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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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Novel Continuous Auction Algorithm with Congestion Management for the Japanese Electricity Forward Market
Marmiroli Marta ; Yokoyama Ryuichi ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 1~7
DOI : 10.5370/JEET.2006.1.1.001
In an electricity market, the spot market is normally integrated with a forward or future market. The advantage of the forward market is to allow the market participants to deal in a part or the whole trading portfolio at a fix price in advance and to avoid risk associated to the uncertain price of the spot market. Japan has introduced a continuous auction base forward market from April 2005. This paper analyzes the Japanese forward market rules and operations, and introduces a new algorithm that may improve the efficiency of the market itself. The proposed algorithm enables us to give consideration to the specific characteristics of the power system and to integrate them in the auction mechanism. The benefits of the proposed algorithm are verified on an electronic simulation platform and the results described in this paper.
A Study on Adaptive Autoreclosure Scheme with Real-time Transient Stability
Jang Sung-Ik ; Shin Myong-Chul ; Yoon Chang-Dae ; Campbell Ryan C. ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 8~15
DOI : 10.5370/JEET.2006.1.1.008
Since the power swing depends on the operating time of the relay, the swing's magnitude can be reduced by an autoreclosure relaying system with an optimal reclosing algorithm. This paper proposes a method for stability improvement using optimal reclosure relaying. An optimal reclosure algorithm is applied to identify both temporary and permanent faults, and to predict system stability by applying WAM and high speed communication technology. It provides optimal control by predicting and determining the degree of stability, considering the real time transient stability using EEEAC. For temporary faults, the algorithm determines the system's stability and either recloses optimally for stable systems, or inserts series capacitance before optimal reclosure for unstable systems. It also applies an optimal reclosure algorithm to minimize shock and damage to the power system when reclosure fails due to permanent faults.
A Modified Selective Ground Relay for Ungrounded Distribution Systems
Nam Soon-Ryul ; Kang Sang-Hee ; Park Jong-Keun ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 16~22
DOI : 10.5370/JEET.2006.1.1.016
Selective ground relays (SGRs) are useful fur distinguishing a faulted feeder from the sound feeders in ungrounded systems. However, they sometimes mis-operate due to human or device errors. Particularly, the reversed polarity of zero-sequence current transducers (ZCTs) is the most frequent cause of mis-operation. This paper presents a modified SGR for reducing the probability of mis-operations caused by the reversed polarity of ZCTs. The modification is achieved by introducing an adaptive time delay, which depends on the magnitude of the zero-sequence current and the phase angle deviation from the reference. The modified SGR was successfully demonstrated on a sample ungrounded system without mis-operation.
Verification of Hybrid Real Time HVDC Simulator in Cheju-Haenam HVDC System
Yang Byeong-Mo ; Kim Chan-Ki ; Jung Gil-Jo ; Moon Young-Hyun ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 23~27
DOI : 10.5370/JEET.2006.1.1.023
In this paper a Hybrid Real Time HVDC Simulator fur both operator Training and Researching in the Cheju-Haenam HVDC System is proposed and its performance is studied by means of RTDS (Real Time Digital Simulator), EMTDC (Electro-Magnetic Transients system for DC), PSS/E (Power System Simulator for Engineering), and experienced scenarios. The objective of this paper is to represent the strategy in development for KEPCO's hybrid HVDC simulator for the Cheju-Haenam HVDC system. This simulator consists of two DC stations, DC cables, external digital/analog controllers, monitoring systems and control desk for education, and AC networks. Its suitability for operator's education is tested during startup/shutdown and normal state operations. Dynamic performances of it are also verified.
Development of Power Quality Management System with Power Quality Diagnosis Functions
Chung Il-Yop ; Won Dong-Jun ; Ahn Seon-Ju ; Kim Joong-Moon ; Moon Seung-Il ; Seo Jang-Cheol ; Choe Jong-Woong ; Jang Gil-Soo ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 28~34
DOI : 10.5370/JEET.2006.1.1.028
Recently, in accordance with the development of IT technology, it is prevalent for power quality monitors to be connected to each other via networks and share their data because such networks provide system-wide insights to customers concerning power quality. Those systems can alarm and display power quality events for the convenience of customers. However, if a power quality event occurs, it is difficult for customers to determine its cause and solution because the systems do not provide appropriate power quality diagnosis functions. The power quality management system presented in this paper has been developed to provide customers with various power quality diagnosis functions so that they can cope well with power quality problems with the right measure in the right place. This paper presents the structure and functions of the developed power quality management system and shows some results of the power diagnosis functions.
