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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 2, Issue 4 - Dec 2007
Volume 2, Issue 3 - Sep 2007
Volume 2, Issue 2 - Jun 2007
Volume 2, Issue 1 - Mar 2007
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A Modified Particle Swarm Optimization for Optimal Power Flow
Kim, Jong-Yul ; Lee, Hwa-Seok ; Park, June-Ho ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 413~419
DOI : 10.5370/JEET.2007.2.4.413
The optimal power flow (OPF) problem was introduced by Carpentier in 1962 as a network constrained economic dispatch problem. Since then, it has been intensively studied and widely used in power system operation and planning. In the past few decades, many stochastic optimization methods such as Genetic Algorithm (GA), Evolutionary Programming (EP), and Particle Swarm Optimization (PSO) have been applied to solve the OPF problem. In particular, PSO is a newly proposed population based stochastic optimization algorithm. The main idea behind it is based on the food-searching behavior of birds and fish. Compared with other stochastic optimization methods, PSO has comparable or even superior search performance for some hard optimization problems in real power systems. Nowadays, some modifications such as breeding and selection operators are considered to make the PSO superior and robust. In this paper, we propose the Modified PSO (MPSO), in which the mutation operator of GA is incorporated into the conventional PSO to improve the search performance. To verify the optimal solution searching ability, the proposed approach has been evaluated on an IEEE 3D-bus test system. The results showed that performance of the proposed approach is better than that of the standard PSO.
An Adaptive Undervoltage Load Shedding Against Voltage Collapse Based Power Transfer Stability Index
Nizam, Muhammad ; Mohamed, Azah ; Hussain, Aini ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 420~427
DOI : 10.5370/JEET.2007.2.4.420
This paper highlights the comparison of a proposed methods named adaptive undervoltage load shedding based PTSI techniques for undervoltage load shedding and two previous methods named Fixed Shed Fixed Delay (FSFD) and Variable Shed Variable Delay (VSVD) for avoiding voltage collapse. There are three main area considerations in load shedding schemes as the amount of load to be shed, the timing of load shedding event, and the location where load shed is to be shed. The proposed method, named as adaptive UVLS based PTSI seem to be most appropriate among the uncoordinated schemes. From the simulation result can be shown the Adaptive UVLS based PTSI give faster response, accurate and very sensitive control for the UVLS control technique. This technique is effectively when calculating the amount to be shed. Therefore, it is possible to bring the voltage to the threshold value in one step. Thus, the adaptive load shedding can effectively reduce the computational time for control strategy.
Application of the Implicit Restarted Arnoldi Method to the Small-Signal Stability of Power Systems
Kim, Dong-Joon ; Moon, Young-Hwan ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 428~433
DOI : 10.5370/JEET.2007.2.4.428
This paper describes the new eigenvalue algorithm exploiting the Implicit Restarted Arnoldi Method (IRAM) and its application to power systems. IRAM is a technique for combining the implicitly shifted mechanism with a k-step Arnoldi factorization to obtain a truncated form of the implicitly shifted QR iteration. The numerical difficulties and storage problems normally associated with the Arnoldi process are avoided. Two power systems, one of which has 36 state variables and the other 150 state variables, have been tested using the ARPACK program, which uses IRAM, and the eigenvalue results are compared with the results obtained from the conventional QR method.
Double-Circuit Transmission Lines Fault location Algorithm for Single Line-to-Ground Fault
Yang, Xia ; Choi, Myeon-Song ; Lee, Seung-Jae ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 434~440
DOI : 10.5370/JEET.2007.2.4.434
This paper proposes a fault location algorithm for double-circuit transmission lines in the case of single line-to-ground fault. The proposed algorithm requires the voltage and current from the sending end of the transmission line. The fault distance is simply determined by solving a second order polynomial equation which is achieved directly by the analysis of the circuit. In order to testify the performance of the proposed algorithm, several other conventional approaches have been taken out to compare with it. The test results corroborate its superior effectiveness.
Basic Study of Degradation Test for Magnetic Contactors and Reliability Centered Maintenance
Ryu, Haeng-Soo ; Han, Gyu-Hwan ; Yoon, Nam-Sik ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 441~444
DOI : 10.5370/JEET.2007.2.4.441
The mechanical endurance is the critical characteristic of Magnetic contactors (MCs), which are widely used in such industrial equipments as elevators, cranes, and factory control rooms in order to close and open the control circuit. Testing time, however, is so long in most cases that some method of reducing the testing period is required. Therefore, the degradation test by the detected vibration of MCs is developed to reduce the testing time in this work. The degradation test data are analyzed and the prediction model is provided. Also, the possibility of this technology for Reliability Centered Maintenance (RCM) will be shown. This will reduce the period of the product development and raise the reliability of the equipment in power distribution.
