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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 & Issues
Volume 9, Issue 6 - Nov 2014
Volume 9, Issue 5 - Sep 2014
Volume 9, Issue 4 - Jul 2014
Volume 9, Issue 3 - May 2014
Volume 9, Issue 2 - Mar 2014
Volume 9, Issue 1 - Jan 2014
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A Phase-shifter for Regulating Circulating Power Flow in a Parallel-feeding AC Traction Power System
Choi, Kyu-Hyoung ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1137~1144
DOI : 10.5370/JEET.2014.9.4.1137
A parallel-feeding AC traction power system increases the power supply capacity and decreases voltage fluctuations, but the circulating power flow caused by the phase difference between the traction substations prevents the system from being widely used. A circuit analysis shows that the circulating power flow increases almost linearly as the phase difference increases, which adds extra load to the system and results in increased power dissipation and load unbalance. In this paper, we suggest a phase shifter for the parallel-feeding AC traction power system. The phase shifter regulates the phase difference and the circulating power flow by injecting quadrature voltage which can be obtained directly from the Scott-connection transformer in the traction substation. A case study involving the phase shifter applied to the traction power system of a Korean high-speed rail system shows that a three-level phase shifter can prevent circulating power flow while the phase difference between substations increases up to 12 degrees, mitigate the load unbalance, and reduce power dissipation.
Development of a Reclosing Scheme for Reduction of Turbine Generator Shaft Torsional Torques: A Decision Method to Achieve Optimal Reactor Capacity
Oh, Yun-Sik ; Seo, Hun-Chul ; Yang, Jeong-Jae ; Kim, Chul-Hwan ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1145~1153
DOI : 10.5370/JEET.2014.9.4.1145
It is well known that line switching operations like reclosing are able to cause transient power oscillations which can stress or damage turbine generators. This paper presents a reclosing scheme to reduce the shaft torsional torques of turbine generators by inserting an additional reactor. A novel method to determine optimal reactor capacity to minimize the torsional torque generated in a turbine generator is also proposed. In this paper, the turbine generator shaft is represented by a multi-mass model to measure torsional torques generated in the shaft between the turbine and the generator. Transmission systems based on actual data from Korea are modeled to verify the proposed scheme using ElectroMagnetic Transient Program (EMTP) software. The simulation results clearly show the effectiveness of the proposed scheme and torsional torque can be minimized by applying the proposed scheme.
Developing a New Risk Assessment Methodology for Distribution System Operators Regulated by Quality Regulation Considering Reclosing Time
Saboorideilami, S. ; Abdi, Hamdi ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1154~1162
DOI : 10.5370/JEET.2014.9.4.1154
In the restructured electricity market, Performance-Based Regulation (PBR) regime has been introduced to the distribution network. To ensure the network stability, this regime is used along with quality regulations. Quality regulation impose new financial risks on distribution system operators (DSOs). The poor quality of the network will result in reduced revenues for DSOs. The mentioned financial risks depend on the quality indices of the system. Based on annual variation of these indices, the cost of quality regulation will also vary. In this paper with regard to reclosing fault in distribution network, we develop a risk-based method to assess the financial risks caused by quality regulation for DSOs. Furthermore, in order to take the stochastic behavior of the distribution network and quality indices variations into account, time-sequential Monte Carlo simulation method is used. Using the proposed risk method, the effect of taking reclosing time into account will be examined on system quality indicators and the cost of quality regulation in Swedish rural reliability test system (SRRTS). The results show that taking reclosing fault into consideration, affects the system quality indicators, particularly annual average interruption frequency index of the system (SAIFI). Moreover taking reclosing fault into consideration also affects the quality regulations cost. Therefore, considering reclosing time provides a more realistic viewpoint about the financial risks arising from quality regulation for DSOs.
Transmission Network Expansion Planning for the Penetration of Renewable Energy Sources - Determining an Optimal Installed Capacity of Renewable Energy Sources
Kim, Sung-Yul ; Shin, Je-Seok ; Kim, Jin-O ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1163~1170
DOI : 10.5370/JEET.2014.9.4.1163
Due to global environmental regulations and policies with rapid advancement of renewable energy technologies, the development type of renewable energy sources (RES) in power systems is expanding from small-scale distributed generation to large-scale grid-connected systems. In the near future, it is expected that RES achieves grid parity which means the equilibrium point where the power cost of RES is equal to the power costs of conventional generators. However, although RES would achieve the grid parity, the cost related with development of large-scale RES is still a big burden. Furthermore, it is hard to determine a suitable capacity of RES because of their output characteristics affected by locations and weather effects. Therefore, to determine an optimal capacity for RES becomes an important decision-making problem. This study proposes a method for determining an optimal installed capacity of RES from the business viewpoint of an independent power plant (IPP). In order to verify the proposed method, we have performed case studies on real power system in Incheon and Shiheung areas, South Korea.