Two Terminals Numerical Algorithm for Distance Protection, Fault Location and Acing Faults Recognition Based on Synchronized Phasors
Lee Chan-Joo ; Park Jong-Bae ; Shin Joong-Rin ; Radojevic Zoran ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 35~41
DOI : 10.5370/JEET.2006.1.1.035
This paper presents a new numerical algorithm for fault location estimation and for faults recognition based on the synchronized phasors. The proposed algorithm is based on the synchronized phasor measured from the synchronized PMUs installed at two-terminals of the transmission lines. In order to discriminate the fault type, the arc voltage wave shape is modeled numerically on the basis of a great number of arc voltage records obtained by transient recorder. From the calculated arc voltage amplitude it can make a decision whether the fault is permanent or transient. The results of the proposed algorithm testing through computer simulation are given.
Analysis of Galloping Amplitude for Conductors With Inter-phase Spacers
Kim Hwan-Seong ; Nguyen Tuong-Long ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 42~51
DOI : 10.5370/JEET.2006.1.1.042
The main purpose of this paper is to calculate the behaviors of inter-phase spacers to reduce the amplitude of galloping in conductors. In simulation, three phases and iced-single/two-bundles conductors with/without spacers are considered in viewpoint of standard cases. The implicit/explicit finite element methods are used to calculate the transient response with geometric nonlinear behavior. The ANSYS/LS-DYNA program is also applied. Calculation results can be used to predict the positions to insert the inter-phase spacers between conductors.
A New Simple Sensorless Control Method for Switched Reluctance Motor Drives
Xin Kai ; Zhan Qionghua ; Luo Jianwu ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 52~57
DOI : 10.5370/JEET.2006.1.1.052
In this paper, a new 'impedance sensing' method is described. This method overcomes the shortcomings of the impedance sensing method. According to the new method, sensing voltage pulse is applied to the idle phase in the minimum inductance region and the beginning of the increasing inductance region to detect rotor position. The negative torque produced by the sensing voltage pulse can be neglected in the minimum inductance region and the efficiency of SRM is improved. In the minimum inductance region the back electromotive force (EMF) can be neglected. And in the increasing inductance region the EMF opposes the rise of current in the phase, so the position estimation scheme is reliable. Therefore the new 'impedance sensing' method is sufficiently precise even under the high back EMF effect. The adjustment of turn-on angle and turn-off angle is also easy to be realized. The technique is very useful in applications where cost or size is primary concerns, such as electric bicycle drives. Experimental results are presented to verify the proposed method.
The Fundamental Characteristics of Novel Switched Reluctance Motor with Segment Core Embedded in Aluminum Rotor Block
Oyama Jun ; Higuchi Tsuyoshi ; Abe Takashi ; Tanaka Keisuke ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 58~62
DOI : 10.5370/JEET.2006.1.1.058
We proposed a novel segment type switched reluctance motor (SRM) in which the segment core was embedded in aluminum (conductive metal) rotor block in order to increase the mechanical strength and easy manufacturing as well as to improve the performance characteristics and reduce the vibration and acoustic noise. This paper explains the operation principle and the drive system and shows the experimental results in comparison with the VR type SRM.
Stabilizing Control of DC/DC Buck Converters with Constant Power Loads in Continuous Conduction and Discontinuous Conduction Modes Using Digital Power Alignment Technique
Khaligh Alireza ; Emadi Ali ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 63~72
DOI : 10.5370/JEET.2006.1.1.063
The purpose of this raper is to address the negative impedance instability in DC/DC converters. We present the negative impedance instability of PWM DC/DC converters loaded by constant power loads (CPLs). An approach to design digital controllers for DC/DC converters Is presented. The proposed method, called Power Alignment control technique, is applied to DC/DC step-down choppers operating in continuous conduction or discontinuous conduction modes with CPLs. This approach uses two predefined state variables instead of conventional pulse width modulation (PWM) to regulate the output voltage. A comparator compares actual output voltage with the reference and then switches between the appropriate states. It needs few logic gates and comparators to be implemented thus, making it extremely simple and easy to develop using a low-cost application specific integrated circuit (ASIC) for converters with CPLs. Furthermore, stability of the proposed controllers using the small signal analysis as well as the second theorem of Lyapunov is verified. Finally, simulation and analytical results are presented to describe and verify the proposed technique.
A New Breed of Electric Machines - Basic Analysis and Applications of Dual Mechanical Port Electric Machines
Xu Longya ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 73~79
DOI : 10.5370/JEET.2006.1.1.073
Conceptually, mechanical port of an electric machine can be doubled and the concept of dual-mechanical-port (DMP) will then give birth to a new breed of electric machines. In this paper, the various possible structures of DMP electric machine are discussed. Basic modeling and analysis issues related to the DMP electric machine are presented. An exemplary design of DMP machine is given and verified by FEM results. Potential applications and future research work are given to conclude the paper.
