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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 2, Issue 4 - Dec 2007
Volume 2, Issue 3 - Sep 2007
Volume 2, Issue 2 - Jun 2007
Volume 2, Issue 1 - Mar 2007
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Fault Current Limiting Characteristics of Separated and Integrated Three-Phase Flux-Lock Type SFCLs
Lim, Sung-Hun ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 289~293
DOI : 10.5370/JEET.2007.2.3.289
The fault current limiting characteristics of the separated and the integrated three-phase flux-lock type superconducting fault current limiters (SFCLs) were analyzed. The three-phase flux-lock type SFCL consisted of three flux-lock reactors and three
superconducting (HTSC) elements. In the integrated three-phase flux-lock type SFCL, three flux-lock reactors are connected on the same iron core. On the other hand, three flux-lock reactors of the separated three-phase flux-lock type SFCL are connected on three separated iron cores. The integrated three-phase flux-lock type SFCL showed the different fault current limiting characteristics from the separated three-phase flux-lock type SFCL that the fault phase could affect the sound phase, which resulted in quench of the HTSC element in the sound phase. Through the computer simulation applying numerical analysis for its three-phase equivalent circuit, the fault current limiting characteristics of the separated and the integrated three-phase flux-lock type SFCLs according to the ground fault types were compared.
A Special Protection Scheme Against a Local Low-Voltage Problem and Zone 3 Protection in the KEPCO System
Yun, Ki-Seob ; Lee, Byong-Jun ; Song, Hwa-Chang ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 294~299
DOI : 10.5370/JEET.2007.2.3.294
This paper presents a special protection scheme, which was established in the KEPCO (Korea Electric Power Corporation) system, against a critically low voltage profile in a part of the system after a double-circuit tower outage. Without establishing the scheme, the outage triggers the operation of a zone 3 relay and trips the component. This sequence of events possibly leads to a blackout of the local system. The scheme consists of an inter-substation communication network using PITR (Protective Integrated Transmitter and Receiver) for acquisition of the substations' data, and under-voltage load shedding devices. This paper describes the procedure for determining the load shedding in the scheme and the experiences of the implementation.
Investigation and Mitigation of Overvoltage Due to Ferroresonance in the Distribution Network
Sakarung, Preecha ; Bunyagul, Teratam ; Chatratana, Somchai ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 300~305
DOI : 10.5370/JEET.2007.2.3.300
This paper reports an investigation of overvoltages caused by ferroresonance in the distribution system, which consists of a bank of open-delta single-phase voltage transformers. The high voltage sides of the voltage transformer are connected to the distribution system via three single-phase fuse cutouts. Due to the saturation characteristic of the transformer cores, ferroresonance can occur in the condition that the transformer is energized or deenergized with single-phase switching operation of the fuse cutouts. The simulation tool based on EMTP is used to investigate the overvoltages at the high side of voltage transformer. Bifurcation diagrams are used to present the ferroresonance behavior in ranges of different operating conditions. The simulation results are in good agreement with the results from the experiment of 22 kV voltage transformers. The mitigation technique with additional damping resistors in the secondary windings of the voltage transformers will be introduced. Brief discussion will be made on the physical phenomena related to the overvoltage and the damage of voltage transformer.
Measurement of Transient Electric Field Emission from a 245 kV Gas Insulated Substation Model during Switching
Rao, M. Mohana ; Thomas, M. Joy ; Singh, B.P. ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 306~311
DOI : 10.5370/JEET.2007.2.3.306
The transient fields generated during switching operations in a Gas Insulated Substation (GIS) are associated with high frequency components in the order of few tens of MHz. These transient fields leak into the external environment of the gas-insulated equipment and can interfere with the nearby electronics. Measurements of the transient fields are thus required to characterise the interference caused by switching phenomena in such substations. In view of the above, E-field emission measurement during a switching operation has been carried out for a 245 kV GIS model, using a resonant dipole antenna and D-dot sensor. The characteristics of the E-fields i.e., frequency spectra and their levels have been analysed and are reported in the paper. Suitability of the measurements has been confirmed by comparing frequency spectra of the measured and computed transient fields.