Fast Envelope Estimation Technique for Monitoring Voltage Fluctuations
Marei, Mostafa I. ; Shatshat, Ramadan El ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 445~451
DOI : 10.5370/JEET.2007.2.4.445
Voltage quality problems such as voltage sag, swell, flicker, undervoltage, and overvoltage have been of great concern for both utilities and customers over the last decade. In this paper, a new approach based on the
algorithm to monitor voltage disturbances is presented. The key idea of this approach is to estimate the amplitude of the fundamental component of distorted and noisy voltage waveform instantaneously, and then the information can be extracted from the estimated envelope to identify and classify different voltage related power quality problems. The
algorithm is characterized by a fast tracking, unlike that of existing techniques. The
algorithm outperforms the Kalman Filter (KF) by its fast convergence and robust tracking performance against non-Gaussian noise. The paper investigates the effects of various types of noise on the performance of the
algorithm. Digital simulation results confirm the validity and accuracy of the proposed method. The proposed
algorithm is examined by tracking the flicker produced by a resistance welder simulated in the PSCAD/EMTDC package.
Economic Feasibility on the Interconnected Electric Power Systems in North-East Asia
Chung, Koo-Hyung ; Kim, Bal-Ho H. ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 452~460
DOI : 10.5370/JEET.2007.2.4.452
The interstate electric power system, as an alternative for energy cooperation under regional economic block, was fervently debated prior to the restructuring of electric power industries and rapidly expanded in many regions since the 1990s. Especially, electric power system interconnection in the Northeast Asia region may bring considerable economic benefits since this region has strong supplementation in resource holdings, load shape, fuel mix, and etc. In this paper, we implement the ORIRES model, proposed by ESI of Russia, in order to analyze the economic feasibility on the Northeast Asia Region Electrical System Ties (NEAREST) project.
A Study on Machine Fault Diagnosis using Decision Tree
Nguyen, Ngoc-Tu ; Kwon, Jeong-Min ; Lee, Hong-Hee ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 461~467
DOI : 10.5370/JEET.2007.2.4.461
The paper describes a way to diagnose machine condition based on the expert system. In this paper, an expert system-decision tree is built and experimented to diagnose and to detect machine defects. The main objective of this study is to provide a simple way to monitor machine status by synthesizing the knowledge and experiences on the diagnostic case histories of the rotating machinery. A traditional decision tree has been constructed using vibration-based inputs. Some case studies are provided to illustrate the application and advantages of the decision tree system for machine fault diagnosis.
Problems of Stator Flux Estimation in DTC of PMSM Drives
Kadjoudj, M. ; Golea, N. ; Benbouzid, M.E.H ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 468~477
DOI : 10.5370/JEET.2007.2.4.468
The DTC of voltage source inverter-fed PMSMs is based on hysteresis controllers of torque and flux. It has several advantages, namely, elimination of the mandatory rotor position sensor, less computation time, and rapid torque response. In addition, the stator resistance is the only parameter, which should be known, and no reference frame transformation is required. The DTC theory has achieved great success in the control of induction motors. However, for the control of PMSM drives proposed a few years ago, there are many basic theoretical problems that must be clarified. This paper describes an investigation into the effect of the zero voltage space vectors in the DTC system and points out that if using it rationally, not only can the DTC of the PMSM drive be driven successfully, but torque and flux ripples are reduced and overall performance of the system is improved. The implementation of DTC in PMSM drives is described and the switching tables specific for an interior PMSM are derived. The conventional eight voltage-vector switching table, which is namely used in the DTC of induction motors does not seem to regulate the torque and stator flux in a PMSM well when the motor operates at low speed. Modelling and simulation studies have both revealed that a six voltage-vector switching table is more appropriate for PMSM drives at low speed. In addition, the sources of difficulties, namely, the error in the detection of the initial rotor position, the variation of stator resistance, and the offsets in measurements are analysed and discussed.
Highly Efficient Control of the Doubly Fed Induction Motor
Drid, Said ; Makouf, Abdesslam ; Nait-Said, Mohamed-Said ; Tadjine, Mohamed ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 478~484
DOI : 10.5370/JEET.2007.2.4.478
This paper deals with the high efficient vector control for the reduction of copper losses of the doubly fed motor. Firstly, the feedback linearization control based on Lyapunov approach is employed to design the underlying controller achieving the double fluxes orientation. The fluxes# controllers are designed independently of the speed. The speed controller is designed using the Lyapunov method especially employed to the unknown load torques. The global asymptotic stability of the overall system is theoretically proven. Secondly, a new Torque Copper Losses Factor is proposed to deal with the problem of the machine copper losses. Its main function is to optimize the torque in keeping the machine saturation at an acceptable level. This leads to a reduction in machine currents and therefore their accompanied copper losses guaranteeing improved machine efficiency. The simulation and experimental results in comparative presentation confirm largely the effectiveness of the proposed DFIM control with a very interesting energy saving contribution.
