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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 1, Issue 4 - Dec 2006
Volume 1, Issue 3 - Sep 2006
Volume 1, Issue 2 - Jun 2006
Volume 1, Issue 1 - Mar 2006
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Damping Analysis using IEEEST PSS and PSS2A PSS
Lee Sang-Seung ; Kang Sang-Hee ; Jang Gwang-Soo ; Li Shan-Ying ; Park Jong-Keun ; Moon Seung-Il ; Yoon Yong-Tae ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 271~278
DOI : 10.5370/JEET.2006.1.3.271
This paper scrutinized the damping effects of installing the prototype PSSs by a transient analysis for eight buses of faults in the South Korean power system. The PSSs used have the co-PSS blocks for IEEEST model with a single input and the co+power PSS blocks for PSS2A model with dual inputs. The simulation tool was a TSAT(Transient Security Assessment Tool) developed by Powertech Labs Inc. The voltages of the transmission line for simulations were 765kV and 345kV, and the faults for eight cases were sequenced by considering the open state and the close state of the lines. In the simulations, the three-phase line to ground (L-G) fault generated different points for each region. The simulations were compared to the cases of no PSS, partial IEEEST and PSS2A, absolute IEEEST, and absolute PSS2A to show that the power system oscillation can be effectively damped by PSS modules. Simulations were conducted to confirm the effectiveness for the KEPCO (Korea Electric Power Corporation) power system.
A Method for Estimating an Instantaneous Phasor Based on a Modified Notch Filter
Nam Soon-Ryul ; Sohn Jin-Man ; Kang Sang-Hee ; Park Jong-Keun ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 279~286
DOI : 10.5370/JEET.2006.1.3.279
A method for estimating the instantaneous phasor of a fault current signal is proposed for high-speed distance protection that is immune to a DC-offset. The method uses a modified notch filter in order to eliminate the power frequency component from the fault current signal. Since the output of the modified notch filter is the delayed DC-offset, delay compensation results in the same waveform as the original DC-offset. Subtracting the obtained DC-offset from the fault current signal yields a sinusoidal waveform, which becomes the real part of the instantaneous phasor. The imaginary part of the instantaneous phasor is based on the first difference of the fault current signal. Since a DC-offset also appears in the first difference, the DC-offset is removed trom the first difference using the results of the delay compensation. The performance of the proposed method was evaluated for a-phase to ground faults on a 345kV 100km overhead transmission line. The Electromagnetic Transient Program was utilized to generate fault current signals for different fault locations and fault inception angles. The performance evaluation showed that the proposed method can estimate the instantaneous phasor of a fault current signal with high speed and high accuracy.
Realization of Information Visualization of Electric Power Monitoring System for MV/LV Distribution Customers
Kim Jae-Chul ; Chu Cheol-Min ; Knag Bong-Seok ; Kim Yeong-Il ; Choi Duck-Su ; Kim Kwang-Soon ; Ryu Seung-Ki ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 287~294
DOI : 10.5370/JEET.2006.1.3.287
Recently, switchboards for MV/LV distribution customers have been united and digitalized rapidly. This paper proposes the effective information visualization method for the data measured from cubicle switchboards for MV/LV distribution customers. We developed the algorithm that analyzes abundant data measured by switchboards and displays them to overall users, such as fire information index, power condition index, switchboard safety index, and power diminution index. Using a touch screen made users to operate it easily. User interface was also improved by taking graphic visualization. We guess the information visualization method suggested in this paper shows the new direction that heavy electrical equipments including switchboards are going to develop in the future.
An Improved Technique for Fault Location Estimation Considering Shunt Capacitance on Transmission Line
Kim Hyun-Houng ; Jeong Yun-Won ; Lee Chan-Joo ; Park Jong-Bae ; Shin Joong-Rin ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 295~301
DOI : 10.5370/JEET.2006.1.3.295
This paper presents a new two-terminal numerical algorithm for fault location estimation using the synchronized phasor in time-domain. The proposed algorithm is also based on the synchronized voltage and current phasor measured from the PMUs (Phasor Measurement Units) installed at both ends of the transmission lines. In this paper, the algorithm is given without shunt capacitance and with shunt capacitance using II -model and estimated using DFT (Discrete Fourier Transform) and LES (Least Error Squares Method). The algorithm uses a very short data window and classification for real-time transmission line protection. To verify the validity of the proposed algorithm, the Electro-Magnetic Transient Program (EMTP) and MATLAB are used.