A New Concept of Power Flow Analysis
Kim, Hyung-Chul ; Samann, Nader ; Shin, Dong-Geun ; Ko, Byeong-Hun ; Jang, Gil-Soo ; Cha, Jun-Min ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 312~319
DOI : 10.5370/JEET.2007.2.3.312
The solution of the power flow is one of the most important problems in electrical power systems. These traditional methods such as Gauss-Seidel method and Newton-Raphson (NR) method have had drawbacks up to now such as initial values, abnormal operating solutions and divergences in heavy loads. In order to overcome theses problems, the power flow solution incorporating genetic algorithm (GA) is introduced in this paper. General operator of genetic algorithm, arithmetic crossover, and non-uniform mutation operator of GA are suggested to solve the power flow problem. While abnormal solution cannot be obtained by a NR method, multiple power flow solution can be obtained by a GA method. With a heavy load, both normal solution and abnormal solution can be obtained by a proposed method. In this paper, a floating number representation instead of the binary number representation is introduced for accuracy. Simulation results have been compared with traditional methods.
Sheath Circulating Current Analysis of a Crossbonded Power Cable Systems
Jung, Chae-Kyun ; Lee, Jong-Beom ; Kang, Ji-Won ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 320~328
DOI : 10.5370/JEET.2007.2.3.320
The sheath in underground power cables serves as a layer to prevent moisture ingress into the insulation layer and provide a path for earth return current. Nowadays, owing to the maturity of manufacturing technologies, there are normally no problems for the quality of the sheath itself. However, after the cable is laid in the cable tunnel and is operating as part of the transmission network, due to network construction and some unexpected factors, some problems may be caused to the sheath. One of them is the high sheath circulating current. In a power cable system, the uniform configuration of the cables between sections is sometimes difficult to achieve because of the geometrical limitation. This will cause the increase of sheath circulating current, which results in the increase of sheath loss and the decrease of permissible current. This paper will study the various characteristics and effects of sheath circulating current, and then will prove why the sheath current rises on the underground power cable system. A newly designed device known as the Power Cable Current Analyser, as well as ATP simulation and calculation equation are used for this analysis.
Load Flow Analysis for Distribution Automation System based on Distributed Load Modeling
Yang, Xia ; Choi, Myeon-Song ; Lim, Il-Hyung ; Lee, Seung-Jae ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 329~334
DOI : 10.5370/JEET.2007.2.3.329
In this paper, a new load flow algorithm is proposed on the basis of distributed load modeling in radial distribution networks. Since the correct state data in the distribution power networks is basic for all distribution automation algorithms in the Distribution Automation System (DAS), the distribution networks load flow is essential to obtain the state data. DAS Feeder Remote Terminal Units (FRTUs) are used to measure and acquire the necessary data for load flow calculations. In case studies, the proposed algorithm has been proven to be more accurate than a conventional algorithm; and it has also been tested in a simple radial distribution system.
An Efficient Implementation of Decentralized Optimal Power Flow
Kim, Balho H. ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 335~341
DOI : 10.5370/JEET.2007.2.3.335
In this study, we present an approach to parallelizing OPF that is suitable for distributed implementation and is applicable to very large inter-connected power systems. The approach could be used by utilities for optimal economy interchange without disclosing details of their operating costs to competitors. It could also be used to solve several other computational tasks, such as state estimation and power flow, in a distributed manner. The proposed algorithm was demonstrated with several case study systems.
An Analysis on Price Limits of Imported Power via Northeast Asian Power System Ties
Chung, Koo-Hyung ; Kim, Balho H. ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 342~345
DOI : 10.5370/JEET.2007.2.3.342
This paper presents an engineering approach to derive the optimum price levels of transacted power. In this paper, with the assumption that power import is possible through the system connection in Northeast Asia regions, the upper price limit of imported power deserving economic efficiency was derived with respect to the time and amount of power import. The proposed approach was demonstrated based on the data from the National Power Development Planning in 2004 with the WASP model.
Analysis of an Electromagnetic Actuator for Circuit Breakers
Shin, Dong-Kyu ; Choi, Myung-Jun ; Kwon, Jung-Lok ; Jung, Hyun-Kyo ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 346~352
DOI : 10.5370/JEET.2007.2.3.346
In this paper, we present an analysis of dynamic characteristics of an electromagnetic actuator for circuit breakers. It is indispensable to simultaneously analyze magnetic, electric, and mechanical phenomena to obtain the dynamic characteristics of the electromagnetic actuator because these phenomena are closely related to each other in an electromagnetic actuator system. The magnetic equations are computed by using the finite element method (FEM). The electric equations and the mechanical equations, which include the time derivative terms, are calculated by using the time difference method (TDM). The calculated results, which have been obtained by means of the FEM and the TDM, are presented with experimental data.