Power Quality Early Warning Based on Anomaly Detection
Gu, Wei ; Bai, Jingjing ; Yuan, Xiaodong ; Zhang, Shuai ; Wang, Yuankai ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1171~1181
DOI : 10.5370/JEET.2014.9.4.1171
Different power quality (PQ) disturbance sources can have major impacts on the power supply grid. This study proposes, for the first time, an early warning approach to identifying PQ problems and providing early warning prompts based on the monitored data of PQ disturbance sources. To establish a steady-state power quality early warning index system, the characteristics of PQ disturbance sources are analyzed and summed up. The higher order statistics anomaly detection (HOSAD) algorithm, based on skewness and kurtosis, and hierarchical power quality early warning flow, were then used to mine limit-exceeding and abnormal data and analyze their severity. Cases studies show that the proposed approach is effective and feasible, and that it is possible to provide timely power quality early warnings for limit-exceeding and abnormal data.
Energy Management Strategy and Adaptive Control for SMES in Power System with a Photovoltaic Farm
Kim, Seung-Tak ; Park, Jung-Wook ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1182~1187
DOI : 10.5370/JEET.2014.9.4.1182
This paper proposes an energy management strategy and adaptive control for superconducting magnetic energy storage (SMES) in a distribution power system with a grid-connected photovoltaic (PV) farm. Application of the SMES system can decrease the output power fluctuations of PV system effectively. Also, it can control the real and reactive powers corresponding to the scheduled reference values with adequate converter capacity, which are required at a steady-state operating point. Therefore, the adaptive control strategy for SMES plays a key role in improving the system stability when the PV generation causes uncertain variations due to weather conditions. The performance of proposed energy management strategy and control method for the SMES is then evaluated with several case studies based on the PSCAD/EMTDC
Reliability Evaluation of Electrical Distribution Network Containing Distributed Generation Using Directed-Relation-Graph
Yang, He-Jun ; Xie, Kai-Gui ; Wai, Rong-Jong ; Li, Chun-Yan ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1188~1195
DOI : 10.5370/JEET.2014.9.4.1188
This paper presents an analytical technique for reliability evaluation of electrical distribution network (EDN) containing distributed generation (DG). Based on hierarchical levels of circuit breaker controlling zones and feeder sections, a directed-relation-graph (DRG) for an END is formed to describe the hierarchical structure of the EDN. The reliability indices of EDN and load points can be evaluated directly using the formed DRG, and the reliability evaluation of an EDN containing DGs can also be done without re-forming the DRG. The proposed technique incorporates multi-state models of photovoltaic and diesel generations, as well as weather factors. The IEEE-RBTS Bus 6 EDN is used to validate the proposed technique; and a practical campus EDN containing DG was also analyzed using the proposed technique.
Estimating PMSG Wind Turbines by Inertia and Droop Control Schemes with Intelligent Fuzzy Controller in Indian Development
Josephine, R.L. ; Suja, S. ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1196~1201
DOI : 10.5370/JEET.2014.9.4.1196
This paper presents an exploration on the effect of wind turbine contribution to the frequency control of individual systems that can be used for efficient power production in India. The research includes the study of Permanent Magnet Synchronous Generator (PMSG), in wind farms. The WTs are tested for inertia and for droop responses with intelligent fuzzy logic controllers (FLC) that choose Double Input Single Output (DISO) strategy that automatically sets gain constants, as well as combined responses for the WTs. Quantitative analyses are presented for the WTs for benefits and drawbacks including appropriate selection parameters. The analysis includes inertia, droop and combined inertia, droop schemes. The reconnaissance also incorporates inertia with FLC, droop with FLC, inertia and droop with FLC schemes for detailed study of WTs, so as to forecast and achieve proper frequency control. Moreover, the analysis provides the best suited method for frequency control in PMSG.
Integrated Optimization of Combined Generation and Transmission Expansion Planning Considering Bus Voltage Limits
Kim, Hyoungtae ; Kim, Wook ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1202~1209
DOI : 10.5370/JEET.2014.9.4.1202
A novel integrated optimization method is proposed to combine both generation and transmission line expansion problem considering bus voltage limit. Most of the existing researches on the combined generation and transmission expansion planning cannot consider bus voltages and reactive power flow limits because they are mostly based on the DC power flow model. In this paper the AC power flow model and nonlinear constraints related to reactive power are simplified and modified to improve the computation time and convergence. The proposed method has been successfully applied to Garver's six-bus system which is one of the most frequently used small scale sample systems to verify the transmission expansion method.
