. Azhar, Nashiren F. Mailah, H. Wakiwaka, M. Nirei

         Vol. 6. n. 5, pp. 2253-2260

 

Abstract - This paper discussed on the optimization of a permanent magnet generator (PMG). Generally, the PMG is a slot-less type topology, operated in a single-phase, and it was developed to energize the linear motor in pruner application. Due to this application, a compact generator that can produce up to 100W output power is required since the overall size of the PMG is important. Permeance Analysis Method (PAM) is used to analyzed the PMG performance characteristic. Finite Element Method (FEM) and measurement of the PMG prototype were used to verify the PAM result. Various numbers of poles and rotor size were considered during this analysis. The results show that the slot-less PMG with stator size of 104 mm will produce maximum power of 110 W when it has 6-poles with rotor radius is 37 mm. Based on the results, the calculation method using PAM shows good agreement with measurement and FEM simulation.

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Keywords: Generator, Permanent Magnet, Permeance, Pole Numbers,Slot-Less.

 


 

go to top   Permanent Magnet DC Motor Friction Measurement and Analysis of Friction’s Impact
         by Miroslav Bjekic, Sanja Antic, Alenka Milovanovic

         Vol. 6. n. 5, pp. 2261-2269

 

Abstract - Accurate modeling of permanent magnet (PM) DC motors is a prerequisite for expeditious feedback design in many practical implementations such as electric drive powered mobility vehicles: scooters, wheelchairs, mobility vans, etc. The existing theoretical model, which is often used in the literature and by researchers, does not take into account all the existing frictions. Besides, the friction values are not generally known in advance. So, in order to accurately model a DC motor it is necessary either to measure the frictions values when the classical modeling approach can be used, or apply more sophisticated modeling techniques that are based on system identification. In this paper, the values of unknown static friction, Coulomb friction and viscous friction coefficient were obtained by measuring, using direct armature current control. For the viscous friction coefficient the temperature dependence and thus time dependence has been verified. In order to have an accurate model of a PM DC motor, the recursive least squares (RLS) method is used. Speed of a discrete Simulink model whose parameters were obtained using RLS identification is compared with measured system speed response. The responses are also compared with simulation velocity output when all frictions are neglected and with the simulation output attained using the classical approach when only viscous friction is taken into account. The results confirm the quality of the RLS modeling approach and show that for accurate modeling of a PM DC motor using the classical approach (when this approach can be used), all frictions should be considered. Experiments have been performed on a PM DC motor with a real-time data acquisition NI DAQ 6009 card.

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Keywords: Coulomb Friction, Direct Current Control, Permanent Magnet (PM) DC Motor, Static Friction, Viscous Friction, Recursive Least Squares (RLS) Identification Method.

 


 

go to top   Pole-Changing Line-Start Permanent Magnet Motors: Practical Points and Experimental Results
         by A. Damaki Aliabad, M. Mirsalim

         Vol. 6. n. 5, pp. 2270-2276

 

Abstract - Pole-changing of line-start permanent magnet motors at start-up has many advantages and approximately overcomes all of the drawbacks of these high efficient motors. This paper presents some practical and important points about this starting method and describes the suitable arrangements of stator windings at start-up. To actualize this method a three phase line-start permanent magnet motor with dahlander-type stator winding is fabricated. The practical circuit of pole-changing for various arrangements is described and the case study is simulated by using 2D finite element method. Finally, the experimental results are presented to verify the proposed method, and the theoretical concepts.

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Keywords: Line Start Permanent Magnet Motor, Pole-Changing Starting Method, Dahlander Type Stator Winding, Experimental Results.

 


 

go to top   Estimation End Effect of Single-Sided Linear Induction Motor by Using Discrete Wavelet Packet Transform and Artificial Neural Network
         by İ. Kıyak, G. Gökmen, F. Kentli

         Vol. 6. n. 5, pp. 2277-2285

 

Abstract - Thanks to developing technology, the linear motor applications have been getting popularity these days. Linear motors applications have been chosen in order to increase system performance and efficiency. In this paper, non-sinusoidal magnetic flux of the secondary surface was measured by measurement coils placed in the secondary block. After magnetic flux values placed end coils at entry and exit side of primary, they were remeasured. Measured magnetic flux values decomposed two components (end effect and main signals) by means of discrete wavelet packet transform and artificial neural network that operating with end coils and without end coils. Third level wavelet packet decomposition of measured magnetic values was carried out by Simulink wavelet filter bank and then decomposition signals of magnetic flux were obtained. To get obtain end effect and main signals, which use as target data for ANN model were synthesized respectively.

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Keywords: : Linear Induction Motor, End Effect, Wavelet Packet Transform, ANN, Wavelet Filter Bank.
 


 

go to top  Genetic Algorithm Application to Detect Broken Rotor Bar in Three Phase Squirrel Cage Induction Motors
         by Vahid Rashtchi, Ebrahim Rahimpour, Saeid Fazli

         Vol. 6. n. 5, pp. 2286-2292

 

Abstract - One of the most important faults of a three-phase squirrel cage induction motor is broken rotor bar. The detection of this fault is necessary to avoid outage of motor as swell as subsequent damage to other equipment. Present paper introduces a new systematic straightforward method based on parameter identification for accurate detection of this type of fault in order to help enhance the diagnosis system of induction motors. The proposed method uses a genetic algorithm (GA) with data collected from a simple experiment on the selected motor. The validity of the scheme is shown for a motor with ratings of 1 hp and 380 V, under different operating point conditions. The analysis and decision in the proposed method can be achieved within a proper time.

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

 

Keywords: Induction Motors, Fault Detection, Genetic Algorithm, Broken Bar.

 


 

go to top   Eddy Currents in Euler-Cauchy Magnetic Toroidal Cores
         by J. A. Brandão Faria

         Vol. 6. n. 5, pp. 2293-2301

 

Abstract - A recent topic of research, since 2011, Euler-Cauchy structures (ECS) are especial inhomogeneous cylindrical devices where exact closed-form analytical solutions of the wave equation can be found. This work presents a novel contribution to eddy current analysis in an ECS magnetic circuit where a coil is wound round a radially inhomogeneous magnetic core. Magnetic field and eddy current frequency-domain equations for homogeneous toroidal cores, with rectangular cross section, exhibit analytical solutions described by combinations of Bessel functions. However, in general, when the conductivity, permeability and permittivity of the core material depend on the radial coordinate an analytical solution cannot be encountered. Nonetheless, this paper shows, for the first time, that closed form solutions for the core’s electromagnetic field and coil’s impedance do actually exist provided that a specific type of radial variation of medium parameters is enforced. Analytic and computation results for general and particular ECS are presented and discussed.

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

 

Keywords: Complex Inductance, Eddy Currents, Euler-Cauchy Structures, Magnetic Toroidal Cores, Non-Homogeneous Media.
 