Sustained Oscillation of an Inverter-Fed Induction Motor Drive System and its Stabilization
Li Hongmei ; Hikihara Takashi ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 80~84
DOI : 10.5370/JEET.2006.1.1.080
The sustained oscillation of rotor speed is often experienced in PWM inverter induction motor (IM) drive systems. In this paper the oscillation is investigated from the point of view of Hopf bifurcation theory. The sufficient and necessary conditions for existence of limit cycle are introduced to determine the bifurcation set in the stator voltage versus stator frequency plane. According to the conditions it is clarified that the bifurcation set inherently exists in the instable operation of IM. Moreover, it is numerically shown that the V/f curve can be adjusted to stabilize the sustained oscillation of rotor speed.
Effects of Slot Combination and Skewed Slot on the Electromagnetic Vibration of a 4-pole Capacitor Motor under Load Condition
Hirotsuka Isao ; Tsubouchi Yutaro ; Tsuboi Kazuo ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 85~91
DOI : 10.5370/JEET.2006.1.1.085
Recently, the reduction of electromagnetic vibration and noise of a capacitor motor (CRM) has become a very important subject from the standpoint of environmental improvement. Therefore, the authors have studied the characteristics of the dominant electromagnetic vibration of the CRM under load condition. In this paper, the effects of slot combination and skewed slot on the dominant electromagnetic vibration of a CRM under load condition are discussed both theoretically and experimentally. As a result, the characteristics of the dominant electromagnetic vibration for the slot combination and the reduction effect of the skewed slot on the electromagnetic vibration are clarified for a 4-pole CRM.
Optimal Design of a Permanent Magnetic Actuator for Vacuum Circuit Breaker using FEM
Yoo Yong-Min ; Kim Dae-Kyong ; Kwon Byung-Il ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 92~97
DOI : 10.5370/JEET.2006.1.1.092
This paper presents the characteristic analysis and the optimal design of a permanent magnetic actuator (PMA) for a vacuum circuit breaker (VCB) using a two-dimensional finite element analysis. The purpose of this research about a PMA is to minimize the breaking time and the volume of the permanent magnet within the limits of the holding force and maximum current in the coil. The conjugate gradient method is used as an optimization algorithm. The node moving technique is iteratively implemented until the design variables of the PMA are optimized. In this paper, the optimal design of a PMA is accomplished to improve the conventional design methods.
Effect of Deposition Rate on the Property of ZnO Thin Films Deposited by Pulsed Laser Deposition
Kim Jae-Won ; Kang Hong-Seong ; Lee Sang-Yeol ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 98~100
DOI : 10.5370/JEET.2006.1.1.098
ZnO thin films were deposited at different repetition rates of 5 Hz and 10 Hz by pulsed laser deposition. X-ray diffraction (XRD) full widths at half maximum (FWHMs) of (002) ZnO peak in ZnO thin film deposited at 5 Hz and 10 Hz was 0.22 and
, respectively. The grain size of ZnO thin film deposited at 5 Hz was larger than that of 10 Hz. The variation of repetition rates did not have an effect on the optical property of ZnO thin films. The degradation of the crystalline quality and surface morphology in ZnO thin film deposited at 10 Hz resulted from supersaturation effect by decrease of time interval between a ZnO particle arriving on a substrate by laser shot and a ZnO particle arriving on a substrate by next laser shot.
Characteristics of Disk-type Linear Ultrasonic Motor for Application to x-y Stage
Lim Kee-Joe ; Park Seong-Bee ; Yun Yong-Jin ; Lee Kee-Young ; Kang Seong-Hwa ; Lee Jong-Sub ; Jeong Su-Hyun ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 101~105
DOI : 10.5370/JEET.2006.1.1.101
In this paper, a disk-type ultrasonic motor using a combination of radial and bending vibration modes is newly designed and fabricated. The characteristics of the test motor are also measured. By means of traveling elastic wave induced at the surface of circumference of the elastic disk, a steel bar in contact with the surface of circumference of the elastic disk bonded onto the piezoelectric ceramic disks is driven in both directions by changing the sine and cosine voltage inputs. The stator of the motor is composed of two sheets of piezoelectric ceramic disks to bond onto both surfaces of an elastic disk, respectively. As a result, the diameter of the elastic body is increased and the resonant frequency is decreased. The resonant frequency of the stator is about 92 kHz, which is composed with piezoelectric ceramic disks of 28 mm in diameter and 2 mm in thickness, and an elastic body of 32 mm in diameter and 2 mm in thickness. A driving voltage of 20 VPP Produces 200 rpm with a torque of 1Nm and an efficiency of about 10%.