ANN Based System for the Detection of Winding Insulation Condition and Bearing Wear in Single Phase Induction Motor
Ballal, M.S. ; Suryawanshi, H.M. ; Mishra, Mahesh K. ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 485~493
DOI : 10.5370/JEET.2007.2.4.485
This paper deals with the problem of detection of induction motor incipient faults. Artificial Neural Network (ANN) approach is applied to detect two types of incipient faults (1). Interturn insulation and (2) Bearing wear faults in single-phase induction motor. The experimental data for five measurable parameters (motor intake current, rotor speed, winding temperature, bearing temperature and the noise) is generated in the laboratory on specially designed single-phase induction motor. Initially, the performance is tested with two inputs i.e. motor intake current and rotor speed, later the remaining three input parameters (winding temperature, bearing temperature and the noise) were added sequentially. Depending upon input parameters, the four ANN based fault detectors are developed. The training and testing results of these detectors are illustrated. It is found that the fault detection accuracy is improved with the addition of input parameters.
A Linearized Transmission Model Based Market Equilibrium In Locational Pricing Environments
Joung, Man-Ho ; Kim, Jin-Ho ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 494~499
DOI : 10.5370/JEET.2007.2.4.494
In this paper, we have investigated how transmission network constraints can be modeled in an electricity market equilibrium model. Under Cournot competition assumption, a game model is set up considering transmission line capacity constraints. Based on locational marginal pricing principle, market clearing is formulated as a total consumers# benefit maximization problem, and then converted to a conventional optimal power flow (OPF) formulation with a linearized transmission model. Using market clearing formulation, best response analysis is formulated and, finally, Nash equilibrium is formulated. In order for illustration, a numerical study for a four node system with two generating firms and two loads are presented.
Low Cost Rotor Fault Detection System for Inverter Driven Induction Motor
Kim, Nam-Hun ; Choi, Chang-Ho ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 500~504
DOI : 10.5370/JEET.2007.2.4.500
In this paper, the induction motor rotor fault diagnosis system using current signals, which are measured using axis-transformation method, and speed, which is estimated using current information, are presented. In inverter-fed motor drives unlike line-driven motor drives the stator currents have numerous harmonics components and therefore fault diagnosis using stator currents is very difficult. The current and speed signal for rotor fault diagnosis needs to be precise. Also, high resolution information, which means the diagnosis system, demands additional hardware such as low pass filter, high resolution ADC, encoder and etc. Therefore, the proposed axis-transformation and speed estimation method are expected to contribute to low cost fault diagnosis systems in inverter-fed motor drives without the need for an encoder and any additional hardware. In order to confirm validity of the developed algorithms, various experiments for rotor faults are tested and the line current spectrum of each faulty situation using Park transformation and speed estimation method are compared with the results obtained from fast Fourier transforms.
A Scheme of EDTC Control using an Induction Motor Three-Level Voltage Source Inverter for Electric Vehicles
Zaimeddine, R. ; Berkouk, E.M. ; Refoufi, L. ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 505~512
DOI : 10.5370/JEET.2007.2.4.505
The object of this paper is to study a new control structure for sensorless induction machines dedicated to electrical drives using a three-level voltage source inverter VSI-NPC. The amplitude and the rotating speed of the flux vector can be controlled freely. The scheme investigated is an Enhanced direct torque control "EDTC" for electric vehicle propulsion. The considered application imposes some constraints which are achieved in EDTC control (fast torque response, optimal switching logic, torque control at zero speed, and large speed control. The results obtained for an induction motor indicate superior performance over the FOC type without need for any mechanical sensor.