An Applicability of Teager Energy Operator and Energy Separation Algorithm for Waveform Distortion Analysis : Harmonics, Inter-harmonics and Frequency Variation
Cho, Soo-Hwan ; Hur, Jin ; Chung, Il-Yop ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1210~1216
DOI : 10.5370/JEET.2014.9.4.1210
This paper deals with an application of Teager Energy Operator (TEO) and Energy Separation Algorithm(ESA) to detect and determine various voltage waveform distortions like harmonics, inter-harmonics and frequency variation. Because the TEO and DESA algorithm was initially proposed for speech or communication analysis, its applications are limited to some types of waveform in the power quality analysis area. For example, an undistorted voltage signal is similar with a pure sinusoid. A voltage fluctuation is very similar with an amplitude-modulated signal, from the viewpoint of signal theory. And a continuous frequency variation is similar with a frequency-modulated signal, which is also known as a chirp signal. This paper is written to show that the TEO and DESA algorithm can be used for detecting occurrences of the representative waveform distortions and determining their instantaneous information of amplitude and frequency.
Fault Line Detection Methodology for Four Parallel Lines on the Same Tower
Li, Botong ; Li, Yongli ; Yao, Chuang ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1217~1228
DOI : 10.5370/JEET.2014.9.4.1217
A method for faulted line detection of four parallel lines on the same tower is presented, based on four-summing and double-differential sequences of one terminal current. Four-summing and double-differential sequences of fault current can be calculated using a certain transformation matrix for parameter decoupling of four parallel transmission lines. According to fault boundary conditions, the amplitude and phase characteristics of four-summing and double-differential sequences of fault current is studied under conditions of different types of fault. Through the analysis of the relationship of terminal current and fault current, a novel methodology for fault line detection of four parallel transmission line on the same tower is put forward, which can pick out the fault lines no matter the fault occurs in single line or cross double lines. Simulation results validate that the methodology is correct and reliable under conditions of different load currents, transient resistances and fault locations.
Power Losses Reduction via Simultaneous Optimal Distributed Generation Output and Reconfiguration using ABC Optimization
Jamian, Jasrul Jamani ; Dahalan, Wardiah Mohd ; Mokhlis, Hazlie ; Mustafa, Mohd Wazir ; Lim, Zi Jie ; Abdullah, Mohd Noor ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1229~1239
DOI : 10.5370/JEET.2014.9.4.1229
Optimal Distributed Generation (DG) output and reconfiguration are among the well accepted approach to reduce power loss in a distribution network. In the past, most of the researchers employed optimal DG output and reconfiguration separately. In this work, a simultaneous DG output and reconfiguration analysis is proposed to maximize power loss reduction. The impact of the separated analysis and simultaneous analysis are investigated. The test result on the 33 bus distribution network with 3 units of DG operated in PV mode showed the simultaneous analysis gave the lowest power loss (global optimal) and faster results compared to other combined methods. All the analyses for optimizing the DG as well as reconfiguration are used the Artificial Bee Colony Optimization technique.
Optimal DG Placement in a Smart Distribution Grid Considering Economic Aspects
Buaklee, Wirote ; Hongesombut, Komsan ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1240~1247
DOI : 10.5370/JEET.2014.9.4.1240
The applications of Distributed Generation (DG) in a smart distribution grid environment are widely employed especially for power balancing and supporting demand responses. Using these applications can have both positive and negative impacts on the distribution system. The sizing and location of their installations are the issues that should be taken into consideration to gain the maximum benefit from them when considering the economic aspects. This paper presents an application of the Bat Algorithm (BA) for the optimal sizing and siting of DG in a smart distribution power system in order to maximize the Benefit to Cost Ratio (BCR), subjected to system constraints including real and reactive power generation, line and transformer loading, voltage profile, energy losses, fault level as well as DG operating limits. To demonstrate the effectiveness of the proposed methodology and the impact of considering economic issues on DG placement, a simplify 9-bus radial distribution system of the Provincial Electricity Authority of Thailand (PEA) is selected for the computer simulation to explore the benefit of the optimal DG placement and the performance of the proposed approach.
Maintenance Priority Index of Overhead Transmission Lines for Reliability Centered Approach
Heo, Jae-Haeng ; Kim, Mun-Kyeom ; Kim, Dam ; Lyu, Jae-Kun ; Kang, Yong-Cheol ; Park, Jong-Keun ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1248~1257
DOI : 10.5370/JEET.2014.9.4.1248
Overhead transmission lines are crucial components in power transmission systems. Well-designed maintenance strategy for overhead lines is required for power utilities to minimize operating costs, while improving the reliability of the power system. This paper presents a maintenance priority index (MPI) of overhead lines for a reliability centered approach. Proposed maintenance strategy is composed of a state index and importance indices, taking into account a transmission condition and importance in system reliability, respectively. The state index is used to determine the condition of overhead lines. On the other hand, the proposed importance indices indicate their criticality analysis in transmission system, by using a load effect index (LEI) and failure effect index (FEI). The proposed maintenance method using the MPI has been tested on an IEEE 9-bus system, and a numerical result demonstrates that our strategy is more cost effective than traditional maintenance strategies.