Three-phase Transformer Model and Parameter Estimation for ATP
Cho Sung-Don ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 302~307
DOI : 10.5370/JEET.2006.1.3.302
The purpose of this paper is to develop an improved three-phase transformer model for ATP and parameter estimation methods that can efficiently utilize the limited available information such as factory test reports. In this paper, improved topologically-correct duality-based models are developed for three-phase autotransformers having shell-form cores. The problem in the implementation of detailed models is the lack of complete and reliable data. Therefore, parameter estimation methods are developed to determine the parameters of a given model in cases where available information is incomplete. The transformer nameplate data is required and relative physical dimensions of the core are estimated. The models include a separate representation of each segment of the core, including hysteresis of the core,
saturation characteristic and core loss.
Analysis on Current Distribution of Four-Layer HTSC Power Transmission Cable with a Shield Layer
Lim Sung-Hun ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 308~312
DOI : 10.5370/JEET.2006.1.3.308
The inductance difference between conducting layers of high-Tc superconducting (HTSC) power transmission cable causes the current sharing of each conducting layer to be unequal, which decreases the current transmission capacity of HTSC power cable. Therefore, the design for even current sharing in HTSC power transmission cable is required. In this paper, we investigated the current distribution of HTSC power cable with a shield layer dependent on the pitch length and the winding direction of each layer. To analyze the effect of the shield layer on the current sharing of the conducting layers of HTSC power cable, the current distribution of HTSC power cable without a shield layer was compared with the case of HTSC power cable with a shield layer. It could be found through the analysis from the computer simulations that the shield layer of HTSC power cable could be contributed to the improvement of current distribution of conducting layers at the specific pitch length and the winding direction of conducting layer. The result and discussion for the current distribution calculated for HTSC power transmission cable with a shield layer were presented and compared with the cable without a shield layer.
Enhancement of Interface Flow Limit using Static Synchronous Series Compensators
Kim Seul-Ki ; Song Hwa-Chang ; Lee Byoung-Jun ; Kwon Sae-Hyuk ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 313~319
DOI : 10.5370/JEET.2006.1.3.313
This paper addresses improving the voltage stability limit of interface flow between two different regions in an electric power system using the Static Synchronous Series Compensator (SSSC). The paper presents a power flow analysis model of a SSSC, which is obtained from the injection model of a series voltage source inverter by adding the condition that the SSSC injection voltage is in quadrature with the current of the SSSC-installed transmission line. This model is implemented into the modified continuation power flow (MCPF) to investigate the effect of SSSCs on the interface flow. A methodology for determining the interface flow margin is simply briefed. As a case study, a 771-bus actual system is used to verify that SSSCs enhance the voltage stability limit of interface flow.
Rotor Design to Improve Starting Performance of the Line-start Synchronous Reluctance Motor
Jung Tae-Uk ; Nam Hyuk ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 320~326
DOI : 10.5370/JEET.2006.1.3.320
A single-phase line-start synchronous reluctance motor (LSSynRM) has merits of low cost, high efficiency and reliability. LSSynRM has an unbalanced magnetic circuit caused by flux barriers and various shapes of conductor bars when starting. Thus the motor may generate unstable starting torque in accordance with the initial starting position of the rotor. This paper presents the rotor design to improve starting performance of the LSSynRM. Design variables are the number and the shape of the conductor bars. This design result is compared with the initial prototype and single-phase induction motor.