 

go to top   An Implementation of Induction Motor Drive with Half Wave Symmetrical SVM
         by M. Karabacak, H.I. Eskikurt, A. Öztürk

         Vol. 6. n. 5, pp. 2302-2309

 

Abstract - In this study, the half wave symmetrical Space Vector Pulse Width Modulation (SVM) is employed in a v/f controlled three phase induction motor drive system with the intention of reducing harmonic components of the three phase currents feeding to the induction motor windings without using any artificial intelligence algorithm. The most important part of induction motor drives is the inverter. Inverters are used to convert direct current to alternative current and to modulate amplitude and frequency of the converted alternative current. For control of inverters, various Pulse Width Modulation (PWM) methods have been proposed so far. Among them, SVM method is the most frequently preferred method since it has certain advantages over the other PWM methods. These are primarily efficient DC-bus voltage utilization, high harmonic performance and low switching losses. However, conventional SVM does not have half wave symmetry and hence even order harmonics appear in the output voltages of the inverter. The half wave symmetrical SVM can be achieved by utilizing a specific switching sequence and hence provides better harmonic performance while preserving all the other advantages of the conventional SVM. In this study, the SVM with such switching pattern is applied to an induction motor drive system in order to minimize harmonic components, especially low order harmonics, of the three phase currents feeding the motor windings.

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

 

Keywords: SVM, PWM, Space Vector, Scalar Control, Fourier Transform, Harmonic.
 


 

go to top  New Structures of IPM Machine for HEV Traction: Investigation on Field Weakening Performance and Harmonic Analyzing
         by J. Soleimani, A. Vahedi, A. Ejlali

         Vol. 6. n. 5, pp. 2310-2317

 

Abstract - Recently, Inner permanent magnet (IPM) synchronous motors are widely used in hybrid electric vehicles (HEVs) and vehicular applications, such as starters/alternators, power steering, and air conditioning motors. However, it was found that the performance of this motors is quite depended on field weakening operation. A convenient measure of field weakening performance is the constant power speed range (CPSR), which is the speed range at which the drive can maintain constant power with limited values of voltage and current. This paper presents a new structures of IPM synchronous motor for traction application with fragmental buried rotor magnets in order to achieve less torque ripple, less cogging torque, more power factor and electromagnetic torque per ampere improvement and presents the sensitivity analysis on effect of number of barriers is done using 3D-Finite Element Model, and discussed about harmonic analyzing, back EMF, power factor, cogging torque, Flux density, torque per ampere diagram, PM volume, efficiency, CPSR coefficient value behavior of IPMs. This study can help designers in design approach of such motors.

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Keywords: IPM Synchronous Motor, Barrier, 3D-FEM Model, Traction, Harmonic Analyzing, Field Weakening.

 


 

go to top   Optimal Design of a Surface Mounted Permanent-Magnet BLDC Motor for Spacecraft Applications
         by R.P. Praveen, M.H. Ravichandran, V.T. Sadasivan Achari, V.P. Jagathy Raj, G. Madhu, G.R. Bindu, F. Dubas

         Vol. 6. n. 5, pp. 2318-2328
 

Abstract - This paper presents the optimal design of a surface mounted permanent-magnet (PM) Brushless direct-current (BLDC) motor meant for spacecraft applications. The spacecraft applications requires the choice of a motor with high torque density, minimum cogging torque, better positional stability and high torque to inertia ratio. Performance of two types of machine configurations designed viz Slotted PMBLDC and Slotless PMBLDC with Halbach array and radial magnetization are compared with the help of analytical and finite-element (FE) methods. It is found that unlike a Slotted PMBLDC motor, the Slotless type with Halbach array develops zero cogging torque without reduction in the developed torque, suiting spacecraft applications. Moreover, the machine being coreless provides high torque to inertia ratio and zero magnetic stiction confirming to the requirements of spacecraft applications.

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Keywords: Brushless DC Motor, Slotted, Slotless, Halbach, Torque, Cogging, Space Application.

 


 

go to top   Rotor Position Robust Estimation Method for Sensorless IPMSM at Low Speeds including Standstill Operation
         by Gaolin Wang, Gang Li, Yong Yu, Fan Zhang, Dianguo Xu

         Vol. 6. n. 5, pp. 2329-2337

 

Abstract - A robust position observer of sensorless interior permanent magnet synchronous motor (IPMSM) adopting high frequency signal injection was proposed for low- and zero-speed operation. Rotor position error signal was obtained from magnitude of the produced high frequency currents by using pulsating high frequency voltage injection method. Both signal process and digital filter design were analyzed carefully. On the basis, a rotor position observer with improved robustness to load torque disturbance was presented. Theory design method for the robust observer was carried out considering the dynamic characteristic of load torque change. And pole assignment method was adopted for linear feedback matrix selection of the observer according to load disturbance and expected position estimation error. Experimental results demonstrate feasibility of the robust position estimation scheme by an IPMSM sensorless vector control drive.

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Keywords: : IPMSM, Sensorless Drive, Robust Position Observer, High Frequency Signal Injection, Low Speed Operation, Load Disturbance.
 


 

go to top   A Robust Fuzzy Supervisor Controller applied to a Permanent Magnet Synchronous Motor
         by M.Larbi, S. Hassaine, S. Moreau, B. Mazari

         Vol. 6. n. 5, pp. 2338-2344

 

Abstract - This paper presents an experimental study of a robust fuzzy supervisor PI controller applied to the speed of a Permanent Magnet Synchronous Motor (PMSM) supplied with a space vector modulation (SVM). The experimental results show that the fuzzy supervisor PI controller allows a better control than a classical PI controller in giving the high level of performance while maintaining the excellent response at the time of starting, speed reversal, load perturbation, steady state operation and guaranteeing robustness with respect to parameters variations of motor.

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Keywords: Fuzzy Logic, Speed Control, Permanent Magnet Synchronous Motor (PMSM), Robustness, Digital Signal Processor (DSP).

 


 

go to top   Analytical Calculation and Design of Permanent Magnets in a New Type Multi-DOF Motor Using Finite Element Method
         by Zheng Li

         Vol. 6. n. 5, pp. 2345-2350

 

Abstract - The superior performance of PM spherical Multi-DOF motors is introduced briefly in this paper, four kinds of permanent magnetic rotor design schemes for a new PM spherical Multi -DOF motors have been put forward. Static magnetic flux density modulus value calculation and static magnetic field analysis of every kind of permanent magnet structure are implemented, and then the torque features of permanent magnetic rotor structures in permanent magnet spherical multi-DOF motor are simulated under the circumstance of 3D finite element software. Finally the five cylinder structure of NdFeB rotor is manufactured instead of spherical structures. The experiment results demonstrate the effectiveness of the designed structure.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Spherical Motor, Permanent Magnet, Multi-DOF, 3D Magnetic Field, Finite Element.

 


 

go to top   Design of Robust Controller for PMSM Based on Improved PSO Algorithm
         by Guo-Jun Tan, Miao-Wang Qian, Hui Zhang, Zhi-Xun Ma, Rui-Wen Yu

         Vol. 6. n. 5, pp. 2351-2360

 

Abstract - An H∞ robust control scheme based on non-accurate mathematical model is presented in the paper in order to realize the high-performance control of permanent magnet synchronous motor (PMSM). The scheme could enhance the control performances of PMSM for the reason that various uncertainties are considered in the design of the robust controller. Then aiming at the difficulty of parameter optimization, an improved nonlinear-weight particle swarm optimization algorithm (NLPSO) is proposed for the parameter selection. And the optimization ability of NLPSO is tested and verified with 4 benchmark test functions. The results indicate that NLPSO has obvious advantage compared with standard particle swarm optimization algorithm (PSO) and linear-weight particle swarm optimization algorithm (LPSO). Finally, the experiment based on dSPACE demonstrates that the proposed robust control scheme has faster dynamic response and better load disturbance rejection capability compared with the conventional PI control scheme. Furthermore, the NLPSO algorithm is proved valid for parameter selection of the H∞ robust controller.

