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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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The Korean Institute of Electrical Engineers
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Volume 3, Issue 4 - Dec 2008
Volume 3, Issue 3 - Sep 2008
Volume 3, Issue 2 - Jun 2008
Volume 3, Issue 1 - Mar 2008
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Fuzzy Logic Application in Fault Diagnosis of Transformers Using Dissolved Gases
Hooshmand, Rahmat-Allah ; Banejad, Mahdi ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 293~299
DOI : 10.5370/JEET.2008.3.3.293
One of the problems with the fault diagnosis of transformers based on dissolved gas is the inability to match the result of the different standards of fault diagnosis with real world standards. In this paper, the results of the different standards are analyzed using fuzzy logic and then compared with the empirical test. The proposed method is based on the standards and guidelines of the International Electrotechnical Commission (IEC), the Central Electric Generating Board (CEGB), and the American Society for Testing and Material (ASTM) and its main task is to assist the conventional gas ratio method. The comparison between the suggested method and existing methods indicates the capability of the suggested method in the on-line fault diagnosis of transformers. In addition, in some cases the existing standards are not able to diagnose the fault. For theses instances, the presented method has the potential of diagnosing the fault. In this paper, the information of three real transformers is used to show the capability of the suggested method in diagnosing the fault. The results validate the capability of the presented method in fault diagnosis of the transformer.
A New Approach to Determine the Direction and Cause of Voltage Sag
Ahn, Seon-Ju ; Won, Dong-Jun ; Chung, Il-Yop ; Moon, Seung-Il ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 300~307
DOI : 10.5370/JEET.2008.3.3.300
Event source locating is very important to improving the power quality level. This paper presents a method to determine the relative location of the voltage sag source according to the cause. For this, the concept of the relative location of the source is defined first. Then, the main causes of voltage sag are classified and their characteristics are discussed. From these investigations, the rules to determine the relative location of event source are proposed for each type and the overall algorithm to identify the relative location and the kind of event source is presented. Finally, the proposed method is applied to the IEEE 13-bus test system and it is verified that the method can help to pinpoint the accurate location of the event source.
Study and Simulation of RST Regulator Applied to a Double Fed Induction Machine (DFIM)
Akkari, N. ; Chaghi, A. ; Abbdessemed, R. ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 308~313
DOI : 10.5370/JEET.2008.3.3.308
This article proposes the study and simulation of an RST regulator based on a double fed induction machine. The RST polynomial controller can improve the double fed induction machine performance in terms of overshoot, rapidity, cancellation of disturbance, and capacity to maintain a high level of performance. A control law is synthesized using an RST controller. Simulation results indicate that the proposed regulator has better performance response to speed variation, sensitivity to perturbation, and robustness. The designed control algorithm is tested on a simulation matlab code.
Development of Matlab/Simulink Module for Voltage Flicker Simulation in Distribution Power Systems
Cho, Soo-Hwan ; Jung, Jae-Ahn ; Jang, Gil-Soo ; Kwon, Sae-Hyuk ; Kang, Moon-Ho ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 314~319
DOI : 10.5370/JEET.2008.3.3.314
Power quality simulation plays an important role in many practical cases, for example, when deciding the capacity of the related mitigation devices, assessing the influence of installing a nonlinear load in the distribution part, dissolving the quality issues between utilities and customers, and so on. For these purposes, many dedicated tools have been used in order to assess the level of quality distortions by various kinds of PQ indices. However, there are few modules that can accurately simulate the flicker phenomenon, that is,
and the nonlinear and chaotic behavior of the electrical arc furnace, which is one of the representative nonlinear loads. This paper deals with the useful and simple modules for the voltage flicker simulation in the distribution and transmission level under the environment of Matlab/Simulink. With these modules, the various conditions of distribution systems and the capacities of arc furnaces with the chaotic characteristic can be easily taken into account.
An Improved Dynamic Programming Approach to Economic Power Dispatch with Generator Constraints and Transmission Losses
Balamurugan, R. ; Subramanian, S. ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 320~330
DOI : 10.5370/JEET.2008.3.3.320
This paper presents an improved dynamic programming (IDP) approach to solve the economic power dispatch problem including transmission losses in power systems. A detailed mathematical derivation of recursive dynamic programming approach for the economic power dispatch problem with transmission losses is presented. The transmission losses are augmented with the objective function using price factor. The generalized expression for optimal scheduling of thermal generating units derived in this article can be implemented for the solution of the economic power dispatch problem of a large-scale system. Six-unit, fifteen-unit, and forty-unit sample systems with non-linear characteristics of the generator, such as ramp-rate limits and prohibited operating zones are considered to illustrate the effectiveness of the proposed method. The proposed method results have been compared with the results of genetic algorithm and particle swarm optimization methods reported in the literature. Test results show that the proposed IDP approach can obtain a higher quality solution with better performance.
