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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 5, Issue 4 - Nov 2010
Volume 5, Issue 3 - Sep 2010
Volume 5, Issue 2 - Jun 2010
Volume 5, Issue 1 - Mar 2010
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Accurate Transmission Loss Allocation Algorithm Based on the Virtual Transaction Strategy: Comparison of Path-integral with Discrete Integral Methods
Min, Kyung-Il ; Moon, Young-Hyun ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 511~521
DOI : 10.5370/JEET.2010.5.4.511
This paper presents a new algorithm to determine accurate bus-wise transmission loss allocation utilizing path-integrals dictated by the transaction strategy. For any transaction strategy, the total sum of the allocated transmission losses of all buses is equal to the actual loss given by the AC power-flow calculation considering the distributed slack. In this paper, the bus-wise allocation of the transmission loss is calculated by integrating the differential loss along a path determined by the transaction strategy. The proposed algorithm is also compared with Galiana's method, which is the well-known transmission loss allocation algorithm based on integration. The performance of the proposed algorithm is evaluated by case studies carried out on the WSCC 9-bus, IEEE 14-bus, New England 39-bus, and IEEE 118-bus systems. The simulation results show that the proposed algorithm is fast and accurate with a large step size.
Setting Considerations of Distance Relay for Transmission Line with STATCOM
Zhang, Wen-Hao ; Lee, Seung-Jae ; Choi, Myeon-Song ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 522~529
DOI : 10.5370/JEET.2010.5.4.522
Distance relay plays an important role in the protection of transmission lines. The application of flexible AC transmission systems (FACTS) devices, such as the static synchronous compensator (STATCOM), could affect the performance of the distance relay because of compensation effect. This paper analyzes the application of distance relay on the protection of a transmission line containing STATCOM. New setting principles for different protection zones are proposed based on this analysis. A typical 500 kV transmission system employing STATCOM is modeled using Matlab/Simulink. The impact of STATCOM on distance protection scheme is studied for different fault types, fault locations, and system configurations. Based on simulation results, the performance of distance relay is evaluated. The setting principle can be verified for the transmission line with STATCOM.
The Optimal Operation for Community Energy System Using a Low-Carbon Paradigm with Phase-Type Particle Swarm Optimization
Kim, Sung-Yul ; Bae, In-Su ; Kim, Jin-O ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 530~537
DOI : 10.5370/JEET.2010.5.4.530
By development of renewable energy and more efficient facilities in an increasingly deregulated electricity market, the operation cost of distributed generation (DG) is becoming more competitive. International environmental regulations of the leaking carbon become effective to reinforce global efforts for a low-carbon paradigm. Through increased DG, operators of DG are able to supply electric power to customers who are connected directly to DG as well as loads that are connected to entire network. In this situation, a community energy system (CES) with DGs is a new participant in the energy market. DG's purchase price from the market is different from the DG's sales price to the market due to transmission service charges and other costs. Therefore, CES who owns DGs has to control the produced electric power per hourly period in order to maximize profit. Considering the international environment regulations, CE will be an important element to decide the marginal cost of generators as well as the classified fuel unit cost and unit's efficiency. This paper introduces the optimal operation of CES's DG connected to the distribution network considering CE. The purpose of optimization is to maximize the profit of CES. A Particle Swarm Optimization (PSO) will be used to solve this complicated problem. The optimal operation of DG represented in this paper would guide CES and system operators in determining the decision making criteria.
Estimation of the Separate Primary and Secondary Leakage Inductances of a Y-Δ Transformer Using Least Squares Method
Kang, Yong-Cheol ; Lee, Byung-Eun ; Hwang, Tae-Keun ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 538~544
DOI : 10.5370/JEET.2010.5.4.538
This paper proposes an estimation algorithm for the separate primary and secondary leakage inductances of a three phase
transformer using least squares method. The voltage equations from the primary and secondary windings are combined into a differential equation to estimate the separate primary and secondary leakage inductances in order to use the line current of the delta winding. Separate primary and secondary leakage inductances are obtained by applying least squares method to the differential equation. The performance of the proposed algorithm is validated under transient states, such as magnetic inrush and overexcitation, as well as in the steady state with various cut-off frequencies of low-pass filter. The proposed technique can accurately generate separate leakage inductances both in the steady and transient states.
