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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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Sequential Outage Checkers for Analyzing Cascading Outages and Preventing Large Blackouts
Hur, Jin ; Joung, Man-Ho ; Baldick, Ross ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 585~594
DOI : 10.5370/JEET.2011.6.5.585
This paper presents the use of sequential outage checkers to identify the potential cascading processes that might lead to large blackouts. In order to analyze cascading outages caused by a combination of thermal overloads, low voltages, and under-frequencies following an initial disturbance, sequential outage checkers are proposed. The proposed sequential outage checkers are verified using the AEP 9-bus system, New England 39-bus system, and IEEE 118-bus system.
Harmonic Current Compensation based on Three-phase Three-level Shunt Active Filter using Fuzzy Logic Current Controller
Salim, Chennai ; Benchouia, M.T. ; Golea, A. ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 595~604
DOI : 10.5370/JEET.2011.6.5.595
A three-phase three-level shunt active filter controlled by fuzzy logic current controller which can compensate current harmonics generated by nonlinear loads is presented. Three-level inverters and fuzzy controllers have been successfully employed in several power electronic applications these past years. To improve the conventional pwm controller performance, a new control scheme based on fuzzy current controller is adopted for three-level (NPC) shunt active filter. The scheme is designed to improve compensation capability of APF by adjusting the current error using a fuzzy rule. The inverter current reference signals required to compensate harmonic currents use the synchronous reference detection method. This technique is easy to implement and achieves good results. To maintain the dc voltage across capacitor constant and reduce inverter losses, a proportional integral voltage controller is used. The simulation of global system control and power circuits is performed using Matlab-Simulink and SimPowerSystem toolbox. The results obtained in transient and steady states under various operating conditions show the effectiveness of the proposed shunt active filter based on fuzzy current controller compared to the conventional scheme.
Communication Architecture of the IEC 61850-based Micro Grid System
Yoo, Byong-Kwan ; Yang, Seung-Ho ; Yang, Hyo-Sik ; Kim, Won-Yong ; Jeong, Yu-Seok ; Han, Byung-Moon ; Jang, Kwang-Soo ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 605~612
DOI : 10.5370/JEET.2011.6.5.605
As the power grids are integrated into one big umbrella called a "smart grid," communication protocol plays a key role in successful operations. The successful deployment of smart grid interoperability is a major hurdle that must be overcome. The micro grid, a small power system that distributes energy resource, is operated in diverse regions. Different vendors use different communication protocols in the operation of the micro grid. Recently, the IEC 61850 has been legislated to solve the interoperability problems in power utility automation. The present paper presents a micro grid system based on the IEC 61850 protocol. It consists of a micro grid monitoring system, a protocol converter that transforms serial data to IEC 61850 data, and distributed energy resource controllers for diverse DER nodes. A developed communication gateway can be deployed for DER controllers with serial links to exchange data with IEC 61850-based devices. The gateway can be extended to IEC 61850-based distribution automation systems, substation automation systems, or SCADA.
Dynamic Characteristic Analysis of Electric Actuator for 1 kV/3.2 kA Air Circuit Breaker Based on the Three-link Structure
Lee, Seung-Min ; Kang, Jong-Ho ; Kwak, Sang-Yup ; Kim, Rae-Eun ; Jung, Hyun-Kyo ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 613~617
DOI : 10.5370/JEET.2011.6.5.613
In the present paper, a new type of electrical actuator, an electromagnetic force driving actuator (EMFA), applicable to air circuit breaker is developed and analyzed. Transient analysis is performed to obtain the dynamic characteristics of EMFA. The distribution of static magnetic flux is obtained using the finite element method. The coupled problems of electrics and mechanics governing equations are solved using the time-difference method. According to the interception rate of each contactor, investigation of the contactor spring load condition is conducted and applied to the threelink system. Comparisons of the dynamic characteristics of the three-link simulation and experimental data are performed.
Design and Analysis of Double Excited 3-Degree-of-Freedom Motor for Robots
Kwon, Byung-Il ; Kim, Young-Boong ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 618~625
DOI : 10.5370/JEET.2011.6.5.618
This paper presents a double excited three degree-of-freedom (3DOF) motor. The proposed 3DOF motor is designed with a laminated structure, making it easy to manufacture. In addition, it has windings on the stator and rotor, and does not require an expensive permanent magnet. We explain the structure, principle of motion, and design of the proposed motor, and perform an analysis of the static characteristics using the two- and three-dimensional finite element methods (3D FEM). The feasibility of 3D FEM analysis is confirmed by comparing the 3D FEM analysis and experimental results for the rolling and pitching motion. We also confirm the occurrence of holding torque in every motion.