An Intelligent Fault Detection and Service Restoration Scheme for Ungrounded Distribution Systems
Yu, Fei ; Kim, Tae-Wan ; Lim, Il-Hyung ; Choi, Myeon-Song ; Lee, Seung-Jae ; Lim, Sung-Il ; Lee, Sung-Woo ; Ha, Bok-Nam ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 331~336
DOI : 10.5370/JEET.2008.3.3.331
Electric load components have different characteristics according to the variation of voltage and frequency. This paper presents the load modeling of an electric locomotive by the parameter identification method. The proposed method for load modeling is very simple and easy for application. The proposed load model of the electric locomotive is represented by the combination of the loads that have static and dynamic characteristics. This load modeling is applied to the KTX in Korea to verify the effectiveness of the proposed method. The results of proposed load modeling by the parameter identification follow the field measurements very exactly.
Rough Fuzzy Control of SVC for Power System Stability Enhancement
Mishra, Yateendra ; Mishra, Sukumar ; Dong, Zhao Yang ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 337~345
DOI : 10.5370/JEET.2008.3.3.337
This paper presents a new approach to the design of a rough fuzzy controller for the control loop of the SVC (static VAR system) in a two area power system for stability enhancement with particular emphasis on providing effective damping for oscillatory instabilities. The performances of the rough fuzzy and the conventional fuzzy controller are compared with that of the conventional PI controller for a variety of transient disturbances, highlighting the effectiveness of the rough fuzzy controller in damping the inter-area oscillations. The effect of the rough fuzzy controller in improving the CCT (critical clearing time) of the two area system is elaborated in this paper as well.
A Probabilistic Method Based Protectability Evaluation of Distance Relay in Transmission Networks
Zhang, Wen-Hao ; Choi, Myeon-Song ; Lee, Seung-Jae ; Lim, Il-Hyung ; Rim, Seong-Jeong ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 346~353
DOI : 10.5370/JEET.2008.3.3.346
This paper defines the concept of “protectability” for the performance evaluation of distance relay considering its sensitivity and selectivity. The paper starts from the probabilistic modeling of the errors, and based on this model, a detailed explanation of protectability calculation for each zone of the distance relay is presented. An effect of the Weighting Rate and the Measurement Deviation on the protectability evaluation is also given. By considering this effect, the optimization of relay setting can be realized. The proposed method is applied to a typical model system to show its effectiveness
A Voltage Control Method based on Constants of Four Terminals Network Modeling of Distribution Networks
Yang, Xia ; Lim, Il-Hyung ; Choi, Myeon-Song ; Lee, Seung-Jae ; Kim, Tae-Wan ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 354~362
DOI : 10.5370/JEET.2008.3.3.354
In this paper, a new algorithm of optimal voltage control is proposed for the Distribution Automation System (DAS) based on constants of four terminal network modeling. In the proposed method, the voltage profiles along feeders are estimated from the measurement of the current and power factor by a Feeder Remote Terminal Unit (FRTU) installed at each node. Whenever the voltage profile violates the restriction, the voltage control strategy is applied to keep the voltage levels along the feeders within the pre-specified range through the modification and coordination of the transformer under-load tap changers (ULTC), step voltage regulator (SVR), as well as shunt condenser. In the case studies, the estimation and control of the voltages have been testified in a radial distribution system with 11 nodes.
Knowledge-Based Approach Using Support Vector Machine for Transmission Line Distance Relay Co-ordination
Ravikumar, B. ; Thukaram, D. ; Khincha, H.P. ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 363~372
DOI : 10.5370/JEET.2008.3.3.363
In this paper, knowledge-based approach using Support Vector Machines (SVMs) are used for estimating the coordinated zonal settings of a distance relay. The approach depends on the detailed simulation studies of apparent impedance loci as seen by distance relay during disturbance, considering various operating conditions including fault resistance. In a distance relay, the impedance loci given at the relay location is obtained from extensive transient stability studies. SVMs are used as a pattern classifier for obtaining distance relay co-ordination. The scheme utilizes the apparent impedance values observed during a fault as inputs. An improved performance with the use of SVMs, keeping the reach when faced with different fault conditions as well as system power flow changes, are illustrated with an equivalent 265 bus system of a practical Indian Western Grid.
Real Time Implementation of Active Power Filters for Harmonic Suppression and Reactive Power Compensation using dSPACE DS1104
Kumar, Seethapathy ; Umamaheswari, B. ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 373~378
DOI : 10.5370/JEET.2008.3.3.373
In this paper, an Active Power Filter (APF) is implemented using a dSPACE DS1104 processor to compensate harmonics and reactive power produced by nonlinear load. The reference source current is computed based on the measurement of harmonics in the supply voltage and load current. A hysteresis based current controller has been implemented in a DSP processor for injecting the compensating current into the power system, so that APF allows suppression of the harmonics and reactive power component of load current, resulting in a supply current that is purely sinusoidal. Simulation and experimental results of the proposed APF to meet the IEEE-519 standards are presented.