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

 

Keywords: Permanent Magnet Synchronous Motor, H∞ Robust Control, Particle Swarm Optimization Algorithm, Nonlinear Weight, Parameter Selection.
 


 

go to top   Design and Performance Analysis of Quadruple Winding Redundancy Brushless dc Torque Motor
         by S. Vijayshankar, N. Kannan, K. S. Jayakumar

         Vol. 6. n. 5, pp. 2361-2367

 

Abstract - This paper presents the design and performance analysis of frameless quadruple redundancy permanent magnet brushless dc torque motor. A novel method is adopted in stator assembly to isolate all four quadrant windings physically such that each quadrant behaves as a separate motor in a single stack leading to quadruple redundancy. Fractional slot stator assembly and permanent magnet rotor assembly conforming to the stator quadruple redundancy is designed. The volume of the stator assembly and rotor assembly are apportioned from the given overall envelope dimensions. The electrical loading and magnetic loading are worked out analytically for the desired torque and speed output. Preliminary designed motor is modeled in finite element based electromagnetic software for flux density analysis in the air gap, magnetic core and magnet return ring. Based on the magnetic analysis result proto type motor is fabricated and tested for performance comparison of all four quadrants.

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Keywords: Brushless Dc Motor, Finite Element Analysis, Fractional Slot, Frameless, Quadruple Redundancy.

 


 

go to top   Predictive Control of Brushless DC Generators
         by G. Gatto, I. Marongiu, S. Meo, A. Perfetto, A. Serpi

         Vol. 6. n. 5, pp. 2368-2375

 

Abstract - A predictive control of a brushless DC generator is presented in this paper. The tracking characteristic of the prime-mover is considered for setting the reference value of the electromagnetic torque developed by the generator. This reference is assumed in order to determine the switching pattern of the AC/DC converter, at each sampling period, under minimum Joule losses and minimum torque ripple constraints. In order to highlight the improved performances achievable by means of the proposed predictive control algorithm, two cases are considered: in the first one, the generator supplies a resistive load as in standalone applications, whereas, in the second one, it is connected to a constant voltage DC grid. Hence, the respective conversion systems are computer simulated in the Matlab Simulink environment and the results are compared to those of the traditional systems. The comparison reveals that, in both cases, the torque ripple minimization is achieved and more power can be delivered by using the proposed control technique with respect to those of traditional systems.

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

 

Keywords: Brushless Machines, Permanent Magnet Generators, Predictive Control, Torque Control.

 


 

go to top  Intelligent Unit Commitment with Plug-in Hybrid Electric Vehicles
         by Roozbeh Morsali, Ali Afkousi-Paqaleh, Noradin Ghadimi

         Vol. 6. n. 5, pp. 2376-2385

 

Abstract - Plug-in Hybrid Electric Vehicles (PHEV) technology has drawn great interest in the recent years. Vehicle-to-grid (V2G) is interconnection of energy storage of PHEVs and grid. By implementation of V2G dependencies of the power system on small expensive conventional units can be reduced, resulting in reduced operation cost. This paper proposes an intelligent unit commitment (UC) with V2G optimization based on Improved Harmony Search Algorithm (IHSA). IHSA was conceptualized using the musical process of searching for a perfect state of harmony, just as the optimization process seeks to find a global solution that is determined by an objective function. Intelligent UC with V2G optimization in power system is presented in this paper. Since the number of PHEV in V2G is relatively high, UC with V2G optimization problem is more complex than the basic UC. A case study based on conventional 10-unit test system is conducted to facilitate the effectiveness of the proposed method. Results show a significant amount of cost reduction with integration of V2G in UC problem. Comparison of the results with those obtained by Particle Swarm Optimization shows the effectiveness of the proposed method.

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

 

Keywords: Unit Commitment (UC), Vehicle-to-Grid (V2G), Improved Harmony Search Algorithm, Plug-in Hybrid Electric Vehicle (PHEV).

 

 

International Review of Electrical Engineering - Papers- Part B

 

go to top   A Novel Unified Power Flow Controller with Sub-Synchronous Oscillation Damping
         by M. Karbalaye Zadeh, H. Lesani, Sh. Farhangi

         Vol. 6. n. 5, pp. 2386-2400

 

Abstract - The unified power flow controller (UPFC) as a multi-objective flexible ac transmission system (FACTS) controller, can be utilized to control active and reactive power flows in a transmission line in addition to the bus voltage. Also UPFC can be utilized as a stabilizer in cooperation with the PSS which is discussed here. This paper scrutinizes the detailed analysis of sub-synchronous resonance (SSR) and torsional torques, arising from a power system employing Voltage Sourced Converter (VSC)-based FACTS such as UPFC. Also the main purpose of this paper is to present a damping control of VSC Back to Back (BtB) to relieve SSR in FACTS with series compensation. Furthermore a power controller loop is designed to power flow and reactive power control; both of two control loops are added to an UPFC in a transmission system. Concisely, this work presents the role of supplemental control of an existing VSC -BtB in SSR of a series compensated transmission power system. The supplemental controller is added to an existing VSC-based BtB tie in a transmission grid. The analysis considers different operating modes of the converters. The robustness of the considered supplemental control is tested by time domain nonlinear transient simulation, frequency analysis and also modal analysis. Moreover the frequency analysis is based on the α-β model and the transient simulation considers the α-β frame model and the three-phase detailed model of VSC. The influences of the operating modes of the converters and generator model are involved in this investigation.

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

 

Keywords: Unified Power Flow Controller, Sub-Synchronous Resonance (SSR), Reactive Power, Torsional Torque.

 


 

go to top   Optimal Management of Microgrid in Island-Mode Using Shuffled Frog-Leaping Algorithm
         by Reza Noroozian, Abolfazl Jalilvand, Majid Kazemi, Hesan Vahedi

         Vol. 6. n. 5, pp. 2401-2410

 

Abstract - The study presents the general microgrid architecture of an optimal power management to evaluate potential economic, technical and environmental benefits. In this paper, the system model components from some real manufactural data are constructed. Also, the optimal operating strategy and cost optimization scheme using Shuffled Frog-Leaping Algorithm has been presented in detail. The generation resources and load demand are optimally dispatched and able to operate in island-mode. The battery storage bank is used for charging and discharging modes. However, the proposed cost function takes into consideration the reduction of the emissions caused as well as the operation and maintenance costs. Numerical results show that the optimization strategy has been achieved in an actual Microgrid based on suitable island-mode of operation.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Microgrid, Cost Optimization, Shuffled Frog-Leaping Algorithm, Stand-Alone Operation.