Comparative Study of the Behavior of a Wind Farm Integrating Three Different FACTS Devices
Sarrias, Raul ; Gonzalez, Carlos ; Fernandez, Luis M. ; Garcia, Carlos Andres ; Jurado, Francisco ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1258~1268
DOI : 10.5370/JEET.2014.9.4.1258
Improving grid connection of wind farms is a relevant issue to be addressed, especially for fixed-speed wind turbines. Certain elements, such as FACTS (Flexible AC Transmission Systems), are able to perform voltage and reactive power regulation in order to support voltage stability of wind farms, and compensate reactive power consumption from the grid. Several devices are grouped under the name of FACTS, which embrace different technologies and operating principles. Here, three of them are evaluated and compared, namely STATCOM (Static Synchronous Compensator), SVC (Static Var Compensator) and SSSC (Static Synchronous Series Compensator). They have been modeled in MATLAB/Simulink, and simulated under various scenarios, regarding both normal operation and grid fault conditions. Their response is studied together with the case when no FACTS are implemented. Results show that SSSC improves the voltage stability of the wind farm, whereas STATCOM and SVC provide additional reactive power.
Design and Analysis of SEPIC Converter Based MPPT for Solar PV Module with CPWM
Maglin, J.R. ; Ramesh, R. ; Vaigundamoorthi, M. ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1269~1276
DOI : 10.5370/JEET.2014.9.4.1269
The main objective of this paper is to design DC-DC MPPT circuit using chaotic pulse width modulation to track maximum power from solar PV module for space application. The direct control method of tracking is used to extract maximum power. The nominal duty cycle of the main switch of DC-DC SEPIC converter is adjusted so that the solar panel output impedance is equal to the input resistance of the SEPIC converter which results better spectral performance in the tracked voltages when compared to conventional PWM control. The conversion efficiency of the proposed MPPT system is increased when CPWM is used as a control scheme
Efficiency Improvement for Concentrated Flux IPM Motors for Washing Machines
Yoon, Keun-Young ; Kwon, Byung-Il ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1277~1282
DOI : 10.5370/JEET.2014.9.4.1277
Concentrated flux interior permanent magnet (CFIPM) motors have the advantage that their utilization of flux linkage is more efficient than that of general IPM motors and CFIPM motors are suitable for washing machine motors, which demand low-speed, high-torque specifications. However, low efficiency occurs in the low-speed high-torque mode considering the high-speed operation for spin mode. This paper proposes a magnet overhang structure between the rotor core that reduces leakage flux and improves efficiency for a CFIPM in wash mode. Optimization of the 3D design of magnet overhang structures is performed to improve the efficiency with the same quantity of permanent magnets. The validity of the optimal design is experimentally verified through the fabrication of prototypes.
Effect of Circuit Parameters on Stability of Voltage-fed Buck-Boost Converter in Discontinuous Conduction Mode
Feng, Zhao-He ; Gong, Ren-Xi ; Wang, Qing-Yu ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1283~1289
DOI : 10.5370/JEET.2014.9.4.1283
The state transition matrix are obtained by solving state equations in terms of Laplace inverse transformation and Cayley-Hamilton theorem, and an establishment of a precise discrete-iterative mapping of the voltage-fed buck-boost converter operating in discontinuous conduction mode is made. On the basis of the mapping, the converter bifurcation diagrams and Lyapunov exponent diagrams with the input voltage, the resistance, the inductance and the capacitance as the bifurcation parameters are obtained, and the effect of the parameters on the system stability is deeply studied. The results obtained show that they have a great influence on the stability of the system, and the general trend is that the increase of either the voltage-fed coefficient, input voltage or the load resistance, or the decrease of the filtering inductance, capacitance will make the system stability become poorer, and that all the parameters have a critical value, and when they are greater or less than the values, the system will go through stable 1T orbits, stable 2T orbits, 4T orbits, 8T orbits and eventually approaches chaos.
Comparison of Power Loss and Magnetic Flux Distribution in Octagonal Wound Transformer Core Configurations
Cinar, Mehmet Aytac ; Alboyaci, Bora ; Sengul, Mehlika ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1290~1295
DOI : 10.5370/JEET.2014.9.4.1290
In this paper, various configurations of octagonal wound transformer core topology, which has previously proved advantages on conventional wound cores, are studied. Each configuration has different joint types and different placement of joint zones on the core. Magnetic flux distributions and power losses of each configuration are analyzed and compared. Comparisons are based on both 2D&3D finite element simulations and experimental studies. The results show that, joint types and their placements on the core cause local flux accumulations and dramatically affect power loss of the core.
