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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Electrical Engineering and Technology
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Journal DOI :
The Korean Institute of Electrical Engineers
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Volume & Issues
Volume 6, Issue 6 - Nov 2011
Volume 6, Issue 5 - Sep 2011
Volume 6, Issue 4 - Jul 2011
Volume 6, Issue 3 - May 2011
Volume 6, Issue 2 - Mar 2011
Volume 6, Issue 1 - Jan 2011
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Design of an Asymmetrical Three-phase Inverter for Load Balancing and Power Factor Correction Based on Power Analysis
Mokhtari, M. ; Golshannavaz, S. ; Nazarpour, D. ; Aminifar, F. ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 293~301
DOI : 10.5370/JEET.2011.6.3.293
This paper presents a novel theoretical method based on power analysis to obtain voltage reference values for an inverter-based compensator. This type of compensator, which is installed in parallel with the load, is usually referred to as the active filter. The proposed method is tailored to design the compensator in such a way that it can simultaneously balance the asymmetric load, as well as correct the power factor of the supply side. For clarity, a static compensator is first considered and a recursive algorithm is utilized to calculate the reactance values. The algorithm is then extended to calculate voltage reference values when the compensator is inverter based. It is evident that the compensator would be asymmetric since the load is unbalanced. The salient feature associated with the proposed method is that the circuit representation of system load is not required and that the load is recognized just by its active and reactive consumptions. Hence, the type and connection of load do not matter. The validity and performance of the new approach are analyzed via a numerical example, and the obtained results are thoroughly discussed.
Comparative Study of Two Congestion Management Methods for the Restructured Power Systems
Manikandan, B.V. ; Raja, S. Charles ; Venkatesh, P. ; Mandala, Manasarani ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 302~310
DOI : 10.5370/JEET.2011.6.3.302
Congestion management is one of the most challenging tasks of a system operator to ensure the operation of transmission system within operating limits. In this paper, cluster/zone method and relative electrical distance (RED) method for congestion management are compared based on the considered parameters. In the cluster/zone method, rescheduling of generation is based on user impact on congestion through the use of transmission congestion distribution factors. In the RED method, the desired proportions of generations for the desired overload relieving are obtained. Even after generation rescheduling, if congestion exists, load curtailment option is also introduced. Rescheduling cost, system cost, losses, and voltage stability parameter are also calculated and compared for the above two methods of congestion management. The results are illustrated on sample 6-bus, IEEE 30-bus, and Indian utility 69-bus systems.
Design of a generator control system for small nuclear distributed generation
Yoon, Dong-Hee ; Jang, Gil-Soo ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 311~318
DOI : 10.5370/JEET.2011.6.3.311
Small-scale reactors have recently attracted attention as a potential power generation source for the future. The Regional Energy Research Institute for Next Generation is currently developing a small-scale reactor called Regional Energy rX 10 MVA (REX-10). The current paper deals with a power system to be used with small-scale reactors for multi-purpose regional energy systems. This small nuclear system can supply electric and thermal energy like a co-generation system. The electrical model of the REX-10 has been developed as a part of the SCADA system. REX-10's dynamic and electromagnetic performance on the power system is analyzed. Simulations are carried out on a test system based on Ulleung Island's power system to validate REX-10 availability on a power system. RSCAD/RTDS and PSS/E software tools are used for the simulation.
An Iterative Technique for Real-Time Tracking of Power System Harmonics
Sidhu, T.S. ; Zadeh, M.R.D. ; Pooranalingam, P.J. ; Oh, Yong-Taek ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 319~327
DOI : 10.5370/JEET.2011.6.3.319
An iterative technique based on orthogonal filters and frequency tracking is proposed to estimate harmonic components in power systems. The technique uses frequency interpolation to estimate fundamental frequency and harmonics when the nominal frequency of the signal is a non-integer value. Due to the number of computations involved during the generation of filter coefficients, an offline computation is suggested. Beneficial features of the proposed technique include fixed sampling rate and fixed data window size. The performance of the proposed technique is examined by simulating different power system operating conditions and evaluating the data from these simulations. A technique based on Fast Fourier Transform is also used to estimate the harmonic components for all the simulated signals. These estimates are compared with those obtained from the proposed technique. Results show that the proposed technique can converge to the accurate fundamental frequency and therefore, provide accurate harmonic components even when the fundamental frequency is not equal to the nominal frequency.