 


 

go to top   Electrical Load Forecasting Using Support Vector Machines: a Case Study
         by Belgin Emre Türkay, Dilara Demren

         Vol. 6. n. 5, pp. 2411-2418

 

Abstract - In this study, an application with electrical load forecasting is made by a machine learning method that has recently become popular: Support Vector Machines (SVM). Load forecasting with SVM can model the nonlinear relation with the factors that affect the load in addition to the accurate modelling of the load curve at the weekends and on important calendar days. The data gathered from the Istanbul European Side are used as a sample for the application. In addition to the past load data, daily average temperature, calendar days, holidays and electricity price are considered as an attribute in forecasting. The program Libsvm is used for modelling the system. The results are compared with the Artificial Neural Network (ANN) and real values. In addition to that, another data set is constructed with the same values but without average daily temperatures to observe the effect of weather conditions in such an electrical load forecasting application. It is concluded that the Support Vector Machine algorithm is superior in both data sets to Artificial Neural Networks and is suitable for electrical load forecasting applications.

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Keywords: Artificial Neural Networks, Electrical Load Forecasting, Support Vector Machines.

 


 

go to top   Evaluation of Hopf Bifurcation Considering the Effect of Load Models and Excitation System Parameters
         by Nima Amjady, Mohammad Hossein Velayati

         Vol. 6. n. 5, pp. 2419-2427

 

Abstract - Power system stability is an important problem for power system operation. Determination of different stability margins can result in the optimum utilization of power system with minimum risk. Voltage stability is an important subset of power system stability. To correctly analyze the voltage stability of a power system, suitable dynamic models are usually required. Therefore, in this paper, the Hopf bifurcation boundary of voltage stability feasible region is analyzed by combination of time domain simulation (TDS), bifurcation theory and modal analysis of dynamic Jacobian matrices of power systems. Effect of different load models, branch contingencies and excitation system parameters on critical eigenvalues and participation factors of system states is evaluated. The test results are given for IEEE14 bus test system.

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

 

Keywords: Voltage Stability, Hopf Bifurcation, Static And Composite Load Models, Eigenvalue Analysis, Digsilent Software.
 


 

go to top   Interactive Multi-Objective Daily Operation Management of Distribution Network Considering Fuel Cell Power Plants
         by Javad Olamaei, Hamed Zeinoddini-Meymand

         Vol. 6. n. 5, pp. 2428-2439

 

Abstract - This paper presents an interactive fuzzy satisfying method based on Improved θ-Particle Swarm Optimization (Iθ-PSO) to solve the Multi-objective Optimal Operation Management (MOOM) problem which can be affected by Fuel cell power plants (FCPPs). The objective functions should be minimized are total electrical energy losses, total electrical energy cost, total pollutant emission produced by sources and deviation of bus voltages. A new interactive fuzzy satisfying method is presented to solve the multi-objective problem by assuming that the decision-maker (DM) has fuzzy goals for each of the objective functions. Through the interaction with the DM, the fuzzy goals of the DM are quantified by eliciting the corresponding membership functions. Then by considering the current solution, the DM acts on this solution by updating the reference membership values until the satisfying solution for the DM can be obtained. The MOOM problem is modeled as a mixed integer nonlinear programming problem. Therefore, in order to solve this problem, evolutionary methods because of independence on the type of objective function and constraints can be used. θ-PSO is based on the phase angle vector and can generate a high-quality solution within shorter calculation time in comparing with original PSO and other stochastic methods. θ-PSO the same as PSO is easy to fall into stagnation when no particle discovers a position that is better than its previous best position for several generations. In order to avoid this shortcoming, we have proposed an Improved θ-PSO algorithm to solve MOOM problems. Numerical results for a 69-bus distribution test system have been presented to illustrate the performance and applicability of the proposed method.

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

 

Keywords: Improved Θ-Particle Swarm Optimization (Iθ-PSO), Multi-Objective Optimal Operation Management (MOOM), Interactive Fuzzy Satisfying Method, Multi-Objective Optimization, Fuel Cell Power Plant (FCPP).

 


 

go to top   Optimal Wheeling Transaction based on Maximum Allowable Load of the Buyer Bus using HPSO with Cauchy Mutation
         by S.Venkatesan, Dr .N.Kamaraj S.Chellam

         Vol. 6. n. 5, pp. 2440-2447

 

Abstract - This paper describes a novel method to estimate maximum allowable load at the buyer buses for the estimated value of Independent Power Producer (IPP) without violating thermal limit for the best possible wheeling transaction in competitive electricity market. The above problems are formulated as a non-linear optimization problem. The proposed methodology consists of employing a developed optimal power flow based on estimating maximum load in each bus. A New Hybrid Particle Swarm Optimization (HPSO) with cauchy mutation on the best particle has been proposed to solve this problem. In the context of electricity market, transmission pricing is an important tool to achieve an efficient operation of the system. Therefore, Optimal-wheeling price for the feasible transaction is also determined to enhance efficient operation of the system. This new concept is illustrated on IEEE 30-bus system and Indian 69 bus utility systems.

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

 

Keywords: Cauchy Mutation, Hybrid Particle Swarm Optimization Independent Power Producer, Maximum Allowable Load, Wheeling Pricing, Wheeling Transaction.

 


 

go to top   Comparison of Harmony Search Algorithm and Particle Swarm Optimization for Optimal Placement and Sizing of Unified Power Flow Controllers in Deregulated Power Systems
         by D. Dehghani Mahmoudabadi, A. Rezazadeh, M. Sedighizadeh

         Vol. 6. n. 5, pp. 2448-2455

 

Abstract - This paper presents a Harmony Search Algorithm (HSA) to obtain the optimal location and parameters of Unified Power Flow Controller (UPFC) in deregulated electric power system. UPFC has great flexibility that can control the active and reactive power flow and bus voltages, simultaneously. UPFC is applied to maximize the system loadability subject to the transmission line capacity limits. HSA was conceptualized using the musical process of searching for a perfect state of harmony, just as the optimization process seeks to find a global solution that is determined by an objective function. The results of the proposed optimization problem are also obtained using the Particle Swarm Optimization (PSO) as the method of optimization. These results are compared with those obtained from HSA to show the effectiveness of the proposed method in finding the best solution for the optimization problem. The proposed approach is conducted and tested on IEEE 9-bus and IEEE 14-bus test systems. The results show that the loadability of the power transmission system can be effectively enhanced through the optimal location and proper parameters selection of the UPFC.

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

 

Keywords: Power System Loadability, Unified Power Flow Controller (UPFC), Harmony Search Algorithm, Particle Swarm Optimization.

 


 

go to top   Cascade Hydropower Plants Optimization with Honey Bee Mating Optimization Algorithm
         by Mihai Gavrilas, Vasile Stahie

         Vol. 6. n. 5, pp. 2456-2466

 

Abstract - The optimization of hydroelectric power plants operation is one of the most popular problems in the field of hydroelectricity. Concurrently with the traditional optimization methods, new methods appeared, based on stochastic search techniques, fuzzy logic or artificial neural networks. In the present work the authors propose to use a nature-inspired searching algorithm, namely Honey Bee Mating Optimization (HBMO) Algorithm, meant to optimize the operation of a hydroelectric system consisting of several hydroelectric plants in a cascade arrangement along the same sector of a river. The objective of the optimization problem consists in minimizing the amount of water necessary to produce a certain quantity of electricity, previously set on the basis of trading arrangements scheduled on the Day Ahead Electricity Market (DAEM).