Analysis of Torque Characteristics for the Single-phase Induction Motor Considering Space Harmonics
Kim Byung-Taek ; Lee Sung-Ho ; Kwon Byung-Il ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 327~331
DOI : 10.5370/JEET.2006.1.3.327
This paper presents the analysis method for the torque characteristic of the 1-phase induction motor considering space harmonics in the air gap. The equivalent circuit method is used, where the circuit constants are obtained by classic theory. In addition, the space harmonic components in air gap magneto motive force are analyzed and added to the equivalent circuit to obtain accurate torque characteristics in low speed regions. Each torque component due to the harmonics is calculated and the total torque characteristic is obtained and compared with the measurement result.
Electronic Ballast with Constant Power Output Controller for 250W MH Lamp
Jung Dong-Youl ; Park Jong-Yeon ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 332~337
DOI : 10.5370/JEET.2006.1.3.332
In this paper, an electronic ballast was developed to control a 250W metal halide lamp. To avoid acoustic resonance phenomenon, we calculated the acoustic resonance band and determined the driving frequency from 70kHz to 100kHz. Due to the switching loss of MOSFET, many problems are caused in the inverter circuit during lamp lighting, so we reduced the loss by connecting the capacitor that minimizes the magnitude of the impulsive voltage. In this paper, the main point of research is to find the methods to operate the lamp on the rated output power. After detecting the current and the voltage of the lamp, we changed the driving frequency by adjusting the DC voltage level of the VCO input.
Power Loss Calculation of High Frequency Transformers
Choi Geun-Soo ; Yoon Shin-Yong ; Baek Soo-Hyun ; Kim Yong ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 338~342
DOI : 10.5370/JEET.2006.1.3.338
This paper analyzed the power loss of transformers considering the magnetic component. For this, each winding strategy and the effect of air gap between the ferrite core have been an important variable for optimal parameter calculation. Inductors are very well known design rules to devise, but the performance of the flyback converter as a function of transformer winding strategy has not been fully developed. The transformer analysis tool used was PExpert. The influence of the insulator thickness, effect of the air gap, how the window height and variation of the capacitive value effects the coil and insulator materials are some of parameters that have been analyzed in this work. The parameter analysis is calculated to a high frequency of 48[kHz]. Therefore, the final goal of this paper was to calculate and adjust the parameters according to the method of winding array and air gap minimizing the power loss.
A New High Efficient Bi-directional DC/DC Converter in the Dual Voltage System
Lee Su-Won ; Lee Seong-Ryong ; Jeon Chil-Hwan ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 343~350
DOI : 10.5370/JEET.2006.1.3.343
This paper introduces a new high efficient bi-directional, non-isolated DC/DC converter. Through variations of the topology of the conventional Cuk converter, an optimum bi-directional DC/DC converter is proposed. Voltage and current in the proposed DC/DC converter are continuous. Furthermore, the efficiency in both step-up and step-down mode is improved over that of the conventional bi-directional converter. To prove the validation for the proposed converter, simulations and experiments are executed with a 300W bi-directional converter.
Analysis of the Contactless Power Transfer System Using Modeling and Analysis of the Contactless Transformer
Ryu Myung-Hyo ; Kim Jong-Hyun ; Baek Ju-Won ; Cha Hon-Nyong ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 351~358
DOI : 10.5370/JEET.2006.1.3.351
In this paper, the electrical characteristics of the contactless transformer is presented using the conventional coupled inductor theory. Compared with the conventional transformer, the contactless transformer has a large airgap, long primary wire and multi-secondary wire. As such, the contactless transformer has a large leakage inductance, small magnetizing inductance and poor coupling coefficient. Therefore, large magnetizing currents flow through the entire primary system due to small magnetizing inductance, resulting in low overall system efficiency. In high power applications, the contactless transformer is so bulky and heavy that it needs to be split by some light and small transformers. So, the contactless transformer needs several small transformer modules that are connected in series or parallel to transfer the primary power to the secondary one. This paper shows the analysis and measurement results of each contactless transformer module and comparison results between the series- and parallel-connection of the contactless transformer. The results are verified on the simulation based on the theoretical analysis and the 30kW experimental prototype.