A Study on Fast Maximum Efficiency Control of Stator-Flux-oriented Induction Motor Drives
Shin, Myoung-Ho ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 626~633
DOI : 10.5370/JEET.2011.6.5.626
This paper presents a novel maximum efficiency control scheme for convergence improvement in stator-flux-oriented induction motor drives. Three input powers are calculated at three different flux levels, respectively. A quadratic curve is obtained using the quadratic interpolation method using the three points. The flux level at the lowest point of the interpolated curve is calculated, which is not the real minimum input power of the motor, but an estimated one. Hence, the quadratic interpolations are repeated with three new points chosen using the selection method for new points for refitting until the convergence criteria are satisfied. The proposed method is verified by simulation results.
Magnetic Saturation Effect on the Rotor Core of Synchronous Reluctance Motor
Kim, Ki-Chan ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 634~639
DOI : 10.5370/JEET.2011.6.5.634
This paper presents a study on the design parameters that consider the magnetic saturation effect in a rotor core of a synchronous reluctance motor. Two important design parameters in a rotor are selected to analyze the saturation effect of a synchronous reluctance motor, particularly in a rotor core. The thickness of the main segment, which is the main path of the d-axis flux, and the end rip, which affects the q-axis flux, are analyzed using the d-axis and q-axis inductances. Moreover, the characteristics of torque and torque ripple when magnetic saturation takes place are analyzed. The saturation effect is verified by comparing the reluctance torque between the experiment and FEM simulation.
Performance of High-Speed 4/2 Switched Reluctance Motor
Lee, Dong-Hee ; Ahn, Jin-Woo ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 640~646
DOI : 10.5370/JEET.2011.6.5.640
The current study presents the design and performance of a novel 4/2 switched reluctance motor (SRM) for a high-speed air blower. With a comparative study of some rotor structures for a high-speed drive, a stepper-type rotor is optimized to produce a continuous torque and a low torque ripple. Rotor pole arc is modified to have a wide continuous output torque region, and air gap is determined to develop less torque ripple. The rotor radius is determined to reduce torque ripple with a reiterative FEM analysis. The designed rotor has three regions: short uniform, long uniform, and nonuniform air-gap region. The positive torque region is wider than a conventional 4/2 SRM without any torque dead zone. A prototype is tested and the efficiency is up to 72[%] at 30,000[rpm], 600[w] output.
Sliding Mode Control with Fixed Switching Frequency for Four-wire Shunt Active Filter
Hamoudi, Farid ; Chaghi, A. Aziz ; Amimeur, Hocine ; Merabet, El Kheir ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 647~657
DOI : 10.5370/JEET.2011.6.5.647
The present paper proposes a sliding mode control with fixed switching frequency for three-phase three-leg voltage source inverter based four-wire shunt active power filter. The aim is to improve phase current waveform, neutral current mitigation, and reactive power compensation in electric power distribution system. The performed sliding mode for active filter current control is formulated using elementary differential geometry. The discrete control vector is deduced from the sliding surface accessibility using the Lyapunov stability. The problem of the switching frequency is addressed by considering hysteresis comparators for the switched signals generation. Through this method, a variable hysteresis band has been established as a function of the sliding mode equivalent control and a predefined switching frequency in order to keep this band constant. The proposed control has been verified with computer simulation which showed satisfactory results.
Novel Fast Peak Detector for Single- or Three-phase Unsymmetrical Voltage Sags
Lee, Sang-Hoey ; Cha, Han-Ju ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 658~665
DOI : 10.5370/JEET.2011.6.5.658
In the present paper, a novel fast peak detector for single- or three-phase unsymmetrical voltage sags is proposed. The proposed detector is modified from a single-phase digital phase-locked loop based on a d-q transformation using an all-pass filter (APF). APF generates a virtual phase with
phase delay. However, this virtual phase cannot reflect a sudden change of the grid voltage in the moment of voltage sag, which causes a peak value to be significantly distorted and to settle down slowly. Specifically, the settling time of the peak value is too long when voltage sag occurs around a zero crossing, such as phase
. This paper describes the operating principle of the APF problem and proposes a modified all-pass filter (MAPF) to mitigate the inherent APF problem. In addition, a new fast peak detector using MAPF is proposed. The proposed detector is able to calculate a peak value within 0.5 ms, even when voltage sag occurs around zero crossing. The proposed fast peak detector is compared with the conventional detector using APF. Results show that the proposed detector has faster detection time in the whole phase range. Furthermore, the proposed fast peak detector can be effectively applied to unsymmetrical three-phase voltage sags. Simulation and experimental results verify the advantages of the proposed detector and MAPF.