Harmonic Elimination and Optimization of Stepped Voltage of Multilevel Inverter by Bacterial Foraging Algorithm
Salehi, Reza ; Vahidi, Behrooz ; Farokhnia, Naeem ; Abedi, Mehrdad ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 545~551
DOI : 10.5370/JEET.2010.5.4.545
A new family of DC to AC converters, referred to as multilevel inverter, has received much attention from industries and researchers for its high power and voltage applications. One of the conventional techniques for implementing the switching algorithm in these inverters is optimized harmonic stepped waveform (OHSW). However, the major problem in using this technique is eliminating low order harmonics by solving the nonlinear and complex equations. In this paper, a new approach called the "bacterial foraging algorithm" (BFA) is employed. This algorithm eliminates and optimizes the harmonics in a multilevel inverter. This method has higher speed, precision, and convergence power compared with the genetic algorithm (GA), a famous evolutionary algorithm. The proposed technique can be expanded in any number of levels. The purpose of optimization is to remove some low order harmonics, as well as to ensure the fundamental harmonic retained at the desired value. As a case study, a 13-level inverter is chosen. The comparison results by MATLAB software between the two optimization methods (BFA and GA) have shown the effectiveness and superiority of BFA over GA where convergence is desired to achieve global optimum.
Stability Analysis and Effect of CES on ANN Based AGC for Frequency Excursion
Raja, J. ; Rajan, C.Christober Asir ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 552~560
DOI : 10.5370/JEET.2010.5.4.552
This paper presents an application of layered Artificial Neural Network controller to study load frequency control problem in power system. The objective of control scheme guarantees that steady state error of frequencies and inadvertent interchange of tie-lines are maintained in a given tolerance limitation. The proposed controller has been designed for a two-area interconnected power system. Only one artificial neural network controller (ANN), which controls the inputs of each area in the power system together, is considered. In this study, back propagation-through time algorithm is used as neural network learning rule. The performance of the power system is simulated by using conventional integral controller and ANN controller, separately. For the first time comparative study has been carried out between SMES and CES unit, all of the areas are included with SMES and CES unit separately. By comparing the results for both cases, the performance of ANN controller with CES unit is found to be better than conventional controllers with SMES, CES and ANN with SMES.
Advanced Interchangeable Dynamic Simulation Model for the Optimal Design of a Fuel Cell Power Conditioning System
Kim, Jong-Soo ; Choe, Gyu-Yeong ; Lee, Byoung-Kuk ; Shim, Jae-Sun ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 561~570
DOI : 10.5370/JEET.2010.5.4.561
This paper presents an advanced dynamic simulation model of a proton exchange membrane fuel cell for the optimal design of a fuel cell power conditioning system (FC-PCS). For the development of fuel cell models, the dynamic characteristics of the fuel cell are considered, including its static characteristics. Then, software fuel cell simulation is realized using Matlab-Simulink. Specifically, the design consideration of PCS (i.e., power semiconductor switch, capacitor, and inductor) is discussed by comparatively analyzing the developed simulator and ideal DC source. In addition, a cosimulation between the fuel cell model and PCS realized using the PSIM software is performed with the help of the SimCoupler module. Detailed analysis and informative simulation results are provided for the optimal design of fuel cell PCS.