Bearing Fault Diagnosis Using Fuzzy Inference Optimized by Neural Network and Genetic Algorithm
Lee, Hong-Hee ; Nguyen, Ngoc-Tu ; Kwon, Jeong-Min ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 353~357
DOI : 10.5370/JEET.2007.2.3.353
The bearing diagnostics method is presented in this paper using fuzzy inference based on vibration data. Both time-domain and frequency-domain features are used as input data for bearing fault detection. The Adaptive Network based Fuzzy Inference System (ANFIS) and Genetic Algorithm (GA) have been proposed to select the fuzzy model input and output parameters. Training results give the optimized fuzzy inference system for bearing diagnosis based on measured vibration data. The result is also tested with other sets of bearing data to illustrate the reliability of the chosen model.
A Novel Solid State Controller for Parallel Operated Isolated Asynchronous Generators in Pico Hydro Systems
Singh, Bhim ; Kasal, Gaurav Kumar ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 358~365
DOI : 10.5370/JEET.2007.2.3.358
This paper deals with a novel solid state controller (NSSC) for parallel operated isolated asynchronous generators (IAG) feeding 3-phase 4-wire loads in constant power applications, such as uncontrolled pico hydro turbines. AC capacitor banks are used to meet the reactive power requirement of asynchronous generators. The proposed NSSC is realized using a set of IGBTs (Insulated gate bipolar junction transistors) based current controlled 4-leg voltage source converter (CC-VSC) and a DC chopper at its DC bus, which keeps the generated voltage and frequency constant in spite of changes in consumer loads. The complete system is modeled in MATLAB along with simulink and PSB (power system block set) toolboxes. The simulated results are presented to demonstrate the capability of isolated generating system consisting of NSSC and parallel operated asynchronous generators driven by uncontrolled pico hydro turbines and feeding 3-phase 4-wire loads.
Characteristics of Pulse MIG Arc Welding with a Wire Melting Rate Change by Current Polarity Effect
Kim, Tae-Jin ; Lee, Jong-Pil ; Min, Byung-Duk ; Yoo, Dong-Wook ; Kim, Cheul-U ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 366~372
DOI : 10.5370/JEET.2007.2.3.366
Joining thin aluminum alloy is difficult using most welding techniques. Many of the problems are associated with bum-through by the high heat input. Common welding techniques are TIG (Tungsten Inert Gas), MIG (Metal Inert Gas), and PULSE-MIG welding. The method provides more control of the heat balance in the welding arc by taking advantage of the different arc characteristics obtained with each of the two polarities. In this paper, we proposed a new welding method by control DSP 320C32, and the characteristic and experiment result-voltage, current, welding bead, and penetrations by this method are presented.
High-Efficiency Ballast for HID Lamp using Soft-Switching Multi-Level Inverter
Lee, Baek-Haeng ; Kim, Hee-Jun ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 373~378
DOI : 10.5370/JEET.2007.2.3.373
Soft switching was applied to the multi-level inverter to enhance the performance of the high-intensity discharge (HID) ballast used in vehicle headlights. The electrical properties were investigated and the available modeling of ballast in steady state was calculated using mathematical methods. The result was used in analyzing the power characteristics. The modeling was confirmed by the experiment.
Reliable Ethernet Architecture with Redundancy Scheme for Railway Signaling Systems
Hwang, Jong-Gyu ; Jo, Hyun-Jeong ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 379~385
DOI : 10.5370/JEET.2007.2.3.379
Recently, vital devices of the railway signaling systems have been computerized in order to ensure safe train operation. Due to this computerization, we have gradually come to need networking interfaces between these devices. Thus it is important that there be reliable communication links in the signaling systems. Network technologies are applied in the real-time industrial control system, and there are numerous studies to be carried out on the computer network technology for vital control systems such as railway signaling systems. For deploying the studies, we consider costs, reliability, safety assurance technique, compatibility, and etc. In this paper, we propose the Ethernet for railway signaling systems and also precisely describe the computer network characteristics of vital railway signaling systems. Then we demonstrate the experimental results of the proposed network algorithm, which is based on switched Ethernet technology with redundancy scheme.
Quantitative Reliability Assessment for Safety Critical System Software
Chung, Dae-Won ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 386~390
DOI : 10.5370/JEET.2007.2.3.386
At recent times, an essential issue in the replacement of the old analogue I&C to computer-based digital systems in nuclear power plants becomes the quantitative software reliability assessment. Software reliability models have been successfully applied to many industrial applications, but have the unfortunate drawback of requiring data from which one can formulate a model. Software that is developed for safety critical applications is frequently unable to produce such data for at least two reasons. First, the software is frequently one-of-a-kind, and second, it rarely fails. Safety critical software is normally expected to pass every unit test producing precious little failure data. The basic premise of the rare events approach is that well-tested software does not fail under normal routine and input signals, which means that failures must be triggered by unusual input data and computer states. The failure data found under the reasonable testing cases and testing time for these conditions should be considered for the quantitative reliability assessment. We presented the quantitative reliability assessment methodology of safety critical software for rare failure cases in this paper.