Analysis and Implementation of a New ZVS DC Converter for Medium Power Application
Lin, Bor-Ren ; Shiau, Tung-Yuan ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1296~1308
DOI : 10.5370/JEET.2014.9.4.1296
This paper presents a new zero voltage switching (ZVS) converter for medium power and high input voltage applications. Three three-level pulse-width modulation (PWM) circuits with the same power switches are adopted to clamp the voltage stress of MOSFETs at
and to achieve load current sharing. Thus, the current stresses and power ratings of transformers and power semiconductors at the secondary side are reduced. The resonant inductance and resonant capacitance are resonant at the transition interval such that active switches are turned on at ZVS within a wide range of input voltage and load condition. The series-connected transformers are adopted in each three-level circuit. Each transformer can work as an inductor to smooth the output current or a transformer to achieve the electric isolation and power transfer. Thus, no output inductor is needed at the secondary side. Three center-tapped rectifiers connected in parallel are used at the secondary side to achieve load current sharing. Compared with the conventional parallel three-level converters, the proposed converter has less switch counts. Finally, experiments based on a 1.44kW prototype are provided to verify the operation principle of proposed converter.
Measurement of Stator Core Loss of an Induction Motor at Each Manufacturing Process
Jeong, Kwangyoung ; Ren, Ziyan ; Yoon, Heesung ; Koh, Chang-Seop ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1309~1314
DOI : 10.5370/JEET.2014.9.4.1309
The measurement of stator core loss for an induction motor at each manufacturing process is carried out in this paper. Iron loss in the stator core of induction motor changes after each manufacturing process due to the mechanical stress, which can cause the deterioration of the magnetic performances. This paper proposes a new iron loss measuring system of the stator core in an induction motor, which can be applied to the case when the distribution of magnetic flux density is not uniform along the magnetic flux path. In the system, the iron loss is calculated based on the induced voltage of the B-search coil and exciting current.
Optimum Rotor Shaping for Torque Improvement of Double Stator Switched Reluctance Motor
Tavakkoli, Mohammadali ; Moallem, Mehdi ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1315~1323
DOI : 10.5370/JEET.2014.9.4.1315
Although the power density in Double Stator Switched Reluctance Motor (DSSRM) has been improved, the torque ripple is still very high. So, it is important to reduce the torque ripple for specific applications such as Electric Vehicles (EVs). In This paper, an effective rotor shaping optimization technique for torque ripple reduction of DSSRM is presented. This method leads to the lower torque pulsation without significant reduction in the average torque. The method is based on shape optimization of the rotor using Finite Element Method and Taguchi's optimization method for rotor reshaping for redistribution of the flux so that the phase inductance profile has smoother variation as the rotor poles move into alignment with excited stator poles. To check on new design robustness, mechanical analysis was used to evaluate structural conformity against local electromagnetic forces which cause vibration and deformation. The results show that this shape optimization technique has profound effect on the torque ripple reduction.
Compensation PWM Technique for Extended Output Voltage Range in Three-Phase VSI Using Three Shunt Resistors
Shin, Seung-Min ; Park, Rae-Kwan ; Lee, Byoung-Kuk ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1324~1331
DOI : 10.5370/JEET.2014.9.4.1324
This paper proposes a compensation PWM technique for the extension of output voltage ranges in three-phase VSI applications using three shunt resistors. The proposed technique aims to solve the dead zone, which occurs in high modulation indexes. In the dead zone, two phase currents cannot be sampled correctly, so that the three-phase VSI cannot be operated up to the maximum output voltage. The dead zone is analyzed in detail, and the compensation PWM algorithm is developed. The proposed algorithm is verified by numerical analysis and experimental results.
A Novel Circuit for Characteristics Measurement of SiC Transistors
Cao, Guoen ; Kim, Hee-Jun ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1332~1342
DOI : 10.5370/JEET.2014.9.4.1332
This paper proposes a novel test circuit for SiC transistors. On-state resistance under practical application conditions is an important characteristic for the device reliability and conduction efficiency of SiC transistors. In order to measure the on-state resistance in practical applications, high voltage is needed, and high current is also necessary to ignite performance for the devices. A soft-switching circuit based on synchronous buck topology is developed in this paper. To provide high-voltage and high-current stresses for the devices without additional spikes and oscillations, a resonant circuit has been introduced. Using the novel circuit technology, soft-switching can be successfully realized for all the switches. Furthermore, in order to achieve accurate measurement of on-state resistance under switching operations, an active clamp circuit is employed. Operation principle and design analysis of the circuit are discussed. The dynamic measurement method is illustrated in detail. Simulation and experiments were carried out to verify the feasibility of the circuit. A special test circuit has been developed and built. Experimental results confirm that the proposed circuit gives a good insight of the devices performance in real applications.