Classification and Analysis of Switched Reluctance Converters
Ahn, Jin-Woo ; Liang, Jianing ; Lee, Dong-Hee ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 571~579
DOI : 10.5370/JEET.2010.5.4.571
This paper reviews and analyzes converters for SRM(Switched Reluctance Motor) drive. Conventional classification focuses on the number of power switches and diodes. It is easy to find the number of semiconductors and the cost by counting the number of active components, but it does not show the important characteristics of a power converter. The voltage ratings for the power switches and diodes are also difficult to identify. This paper proposes a switched reluctance (SR) converter configuration that is classified based on the commutation type and magnetic energy path. The converter has three parts: utility interface, front-end circuit, and power converter. Based on the overview on the conventional SR drive, the most important characteristic of the converter is determined by the topology of front-end in conjunction with the power converter. An SR converter has two parts: front-end and power converter. Inasmuch as the capacitive front-end is widely used for voltage source converters, this paper focuses on topologies for the front-end.
A Nonlinear Observer Design for P-Cells Chopper
Benmansour, K. ; Bouchhida, O. ; Tlemcani, A. ; Leon, J. De ; Djemail, M. ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 580~591
DOI : 10.5370/JEET.2010.5.4.580
This paper deals with an observer design for a P-Cell Chopper. The goal is to reduce drastically the number of sensors in such system by using an observer in order to estimate all the capacitor voltages. Furthermore, considering an instantaneous model of a p-cell chopper, an interconnected observer is designed in order to estimate the capacitor voltages and some parameters of the model. This is realized by using only the load current measurement. Simulation results are given in order to illustrate the performance of such observer. To show the validity of our approach, experimental based a DSP results are presented.
Characteristic Analysis for IPMSM Considering Flux-Linkage Ripple
Woo, Dong-Kyun ; Kwak, Sang-Yeop ; Seo, Jang-Ho ; Jung, Hyun-Kyo ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 592~596
DOI : 10.5370/JEET.2010.5.4.592
In a multi-layer interior permanent magnet synchronous motor, the d- and q-axis parameters vary nonlinearly according to different load conditions, consequently changing the level of saturation. The flux-linkage of d- and q-axis conveys ripple characteristics resulting from mechanical structure and degree of magnetic saturation. If the calculated flux-linkage is correct, the torque using the Maxwell stress tensor method is the same torque calculated by the flux-linkage. However, discrepancy between results exists. In this paper, the d- and q-axis flux-linkage, in consideration of the ripple characteristic, is calculated. Simulation results are then compared with experimental results.
Parameter Identification of Induction Motors using Variable-weighted Cost Function of Genetic Algorithms
Megherbi, A.C. ; Megherbi, H. ; Benmahamed, K. ; Aissaoui, A.G. ; Tahour, A. ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 597~605
DOI : 10.5370/JEET.2010.5.4.597
This paper presents a contribution to parameter identification of a non-linear system using a new strategy to improve the genetic algorithm (GA) method. Since cost function plays an important role in GA-based parameter identification, we propose to improve the simple version of GA, where weights of the cost function are not taken as constant values, but varying along the procedure of parameter identification. This modified version of GA is applied to the induction motor (IM) as an example of nonlinear system. The GA cost function is the weighted sum of stator current and rotor speed errors between the plant and the model of induction motor. Simulation results show that the identification method based on improved GA is feasible and gives high precision.
Design and Implementation of Photovoltaic Power Conditioning System using a Current-based Maximum Power Point Tracking
Lee, Sang-Hoey ; Kim, Jae-Eon ; Cha, Han-Ju ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 606~613
DOI : 10.5370/JEET.2010.5.4.606
This paper proposes a novel current-based maximum power point tracking (CMPPT) method for a single-phase photovoltaic power conditioning system (PV PCS) by using a modified incremental conductance method. The CMPPT method simplifies the entire control structure of the power conditioning system and uses an inherent current source characteristic of solar cell arrays. Therefore, it exhibits robust and fast response under a rapidly changing environmental condition. Digital phase locked loop technique using an all-pass filter is also introduced to detect the phase of grid voltage, as well as the peak voltage. Controllers of dc/dc boost converter, dc-link voltage, and dc/ac inverter are designed for coordinated operation. Furthermore, a current control using a pseudo synchronous d-q transformation is employed for grid current control with unity power factor. A 3 kW prototype PV PCS is built, and its experimental results are given to verify the effectiveness of the proposed control schemes.
