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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 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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Trust-Tech based Parameter Estimation and its Application to Power System Load Modeling
Choi, Byoung-Kon ; Chiang, Hsiao-Dong ; Yu, David C. ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 451~459
DOI : 10.5370/JEET.2008.3.4.451
Accurate load modeling is essential for power system static and dynamic analysis. By the nature of the problem of parameter estimation for power system load modeling using actual measurements, multiple local optimal solutions may exist and local methods can be trapped in a local optimal solution giving possibly poor performance. In this paper, Trust-Tech, a novel methodology for global optimization, is applied to tackle the multiple local optimal solutions issue in measurement-based power system load modeling. Multiple sets of parameter values of a composite load model are obtained using Trust-Tech in a deterministic manner. Numerical studies indicate that Trust-Tech along with conventional local methods can be successfully applied to power system load model parameter estimation in measurement-based approaches.
Two-Terminal Numerical Algorithm for Single-Phase Arcing Fault Detection and Fault Location Estimation Based on the Spectral Information
Kim, Hyun-Houng ; Lee, Chan-Joo ; Park, Jong-Bae ; Shin, Joong-Rin ; Jeong, Sang-Yun ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 460~467
DOI : 10.5370/JEET.2008.3.4.460
This paper presents a new numerical algorithm for the fault location estimation and arcing fault detection when a single-phase arcing ground fault occurs on a transmission line. The proposed algorithm derived in the spectrum domain is based on the synchronized voltage and current samples measured from the PMUs(Phasor Measurement Units) installed at both ends of the transmission lines. In this paper, the algorithm uses DFT(Discrete Fourier Transform) for estimation. The algorithm uses a short data window for real-time transmission line protection. Also, from the calculated arc voltage amplitude, a decision can be made whether the fault is permanent or transient. The proposed algorithm is tested through computer simulation to show its effectiveness.
Radial Basis Function Neural Network for Power System Transient Energy Margin Estimation
Karami, Ali ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 468~475
DOI : 10.5370/JEET.2008.3.4.468
This paper presents a method for estimating the transient stability status of the power system using radial basis function(RBF) neural network with a fast hybrid training approach. A normalized transient energy margin(
) has been obtained by the potential energy boundary surface(PEBS) method along with a time-domain simulation technique, and is used as an output of the RBF neural network. The RBF neural network is then trained to map the operating conditions of the power system to the
, which provides a measure of the transient stability of the power system. The proposed approach has been successfully applied to the 10-machine 39-bus New England test system, and the results are given.
Hybrid Differential Evolution Technique for Economic Dispatch Problems
Jayabarathi, T. ; Ramesh, V. ; Kothari, D. P. ; Pavan, Kusuma ; Thumbi, Mithun ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 476~483
DOI : 10.5370/JEET.2008.3.4.476
This paper is aimed at presenting techniques of hybrid differential evolution for solving various kinds of Economic Dispatch(ED) problems such as those including prohibited zones, emission dispatch, multiple fuels, and multiple areas. The results obtained for typical problems are compared with those obtained by other techniques such as Particle Swarm Optimization(PSO) and Classical Evolutionary Programming(CEP) techniques. The comparison of the results proves that hybrid differential evolution is quite favorable for solving ED problems with no restrictions on the shapes of the input-output functions of the generator.
Ungrounded System Fault Section Detection Method by Comparison of Phase Angle of Zero-Sequence Current
Yang, Xia ; Choi, Myeon-Song ; Lee, Seung-Jae ; Lim, Il-Hyung ; Lim, Seong-Il ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 484~490
DOI : 10.5370/JEET.2008.3.4.484
In this paper, an integrated fault section detection and isolation strategy is proposed based on the application of the Distribution Automation System(DAS) utilizing advanced IT and communication technologies. The Feeder Remote Terminal Unit(FRTU) has been widely used to collect data in the Korean distribution system. The achieved data is adopted in this method for detecting multiple fault types. Especially in the case of single phase-to-ground fault, the fault section is detected by comparison of the zero-sequence current phase angle. The test results have verified the effectiveness of the proposed method in a radial distribution system through extensive simulations in Matlab/Simulink. Furthermore, a communication-based demo system identical to the simulation model has been developed, and it can be applied as an online monitoring and control program for fault section detection and isolation.
Decoupled Control of Doubly Fed Induction Machine Fed by SVM Matrix Converter
Dendouga, Abdelhakim ; Abdessemed, Rachid ; Bendaas, Mohamed Lokmane ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 491~498
DOI : 10.5370/JEET.2008.3.4.491
In this paper a decoupled control of a doubly-fed induction machine(DFIM) feed by a matrix converter is presented. It provides a robust regulation of the stator side active and reactive powers by the direct and quadratic components of the stator current vector, presented in a line-voltage-oriented reference frame. In this case, the stator windings are directly connected to the line grid, while the rotor windings are supplied by this later through a matrix converter controlled by a space vector modulation technique. The proposed solution is suitable for both energy generation and electrical drive applications with restricted speed variation range.