Optimization and Characterization of Gate Electrode Dependent Flicker Noise in Silicon Nanowire Transistors
Anandan, P. ; Mohankumar, N. ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1343~1348
DOI : 10.5370/JEET.2014.9.4.1343
The low frequency noise in Silicon Nanowire Field Effect Transistors is analyzed by characterizing the gate electrode dependence on various geometrical parameters. It shows that gate electrodes have a strong impact in the flicker noise of Silicon Nanowire Field effect transistors. Optimization of gate electrode was done by comparing different performance metrics such a DIBL, SS,
and fringing capacitance using TCAD simulations. Molybdenum based gate electrode showed significant improvement in terms of high drive current, Low DIBL and high
. The noise power sepctral density is reduced by characterizing the device at higher frequencies. Silicon Nanowire with Si3N4 spacer decreases the drain current spectral density which interms reduces the fringing fields there by decreasing the flicker noise.
A Study on Optimization of Compact High-voltage Generator Based on Magnetic-core Tesla Transformer
Jeong, Young-Kyung ; Youn, Dong-Gi ; Lee, Moon-Qee ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1349~1354
DOI : 10.5370/JEET.2014.9.4.1349
This paper presents a compact and portable high-voltage generator based on magnetic-core Tesla transformer for driving an UWB high power electromagnetic source. In order to optimize the performance of the high-voltage generator, a novel open-loop cylindrical magnetic-core adopting the quad-division lamination structure is proposed and manufactured. The designed high-voltage generator using the proposed magnetic core has a battery-powered operation and compact size of
in length and diameter, respectively. The high-voltage generator can produce a voltage pulse waveform with peak amplitude of 450 kV, a rise time of 1.5 ns, and pulse duration of 2.5 ns at the 800 V input voltage.
A 2D Analytical Modeling of Single Halo Triple Material Surrounding Gate (SHTMSG) MOSFET
Dhanaselvam, P. Suveetha ; Balamurugan, N.B. ; Chakaravarthi, G.C. Vivek ; Ramesh, R.P. ; Kumar, B.R. Sathish ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1355~1359
DOI : 10.5370/JEET.2014.9.4.1355
In the proposed work a 2D analytical modeling of single halo Triple material Surrounding Gate (SH-TMSG) MOSFET is developed. The Surface potential and Electric Field has been derived using parabolic approximation method and the simulation results are analyzed. The essential substantive is provided which elicits the deterioration of short channel effects and the results of the analytical model are delineated and compared with MEDICI simulation results and it is well corroborated.
Investigation of the Finite Planar Frequency Selective Surface with Defect Patterns
Hong, Ic-Pyo ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1360~1364
DOI : 10.5370/JEET.2014.9.4.1360
In this paper, RCS characteristics on defect pattern of crossed dipole slot FSS having a finite size have been analyzed. To analyze RCS, we applied the electric field integral equation analysis which applies BiCGSTab algorithm with iterative method and uses RWG basis function. To verify the validity of this paper, RCS of PEC sphere has been compared to the theoretical results and FSSs with defect patterns are fabricated and measured. As defect patterns in FSS, missing one column, missing some elements, and discontinuity in surfaces are simulated and compared with the measurement results. Resonant frequency shifts in pass band and changes in bandwidth are observed. From the results, precisely predicting and designing frequency characteristics over defect patterns are essential when applying FSS structures such as FSS radomes.
CPW-fed to CPS Dipole Antenna of Microstrip Tapered Balun with Triangular Loop Director
Lee, Hyeonjin ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1365~1368
DOI : 10.5370/JEET.2014.9.4.1365
A CPW-fed to CPS dipole antenna of triangular loop director by microstrip tapered balun is proposed for dual and wide band operations, in this paper. The proposed antenna is consisted of a CPW-fed to CPS transform, microstrip tapered balun element, CPS dipole driver and triangular loop director. A dual and wide bandwidth of the proposed dipole antenna is realized by introducing the triangular loop director and taper matching element. The operated frequency bandwidth is 1GHz (2.14~3.14 GHz) and 1.9 GHz (4.6~6.5 GHz) to return loss criterion of less than 10 dB. The measured return loss of the proposed antenna showed good results of the dual and wide band operating frequency and the radiation pattern. The proposed antenna is able to support WLAN wireless communications applications.
