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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 4, Issue 4 - Dec 2009
Volume 4, Issue 3 - Sep 2009
Volume 4, Issue 2 - Jun 2009
Volume 4, Issue 1 - Mar 2009
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Hybrid Control System for Managing Voltage and Reactive Power in the JEJU Power System
Seo, Sang-Soo ; Choi, Yun-Hyuk ; Kang, Sang-Gyun ; Lee, Byong-Jun ; Shin, Jeong-Hoon ; Kim, Tae-Kyun ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 429~437
DOI : 10.5370/JEET.2009.4.4.429
This paper proposes a hybrid voltage controller based on a hierarchical control structure for implementation in the Jeju power system. The hybrid voltage controller utilizes the coordination of various reactive power devices such as generators, switched shunt devices and LTC to regulate the pilot voltage of an area or zone. The reactive power source can be classified into two groups based on action characteristics, namely continuous and discrete. The controller, which regulates the pilot bus voltage, reflects these characteristics in the coordination of the two types of reactive power source. However, the continuous type source like generators is a more important source than the discrete type for an emergency state such as a voltage collapse, thereby requiring a more reactive power reserve of the continuous type to be utilized in the coordination in order to regulate the pilot bus voltage. Results show that the hybrid controller, when compared to conventional methods, has a considerable improvement in performance when adopted to control the pilot bus voltage of the Jeju island system.
Stability Index Based Voltage Collapse Prediction and Contingency Analysis
Subramani, C. ; Dash, Subhransu Sekhar ; Jagdeeshkumar, M. ; Bhaskar, M. Arun ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 438~442
DOI : 10.5370/JEET.2009.4.4.438
Voltage instability is a phenomenon that could occur in power systems due to stressed conditions. The result would be an occurrence of voltage collapse leading to total blackout of the system. Therefore, voltage collapse prediction is an important part of power system planning and operation, and can help ensure that voltage collapse due to voltage instability is avoided. Line outages in power systems may also cause voltage collapse, thereby implying the contingency in the system. Contingency problems caused by line outages have been identified as one of the main causes of voltage instability in power systems. This paper presents a new technique for contingency ranking based on voltage stability conditions in power systems. A new line stability index was formulated and used to identify the critical line outages and sensitive lines in the system. Line outage contingency ranking was performed on several loading conditions in order to identify the effect of an increase in loading to critical line outages. Correlation studies on the results obtained from contingency ranking and voltage stability analysis were also conducted, and it was found that line outages in weak lines would cause voltage instability conditions in a system. Subsequently, using the results from the contingency ranking, weak areas in the system can be identified. The proposed contingency ranking technique was tested on the IEEE reliability test system.
Decentralized Load-Frequency Control of Interconnected Power Systems with SMES Units and Governor Dead Band using Multi-Objective Evolutionary Algorithm
Ganapathy, S. ; Velusami, S. ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 443~450
DOI : 10.5370/JEET.2009.4.4.443
This paper deals with the design of decentralized controller for load-frequency control of interconnected power systems with superconducting magnetic energy storage units and Governor Dead Band Nonlinearity using Multi-Objective Evolutionary Algorithm. The superconducting magnetic energy storage unit exhibits favourable damping effects by suppressing the frequency oscillations as well as stabilizing the inter-area oscillations effectively. The proposed control strategy is mainly based on a compromise between Integral Squared Error and Maximum Stability Margin criteria. Analysis on a two-area interconnected thermal power system reveals that the proposed controller improves the dynamic performance of the system and guarantees good closed-loop stability even in the presence of nonlinearities and with parameter changes.
Real Time Wide Area Voltage Stability Index in the Korean Metropolitan Area
Han, Sang-Wook ; Lee, Byong-Jun ; Kim, Sang-Tae ; Moon, Young-Hwan ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 451~456
DOI : 10.5370/JEET.2009.4.4.451
Through the development of phasor measurement units (PMU), various aspects of power system dynamic behavior could be monitored and diagnosed. Monitoring dynamic voltage stability has become one of the achievements we can obtain from PMUs. It is very important to select the most appropriate method for the Korea Electric Power Corporation (KEPCO) system since there are many voltage stability indices. In this paper, we propose an advanced WAVI (Wide Area Voltage Stability) that is well suited for the purposes of monitoring the dynamic voltage stability of KEPCO`s PMU installation plan. The salient features of the proposed index are: i) it uses only PMU measurements without coupling with EMS data; ii) it is computationally unburdened and can be applied to real-time situations. The proposed index is applied to the KEPCO test system and the results show that it successfully predicts voltage instability through comparative studies.