An Algorithm on Optimal Placement Decision of Automatic Switches for 6 Sections/3 Links Configuration in DAS
Lim, Il-Hyung ; Zhang, Wen-Hao ; Trirohadi, Hamsyah ; Choi, Myeon-Song ; Lee, Seung-Jae ; Ha, Bok-Nam ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 328~333
DOI : 10.5370/JEET.2011.6.3.328
A Distribution Automation System (DAS) is operated by monitoring and control of the field statesusing Feeder Remote Terminal Units (FRTUs) installed together withautomatic switches.An optimal placement of automatic switchescan enhanceefficiencyof the operation and restoration, and improve the power supply reliability ofa DAS.This paper proposes an algorithm to decide the optimal placement of automatic switches ina DAS.The proposed algorithm was developed ona DAS witha six sections and three links configuration. The proposed algorithm was provided inaneight-feeder power distribution system.
Harmonic Elimination in Three-Phase Voltage Source Inverters by Particle Swarm Optimization
Azab, Mohamed ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 334~341
DOI : 10.5370/JEET.2011.6.3.334
This paper presents accurate solutions for nonlinear transcendental equations of the selective harmonic elimination technique used in three-phase PWM inverters feeding the induction motor by particle swarm optimization (PSO). With the proposed approach, the required switching angles are computed efficiently to eliminate low order harmonics up to the
from the inverter voltage waveform, whereas the magnitude of the fundamental component is controlled to the desired value. A set of solutions and the evaluation of the proposed method are presented. The obtained results prove that the algorithm converges to a precise solution after several iterations. The salient contribution of the paper is the application of the particle swarm algorithm to attenuate successfully any undesired loworder harmonics from the inverter output voltage. The current paper demonstrates that the PSO is a promising approach to control the operation of a three-phase voltage source inverter with a selective harmonic elimination strategy to be applied in induction motor drives.
Study of Rotor Asymmetry Effects of an Induction Machine by Finite Element Method
Abdesselam, Lebaroud ; Guy, Clerc ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 342~349
DOI : 10.5370/JEET.2011.6.3.342
This paper presents a study on rotor asymmetry caused by broken bars and its effects on the stator current of an induction machine under an unbalanced supply voltage. The simulation of the induction machine is based on the finite element method. In the early stage of diagnosis, we show new sidebands specific to the partial rupture of the rotor bar. Experimental tests corroborate with the simulation results.
Comparative Study of Stator Core Composition in Transverse Flux Rotary Machine
Lee, Ji-Young ; Moon, Seung-Ryul ; Koo, Dae-Hyun ; Kang, Do-Hyun ; Lee, Geun-Ho ; Hong, Jung-Pyo ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 350~355
DOI : 10.5370/JEET.2011.6.3.350
This paper deals with the comparison of magnetic characteristics in transverse flux rotary machine according to different stator core composition with the same rotor. Three different stator designs are considered in the analysis according to the material composition of inner and outer stator cores. Electromotive force (EMF), inductance, torque, and core losses are calculated by threedimensional finite element analysis. Calculated and measured results of back-EMF according to the analysis models in dependency on speed are presented.
Impact of Eccentricity and Demagnetization Faults on Magnetic Noise Generation in Brushless Permanent Magnet DC Motors
Rezig, Ali ; Mekideche, Mohammed Rachid ; Djerdir, Abdesslem ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 356~363
DOI : 10.5370/JEET.2011.6.3.356
Vibrations and noise in electrical machines are directly related to the characteristics of the radial forces on one hand, and mechanical behavior on the other [1, 4]. The characteristics of these forces depend on the air gap flux density, which is also influenced by other factors, such as stator slots and poles, saturation level, winding type, and certain faults. The aim of this work is to investigate the effect of eccentricity and demagnetization faults on electromagnetic noise generated by the external surface of Permanent Magnet Synchronous Machine [PMSM]. For this purpose, an analytical electromagnetic vibroacoustic model is developed. The results confirm the effect of eccentricity and demagnetization fault in generating some low modes radial forces.
Magnetic Interference on the Infrastructure for a Super-speed Tube Train
Lee, Hyung-Woo ; Jang, Seung-Yup ; Kang, Bu-Byoung ; Cho, Su-Yeon ; Lee, Ju ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 364~368
DOI : 10.5370/JEET.2011.6.3.364
The super-speed tube train was introduced to increase the speed of ground transportation. It levitates magnetically and runs in a partial vacuum tube, which significantly reduces air resistance. However, strong magnetic force sufficient to propel the massive train can affect the infrastructure. The induced eddy current produces joule heat, and raises the inside temperature of the girder, which might lead to electrochemical corrosion on the girder, thereby weakening its durability. In this paper, the authors analyzed the magnetic flux and induced eddy current in the reinforced concrete girder by using three-dimensional FEM, particularly by varying the number of reinforcing steels of the upper flange of the girder to the condition of almost the same flexural strength and reinforcing steel amount.