A Study of the Photo-Electric Efficiency of Dye-Sensitized Solar Cells Under Lower Light Intensity
Kim, Hee-Je ; Kim, Yong-Chul ; Hong, Ji-Tae ; Kim, Mi-Jeong ; Seo, Hyun-Woong ; Park, Je-Wook ; Choi, Jin-Young ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 513~517
DOI : 10.5370/JEET.2007.2.4.513
To elucidate possible challenges for outdoor practical use of dye-sensitized solar cells (DSCs), we compared conventional Si solar cells with DSCs. DSC modules still require a larger area than conventional Si solar modules to attain the same rated output because of lower photoelectron-chemical conversion efficiency. However, in backup systems by using batteries, the measured data shows that DSCs generated 15% more electricity than Si solar cells of the same rated output power in the same interval of cloudy daylight. Moreover, the battery charging time of DSCs is about 1 hour faster than the same rate of Si solar cells under outdoor cloudy daylight. This result also indicates that conversion efficiency obtained by the certified condition less than AM 1.5 condition does not always coincide with the electricity generated outdoors daily, and it is not a crucial measure to evaluate the performance of solar cells.
Electrical and Optical Propeties of a UV-Sensitive CCD Imager
Kim, Man-Ho ; Choi, Jae-Ha ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 518~524
DOI : 10.5370/JEET.2007.2.4.518
This paper describes several improved characterizations of the EPIC CCD, which now has modified electrode and channel structures. From a 3-D numerical simulation of the device, its channel doping and potential distributions are then observed for the optimization of the charge transfer. A wavelength-dependence on the device structure is observed in terms of the reflectivity of the incident radiation. The optical properties of ultra-low energy levels, when using an open-electrode structure, are then considered to improve their quantum efficiency.
Fabrication and Characterization of Ni-Cr Alloy Thin Films for Application to Precision Thin Film Resistors
Lee, Boong-Joo ; Shin, Paik-Kyun ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 525~531
DOI : 10.5370/JEET.2007.2.4.525
Ni(75 wt.%)-Cr(20 wt.%)-Al(3 wt.%)-Mn(4 wt.%)-Si(1 wt.%) alloy thin films were prepared using the DC magnetron sputtering process by varying the sputtering conditions such as power, pressure, substrate temperature, and post-deposition annealing temperature in order to fabricate a precision thin film resistor. For all the thin film resistors, sheet resistance, temperature coefficient of resistance (TCR), and crystallinity were analyzed and the effects of sputtering conditions on their properties were also investigated. The oxygen content and TCR of Ni-Cr-Al-Mn-Si resistors were decreased by increasing the sputtering pressure. Their sheet resistance, TCR, and crystallinity were enhanced by elevating the substrate temperature. In addition, the annealing of the resistor thin films in air at a temperature higher than
lead to a remarkable rise in their sheet resistance and TCR. This may be attributed to the improved formation of NiO layer on the surface of the resistor thin film at an elevated temperature.
Carbon Nanotube Synthesis using Magnetic Null Discharge Plasma Production Technology
Sung, Youl-Moon ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 532~536
DOI : 10.5370/JEET.2007.2.4.532
Carbon nanotube (CNT) properties, produced using a magnetic null discharge (MND) plasma production technology, were investigated. We firstly deposited the Fe layer 200 nm in thickness on Si substrate by the magnetic null discharge sputter method at the substrate temperature of
, and then prepared CNTs on the catalyst layer by using the magnetic null discharge (MND) based CVD method. CNTs were deposited in a gas mixture of CH4 and N2 at a total pressure of 1 Torr by the MND-CVD method. The substrate temperature and the RF power were
and 600W, respectively. The characterization data indicated that the proposed source could synthesize CNTs even under relatively severe conditions for the magnetic null discharge formation.
A Design of Free Velocity Bias for GPS Receiver
Nguyen, Phi-Long ; Kim, Hyun-Soo ; Kim, Han-Sil ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 537~542
DOI : 10.5370/JEET.2007.2.4.537
This paper proposes a 2-step Kalman filter model for land vehicle navigation using civilian-band GPS measurements. The velocity bias caused by the Earth#s rotation would be removed completely when applying this model. Because the linearization of velocity equations in this model is not necessary, the error is significantly reduced. The experiment reveals that estimated position error with stationary data is about 5m during a 15-20 minute interval. The other benefit of this model is that it can be feasibly applied as a GPS receiver module thanks to the small sizes of the necessary manipulating matrices.
Design of Time-varying Stochastic Process with Dynamic Bayesian Networks
Cho, Hyun-Cheol ; Fadali, M.Sami ; Lee, Kwon-Soon ;
Journal of Electrical Engineering and Technology, volume 2, issue 4, 2007, Pages 543~548
DOI : 10.5370/JEET.2007.2.4.543
We present a dynamic Bayesian network (DBN) model of a generalized class of nonstationary birth-death processes. The model includes birth and death rate parameters that are randomly selected from a known discrete set of values. We present an on-line algorithm to obtain optimal estimates of the parameters. We provide a simulation of real-time characterization of load traffic estimation using our DBN approach.