Optimal Power Flow with Discontinous Fuel Cost Functions Using Decomposed GA Coordinated with Shunt FACTS
Mahdad, Belkacem ; Srairi, K. ; Bouktir, T. ; Benbouzid, M.EL. ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 457~466
DOI : 10.5370/JEET.2009.4.4.457
This paper presents efficient parallel genetic algorithm (EPGA) based decomposed network for optimal power flow with various kinds of objective functions such as those including prohibited zones, multiple fuels, and multiple areas. Two coordinated sub problems are proposed: the first sub problem is an active power dispatch (APD) based parallel GA; a global database generated containing the best partitioned network: the second subproblem is an optimal setting of control variables such as generators voltages, tap position of tap changing transformers, and the dynamic reactive power of SVC Controllers installed at a critical buses. The proposed approach tested on IEEE 6-bus, IEEE 30-bus and to 15 generating units and compared with global optimization methods (GA, DE, FGA, PSO, MDE, ICA-PSO). The results show that the proposed approach can converge to the near solution and obtain a competitive solution with a reasonable time.
Congestion Management in Deregulated Power System by Optimal Choice and Allocation of FACTS Controllers Using Multi-Objective Genetic Algorithm
Reddy, S. Surender ; Kumari, M. Sailaja ; Sydulu, M. ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 467~475
DOI : 10.5370/JEET.2009.4.4.467
Congestion management is one of the technical challenges in power system deregulation. This paper presents single objective and multi-objective optimization approaches for optimal choice, location and size of Static Var Compensators (SVC) and Thyristor Controlled Series Capacitors (TCSC) in deregulated power system to improve branch loading (minimize congestion), improve voltage stability and reduce line losses. Though FACTS controllers offer many advantages, their installation cost is very high. Hence Independent System Operator (ISO) has to locate them optimally to satisfy a desired objective. This paper presents optimal location of FACTS controllers considering branch loading (BL), voltage stability (VS) and loss minimization (LM) as objectives at once using GA. It is observed that the locations that are most favorable with respect to one objective are not suitable locations with respect to other two objectives. Later these competing objectives are optimized simultaneously considering two and three objectives at a time using multi-objective Strength Pareto Evolutionary Algorithms (SPEA). The developed algorithms are tested on IEEE 30 bus system. Various cases like i) uniform line loading ii) line outage iii) bilateral and multilateral transactions between source and sink nodes have been considered to create congestion in the system. The developed algorithms show effective locations for all the cases considered for both single and multiobjective optimization studies.
Application of Multi-step Undervoltage Load Shedding Schemes to the KEPCO System
Shin, Jeong-Hoon ; Nam, Su-Chul ; Lee, Jae-Gul ; Choy, Young-Do ; Kim, Tae-Kyun ; Song, Hwa-Chang ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 476~484
DOI : 10.5370/JEET.2009.4.4.476
This paper deals with improvements to the special protection schemes (SPS) which have been applied to the low probability and high impact contingencies in the Korea Electric Power Corporation (KEPCO) system since 2004. Among them, the SPS for voltage instability in the Seoul metropolitan area is considered in this paper, and is a form of event-based undervoltage load shedding with a single-step scheme. Simulation results based upon a recent event that occurred on 765kV lines show that the current setting values of the SPS have to be revised and enhanced. In addition, by applying response-based multi-step undervoltage load shedding (UVLS) schemes to severe contingencies in the system, more effective results than those of the existing single-step SPS can be obtained. Centralized and distributed UVLS schemes are considered in the simulation. ULTC-based load recovery models and over excitation limiters (OXL) for the KEPCO system are also included in the long-term voltage instability studies.
Probabilistic Reliability Evaluation of Power Systems Including Wind Turbine Generators Considering Wind Speed Correlation
Wu, Liang ; Park, Jeong-Je ; Choi, Jae-Seok ; Ei-Keib, A.A. ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 485~491
DOI : 10.5370/JEET.2009.4.4.485
The importance of renewable energy sources has been growing at a high rate as a result of being environment friendly. In particular, wind power is one of the most successfully utilized of such sources to produce electrical energy. Because of the randomness of wind speed, the reliability impact on this highly variable energy power is important aspect that needs to be assessed. In this paper, the impact on the reliability indices of wind speed correlation between two farms is considered.
Loss Optimization for Voltage Stability Enhancement Incorporating UPFC Using Particle Swarm Optimization
Kowsalya, M. ; Ray, K.K. ; Kothari, D.P. ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 492~498
DOI : 10.5370/JEET.2009.4.4.492
The placement of the UPFC is the major concern to ensure the full potential of utilization in the transmission network. Voltage stability enhancement with the optimal placement of UPFC using stability index such as modal analysis, Voltage Phasor method is made and the loss minimization including UPFC is formulated as an optimization problem. This paper proposes particle swarm optimization for the exact real power loss minimization including UPFC. The implementation of loss minimization for the optimal location of UPFC was tested with IEEE-14 and IEEE-57 bus system.