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

 

Keywords: Hydroelectric Power Plants, Honey Bee Mating Optimization Algorithm, Reservoir Optimization, Power Generation.

 


 

go to top   Multi-objective Optimal Generation Location Using Non-dominated Sorting Genetic Algorithm-II
         by M. Y. Hassan, M. N. Suharto, M. P. Abdullah, M. S. Majid, F. Hussin

         Vol. 6. n. 5, pp. 2467-2476

 

Abstract - There has been an enormous increase in the global demand for energy especially in developing countries as a result of rapid industrial development, population growth and economic growth. Therefore, utilities are continuously planning the expansion of their power generation capacity to meet the increasing load demand by augmenting the existing power plant or setting up new power plant at new location. The location of new power plant affects many ways on power system network. This paper presents a multi-objective optimization approach to find the optimal location for installing a new generator in which the economic, environmental and technical aspects are taken into consideration. Hence, a multi-objective approach, based on the Non-dominated Sorting Genetic Algorithm-II (NSGA-II), has been employed to minimize simultaneously the cost of generation and emission levels of overall system subject to technical constraints by varying locations of the new generator. Moreover, an approach based on fuzzy set theory is adopted to extract one of the Pareto-optimal solutions as the best compromise solution. The proposed approach is tested on IEEE 30-bus system to illustrate its potential. Results show that the proposed approach is capable of determining the optimal generation location that can save the overall fuel cost as well as reduce the emission levels of generators in the network. The comparison with the classical technique demonstrates the superiority of the proposed algorithm.

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

 

Keywords: Optimal Generation Location, Generation Planning, Multi-objective Optimization, Non-dominated Sorting Genetic Algorithm-II.

 


 

go to top   Optimal Placement of Distributed Generation Using Shuffled Frog Leaping and Genetic Algorithms
         by A. Jalilvand, S. Jalilzadeh, M. Sabouri, M. R. Javadi

         Vol. 6. n. 5, pp. 2477-2482

 

Abstract - In this paper the Shuffled Frog Leaping Algorithm (SFLA) and Genetic Algorithm (GA) have been used for optimal placement of Distributed Generation (DG) in a primary distribution system to minimize the total real power loss. The SFLA and GA are used to determine optimal sizes and locations of multi-DGs to reduce the real power loss and improve the voltage profile. The exact loss has been calculated by using the distribution load flow; before and after DG installation. The results obtained from the proposed methodology applied to a 45-bus radial distribution system demonstrate its good performance and applicability. Test results indicate that SFLA and GA method can obtain better results than the simple heuristic search method. Also the results show that the SFLA is better than GA in order to obtain maximum loss reduction for each case of optimally placed multi-DGs. Moreover, it can be concluded that the voltage profile has been improved by using the proposed methods.

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

 

Keywords: Distribution System, Real Power Loss, Voltage Profile, Distributed Generation.

 


 

go to top   Islanding Detection of Wind Turbine DG Units Based on Frequency Analysis
         by Behrooz Sobhani, Hossein Kazemi Kargar, Noradin Ghadimi

         Vol. 6. n. 5, pp. 2483-2489

 

Abstract - This paper presents a passive islanding detection method based on frequency Analysis for wind turbines. The proposed method is based on frequency measurements and processing of the rate of change of frequency and accelerate of change of frequency. This method detects the islanding conditions with the analysis of these signals. The studies reported in this paper are based on time-domain simulations using MATLAB, and the feasibility of the proposed method is evaluated with an experimental system. The experimental system parameters are the same as those of the simulated system. The results show that the proposed islanding detection method succeeds in detecting islanding both in the experimental and simulated systems.

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Keywords: Distributed Generation, Islanding, Rate of Change of Frequency (ROCOF)-Wind Turbine, accelerate of change of frequency (ACOF).

 


 

go to top   Improved Time Variant PSO Based Design of Multiple Power System Stabilizer
         by H. Shayeghi, A. Ghasemi

         Vol. 6. n. 5, pp. 2490-2501

 

Abstract - The effective device for damping of the inter-area and intra-area low frequency oscillations is the Power System Stabilizers (PSSs) to enhance power system stability and optimal power flow. Optimal setting of the PSS parameters is importance and a challenging task to accommodate variations in the power system dynamics, particularly when several PSSs are used. Because, it is a multimodal optimization problem. In this paper, in order to reduce the PSS design effort and find the best possible solution a bio-inspired algorithm which called Particle Swarm Optimization with Time-Varying Acceleration Coefficients (PSO-TVAC) is presented for optimal tuning of multiple PSSs parameters, simultaneously. The non-linear time domain-based objective function under multiple operating conditions is used to determine the optimal parameters of PSSs. The PSO-TVAC uses a new parameter automation strategy to control both global and local search for considerable increasing the probability of finding the global optimum solution within a reasonable computation effort. The effectiveness of the proposed method is investigated on a two-area four machine power system in comparison with the classical PSO, bacterial foraging algorithm and conventional method based designed PSSs through the nonlinear time domain simulation and some performance indices for a wide range of loading condition. The results analysis reveals that the PSO-TVAC based PSSs is effective and provides good low frequency oscillations damping ability. Moreover, it is superior that of the other PSO method in terms of accuracy, convergence and computational effort.

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Keywords: PSO-TVAC, Multiple PSS Design, Multi-machine Power Systems, Particle Swarm Optimization, Power System Dynamics.

 


 

go to top   Voltage Sag Mitigation by Combining Optimal Network Reconfiguration and DSTATCOM Placement Using Gravitational Search Algorithm
         by N. Salman, A. Mohammed, H. Shareef

         Vol. 6. n. 5, pp. 2502-2512

 

Abstract - In this paper, a combination of two techniques for improving bus voltage magnitudes during voltage sag is presented. Initially network reconfiguration is applied to the exposed weak area in distribution systems. Then to further mitigate the voltage sag, DSTATCOM placement is considered as a second approach. Gravitational Search Algorithm (GSA) is considered as new heuristic optimization algorithm. It is used for finding the optimal solution in both proposed techniques. Suitable encoding methods are used to establish DSTATCOM location and to maintain radial structure of distribution network respectively. The simulation results show that the proposed method is efficient and feasible for improving the bus voltage profile during voltage sag considering the benefits obtained from the reduction of the financial losses by the load outages due to voltage sag problems. The proposed method may assist the utility engineers in taking the right decision for network reconfiguration and voltage sag mitigation.

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

 

Keywords: Voltage Sag, Network Reconfiguration, Distribution Systems, DSTATCOM, GSA And Power Quality.