Development of Hard-wired Instrumentation and Control for the Neutral Beam Test Facility at KAERI
Jung Ki-Sok ; Yoon Byung-Joo ; Yoon Jae-Sung ; Seo Min-Seok ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 359~365
DOI : 10.5370/JEET.2006.1.3.359
Since the start of the KSTAR (Korea Superconducting Tokamak Advanced Research) project, Instrumentation and Control (I&C) of the Neutral Beam Test Facility (NB-TF) has been striving to answer diverse requests arising from various facets during the project's development and construction phases. Hard-wired electrical circuits have been designed, tested, fabricated, and finally installed to the relevant parts of the system. In relation to the vacuum system I&C, controlling functions for the rotary pumps, a Roots pump, two turbomolecular pumps, and four cryosorption pumps have been constructed. I&C for the ion source operation are the temperature and flow rate signal monitoring, Langmuir probe signal measurements, gradient grid current measurements, and arc detector circuit. For the huge power system to be monitored or safely operated, many temperature measurement functions have also been implemented for the beam line components like the neutralizer, bending magnet, ion dump, and calorimeter. Nearly all of the control and probe signals between the NB test stand and the control room were made to be transmitted through the optical cables. Failures of coolant flow or beam line vacuum pressure were made to be safely blocked from influencing the system by an appropriate interlock circuit that will shut down the extraction voltage application to the system or prevent damages to the vacuum components. Preliminary estimation of the beam power through the calorimetric measurement shows that 87.9% of the total power of the 60kV/18A beam with 200 seconds duration is absorbed by the calorimeter surface. Most of these I&C results would be highly appropriate for the construction of the main NBI facility for the KSTAR national fusion research project.
Determination of the NDR and Electron Transport Properties of Self-Assembled Nitro-Benzene Monolayers Using UHV-STM
Lee Nam-Suk ; Chang Jeong-Soo ; Kwon Young-Soo ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 366~370
DOI : 10.5370/JEET.2006.1.3.366
We investigated the negative differential resistance (NDR) property of self-assembled 4,4-di(ethynylphenyl)-2'-nitro-l-(thioacetyl)benzene ('nitro-benzene'), which has been well known as a conducting molecule , Self-assembly monolayers (SAMs) were prepared on Au (111), which had been thermally deposited onto pre-treated
Si, The Au substrate was exposed to a 1mM solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing of the sample, it was exposed to a
solution of nitro-benzene in dimethylformamide (DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. Following the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and
, and finally blown dry with
. Under these conditions, we measured the electrical properties of SAMs using ultra high vacuum scanning tunneling microscopy (UHV-STM) and scanning tunneling spectroscopy (STS) . As a result, we confirmed the properties of NDR in between the positive and negative region.
Electrical Properties of a High Tc Superconductor for Renewed Electric Power Energy
Lee Sang-Heon ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 371~375
DOI : 10.5370/JEET.2006.1.3.371
doping on the electromagnetic properties in the BiSrCaCuO superconductor. The electromagnetic properties of doped and undoped
in the BiSrCaCuO superconductor were evaluated to investigate the contribution of the pinning centers. It was confirmed experimentally that a larger amount of magnetic flux was trapped in the
doped sample than in the undoped one, indicating that the pinning centers of magnetic flux are related closely to the occurrence of the magnetic effect. We have fabricated superconductor ceramics by the chemical process. A high Tc superconductor with a nominal composition of
was prepared by the organic metal salts method. Experimental results suggest that the intermediate phase formed before the formation of the superconductor phase may be the most important factor. The relation between electromagnetic properties of Bi HTS and the external applied magnetic field was studied. The electrical resistance of the superconductor was increased by the application of the external magnetic field. But the increase in the electrical resistance continues even after the removal of the magnetic field. The reason is as follows; the magnetic flux due to the external magnetic field penetrates through the superconductor and the penetrated magnetic flux is trapped after the removal of the magnetic flux. During the sintering, doped
was converted to Ag particles that were finely dispersed in superconductor samples. It is considered that the area where normal conduction takes place increases by adding
and the magnetic flux penetrating through the sample increases. The results suggested that
acts to amplify pinning centers of magnetic flux, contributing to the occurrence of the electromagnetic properties.