On Power System Frequency Control in Emergency Conditions
Bevrani, H. ; Ledwich, G. ; Ford, J. J. ; Dong, Z.Y. ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 499~508
DOI : 10.5370/JEET.2008.3.4.499
Frequency regulation in off-normal conditions has been an important problem in electric power system design/operation and is becoming much more significant today due to the increasing size, changing structure and complexity of interconnected power systems. Increasing economic pressures for power system efficiency and reliability have led to a requirement for maintaining power system frequency closer to nominal value. This paper presents a decentralized frequency control framework using a modified low-order frequency response model containing a proportional-integral(PI) controller. The proposed framework is suitable for near-normal and emergency operating conditions. An
control technique is applied to achieve optimal PI parameters, and an analytic approach is used to analyse the system frequency response for wide area operating conditions. Time-domain simulations with a multi-area power system example show that the simulated results agree with those predicted analytically.
The Ramp-Rate Constraint Effects on the Generators' Equilibrium Strategy in Electricity Markets
Joung, Man-Ho ; Kim, Jin-Ho ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 509~513
DOI : 10.5370/JEET.2008.3.4.509
In this paper, we investigate how generators' ramp-rate constraints may influence their equilibrium strategy formulation. In the market model proposed in this study, the generators' ramp-rate constraints are explicitly represented. In order to fully characterize the inter-temporal nature of the ramp-rate constraints, a dynamic game model is presented. The subgame perfect Nash equilibrium is adopted as the solution of the game and the backward induction procedure for the solution of the game is designed in this paper. The inter-temporal nature of the ramp-rate constraints results in the Markov property of the game, and we have found that the Markov property of the game significantly simplifies the subgame perfect Nash equilibrium characterization. Finally, a simple electricity market numerical illustration is presented for the successful application of the approach proposed.
Unit Commitment by Separable Augmented Lagrangian Relaxation
Moon, Guk-Hyun ; Joo, Sung-Kwan ; Lee, Ki-Sung ; Choi, Jae-Seok ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 514~519
DOI : 10.5370/JEET.2008.3.4.514
The non-separable quadratic penalty terms create an inherent difficulty when applying the standard augmented Lagrangian relaxation(ALR) method for decomposing the unit commitment problem into independent subproblems. This paper presents a separable augmented Lagrangian relaxation method for solving the unit commitment problem. The proposed method is designed to have a separable structure by introducing the quadratic terms with additional auxiliary terms in the augmented Lagrangian function. Numerical results are presented to validate the effectiveness of the proposed method.
Harmonic Mitigation and Power Factor Improvement using Fuzzy Logic and Neural Network Controlled Active Power Filter
Kumar, V.Suresh ; Kavitha, D. ; Kalaiselvi, K. ; Kannan, P. S. ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 520~527
DOI : 10.5370/JEET.2008.3.4.520
This work focuses on the evaluation of active power filter which is controlled by fuzzy logic and neural network based controller for harmonic mitigation and power factor enhancement. The APF consists of a variable DC voltage source and a DC/AC inverter. The task of an APF is to make the line current waveform as close as possible to a sinusoid in phase with the line voltage by injecting the compensation current. The compensation current is estimated using adaptive neural network. Using the estimated current, the proposed APF is controlled using neural network and fuzzy logic. Computer simulations of the proposed APF are performed using MATLAB. The results show that the proposed techniques for the evaluation of APF can reduce the total harmonic distortion less than 3% and improve the power factor of the system to almost unity.
Modeling and Control of Integrated STATCOM-SMES System to Improve Power System Oscillations Damping
Molina, Marcelo G. ; Mercado, Pedro E. ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 528~537
DOI : 10.5370/JEET.2008.3.4.528
Primary frequency control(PFC) has the ability to regulate short period random variations of frequency during normal operation conditions and also to respond rapidly to emergencies. However, during the past decade, numerous significant sized blackouts occurred worldwide that resulted in serious economic losses. Therefore, the conclusion has been reached that the ability of the current PFC to meet an emergency is poor, and security of power systems should be improved. An alternative to enhance the PFC and thus security is to store excessive amounts of energy during off-peak load periods in efficient energy storage systems for substituting the primary control reserve. In this sense, superconducting magnetic energy storage(SMES) in combination with a static synchronous compensator(STATCOM) is capable of supplying power systems with both active and reactive powers simultaneously and very rapidly, and thus is able to enhance the security dramatically. In this paper, a new concept of PFC based on incorporating a STATCOM-SMES is presented. A complete detailed model is proposed and a new control scheme is designed, comprising an enhanced frequency control scheme, and a fully decoupled current control strategy in d-q coordinates with a novel controller to prevent dc bus capacitors voltage drift/imbalance. The performance of the proposed control schemes is validated through digital simulation carried out using MATLAB/Simulink.