Diagnosis of Medium Voltage Cables for Nuclear Power Plant
Ha, Che-Wung ; Lee, Do Hwan ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1369~1374
DOI : 10.5370/JEET.2014.9.4.1369
Most accidents of medium-voltage cables installed in nuclear power plants result from the initial defect of internal insulators or the initial failure due to poor construction. However, as the service years of plants increase, the possibility of cable accidents is also rapidly increases. This is primarily caused by electric, mechanical, thermal, and radiation stresses. Recently, much attention is paid to the study of cable diagnoses. To date, partial discharge and Tan
measurements are known as reliable methods to diagnose the aging of medium-voltage cables. High frequency partial discharge measurement techniques have been widely used to diagnose cables in transmission and distribution systems. However, the on-line high frequency partial discharge technique has not been used in the nuclear power plants because of the plant shutdown risk, degraded measurement sensitivity, and application problems. In this paper, the partial discharge measurement with a portable device was tried to evaluate the integrity of the 4.16kV and 13.8kV cable lines. The test results show that the high detection sensitivity can be achieved by the high frequency partial discharge technique. The present technique is highly attractive to diagnose medium voltage cables in nuclear power plants.
Flashover Prediction of Polymeric Insulators Using PD Signal Time-Frequency Analysis and BPA Neural Network Technique
Narayanan, V. Jayaprakash ; Karthik, B. ; Chandrasekar, S. ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1375~1384
DOI : 10.5370/JEET.2014.9.4.1375
Flashover of power transmission line insulators is a major threat to the reliable operation of power system. This paper deals with the flashover prediction of polymeric insulators used in power transmission line applications using the novel condition monitoring technique developed by PD signal time-frequency map and neural network technique. Laboratory experiments on polymeric insulators were carried out as per IEC 60507 under AC voltage, at different humidity and contamination levels using NaCl as a contaminant. Partial discharge signals were acquired using advanced ultra wide band detection system. Salient features from the Time-Frequency map and PRPD pattern at different pollution levels were extracted. The flashover prediction of polymeric insulators was automated using artificial neural network (ANN) with back propagation algorithm (BPA). From the results, it can be speculated that PD signal feature extraction along with back propagation classification is a well suited technique to predict flashover of polymeric insulators.
On-line Temperature Monitoring of the GIS Contacts Based on Infrared Sensing Technology
Li, Qingmin ; Cong, Haoxi ; Xing, Jinyuan ; Qi, Bo ; Li, Chengrong ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1385~1393
DOI : 10.5370/JEET.2014.9.4.1385
Gas insulated switchgear (GIS) is widely used in the power systems, however, the contacts overheating of the inside circuit breaker or disconnector may be a potential cause of developing accidents. As the temperature of the contacts cannot be directly acquired due to existence of the metallic shield, an infrared sensor is adopted to directly measure the temperature of the shield and then the contacts temperature can be indirectly obtained by data fitting, based on which the on-line temperature monitoring technology specifically for GIS contacts based on infrared sensing is proposed in this paper. A real GIS test platform is constructed and experimental studies are carried out to account for the influential factors that affect the accuracy of the infrared temperature measurement. A heat transfer model of the GIS module is also developed, together with experimental studies, the nonlinear temperature relationship among the contacts, the metallic shield and the environment based on a neural network algorithm is established. Finally, an integrated on-line temperature monitoring system for the GIS contacts is developed for on-site applications.
A Simulator for Calculating Normal Induced Voltage on Communication Line
Heo, Jeong-Yong ; Seo, Hun-Chul ; Lee, Soon-Jeong ; Kim, Yoon Sang ; Kim, Chul-Hwan ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1394~1400
DOI : 10.5370/JEET.2014.9.4.1394
The current flowing through the overhead transmission lines causes induced voltage on the communication lines, which can be prevented by calculating the induced voltage at the planning stage for overhead transmission line installment through an agreement between the communication and electric power companies. The procedures to calculate the induced voltages, however, are complicated due to the variety of parameters and tower types of the overhead transmission lines. The difficulty necessitates the development of a simulator to measure the induced voltage on the communication lines. This paper presents two simulators developed for this purpose; one using the Data Base (DB) index method and the other using the Graphic User Interface (GUI) method. The simulators described in this paper have been implemented by the EMTP (Electromagnetic Transient Program).
Satellite Fault Detection and Isolation Scheme with Modified Adaptive Fading EKF
Lim, Jun Kyu ; Park, Chan Gook ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1401~1410
DOI : 10.5370/JEET.2014.9.4.1401
This paper presents a modified adaptive fading EKF (AFEKF) for sensor fault detection and isolation in the satellite. Also, the fault detection and isolation (FDI) scheme is developed in three phases. In the first phase, the AFEKF is modified to increase sensor fault detection performance. The sensor fault detection and sensor selection method are proposed. In the second phase, the IMM filer with scalar penalty is designed to detect wherever actuator faults occur. In the third phase of the FDI scheme, the sub-IMM filter is designed to identify the fault type which is either the total or partial fault. An important feature of the proposed FDI scheme can decrease the number of filters for detecting sensor fault. Also, the proposed scheme can classify fault detection and isolation as well as fault type identification.