Tunable Properties of Ferroelectric Thick Films With MgO Added on (BaSr)TiO
Kim, In-Sung ; Song, Jae-Sung ; Jeong, Soon-Jong ; Jeon, So-Hyun ; Chung, Jun-Ki ; Kim, Won-Jeong ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 391~395
DOI : 10.5370/JEET.2007.2.3.391
thick films have been fabricated by a tape casting and firing method for tunable devices on the microwave frequency band. In order to improve ferroelectric properties, the composite thick films enhanced with MgO on BST have been asymmetrically annealed by a focused halogen beam method. Dielectric constants of composite thick films are changed from 1050 to 1300 at 100 kHz after 60 s and 150 s annealing by the focused halogen beam. Even though no prominent changes were previously observed from the thick films before and after annealing in terms of chemical composition and surface morphology, it is clear that the average particle size of the thick films calculated by Scherrer's formula were increased by annealing. Furthermore, a strong correlation between particle size and dielectric constant of the composite thick films has been observed; dielectric constant increases with increased particle size. This has been attributed to the increased volume of ferroelectric domain due to increased particle sizes. As a result, the tuning range was improved by halogen beam annealing.
An Application of the Novel Techniques Detecting Partial Discharge Employable to GIS Using Optical Sensor
Ryu, Cheol-Hwi ; Jung, Seung-Yong ; Koo, Ja-Yoon ; Yeon, Man-Seung ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 396~400
DOI : 10.5370/JEET.2007.2.3.396
A novel technique has been proposed and related experimental works have been performed in order to detect the partial discharges and the location of the possible defects introduced into the Gas Insulated Switchgear. For this purpose, a prototype HY Pockels sensor has been developed and then employed in order to investigate its field applicability for finding the location of the defects using a 170kV GIS mock-up. Our proposed sensor enables us to measure the electric field variation due to the PD occurrence. In addition, the different PD patterns are observed, which might be dependant on the location and the distance of the sensor with respect to the PD source. Throughout this work, its linear response has been proved to be admissible as a function of the applied voltage. And also the position of the PD source might be distinguished by comparing the PD patterns.
Uncertainty Analysis in Potential Transformer Calibration Using a High Voltage Capacitance Bridge
Jung, Jae-Kap ; Lee, Sang-Hwa ; Kang, Jeon-Hong ; Kwon, Sung-Won ; Kim, Myung-Soo ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 401~407
DOI : 10.5370/JEET.2007.2.3.401
Precise absolute measurement of the errors in a potential transformer (PT) can be achieved using high voltage capacitance bridge (HVCB) and capacitive divider. The uncertainty in a PT measurement using the HVCB system was evaluated by considering the overall factors affecting during the calibration of a PT. The expanded uncertainties are found to be not more than
for ratio and
for phase up to the primary voltage of
. For same PTs, the measured errors in KRISS (Korea Research Institute of Standards and Science) using our bridge are well coincide with those in NMIA (National Measurement Institute of Australia) and PTB (Physikalisch-Technische Bundesanstalt) within the corresponding uncertainties.
Design of a Smart Gas Sensor System for Room Air-Cleaner of Automobile (Thick-Film Metal Oxide Semiconductor Gas Sensor)
Kim, Jung-Yoon ; Shin, Tae-Zi ; Yang, Myung-Kook ;
Journal of Electrical Engineering and Technology, volume 2, issue 3, 2007, Pages 408~412
DOI : 10.5370/JEET.2007.2.3.408
It is almost impossible to secure the reproductibility and stability of a commercial Thick-Film Metal Oxide Semiconductor Gas Sensor since it is very difficult to keep the consistency of the manufacturing environment. Thus it is widely known that the general Semiconductor-Oxide Gas Sensors are not appropriate for precise measurement systems. In this paper, the output characteristic analyzer of the various Thick-Film Metal Oxide Semiconductor Gas Sensors that are used to recognize the air quality within an automobile are proposed and examined. The analyzed output characters in a normal air chamber are grouped by sensor ranks and used to fill out the characteristic table of the Thick-Film Metal Oxide Semiconductor Gas Sensors. The characteristic table is used to determine the rank of the sensor that is equipped in the current air cleaner system of an automobile. The proposed air control system can also adapt the on-demand operation that recognizes the history of the passenger's manual-control.