Characteristics of a Miniaturized Ultrasonic Motor for Auto-focusing of a Mobile Phone
Lim Kee-Joe ; Lee Jong-Sub ; Kang Seong-Hwa ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 106~109
DOI : 10.5370/JEET.2006.1.1.106
In this paper, the design and characteristics of a novel ultrasonic motor are investigated. Such a motor is appropriate far use in the optical zoom or auto focusing functions of the lens system in mobile phones. Its design and simulation of performances are carried out by FEM commercial software (ATILA). The shape of the motor is similar to a square without one side, on which an optical lens can be mounted. Two sheets of piezoelectric ceramics are adhered to both sides of two legs of the elastic body, respectively To drive the ultrasonic motor, the voltage is applied to two sheets of piezoelectric ceramics bonded to one leg. The rotation direction can be easily changed by switching the piezoelectric sheets bonded to the other leg, to which voltage is applied. A proto type of the motor is fabricated and its outer size is
including the camera lens of which the diameter is 7.5(mm). Its power consumption is about 0.3[W] and the speed of rotation is adjustable from 10 to 200[rpm] according to the applied voltage
Sputtering Technique of Magnesium Oxide Thin Film for Plasma Display Panel Applications
Choi Young-Wook ; Kim Jee-Hyun ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 110~113
DOI : 10.5370/JEET.2006.1.1.110
A high rate deposition sputtering process of magnesium oxide thin film in oxide mode has been developed using a 20 kW unipolar pulsed power supply. The power supply was operated at a maximum constant voltage of 500 V and a constant current of 40 A. The pulse repetition rate and the duty were changed in the ranges of
, respectively. The deposition rate increased with rising incident power to the target. Maximum incident power to the magnesium target was obtained by the control of frequency, duty and current. The deposition rate of a moving state was 9 nm m/min at the average power of 1.5 kW. This result shows higher deposition rate than any other previous work involving reactive sputtering in oxide mode. The thickness uniformities over the entire substrate area of
were observed at the processing pressure of
mTorr. The thickness distribution was improved at lower pressure. This technique is proposed for application to a high through-put sputtering system for plasma display panels.
Leakage Current Waveforms of Outdoor Polymeric Insulators and Possibility of Application for Diagnostics of Insulator Conditions
Suwarno Suwarno ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 114~119
DOI : 10.5370/JEET.2006.1.1.114
This paper reports the investigation results on the leakage currents (LC) on polymeric outdoor insulators. The samples used were EPDM (ethylene prophylene diene monomer) insulators used at 20 kV distribution lines. AC voltage was applied and the LC waveforms were measured under various environmental conditions (humidity and pollution). Digital data of the LC was transferred from a digital storage oscilloscope to a computer for further analysis. The LC waveform parameters such as magnitude and harmonic content (as indicated by the total harmonic distortion (THD)) were analyzed. The experimental results showed that 3rd, 5th and 7th harmonics and higher odd harmonics were observed for symmetrical-distorted LC waveforms while for unsymmetrical-distorted LC waveforms, odd and even harmonics were observed. The LC analysis indicated that there are 5 stages of insulator conditions from normal condition up to flashover correlated with different kind of LC waveforms. The results also showed that in general the magnitude of LC was good enough to show the condition of the insulators. However, under discharge condition (for example as a result of dry band arching) the LC magnitude should be combined by the THD to show a better correlation with the insulator condition. The product between THD and LC magnitude may be used as a diagnostic parameter.
Dielectric Properties of Ti-doped K(Ta,Nb)O
Thin Films for Tunable Microwave Applications
Bae Hyung-Jin ; Koo Jayl ; Hong Jun-Pyo ;
Journal of Electrical Engineering and Technology, volume 1, issue 1, 2006, Pages 120~126
DOI : 10.5370/JEET.2006.1.1.120
Ferroelectric materials have been widely investigated for high density dynamic random access memories, opto-electrics, and tunable microwave devices due to their properties. In this study, we have investigated the dielectric properties of Ti doped
thin films. By doping Ti Into the
system, Ti with a valence value of +4 will substitute Ta or Nb ions with a valence value of +5. This substitution will introduce an acceptor state. Therefore, this introduced acceptor state will reduce dielectric loss by trapping electrons. Using 3% Ti-doped
:Ti films were grown in MgO(001) crystals using pulsed laser deposition. First, growth conditions were optimized. A reduction in the loss tangent was observed for Ti-doped
relative to undoped films, although a reduction in tunability is also seen. The crystallinity, morphology, and tunability of
:Ti films are reported.