An Improved Control Method for a DFIG in a Wind Turbine under an Unbalanced Grid Voltage Condition
Lee, Sol-Bin ; Lee, Kyo-Beum ; Lee, Dong-Choon ; Kim, Jang-Mok ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 614~622
DOI : 10.5370/JEET.2010.5.4.614
This paper presents a control method, which reduces the pulsating torque and DC voltage problems of a doubly fed induction generator (DFIG)-based wind turbine system. To reduce the torque and power ripple, a current control scheme consisting of a proportional integral (PI) controller is presented in a positive synchronously rotating reference frame, which is capable of providing precise current control for a rotor-side converter with separated positive and negative components. The power theory can reduce the oscillation of the DC-link voltage in the grid-side converter. In this paper, the generator model is examined, and simulation results are obtained with a 3 kW DFIG-based wind turbine system to verify the proposed control strategy.
Drive System Design for a Permanent Magnet Motor with Independent Excitation Winding for an Electric Bicycle
Son, Young-Dae ; Kang, Gyu-Hong ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 623~630
DOI : 10.5370/JEET.2010.5.4.623
This paper presents the implementation and characteristic analysis of a drive system for a three-phase permanent magnet motor with independent excitation winding that is applicable for electric bicycles. The design features improves the phase current waveform, output power, and torque by using advance angle control. This adjusts the phase angle of each phase current in relation to back EMF. In addition, a DC-side PI current control is performed through PWM generation circuit using a low-cost one-chip microcontroller and a CPLD chip, resulting in reduced system costs. Finally, the validity of this control scheme for driving electric bicycles and output/torque improvement characteristics are verified through analysis and experimental results.
Effect of Metallic Particles on E-field Enhancement in Extra High Voltage Gas-insulated Transmission Lines
Rao, M. Mohana ; Satyanarayana, S. ; Kumar, S. Vinay ; Jain, H.S. ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 631~636
DOI : 10.5370/JEET.2010.5.4.631
Gas-insulated transmission lines (GITL) are valued as technological solutions in hydro-power stations due to their enormous power handling capabilities. The performance of GITL is a function of the size of metallic particles inside the gas-insulated chamber. Electrostatic field (E-field) enhancement is a common phenomenon in gas-insulated lines due to these metallic particles. In this study, the E-field enhancement factor is calculated by considering metallic particles at various locations in the gas-insulated line/bus section, such as high-tension (HT) conductor, high-voltage shields, support insulator, and inner surface of grounded enclosure. For this purpose, a two-dimensional model based on finite element (FE) method is developed. The length of the metallic particle is in the range of 1 to 10 mm while the diameter is between 1 to 3 mm. E-field enhancement is also computed for various particle configurations of the gas-insulated system, with focus on dielectric coating made of epoxy on HT conductor and inner surface of grounded enclosure.
Photoluminescence of Hexagonal Boron Nitride (h-BN) Film
Jin, Moon-Seog ; Kim, Nam-Oh ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 637~639
DOI : 10.5370/JEET.2010.5.4.637
Hexagonal boron nitride (BN) films were prepared. The process involved, spraying BN powder-dispersed
-ethyl alcohol solution on quartz plates, and the drying off quartz plates before, and annealing at
in a nitrogen atmosphere. The optical energy band gap of the BN films was 5.28 eV. Photoluminescence peaks with energies of 3.44, 3.16, 2.97, and 2.35 eV at 10 K were observed and analyzed. Accordingly, these have resulted from donor-acceptor pair recombinations.