 


 

go to top   Stochastic Assessment of Voltage Sags for Balanced and Unbalanced Faults
         by R. Jeyagopi, V.K. Ramachandaramurthy

         Vol. 6. n. 5, pp. 2513-2521

 

Abstract - Stochastic assessment is a technique to predict the severity and number of voltage sags at a bus of interest in the transmission and distribution network. In this paper, an analytical technique using secant technique is developed to predict the voltage magnitudes and duration due to balanced and unbalanced faults in unlimited buses in an electrical network. The proposed secant technique is compared with the method of critical distance and fault position method in terms of accuracy and practical application. The proposed technique was applied to an IEEE 24-buses electrical network to illustrate its application. The results show that the proposed technique is able to predict the voltage sag magnitude and duration at any buses and the number of sags per year for both balanced and unbalanced fault.

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Keywords: Power Quality, Stochastic Technique, Secant, Voltage Sags, Balanced And Unbalanced Fault.

 


 

go to top   Voltage Sag Source Location Based on Current Information Only
         by Mohammad H.Moradi, Younes Mohammadi, Hemen Showkati

         Vol. 6. n. 5, pp. 2522-2529

 

Abstract - This paper proposes a new method for voltage sag source location (upstream or downstream) in a powertransmission system.The proposed method uses current information only (during sag and pre sag) recorded by power quality (PQ)monitor.The variation of magnitude of measured current positive-sequence component and the sign of its phase-angle jumpis employed for relative location of voltage sag source. The proposed method is tested on an actual regional network including transmission and sub-transmission levels. This network is modeled using PSCAD/EMTDC and the output data are processed via MATLAB codes. This method is compared with distance relay (DR) and phase change in sequence current (PCSC) methods. The results state the good performance of the new method under both symmetrical and asymmetrical fault conditions in actual power systems and its unique applicability in cases where only current informationisavailable.

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Keywords: Power Quality (PQ), Voltage Sag (Dip), Positive-Sequence, Phase-Angle Jump,Source Location.

 


 

go to top   A New Power Quality Monitor Placement Method Using the Multivariable Regression Model and Statistical Indices
         by A. Kazemi, A. Mohamed, H. Shareef

         Vol. 6. n. 5, pp. 2530-2536

 

Abstract - This paper presents a new method for the placement of power quality monitors (PQMs) by using the multivariable regression (MVR) model and statistical indices. In this method, initially, the correlation coefficients (CC) which show the relationship between buses during system disturbances are calculated and the two buses with highest CC values are identified. These buses are considered as the most sensitive buses in the system. The identified bus voltages are then considered as independent variables in the developed MVR model to estimate the other bus voltages. Finally, the sum square error of the estimator, and mean square error are employed to obtain the Mallows Cp statistic. The appropriate number and placement of PQMs is then determined based on the lowest value of the Mallows Cp statistic. To illustrate the effectiveness of proposed method, the method is tested on two test systems, namely, the 6 bus and the IEEE 9 bus systems.

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Keywords: Power Quality Monitor Placement, Multivariable Regression, Correlation Coefficient, Mallows Cp Statistic
 


 

go to top   Researches on Power System Low-Frequency Oscillations Damping with FESS
         by Qingshan Xu, Haixiang Zang, Linjun Shi, Pengwei Du

         Vol. 6. n. 5, pp. 2537-2544

 

Abstract - With independent active and reactive power control capability, flywheel energy storage system (FESS) can be utilized for damping power system low-frequency oscillations by compensating for the imbalance power with appropriate control strategy. Mechanism of damping power system low-frequency oscillations with FESS is mainly discussed in this paper, based on damping torque analysis (DTA) method. Furthermore, it is also investigated about selection of the optimal installing location, damping control loop, feedback signal based on DTA, and FESS-based stabilizer design with phase compensation. All of the analytical conclusions have been confirmed by the simulation results based on a four-machine power system case.

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Keywords: FESS, Low-Frequency Oscillations, DFIM, Phillps-Heffron Model, DTA.

 


 

go to top  Self Adaptive Differential Evolution for Handling Economic Load Dispatch with Generator Constraints
         by Xiangtao Li, Minghao Yin, Xiaowei Zhao

         Vol. 6. n. 5, pp. 2545-2556

 

Abstract - Economic load dispatch (ELD) is a constrained optimization in power systems that have the objective of dividing the total power demand among the online participating generators economically. The ELD problem has nonsmooth cost function with equality and inequality constraints which make it difficult to be effectively solved. Different kinds of approaches have been proposed to solve this problem and obtained some achievements in previous study. In this paper, Self adaptive differential evolution (SADE) is proposed, in which both trail vector generation strategies and their associated control parameter values are gradually self adapted by learning from their previous experiences in generating promising solution. The proposed approach is tested with two power system cases consisting of 6 and 15 thermal units with generator constraints. Compared with other modern metaheuristic optimization techniques, the promising results illustrate the efficiency of the proposed method and show that the SADE could be used as a reliable tool for solving ELD problems with generator constraints.

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Keywords: Economic Load Dispatch, Differential Evolution, Self Adaptive Differential Evolution, Metaheuristics.

 


 

go to top   Maximizing Social Welfare in Double-Sided Auction Market by Placement and Sizing of TCSC using Coordinated Aggregation-Based Particle Swarm Optimization
         by Somayeh Hajforoosh, Seyed M.H Nabavi, Mohammad A.S. Masoum

         Vol. 6. n. 5, pp. 2557-2568

 

Abstract - : This paper presents a particle swarm optimization (PSO) based algorithm to perform congestion management and maximize social welfare by placement and sizing of one Thyristor-controlled series capacitor (TCSC) device in a double-sided auction market. Simulation results (with line flow constraints, before and after the compensation) are used to analyze the impact of TCSC on the congestion levels of the modified IEEE 14-bus and 30-bus test systems. The algorithm utilizes conventional quadratic smooth and augmented quadratic nonsmooth generator cost curves with sine components to improve the accurate of the model by incorporating the valve loading effects. It also employs quadratic smooth consumer benefit functions. However, consideration of valve point effect presents nondifferentiable and nonconvex regions in the model that introduced additional challenges in most gradient-based optimization algorithms. The proposed approach makes use of the PSO algorithm to allocate the near-optimal GenCos, DisCos and TCSC (location and size) while the Newton–Raphson solution minimizes the mismatch of the power flow equations. Several case studies are investigated to test and validate the consistency of detecting near-global solutions. Simulation results by the proposed PSO algorithm are compared to solutions obtained by sequential quadratic programming (SQP) and Fuzzy based genetic algorithm (Fuzzy-GA) approaches. The main contributions are inclusion of customer benefit in the congestion management objective function, consideration of nonsmooth generator characteristics and the utilization of a coordinated aggregation-based PSO for locating/sizing of TCSC.

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

 

Keywords: Congestion Management, Social Welfare, Double-Sided Auction Market, Rescheduling, TCSC, PSO.