A Method for Indentifying Broken Rotor Bar and Stator Winding Fault in a Low-voltage Squirrel-cage Induction Motor Using Radial Flux Sensor
Youn, Young-Woo ; Hwang, Don-Ha ; Sun, Jong-Ho ; Kang, Dong-Sik ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 666~670
DOI : 10.5370/JEET.2011.6.5.666
In this paper, a method for detecting broken rotor bar and stator winding fault in a low voltage squirrel-case induction motor using an air-gap flux variation analysis is proposed to develop a simple and low cost diagnosis technique. To measure the leakage flux in radial direction, a radial flux sensor is designed as a search coil and installed between stator slots. The proposed method is able to identify two kinds of motor faults by calculating load condition of motors and monitoring abnormal signals those are related with motor faults. Experimental results obtained on 7.5kW three-phase squirrel-cage induction motors are discussed to verify the performance of the proposed method.
Modeling and Investigation of Multilayer Piezoelectric Transformer with a Central Hole for Heat Dissipation
Thang, Vo Viet ; Kim, In-Sung ; Jeong, Soon-Jong ; Kim, Min-Soo ; Song, Jae-Sung ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 671~676
DOI : 10.5370/JEET.2011.6.5.671
A multilayer square-type piezoelectric transformer with a hole at the center was investigated in this paper. Temperature distribution at the center was improved by using this construction, therefore increasing input voltage and output power. This model was simulated and investigated successfully by applying a finite element method (FEM) in ATILA software. An optimized structure was then fabricated, examined, and compared to the simulation results. Electrical characteristics, including output voltage and output power, were measured at different load resistances. The temperature distribution was also monitored using an infrared camera. The piezoelectric transformer operated at first radial vibration mode and a frequency area of 70 kHz. The 16 W output power was achieved in a three-layer transformer with 96% efficiency and
temperature rise from room temperature under 115 V driving voltage, 100
size, and 2 mm hole diameter. With these square-type multilayer piezoelectric transformers, the temperature was concentrated around the hole and lower than in piezoelectric transformers without a hole.
Setup of standard PD calibrator and its uncertainties
Kim, Kwang-Hwa ; Yi, Sang-Hwa ; Lee, Heun-Jin ; Kang, Dong-Sik ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 677~683
DOI : 10.5370/JEET.2011.6.5.677
The present paper describes the setup of standard partial discharge calibrator for measuring partial discharge and estimating uncertainties. The standard PD calibrator was designed and set up, consisting of a digital pulse generator, capacitor modules, and a digital oscilloscope controlled by software developed in the laboratory. Using this software, averages of charges and rising times and their standard deviations in the measured pulses can also be calculated. The standard PD calibrator generates five types of pulses: single, double, random, oscillating, and long-rising. The coefficient sensitivities to estimate the uncertainties of pulses were extracted in the model circuit of the standard PD calibrator. The uncertainties of charges and rising times in pulses of the standard PD calibrator were estimated with single pulses. These values were 0.3%-1.4% in charges and 1.9%-7.0% in rising time; however, these values are lower than the limit values in IEC 60270.
Comparison of transparent conductive indium tin oxide, titanium-doped indium oxide, and fluorine-doped tin oxide films for dye-sensitized solar cell application
Kwak, Dong-Joo ; Moon, Byung-Ho ; Lee, Don-Kyu ; Park, Cha-Soo ; Sung, Youl-Moon ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 684~687
DOI : 10.5370/JEET.2011.6.5.684
In this study, we investigate the photovoltaic performance of transparent conductive indium tin oxide (ITO), titanium-doped indium oxide (ITiO), and fluorine-doped tin oxide (FTO) films. ITO and ITiO films are prepared by radio frequency magnetron sputtering on soda-lime glass substrate at
, and the FTO film used is a commercial product. We measure the X-ray diffraction patterns, AFM micrographs, transmittance, sheet resistances after heat treatment, and transparent conductive characteristics of each film. The value of electrical resistivity and optical transmittance of the ITiO films was
. The near-infrared ray transmittance of ITiO is the highest for wavelengths over 1,000 nm, which can increase dye sensitization compared to ITO and FTO. The photoconversion efficiency (
) of the dye-sensitized solar cell (DSC) sample using ITiO was 5.64%, whereas it was 2.73% and 6.47% for DSC samples with ITO and FTO, respectively, both at 100 mW/
Atomic Layer Deposition-incorporated Catalyst Deposition for the Vertical Integration of Carbon Nanotubes
Jung, Sung-Hwan ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 688~692
DOI : 10.5370/JEET.2011.6.5.688
Carbon nanotubes (CNTs) are vertically grown inside high-aspect-ratio vertical pores of anodized aluminum oxide. A CNT catalyst layer is introduced by atomic layer deposition to the bottom of the pores, after which the CNTs are successfully grown from the layer using chemical vapor deposition. The CNTs formed a complete vertical conductive path. The conductivity of the CNT-vertical path is also measured and discussed. The present atomic layer deposition-incorporated catalyst deposition is predicted to enable the integration of CNTs with various challenging configurations, including high-aspect-ratio vertical channels or vertical interconnects.