The Influence of Magnetization Pattern on the Performance of Permanent Magnet Eddy Current Couplings and Brakes
Cha, Hyun-Rok ; Cho, Han-Wook ; Lee, Sung-Ho ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 379~384
DOI : 10.5370/JEET.2008.3.3.379
This paper examines permanent magnet eddy current couplings and brakes. Specifically, the effect of permanent magnet magnetization patterns on the magnetic field and force production is investigated. The eddy current couplings and brakes employ high energy-product neodymium-iron-boron (NdFeB) permanent magnets that act on iron-backed copper drums to provide torque transfer from motor to load without mechanical contact. A 2-dimensional finite element modeling is performed to predict the electromagnetic behavior and the torque-speed characteristics of permanent magnet type eddy current couplings and brakes under constant speed operation.
A Computationally Efficient Finite Element Analysis Algorithm Considering 2-D Magnetic Properties of Electrical Steel Sheet
Yao, Yingying ; Li, Wei ; Yoon, Hee-Sung ; Fujiwara, Koji ; Koh, Chang-Seop ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 385~390
DOI : 10.5370/JEET.2008.3.3.385
For taking account of the two-dimensional magnetic properties of a grain-oriented electrical steel sheet, the effective anisotropic tensor reluctivity is examined, and a computationally efficient algorithm is suggested by using the response surface method to model the two-dimensional magnetic properties. It is shown that the reconstructed two-dimensional magnetic properties are fairly effective to stabilize the convergence characteristics of the Newton-Raphson iteration in the nonlinear magnetic field analysis.
Analysis of a Harmonics Neutralized 48-Pulse STATCOM with GTO Based Voltage Source Converters
Singh, Bhim ; Saha, Radheshyam ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 391~400
DOI : 10.5370/JEET.2008.3.3.391
Multi-pulse topology of converters using elementary six-pulse GTO - VSC (gate turn off based voltage source converter) operated under fundamental frequency switching (FFS) control is widely adopted in high power rating static synchronous compensators (STATCOM). Practically, a 48-pulse (
pulse) configuration is used with the phase angle control algorithm employing proportional and integral (PI) control methodology. These kinds of controllers, for example the
compensator at Inuyama switching station, KEPCO, Japan, employs two stages of magnetics viz. intermediate transformers (as many as VSCs) and a main coupling transformer to minimize harmonics distortion in the line and to achieve a desired operational efficiency. The magnetic circuit needs altogether nine transformers of which eight are phase shifting transformers (PST) used in the intermediate stage, each rating equal to or more than one eighth of the compensator rating, and the other one is the main coupling transformer having a power rating equal to that of the compensator. In this paper, a two-level 48-pulse
STATCOM is proposed where eight, six-pulse GTO-VSC are employed and magnetics is simplified to single-stage using four transformers of which three are PSTs and the other is a normal transformer. Thus, it reduces the magnetics to half of the value needed in the commercially available compensator. By adopting the simple PI-controllers, the model is simulated in a MATLAB environment by SimPowerSystems toolbox for voltage regulation in the transmission system. The simulation results show that the THD levels in line voltage and current are well below the limiting values specified in the IEEE Std 519-1992 for harmonic control in electrical power systems. The controller performance is observed reasonably well during capacitive and inductive modes of operation.
A Method of Hysteresis Modeling and Traction Control for a Piezoelectric Actuator
Sung, Baek-Ju ; Lee, Eun-Woong ; Lee, Jae-Gyu ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 401~407
DOI : 10.5370/JEET.2008.3.3.401
The dynamic model and displacement control of piezoelectric actuators, which are commercially available materials for managing extremely small displacements in the range of sub-nanometers, are presented. Piezoceramics have electromechanical characteristics that transduce energy between the electrical and mechanical domains. However, they have hysteresis between the input voltage and output displacement, and this behavior is very demanding and complicated. In this paper, we propose a method of designing the control algorithm, and present the dynamic modeling equations that represent the hysteretic behavior between input voltage and output displacement. For this process, the piezoelectric actuator is treated as a second-order linear dynamic system and system constants are determined by the system identification method. Also, a classical PID controller is designed and used to regulate the output displacement of the actuator. To evaluate the performance of the proposed method, numerical simulation results are presented.