Torque Control Strategy for High Performance SR Drive
Ahn, Jin-Woo ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 538~545
DOI : 10.5370/JEET.2008.3.4.538
This paper attempts to summarize torque control strategy for high performance SR drive. There are primarily two strategies for torque control. One method is direct torque control, which uses the simple control scheme and hysteresis controller to reduce the torque ripple. Another method is indirect torque control, which uses the complicated algorithms or simple distribution function to distribute each phase torque and obtain current command. The current controller is used to control phase torque by a given current command. In order to compare these two strategies of torque control, five torque control methods are introduced. The advantages and disadvantages of each method are presented. At last, they are verified by some simulations and experimental results.
Operational Characteristics of a Flux-Lock Type SFCL Integrated with Voltage-Controlled Voltage Source Inverter
Lee, Su-Won ; Lim, Sung-Hun ; Ko, Sung-Hun ; Lee, Seong-Ryong ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 546~551
DOI : 10.5370/JEET.2008.3.4.546
In this paper, a flux-lock type superconducting fault current limiter(SFCL) integrated with a voltage-controlled voltage source inverter(VC-VSI) is proposed. The suggested equipment, which consists of a flux-lock type SFCL and a VCVSI, can perform the fault current limiting operation from the occurrence of a short-circuit. In addition, it can compensate the reactive power that the non-linear load requires and also perform the uninterruptible power supply(UPS) as well as the load voltage stabilization by controlling the amplitude and the phase of the inverter's output voltage. The specification for a test model was determined and its various functions such as the fault current limiting and the power conditioning operations were presented and analyzed via computer simulation. Through the analytical results based on the computer simulation, the validity of the analysis was confirmed and its multi-operation was discussed.
Optimal Design of a Direct-Driven PM Wind Generator Aimed at Maximum AEP using Coupled FEA and Parallel Computing GA
Jung, Ho-Chang ; Lee, Cheol-Gyun ; Hahn, Sung-Chin ; Jung, Sang-Yong ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 552~558
DOI : 10.5370/JEET.2008.3.4.552
Optimal design of the direct-driven Permanent Magnet(PM) wind generator, combined with F.E.A(Finite Element Analysis) and Genetic Algorithm(GA), has been performed to maximize the Annual Energy Production(AEP) over the entire wind speed characterized by the statistical model of wind speed distribution. Particularly, the proposed parallel computing via internet web service has contributed to reducing excessive computing times for optimization.
A Study on the Design of a Planar Loop Sensor for Partial Discharge Diagnosis of 22.9 kV XLPE Power Cables
Lim, Kwang-Jin ; Yang, Sang-Hyun ; Shin, Dong-Hoon ; Park, Noh-Joon ; Park, Dae-Hee ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 559~565
DOI : 10.5370/JEET.2008.3.4.559
This study designed a new type of loop antenna that is able to detect partial discharges based on microstrip line technology. In the diagnosis of power cables, partial discharge signals are generally produced at a frequency range less than 100MHz because high frequency PD signals are lost along a propagation path in such cables. The new type of loop antenna sensor has been studied using simulation software known as CST microwave studio version 5.0. In partial discharge measurement experiments, a commercial HFCT sensor was used as a reference sensor. Several experiments were made over HFCT and loop antenna sensors for detecting partial discharges on 22.9kV MV XLPE cable. In this study, we showed the loop antenna designed in this study that can be applied as a commercial HFCT sensor.
Design of Next Generation Amplifiers Using Nanowire FETs
Hamedi-Hagh, Sotoudeh ; Oh, Soo-Seok ; Bindal, Ahmet ; Park, Dae-Hee ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 566~570
DOI : 10.5370/JEET.2008.3.4.566
Vertical nanowire SGFETs(Surrounding Gate Field Effect Transistors) provide full gate control over the channel to eliminate short channel effects. This paper presents design and characterization of a differential pair amplifier using NMOS and PMOS SGFETs with a 10nm channel length and a 2nm channel radius. The amplifier dissipates
power and provides 5THz bandwidth with a voltage gain of 16, a linear output voltage swing of 0.5V, and a distortion better than 3% from a 1.8V power supply and a 20aF capacitive load. The 2nd and 3rd order harmonic distortions of the amplifier are -40dBm and -52dBm, respectively, and the 3rd order intermodulation is -24dBm for a two-tone input signal with 10mV amplitude and 10GHz frequency spacing. All these parameters indicate that vertical nanowire surrounding gate transistors are promising candidates for the next generation high speed analog and VLSI technologies.