Power Generating Characteristics of Zinc Oxide Nanorods Grown on a Flexible Substrate by a Hydrothermal Method
Choi, Jae-Hoon ; You, Xueqiu ; Kim, Chul ; Park, Jung-Il ; Pak, James Jung-Ho ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 640~645
DOI : 10.5370/JEET.2010.5.4.640
This paper describes the power generating property of hydrothermally grown ZnO nanorods on a flexible polyethersulfone (PES) substrate. The piezoelectric currents generated by the ZnO nanorods were measured when bending the ZnO nanorod by using I-AFM, and the measured piezoelectric currents ranged from 60 to 100 pA. When the PtIr coated tip bends a ZnO nanorod, piezoelectrical asymmetric potential is created on the nanorod surface. The Schottky barrier at the ZnO-metal interface accumulates elecntrons and then release very quickly generating the currents when the tip moves from tensile to compressed part of ZnO nanorod. These ZnO nanorods were grown almost vertically with the length of 300-500 nm and the diameter of 30-60 nm on the Ag/Ti/PES substrate at
for 6 hours by hydrothermal method. The metal-semiconductor interface property was evaluated by using a HP 4145B Semiconductor Parameter Analyzer and the piezoelectric effect of the ZnO nanorods were evaluated by using an I-AFM. From the measured I-V characteristics, it was observed that ZnO-Ag and ZnO-Au metal-semiconductor interfaces showed an ohmic and a Schottky contact characteristics, respectively. ANSYS finite element simulation was performed in order to understand the power generation mechanism of the ZnO nanorods under applied external stress theoretically.
Improving Breakdown Voltage Characteristics of GDAs using Trigger Voltage
Lee, Sei-Hyun ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 646~652
DOI : 10.5370/JEET.2010.5.4.646
This paper investigates a method to improve the breakdown voltage characteristics of a gas discharge arrester (GDA) for a surge suppressor. The middle electrode is inserted between two terminal electrodes. Voltage application to the electrode synchronized and amplified by the impulse voltage decreases spark overvoltage from 45% to 57.6%. The decrease is caused by higher voltage slope, as opposed to applied impulse voltage (by 5.5 to 6.2 times). In addition, the GDA model using ATP-Draw was used to analyze the operation characteristics of GDAs. The test and simulation results agree to within 2% when the trigger source was used.
The Design of Fuzzy Controller Based on Genetic Optimization and Neurofuzzy Networks
Oh, Sung-Kwun ; Roh, Seok-Beom ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 653~665
DOI : 10.5370/JEET.2010.5.4.653
In this study, we introduce a neurofuzzy approach to the design of fuzzy controllers. The development process exploits key technologies of Computational Intelligence (CI), namely, genetic algorithms (GA) and neurofuzzy networks. The crux of the design methodology deals with the selection and determination of optimal values of the scaling factors of fuzzy controllers, which are essential to the entire optimization process. First, the tuning of the scaling factors of the fuzzy controller is carried out. Next, we form a nonlinear mapping for the scaling factors, which are realized by GA-based neurofuzzy networks by using a fuzzy set or fuzzy relation. The proposed approach is applied to control nonlinear systems like the inverted pendulum. Results of comprehensive numerical studies are presented through a detailed comparative analysis.
Classification of the Types of Defects in Steam Generator Tubes using the Quasi-Newton Method
Lee, Joon-Pyo ; Jo, Nam-H. ; Roh, Young-Su ;
Journal of Electrical Engineering and Technology, volume 5, issue 4, 2010, Pages 666~671
DOI : 10.5370/JEET.2010.5.4.666
Multi-layer perceptron neural networks have been constructed to classify four types of defects in steam generator tubes. Three features are extracted from the signals of the eddy current testing method. These include maximum impedance, phase angle at the point of maximum impedance, and an angle between the point of maximum impedance and the point of half the maximum impedance. Two hundred sets of these features are used for training and assessing the networks. Two approaches are involved to train the networks and to classify the defect type. One is the conjugate gradient method and the other is the Broydon-Fletcher-Goldfarb-Shanno method which is recognized as the most popular algorithm of quasi-Newton methods. It is found from the computation results that the training time of the Broydon-Fletcher-Goldfarb-Shanno method is much faster than that of the conjugate gradient method in most cases. On the other hand, no significant difference of the classification performance between the two methods is observed.