 


 

go to top   Solving Economic Load Dispatch Problems with Valve Point Effects Using Artificial Bee Colony Algorithm
         by H. Shayeghi, A. Ghasemi

         Vol. 6. n. 5, pp. 2569-2577

 

Abstract - This paper addresses an Artificial Bee Colony (ABC) algorithm to find the feasible optimal solution of the economic load dispatch (ELD) problem with various generator constraints in power systems. For practical generator operation, many nonlinear constraints of the generator, such as ramp rate limits, prohibited operating zone, generation limits, transmission line loss and non-smooth cost functions are all considered using the proposed method. The ABC algorithm describes the food foraging behavior, memorizing and information sharing characteristics of honey bee swarm to find the best possible solution within a reasonable computation time. It carries out both global and local search in each iteration process for significant increasing the probability of finding the optimal solution and efficiently avoiding local optimum to a large extent. For this reason, ABC algorithm is used to solve ELD problem in order to efficiently control the local search and convergence to the global optimum and solution quality. Effectiveness of the proposed method is demonstrated for three different systems, including 6, 15 and 40 unit generating in comparison with the performance of the other recently optimization algorithms reported in the literature in terms of the solution quality and computation efficiency. The results analysis confirms that the proposed approach has an excellent capability to determine optimal solution of the ELD problems over the other existing methods and enhances efficiently the solutions quality of the power systems.

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

 

Keywords: Economic Load Dispatch, ABC, Valve point Effects, Heuristic Optimization.
 


 

go to top   Economic Load Dispatch of Proton Exchange Membrane for Residential Application Using PCOLONALG Algorithm
         by A. Pahlavanhoseini, A. Rezazadeh, F. Rastegari

         Vol. 6. n. 5, pp. 2578-2583

 

Abstract - Nowadays fuel cells are one of the most important candidates in power supply. Although vast progresses in fuel cell technology there are still some unsolved obstacles like economical problems, preventing their commercializing. Economic feasibility has a great role in fuel cell future. Now, fuel cell is used for micro-grid community power supply. In this paper a combined PSO and CLONAL algorithm optimization method, called as PCLONALG, is used to manage daily operation of Proton Exchange Membrane (PEM) Fuel Cell Power Plant (FCPP). Pay attention to FCPP management scenario, FCPP optimum loading for a seasonal loads is achieved. A comprehensive economical model of FCPP, considering electrical, thermal powers and hydrogen management also is introduced and employed to find optimal operation of FCPP. The results are compared with PSO optimization solutions.

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

 

Keywords: Economic Load Dispatch, Fuel Cell, PSO, PCLONALG.

 


 

go to top   Economic-Emission Load Dispatch by Refined Particle Swarm Optimization and Interactive Bi-Objective Programming
         by Po-Hung Chen, Cheng-Chien Kuo

         Vol. 6. n. 5, pp. 2584-2595

 

Abstract - This paper presents a novel solution approach that combines a refined particle swarm optimization (RPSO) with an interactive bi-objective programming (IBOP) to solve the economic-emission load dispatch (EELD) problem. In this work, two conflicting objective functions, fuel cost and emission, are considered concurrently in the optimization. The RPSO technique is developed to obtain a Pareto-optimal solution. The RPSO technique combines a basic PSO with novel binary encoding/decoding algorithms, which can prevent infeasible solutions, and a mutation operation, which can speed up convergence and escape local optima. The IBOP is then adopted to seek a best compromise solution by following the compromising intention of the decision maker. Moreover, the nonlinear characteristics of generation units and their operation constraints are all considered in this work for practical applications. The attractive properties of the proposed approach in both the solution quality and computational efficiency are demonstrated by three test systems and compared to those of existing methods. Experimental results reveal that the proposed approach can find the most suitable solution and exhibit robust convergence behavior.

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

 

Keywords: Economic-Emission Load Dispatch, Refined Particle Swarm Optimization, Interactive Bi-Objective Programming, Pareto-Optimal Solution.
 


 

go to top   Market Power Appearance through Game Theoretic Maintenance Scheduling of Distributed Generations
         by M. A. Fotouhi Ghazvini, A. Estebsari

         Vol. 6. n. 5, pp. 2596-2603

 

Abstract - The oligopoly structure of the market and the network constraints may produce results far from the perfect competition. Maintenance decisions in an oligopolistic electricity market have a strategic function, because GENCOs usually have impacts on market prices through capacity outages.This paper describes generation maintenance planning in an oligopolistic environment as a strategic decision. In this paper a game theoretic framework is modeled to analyze strategic behaviors of GENCOs. Each GENCO tries to maximize its payoff by strategically making decisions, taking into account its rival GENCOs’ decisions. Some GENCOs own DG units, such as wind, diesel, biomass and fuel cell plants. If different GENCOs find out they have the conditions of exerting market power exact in maintenance periods; they will share their data and they will cause some area monopolies. Cournot-Nash equilibrium is used for decision making on maintenance problem in Oligopolistic electricity market. The Cournot-Nash problem is modeled as a mixed integer nonlinear programming optimization problem. The analytic framework presented in this paper enables joint assessment of maintenance and generation strategies.

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

 

Keywords: Cournot-Nash Equilibrium, Game Theory, Distributed Generation, Maintenance Scheduling of Generating Units, Market Power, Monopolistic and Oligopolistic Market.

 


 

go to top   NSGA-II Optimized Neural Network Controlled Active Power Line Conditioner under Nonsinusoidal Conditions
         by D.Kavitha, Ahmed F. Zobaa, V.Suresh Kumar, P.Renuga

         Vol. 6. n. 5, pp. 2604-2610

 

Abstract - Optimization of total harmonic distortion (THD) and power factor subjected to power quality constraints for the evaluation of proposed Active power line conditioner (APLC) is carried out in this paper. Non dominated sorting genetic algorithm-II is used to obtain the reference source current to optimize both power factor and THD. The proposed APLC is evaluated using conventional fixed frequency variable slope (FFVS) technique and neural network which is trained from the samples obtained using FFVS. Computer simulations of the proposed APLC have been performed using MATLAB and the results are encouraging. The results show that the proposed APLC can reduce the total harmonics distortion of a specific non linear load from 25% to about 2% and improve the power factor close to unity under nonsinusoidal conditions.

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

 


 

go to top   The Performance of the Back-to-Back Converter to Control the Bidirectional Power Flow
         by A. J. Alcalá, V. Cárdenas, J. Pérez, R. Alvarez-Salas

         Vol. 6. n. 5, pp. 2611-2621

 

Abstract - This paper analyses the capability of the Back-to-Back (BTB) power converter to control the bidirectional power flow between two interconnected AC systems; to control the power flow a nonlinear control strategy is used. The system model is analyzed in the dq synchronous reference frame. The proposed system is studied in three different operating modes. The first case (mode 1), analyses the active power sharing; in the second case (mode 2), the capability of the BTB converter to control the bidirectional power flow is presented; and in the third case (mode 3), the bidirectional flow of active and reactive are controlled simultaneously. The system stability is explored considering several power transients using a BTB converter up to 30kVA and experimental tests are developed on micro scale prototype (10:1).

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

 

Keywords: Back-to-Back Converter, Decoupled Linear Control, Power Flow Control.