A Feasibility Design of PEMFC Parallel Operation for a Fuel Cell Generation System
Kang, Hyun-Soo ; Choe, Gyu-Yeong ; Lee, Byoung-Kuk ; Hur, Jin ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 408~421
DOI : 10.5370/JEET.2008.3.3.408
In this paper, the parallel operation for a FC generation system is introduced and designed in order to increase the capacity for the distributed generation of a proton exchange membrane fuel cell (PEMFC) system. The equipment is the type that is used by parallel operated PEMFC generation systems which have two PEMFC systems, two dc/dc boost converters with shared dc link, and a grid-connected dc/ac inverter for embedded generation. The system requirement for the purpose of parallel operated generation using PEMFC system is also described. Aspects related to the mechanical (MBOP) and electrical (EBOP) component, size, and system complexity of the distributed generation system, it is explained in order to design an optimal distributed generation system using PEMFC. The optimal controller design for the parallel operation of the converter is suggested and informative simulations and experimental results are provided.
PD Diagnosis on 22.9kV XLPE Underground Cable using Ultra-wideband Sensor
Lwin, Kyaw-Soe ; Lim, Kwang-Jin ; Park, Noh-Joon ; Park, Dae-Hee ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 422~429
DOI : 10.5370/JEET.2008.3.3.422
This paper presents compact low frequency ultra-wide band (UWB) sensor design and study of the partial discharge diagnosis by sensing electromagnetic pulse emitted from the partial discharge source with the newly designed UWB sensor. In this study, we designed a new type of compact low frequency UWB sensor based on microstrip antenna technology to detect both the low frequency and high frequency band of the partial discharge signal. Experiments of offline PD testing on medium voltage (22.9kV) underground cable mention the comparative results with the traditional HFCT as a reference sensor in the laboratory. In the series of comparative tests, the calibration signal injection test provided with the conventional IEC 60270 method and high voltage injection testing are included.
Constraint Algorithm in Double-Base Number System for High Speed A/D Converters
Nguyen, Minh Son ; Kim, Man-Ho ; Kim, Jong-Soo ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 430~435
DOI : 10.5370/JEET.2008.3.3.430
In the paper, an algorithm called a Constraint algorithm is proposed to solve the fan-in problem occurred in ADC encoding circuits. The Flash ADC architecture uses a double-base number system (DBNS). The DBNS has known to represent the multi-dimensional logarithmic number system (MDLNS) used for implementing the multiplier accumulator architecture of FIR filter in digital signal processing (DSP) applications. The authors use the DBNS with the base 2 and 3 to represent binary output of ADC. A symmetric map is analyzed first, and then asymmetric map is followed to provide addition read DBNS to DSP circuitry. The simulation results are shown for the Double-Base Integer Encoder (DBIE) of the 6-bit ADC to demonstrate an effectiveness of the Constraint algorithm, using
CMOS technology. The DBIE’s processing speed of the ADC is fast compared to the FAT tree encoder circuit by 0.95 GHz.
3D Building Detection and Reconstruction from Aerial Images Using Perceptual Organization and Fast Graph Search
Woo, Dong-Min ; Nguyen, Quoc-Dat ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 436~443
DOI : 10.5370/JEET.2008.3.3.436
This paper presents a new method for building detection and reconstruction from aerial images. In our approach, we extract useful building location information from the generated disparity map to segment the interested objects and consequently reduce unnecessary line segments extracted in the low level feature extraction step. Hypothesis selection is carried out by using an undirected graph, in which close cycles represent complete rooftops hypotheses. We test the proposed method with the synthetic images generated from Avenches dataset of Ascona aerial images. The experiment result shows that the extracted 3D line segments of the reconstructed buildings have an average error of 1.69m and our method can be efficiently used for the task of building detection and reconstruction from aerial images.
Compensation on Impedance of the Stratum Corneum
Kim, Ki-Won ; Choi, Han-Yoon ; Sim, Myeong-Heon ; Jeong, In-Cheol ; Yoon, Hyung-Ro ;
Journal of Electrical Engineering and Technology, volume 3, issue 3, 2008, Pages 444~449
DOI : 10.5370/JEET.2008.3.3.444
This study aims at compensation of the skin moisture level using skin impedance and SR factor. SR factor is related with the current diffusion into the skin layer. To efficiently analyze the current diffusion on the skin model, we used an electromagnetic simulation program called Ansys 10.0 Emag. We confirmed that the measured value decreases as the electric current gets more diffused to the layer below the horny layer. In order to conduct actual experiments based on the simulated result, we manufactured special electrodes with 24 pins by arranging 0.8mm-diameter electrodes every 0.5mm, in a
array. By simultaneously achieving both impedance value and SR value of skin with the manufactured electrodes, we compared the skin moisture level using the existing equipment to the skin moisture level applied using the skin impedance as well as the SR factor developed in this study. The correlation coefficient between the skin moisture level achieved from the existing equipment and the reference value was 0.615 (p<0.01), whereas the correlation coefficient between the skin moisture achieved from the regression equation in this study was 0.677 (p<0.01). Accordingly, it was confirmed that applying SR factor additionally improves the moisture level more precisely.