Multi-symbol Accessing Huffman Decoding Method for MPEG-2 AAC
Lee, Eun-Seo ; Lee, Kyoung-Cheol ; Son, Kyou-Jung ; Moon, Seong-Pil ; Chang, Tae-Gyu ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1411~1417
DOI : 10.5370/JEET.2014.9.4.1411
An MPEG-2 AAC Huffman decoding method based on the fixed length compacted codeword tables, where each codeword can contain multiple number of Huffman codes, was proposed. The proposed method enhances the searching efficiency by finding multiple symbols in a single search, i.e., a direct memory reading of the compacted codeword table. The memory usage is significantly saved by separately handling the Huffman codes that exceed the length of the compacted codewords. The trade-off relation between the computational complexity and the amount of memory usage was analytically derived to find the proper codeword length of the compacted codewords for the design of MPEG-2 AAC decoder. To validate the proposed algorithm, its performance was experimentally evaluated with an implemented MPEG-2 AAC decoder. The results showed that the computational complexity of the proposed method is reduced to 54% of that of the most up-to-date method.
Spatial Compounding of Ultrasonic Diagnostic Images for Rotating Linear Probe with Geometric Parameter Error Compensation
Choi, Myoung Hwan ; Bae, Moo Ho ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1418~1425
DOI : 10.5370/JEET.2014.9.4.1418
In ultrasonic medical imaging, spatial compounding of images is a technique where ultrasonic beam is steered to examine patient tissues in multiple angles. In the conventional ultrasonic diagnostic imaging, the steering of the ultrasonic beam is achieved electronically using the phased array transducer elements. In this paper, a spatial compounding approach is presented where the ultrasonic probe element is rotated mechanically and the beam steering is achieved mechanically. In the spatial compounding, target position is computed using the value of the rotation axis and the transducer array angular position. However, in the process of the rotation mechanism construction and the control system there arises the inevitable uncertainties in these values. These geometric parameter errors result in the target position error, and the consequence is a blurry compounded image. In order to reduce these target position errors, we present a spatial compounding scheme where error correcting transformation matrices are computed and applied to the raw images before spatial compounding to reduce the blurriness in the compounded image. The proposed scheme is illustrated using phantom and live scan images of human knee, and it is shown that the blurriness is effectively reduced.
Intelligent Approach for Segmenting CT Lung Images Using Fuzzy Logic with Bitplane
Khan, Z. Faizal ; Kannan, A. ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1426~1436
DOI : 10.5370/JEET.2014.9.4.1426
In this article, we present a new grey scale image segmentation method based on Fuzzy logic and bitplane techniques which combines the bits of different bitplanes of a pixel inorder to increase the segmentation quality and to get a more reliable and accurate segmentation result. The proposed segmentation approach is conceptually different and explores a new strategy. Infact, our technique consists in combining many realizations of the image together inorder to increase the information quality and to get an optimal segmented image. For segmentation, we proceed in two steps. In the first step, we begin by identifying the bitplanes that represent the lungs clearly. For this purpose, the intensity value of a pixel is separated into bitplanes. In the second step, segmentation values are assigned for each bitplane based on membership table. The segmented values of foreground are combined and the segmentation values of background are combined. The algorithm is demonstrated through the medical computed tomography (CT) images. The segmentation accuracy of the proposed method is compared with two existing techniques. Satisfactory segmentation results have been obtained showing the effectiveness and superiority of the proposed method.
A Novel Linearization Method of Sin/Cos Sensor Signals Used for Angular Position Determination
Zivanovi, Dragan ; Lukic, Jelena ; Denic, Dragan ;
Journal of Electrical Engineering and Technology, volume 9, issue 4, 2014, Pages 1437~1445
DOI : 10.5370/JEET.2014.9.4.1437
In this paper a novel method for angular position determination using sensors with sin/cos output and without an excitation signal, is presented. The linearization of the sensor transfer characteristic and digitalization of the measurement results are performed simultaneously with a goal to increase the measurement resolution. This improvement is particularly important for low angular velocities, and can be used to increase the resolution of incremental Hall, magnetic and optical sensors. This method includes two phases of sin/cos signal linearization. In the first linearization phase the pseudo-linear signal is generated. The second linearization phase, executed by the two-stage piecewise linear ADC, is an additional linearization of the pseudo-linear signal. Based on the LabVIEW software simulations of the proposed method, the contribution of each processing phase to a final measurement error is examined. After the proposed method is applied within
[rad] range, the maximal nonlinearity is reduced from 0.3307 [rad] (