 


 

go to top   Two-Level Quasi Multi-Pulse Voltage Source Converter Based Generalized Unified Power Flow Controller
         by A.M. Vural, K.C. Bayindir

         Vol. 6. n. 5, pp. 2622-2637

 

Abstract - A multi voltage source converter (VSC) based flexible alternating current transmission system (FACTS) device, such as generalized unified power flow controller (GUPFC) has more control parameters than its successor unified power flow controller (UPFC). Owing to its multi VSC based configuration, GUPFC can concurrently control real/reactive power flows of two or more transmission lines and AC bus voltage magnitude. In this work, PSCAD/EMTDC model of GTO based GUPFC is developed consisting of two series-VSCs and a shunt VSC. Each VSC is designed in detail which is comprised of eight two-level VSCs, switching at fundamental frequency of 60 Hz. The so-called “2 angle method” is adapted to control both magnitude and phase angle of each VSC independently. Stability and the reasonable dynamic performance of GUPFC are ensured by the optimization of GUPFC’s six PI controllers using simplex method, which is a multi-parameter non-gradient optimization routine. The model is verified and tested in WSCC 3-machine 9-bus test system in different operating conditions and when the system is subjected to two types of fault. The results have proven that the tuned controllers are stable in all operation modes and GUPFC shows competence in dynamic control of real/reactive power flows of transmission lines and bus voltage.

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

 

Keywords: : Flexible AC Transmission Systems (FACTS); Generalized Unified Power Flow Controller (GUPFC), Quasi Multi-Pulse Voltage Source Converter, Simplex Method; Power Flow Control; Voltage Control.

 


 

go to top  Power Delivery by a Novel Multi-stage DC/AC Converter Based on Multilevel AC/AC Converter
         by
M. R. Banaei, E. Salary

         Vol. 6. n. 5, pp. 2638-2644

 

Abstract - This paper presents a novel topology for multi-stage converter. The proposed circuit consists of three-parts: H-bridge voltage source converter, high or medium frequency (HF or MF) transformer and AC/AC converter. The proposed converter can generate staircase (near sinusoidal) output voltage and it can change voltage level. This converter can be used as symmetric or asymmetric converter. In many applications it may be available through renewable energy sources such as photovoltaic panels or fuel cells or with energy storage devices such as capacitors or batteries. Simulation results carried out by MATLAB/SIMULINK show the voltage production capability of converter.

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

 

Keywords: Distributed Generation, Symmetric Converter, Asymmetric Converter, AC /AC Converter.

 


 

go to topOperational Conveyor-Based Precision Full-Wave Rectifier
         by Slobodan R. Djukic, Zoran Z. Ebersold, Milan D. Veskovic

         Vol. 6. n. 5, pp. 2645-2651

 

Abstract - Precision full-wave rectifier with operational conveyor and current mirrors is presented in this paper. Operational conveyor circuit topology based on current-steering output stage and unity-gain current mirror, are also described and analyzed. Precision full-wave rectifier is realized with operational conveyor as voltage to current converter, four unity-gain current mirrors and three DC current sources. PSPICE program was used to verify the proposed design of the operational conveyor and precision full-wave rectifier. The results of the simulation are presented and compared with simulation results of the realization that was published.

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

 

Keywords: Rectifier, Operational Conveyor, Current Conveyor, Current Mirror.

 


 

go to top   Analysis of Transient Recovery Voltage in 400 kV SF6 Circuit Breaker Due to Transmission Line Faults
         by Božidar Filipović-Grčić, Ivo Uglešić, Dalibor Filipović-Grčić

         Vol. 6. n. 5, pp. 2652-2658
 

Abstract - Transient recovery voltage (TRV) is calculated according to the IEC standards and using the EMTP-ATP software. Modeling of electric arc for the SF6 circuit breaker is presented. Influence of grading capacitors and line bay disposition on the TRV waveform on the side of the line in a 400 kV substation is analyzed for the short-line fault (SLF) conditions. Fault location at which the rate of rise of recovery voltage (RRRV) is the highest was determined using the EMTP-ATP simulations. Results obtained according to the IEC standards and using the EMTP-ATP are compared.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Transient Recovery Voltage, Short-Line Fault, SF6 Circuit Breaker, Electric Arc Model, EMTP Simulations.

 


 

go to top   Busbar Temperature Monitoring and Correlation with Protection Electrical Apparatus
         by Adrian Pleşca

         Vol. 6. n. 5, pp. 2659-2665

 

Abstract - Busbar technology is more and more used to realize connections within power supply systems in answer to the need of compactness. The integrated problem on heat conduction and radiation-convective heat exchange describes the temperature regime in current conductors and current carrying busbars of power electrical apparatus such as circuit breakers or high breaking capacity fuses. Beside steady-state conditions, the transient thermal regime of busbar has an important influence upon whole power supply system from thermal behaviour point of view. Hence, an on-line temperature monitoring system of busbars has been developed. Also, the thermal transient impedance for the busbar has been computed. This allows a better correlation between protection characteristics of the fuse and circuit breaker and busbar desig.

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

 

Keywords: Busbar, Temperature Monitoring, Protection Characteristics.
 


 

go to top   Feasible Installation of Transmission Line Surge Arresters to Decrease Lightning Transient Over-Voltages in Power Systems
         by M. Majidi, H. Javadi

         Vol. 6. n. 5, pp. 2666-2674

 

Abstract - This paper studies lightning transient over-voltages in substations which their transmission lines directly have been connected to auto-transformers via high voltage cables. Generally, this configuration can be seen in Gas Insulated Substations (GIS) which has GIS bus model on a voltage level side and has AIS bus model on the other side of voltage level. These lightning transient over-voltages may cause many destructive effects such as: cable damages in these substations. In addition, existed surge arresters in this system cannot confine over-voltage amplitudes. Thus, feasibility studies (determining quantity and optimum placement) of installing line surge arrester are presented. Reviewing the behaviors of these swift over-voltages can help substation designers to decide optimally. This paper can be a valuable guide for them to configure substation equipment and network elements efficiently. The 230kV bus configuration of 400/230kV Bushehr GIS has been considered as a real case study and EMTP-RV software environment is also used to simulate transient over-voltages due to lightning stroke.

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

 

Keywords: Lightning Over-Voltages, Transmission Line Surge Arrester, GIS, XLPE Cable, EMTP-RV.

 


 

go to top   Comparative Study of Streamers in Natural Esters for High Voltage Applications and Nutrition Esters under Lightning Impulse Voltage
         by Viet-Hung Dang, A. Beroual , C. Perrier

         Vol. 6. n. 5, pp. 2675-2680

 

Abstract - This paper reports on both initiation and propagation phases of streamers in natural esters (vegetable oils) for high voltage applications, in a point – plane electrode arrangement under lightning impulse voltage (1.2/50 µs). Four treated oils (VO1/G, VO2/F, VO3/E and VO4/H) and three untreated oils (natural ester for nutrition) extracted from grape seeds (GS), sunflower (SF) and rape seed (RS) are investigated. A synthetic ester (SE1/D) is also tested for comparison. It’s shown that the streamers are filamentary in the different tested oils whatever the polarity. For a given voltage, the stopping lengths (Lf) and velocities of streamers are generally close enough whatever the kind of oil. The values of Lf as well as the velocities are more important with a positive point than with a negative one. In the view point of stopping lengths and velocities of streamers, there is no difference between treated and untreated vegetable oils.

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Keywords: Vegetable Oils, Streamers, Stopping Length, Velocity, Current and Electrical Charge.

 

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