Comparison of Biot-Savart's Law and 3D FEM in the Study of Electromagnetic Forces Acting on End Winding
Kim, Ki-Chan ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 369~374
DOI : 10.5370/JEET.2011.6.3.369
An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot-Savart's law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.
Real-Time Hardware Simulator for Grid-Tied PMSG Wind Power System
Choy, Young-Do ; Han, Byung-Moon ; Lee, Jun-Young ; Jang, Gil-Soo ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 375~383
DOI : 10.5370/JEET.2011.6.3.375
This paper describes a real-time hardware simulator for a grid-tied Permanent Magnet Synchronous Generator (PMSG) wind power system, which consists of an anemometer, a data logger, a motor-generator set with vector drive, and a back-to-back power converter with a digital signal processor (DSP) controller. The anemometer measures real wind speed, and the data is sent to the data logger to calculate the turbine torque. The calculated torque is sent to the vector drive for the induction motor after it is scaled down to the rated simulator power. The motor generates the mechanical power for the PMSG, and the generated electrical power is connected to the grid through a back-to-back converter. The generator-side converter in a back-to-back converter operates in current control mode to track the maximum power point at the given wind speed. The grid-side converter operates to control the direct current link voltage and to correct the power factor. The developed simulator can be used to analyze various mechanical and electrical characteristics of a grid-tied PMSG wind power system. It can also be utilized to educate students or engineers on the operation of grid-tied PMSG wind power system.
Analysis of Insulation Quality in Large Generator Stator Windings
Kim, Hee-Dong ; Kong, Tae-Sik ; Ju, Young-Ho ; Kim, Byong-Han ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 384~390
DOI : 10.5370/JEET.2011.6.2.384
To evaluate the condition of stator winding insulation in generators that have been operated for a long period of time, diagnostic tests were performed on the stator bars of a 500 MW, 22 kV generator under accelerated thermal and electrical aging procedures. The tests included measurements of AC current (
), dissipation factor (
), partial discharge (PD) magnitude, and capacitance (C). In addition, the AC current test was performed on the stator winding of a 350 MW, 24 kV generator under operation to confirm insulation deterioration. The values of
, and PD magnitude in one stator bar indicated serious insulation deterioration. In another stator bar, the
measurements showed that the insulation was in good condition, whereas the values of
and PD magnitude indicated an incipient stage of insulation deterioration. Measurements of
and PD magnitude in all three phases (A, B, C) of the remaining generator stator windings showed that they were in good condition, although the
measurements suggested that the condition of the insulation should be monitored carefully. Overall analysis of the results suggested that the generator stator windings were in good condition. The patterns of PD magnitude in all three phases (A, B, C) were attributed to internal discharge.
Simulation on Surface Tracking Pattern using the Dielectric Breakdown Model
Kim, Jun-Won ; Roh, Young-Su ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 391~396
DOI : 10.5370/JEET.2011.6.3.391
The tracking pattern formed on the dielectric surface due to a surface electrical discharge exhibits fractal structure. In order to quantitatively investigate the fractal characteristics of the surface tracking pattern, the dielectric breakdown model has been employed to numerically generate the surface tracking pattern. In dielectric breakdown model, the pattern growth is determined stochastically by a probability function depending on the local electric potential difference. For the computation of the electric potential for all points of the lattice, a two-dimensional discrete Laplace equation is solved by mean of the successive over-relaxation method combined to the Gauss-Seidel method. The box counting method has been used to calculate the fractal dimensions of the simulated patterns with various exponent
and breakdown voltage
. As a result of the simulation, it is found that the fractal nature of the surface tracking pattern depends strongly on
Hydrodynamic Modeling for Discharge Analysis in a Dielectric Medium with the Finite Element Method under Lightning Impulse
Lee, Ho-Young ; Lee, Se-Hee ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 397~401
DOI : 10.5370/JEET.2011.6.3.397
The response of lightning impulse voltage was explored in dielectric liquids employing hydrodynamic modeling with three charge carriers using the finite element method. To understand the physical behavior of discharge phenomena in dielectric liquids, the response of step voltage has been extensively studied recently using numerical techniques. That of lightning impulse voltage, however, has rarely been investigated in technical literature. Therefore, in this paper, we tested impulse response with a tip-sphere electrode which is explained in IEC standard #60897 in detail. Electric field-dependent molecular ionization is a common term for the breakdown process, so two ionization factors were tested and compared for selecting a suitable coefficient with the lightning impulse voltage. To stabilize our numerical setup, the artificial diffusion technique was adopted, and finer mesh segmentation was generated along with the axial axis. We found that the velocity from the numerical result agrees with that from the experimental result on lightning impulse breakdown testing in the literature.