Diagnostic Technique for Cast Resin Molded Transformer Windings Using Active Thermography
Lim Young-Bae ; Jung Jong-Wook ; Jung Jin-Soo ; Cho Seong-Won ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 376~380
DOI : 10.5370/JEET.2006.1.3.376
Temperature distribution measured to estimate the condition of an electrical apparatus is an absolute reference for the apparatus conditions and the difference between the reference temperature and the current temperature. Because of passive thermography, without the external thermal stimulation, the difference in surface temperature between the region of interest and back ground shows that the results can apply only to the estimation or the monitoring for the condition of loose terminal and the overload pertaining to the rise in temperature. However, a thermal diffusion in the active thermography is differently generated by the structure and condition of the surface and subsurface. This paper presents a nondestructive test using this behavior and deals with the results by heat injection and cooling to the apparatus. The buried discontinuity of subsurface could be detected by these techniques.
A Proposal of Simplified Eigenvalue Equation for an Analysis of Dielectric Slab Waveguide
Choi Young-Kyu ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 381~386
DOI : 10.5370/JEET.2006.1.3.381
In dielectric waveguide analysis and synthesis, we often encounter an awkward task of solving the eigenvalue equation to find the value of propagation constant. Since the dispersion equation is an irrational equation, we cannot solve it directly. Taking advantage of approximated calculation, we attempt here to solve this irrational dispersion equation. A new type of eigenvalue equation, in which guide index is expressed as a function of frequency, has been developed. In practical optical waveguide designing and in calculating the propagation mode, this equation will be used more conveniently than the previous one. To expedite the design of the waveguide, we then solve the eigenvalue equation of a slab waveguide, which is sufficiently accurate for practical purpose.
A Study on the Development of Measurement Techniques for Thermal Flows in MEMS
Ko Han-Seo ; Yang Sang-Sik ; Yoo Jai-Suk ; Kim Hyun-Jung ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 387~395
DOI : 10.5370/JEET.2006.1.3.387
A review on advanced flow visualization techniques is presented particularly for applications to micro scale heat and mass transport measurements. Challenges, development and applications of micro scale visualization techniques are discussed for the study of heating/evaporating thin films, a heated micro channel, and a thermopneumatic micro pump. The developed methods are (1) Molecular Tagging Fluorescence Velocimetry (MTFV) using 10-nm caged seeding molecules (2) Micro Particle Velocimetry (MPIV) and (3) Ratiometric Laser Induced Fluorescence (LIF) for micro-resolution thermometry. These three methods are totally non-intrusive techniques and would be useful to investigate the temperature and flow characteristics in MEMS. Each of these techniques is discussed in three-fold: (1) its operating principle and operation, (2) its application and measurement results, and (3) its future challenges.
3-Dimensional Numerical Analysis of Deep Depletion Buried Channel MOSFETs and CCDs
Kim Man-Ho ;
Journal of Electrical Engineering and Technology, volume 1, issue 3, 2006, Pages 396~405
DOI : 10.5370/JEET.2006.1.3.396
The visual analysis of buried channel (Be) devices such as buried channel MOSFETs and CCDs (Charge Coupled Devices) is investigated to give better understanding and insight for their electrical behaviours using a 3-dimensional (3-D) numerical simulation. This paper clearly demonstrates the capability of the numerical simulation of 'EVEREST' for characterising the analysis of a depletion mode MOSFET and BC CCD, which is a simulation software package of the semiconductor device. The inverse threshold and punch-through voltages obtained from the simulations showed an excellent agreement with those from the measurement involving errors of within approximately 1.8% and 6%, respectively, leading to the channel implanted doping profile of only approximately
error. For simulation of a buried channel CCD an advanced adaptive discretising technique was used to provide more accurate analysis for the potential barrier height between two channels and depletion depth of a deep depletion CCD, thereby reducing the CPU running time and computer storage requirements. The simulated result for the depletion depth also showed good agreement with the measurement. Thus, the results obtained from this simulation can be employed as the input data of a circuit simulator.