Resistive and Inductive Loading Techniques on Microstrip Antenna for Wideband Application
Jeon, Sang-Bong ; Ahn, Chang-Hoi ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 693~696
DOI : 10.5370/JEET.2011.6.5.693
In this work, an exponentially tapered microstrip antenna was implemented using a resistive loading technique in order to suppress the internal reflections. The inductive loading was realized by introducing slits on the antenna to improve radiation efficiency. Compared with a resistive-loaded antenna, the proposed antenna had an average improvement of about 6.2% in radiation efficiency within the range of 2-10.5 GHz. In addition, the highest peak of the radiated short pulse from the proposed antenna became 45% greater than that of an antenna with resistive loading only.
State-Space Analysis on The Stability of Limit Cycle Predicted by Harmonic Balance
Lee, Byung-Jin ; Yun, Suk-Chang ; Kim, Chang-Joo ; Park, Jung-Keun ; Sung, Sang-Kyung ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 697~705
DOI : 10.5370/JEET.2011.6.5.697
In this paper, a closed-loop system constructed with a linear plant and nonlinearity in the feedback connection is considered to argue against its planar orbital stability. Through a state space approach, a main result that presents a sufficient stability criterion of the limit cycle predicted by solving the harmonic balance equation is given. Preliminarily, the harmonic balance of the nonlinear feedback loop is assumed to have a solution that determines the characteristics of the limit cycle. Using a state-space approach, the nonlinear loop equation is reformulated into a linear perturbed model through the introduction of a residual operator. By considering a series of transformations, such as a modified eigenstructure decomposition, periodic averaging, change of variables, and coordinate transformation, the stability of the limit cycle can be simply tested via a scalar function and matrix. Finally, the stability criterion is addressed by constructing a composite Lyapunov function of the transformed system.
Necessary and Sufficient Conditions for the Existence of Decoupling Controllers in the Generalized Plant Model
Park, Ki-Heon ; Choi, Goon-Ho ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 706~712
DOI : 10.5370/JEET.2011.6.5.706
Necessary and sufficient conditions for the existence of diagonal, block-diagonal, and triangular decoupling controllers in linear multivariable systems for the most general setting are presented. The plant model in this study is sufficiently general to accommodate non-square plant and non-unity feedback cases with one-degree-of-freedom (1DOF) or two-degree-of-freedom (2DOF) controller configuration. The existence condition is described in terms of rank conditions on the coefficient matrices in partial fraction expansions.
New Stability Criteria for Linear Systems with Interval Time-varying State Delays
Kwon, Oh-Min ; Cha, Eun-Jong ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 713~722
DOI : 10.5370/JEET.2011.6.5.713
In the present paper, the problem of stability analysis for linear systems with interval time-varying delays is considered. By introducing a new Lyapunov-Krasovskii functional, new stability criteria are derived in terms of linear matrix inequalities (LMIs). Two numerical examples are given to show the superiority of the proposed method.
Rapid Acquisition of CM and CL Code for GPS L2C Software Receivers
Kwon, Keum-Cheol ; Shim, Duk-Sun ;
Journal of Electrical Engineering and Technology, volume 6, issue 5, 2011, Pages 723~730
DOI : 10.5370/JEET.2011.6.5.723
The GPS modernization program offered a new civil signal on the L2 band, and the first modernized GPS Block IIR satellite was launched in September 2005. Currently, eight GPS Block IIRM satellites and two Block IIF satellites transmit L2C signal. The L2C signal contains two codes of CM and CL that are much longer than the L1 C/A code. Thus, the acquisition of the CM and CL codes takes more time compared with that of L1 C/A code. Under the assumption that the L2C signal is strong enough for detection, this paper suggests rapid acquisition methods for the GPS L2C signals for software receivers and compares its performance with that of other methods.