Stator Insulation Quality Assessment for High Voltage Motors Based on Probability Distributions
Kim, Hee-Dong ; Kim, Chung-Hyo ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 571~575
DOI : 10.5370/JEET.2008.3.4.571
Stator insulation quality assessment for high voltage motors is a major issue for the reliable maintenance of industrial and power plants. To assess the condition of stator insulation, nondestructive tests were performed on the sixty coil groups of twelve motors. After completing the nondestructive tests, the AC voltage applied to the stator winding was gradually increased until insulation failure in order to obtain the breakdown voltage. The stator winding of each motor was classified into five coil groups; one group with healthy insulation and four groups with four different types of artificial defects. To analyze the breakdown voltage statistically, Weibull distribution was employed for the tests on the fifty coil groups of ten motors. The 50th percentile values of the measured breakdown voltages based on the statistical data of the five coil groups of ten motors were 26.1kV, 25.0kV, 24.4kV, 26.7kV and 30.5kV, respectively. Almost all of the failures were located in the line-end coil at the exit of the core slot. The breakdown voltages and the types of defects showed strong relation to the stator insulation tests such as in the case of dissipation factor and ac current. It is shown that the condition of the motor insulation can be determined from the relationship between the probability of failure and the type of defect.
Design of Real-Time Autonomic Nervous System Evaluation System Using Heart Instantaneous Frequency
Noh, Yeon-Sik ; Park, Sung-Jun ; Park, Sung-Bin ; Yoon, Hyung-Ro ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 576~583
DOI : 10.5370/JEET.2008.3.4.576
In this study, we attempt to design a real-time autonomic nervous system(ANS) evaluation system usable during exercise using heart instantaneous frequency(HIF). Although heart rate variability(HRV) is considered to be a representative signal widely used ANS evaluation system, the R-peak detection process must be included to obtain an HRV signal, which involves a high sampling frequency and interpolation process. In particular, it cannot accurately evaluate the ANS using HRV signals during exercise because it is difficult to detect the R-peak of electrocardiogram(ECG) signals with exposure to many noises during exercise. Therefore, in this study, we develop the ground for a system that can analyze an ANS in real-time by using the HIF signal circumventing the problem of the HRV signal during exercise. First, we compare the HRV and HIF signals in order to prove that the HIF signal is more efficient for ANS analysis than HRV signals during exercise. Further, we performed real-time ANS analysis using HIF and confirmed that the exerciser's ANS variation experiences massive surges at points of acceleration and deceleration of the treadmill(similar to HRV).
A New Model of Magnetic Force in Magnetic Levitation Systems
Lee, Y.S. ; Yang, J.H. ; Shim, S.Y. ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 584~592
DOI : 10.5370/JEET.2008.3.4.584
In this paper, we propose a new model of the magnetic control force exerted on the levitation object in magnetic levitation systems. The model assumes that the magnetic force is a function of the voltage applied to an electromagnet and the position of a levitation object. The function is not explicitly expressed but represented through a 2D lookup table constructed from the experimentally measured data. Unlike the conventional model that reveals only local characteristics of the magnetic force, the proposed model shows global characteristics satisfactorily. Specially devised measurement equipment is utilized in order to gather the data required for model construction. An experimental procedure to construct the model is presented. We apply the proposed model to designing a sliding mode controller for a lab-built magnetic system. The validity of the proposed model is illustrated by comparing the performances of the controller adopting the conventional model with that of the controller adopting the proposed model.
Power Distribution and Coordinated Control for a Power Split Hybrid Electric Bus
Wang, Feng ; Zhong, Hu ; Ma, Zi-Lin ; Mao, Xiao-Jian ; Zhuo, Bin ;
Journal of Electrical Engineering and Technology, volume 3, issue 4, 2008, Pages 593~598
DOI : 10.5370/JEET.2008.3.4.593
The power distribution is proposed to determine the target operating points of the system components as the basis for maximal the efficiency of the overall system for a power split dual electric machine hybrid electric bus. The coordinated control is constructed on the basis of the power distribution. The basic coordinated control is implemented to satisfy the driver's power demand, in which both the dynamic characteristics of the engine and the dual electric machine are explicitly taken into account. Moreover, the improved coordinated control is suggested to suppress engine dynamic operation and rich fuel injection.