Simplified Ground-type Single-plate Electrowetting Device for Droplet Transport
Chang, Jong-Hyeon ; Kim, Dong-Sik ; Pak, James Jung-Ho ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 402~407
DOI : 10.5370/JEET.2011.6.3.402
The current paper describes a simpler ground-type, single-plate electrowetting configuration for droplet transport in digital microfluidics without performance degradation. The simplified fabrication process is achieved with two photolithography steps. The first step simultaneously patterns both a control electrode array and a reference electrode on a substrate. The second step patterns a dielectric layer at the top to expose the reference electrode for grounding the liquid droplet. In the experiment, a
thick photo-imageable polyimide, with a 3.3 dielectric constant, is used as the dielectric layer. A 10 nm Teflon-AF is coated to obtain a hydrophobic surface with a high water advancing angle of
and a small contact angle hysteresis of
. The droplet movement of 1 mM methylene blue on this simplified device is successfully demonstrated at control voltages above the required 45 V to overcome the contact angle hysteresis.
An Improved Distributed Equivalent Circuit Modeling for RF Components by Real-Coefficient AFS Technique
Kim, Koon-Tae ; Ko, Jae-Hyeong ; Paek, Hyun ; Kahng, Sung-Tek ; Kim, Hyeong-Seok ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 408~413
DOI : 10.5370/JEET.2011.6.3.408
In this paper, a real-coefficient approach to Adaptive Frequency Sampling (AFS) technique is developed for efficient equivalent circuit modeling of RF components. This proposed method is advantageous than the vector fitting technique and the conventional AFS method in terms of fewer samples leading to a lower order of a rational function on a given data and to a direct conversion to an equivalent circuit for PSPICE(Personal Simulation Program with Integrated Circuit Emphsis) simulation, respectively. To validate the proposed method, the distributed equivalent circuit of a presented multi-layered RF low-pass filter is obtained using the proposed real-coefficient AFS, and then comparisons with EM simulation and circuit simulation for the device under consideration are achieved.
Electrochemical Characteristics of Indium Tin Oxide Nanoparticles prepared by Sol-gel Combustion Hybrid Method
Chaoumead, Accarat ; Choi, Woo-Jin ; Lee, Dong-Hoon ; Sung, Youl-Moon ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 414~417
DOI : 10.5370/JEET.2011.6.3.414
Indium tin oxide (In:
) nanoparticles were synthesized employing a sol-gel combustion method followed by annealing. The TG, XRD, XPS and SEM results of the precursor powders and calcinated In:
nanoparticles were investigated. Crystal structures were examined by powder XRD, and those results show shaper intensity peak at
by increased annealing temperature. A particle morphology and size was examined by SEM, and the size of the nanoparticles was found to be in the range of 20~30nm. In:
films could controlled by nanoparticle material at various annealing temperature. The sol-gel combustion method was offered simple and effective route for the synthesis of In:
Compact Design of the Advanced Encryption Standard Algorithm for IEEE 802.15.4 Devices
Song, Oh-Young ; Kim, Ji-Ho ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 418~422
DOI : 10.5370/JEET.2011.6.3.418
For low-power sensor networks, a compact design of advanced encryption standard (AES) algorithm is needed. A very small AES core for ZigBee devices that accelerates computation in AES algorithms is proposed in this paper. The proposed AES core requires only one S-Box, which plays a major role in the optimization. It consumes less power than other block-wide and folded architectures because it uses fewer logic gates. The results show that the proposed design significantly decreases power dissipation; however, the resulting increased clock cycles for 128-bit block data processing are reasonable for IEEE 802.15.4 standard throughputs.
Temperature Control of Ultrasupercritical Once-through Boiler-turbine System Using Multi-input Multi-output Dynamic Matrix Control
Moon, Un-Chul ; Kim, Woo-Hun ;
Journal of Electrical Engineering and Technology, volume 6, issue 3, 2011, Pages 423~430
DOI : 10.5370/JEET.2011.6.3.423
Multi-input multi-output (MIMO) dynamic matrix control (DMC) technique is applied to control steam temperatures in a large-scale ultrasupercritical once-through boiler-turbine system. Specifically, four output variables (i.e., outlet temperatures of platen superheater, finish superheater, primary reheater, and finish reheater) are controlled using four input variables (i.e., two spray valves, bypass valve, and damper). The step-response matrix for the MIMO DMC is constructed using the four input and the four output variables. Online optimization is performed for the MIMO DMC using the model predictive control technique. The MIMO DMC controller is implemented in a full-scope power plant simulator with satisfactory performance.