Fuzzy-Sliding Mode Speed Control for Two Wheels Electric Vehicle Drive
Nasri, Abdelfatah ; Hazzab, Abdeldjabar ; Bousserhane, Ismail Khalil ; Hadjeri, Samir ; Sicard, Pierre ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 499~509
DOI : 10.5370/JEET.2009.4.4.499
Electric vehicles (EV) are developing fast during this decade due to drastic issues on the protection of environment and the shortage of energy sources, so new technologies allow the development of electric vehicles (EV) by means of electric motors associated with static converters. The proposed propulsion system consists of two induction motors (IM) that ensure the drive of the two back driving wheels. The electronic differential system ensures the robust control of the vehicle behavior on the road. It also allows controlling, independently, every driving wheel to turn at different speeds in any curve. This paper presents the study of an hybrid Fuzzy-sliding mode control (SMC) strategy for the electric vehicle driving wheels, stability improvement, in which the fuzzy logic system replace the discontinuous control action of the classical SMC law. Our electric vehicle fuzzy-sliding mode control`s simulated in Matlab SIMULINK environment, the results obtained present the efficiency of the proposed control with no overshoot, the rising time is perfected with good disturbances rejections comparing with the classical control law.
Calculation of Temperature Rise in Gas Insulated Busbar by Coupled Magneto-Thermal-Fluid Analysis
Kim, Hong-Kyu ; Oh, Yeon-Ho ; Lee, Se-Hee ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 510~514
DOI : 10.5370/JEET.2009.4.4.510
This paper presents the coupled analysis method to calculate the temperature rise in a gas insulated busbar (GIB). Harmonic eddy current analysis is carried out and the power losses are calculated in the conductor and enclosure tank. Two methods are presented to analyze the temperature distribution in the conductor and tank. One is to solve the thermal conduction problem with the equivalent natural convection coefficient and is applied to a single phase GIB. The other is to employ the computational fluid dynamics (CFD) tool which directly solves the thermal-fluid equations and is applied to a three-phase GIB. The accuracy of both methods is verified by the comparison of the measured and calculated temperature in a single phase and three-phase GIB.
A Novel Efficiency Optimization Strategy of IPMSM for Pump Applications
Zhou, Guangxu ; Ahn, Jin-Woo ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 515~520
DOI : 10.5370/JEET.2009.4.4.515
According to the operating characteristics of pump applications, they should exhibit high efficiency and energy saving capabilities throughout the whole operating process. A novel efficiency optimization control strategy is presented here to meet the high efficiency demand of a variable speed Permanent Magnet Synchronous Motor (PMSM). The core of this strategy is the excellent integration of mended maximum torque to the current control algorithm, based on the losses model during the dynamic and the grade search method with changed step by fuzzy logic during the steady. The performance experiments for the control system of a variable speed high efficiency PMSM have been completed. The test results verified that the system can reliably operate with a different control strategy during dynamic and steady operation, and the system exhibits better performance when using the efficiency-optimization control.
Comparative Study of Passivity and RST Regulator Applied to Doubly Fed Induction Machine
Aissi, S. ; Saidi, L. ; Abdessemed, R. ; Ababsa, F. ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 521~526
DOI : 10.5370/JEET.2009.4.4.521
In this paper we are interested in the control of Doubly Fed Induction Machine (DFIM) using the Passivity Based Control (PBC). This work presents a solution to the problem of DFIM that requires a state observer. The proposed method shows very important advantages for nonlinear systems, especially in the trajectory tracking to achieve the needed DFIM performance. In the obtained results, the passivity provides high efficiency in DFIM based system, namely in its stability and robustness. An improvement behavior has been observed in comparison to the results given by the RST controller.
Dielectric and Pyroelectric Properties of Dy-doped BSCT Thick Films by Screen-printing Method
Noh, Hyun-Ji ; Lee, Sung-Gap ; Nam, Sung-Pill ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 527~530
DOI : 10.5370/JEET.2009.4.4.527
Simulations of Frequency-dependent Impedance of Ground Rods Considering Multi-layered Soil Structures
Lee, Bok-Hee ; Joe, Jeong-Hyeon ; Choi, Jong-Hyuk ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 531~537
DOI : 10.5370/JEET.2009.4.4.531
Lightning has a broad frequency spectrum from DC to a few MHz. Consequently, the high frequency performance of grounding systems for protection against lightning should be evaluated, with the distributed parameter circuit model in a uniform soil being used to simulate grounding impedances. This paper proposes a simulation method which applies the distributed parameter circuit model for the frequency-dependent impedance of vertically driven ground rods by considering multi-layered soil structures where ground rods are buried. The Matlab program was used to calculate the frequency-dependent ground impedances for two ground rods of different lengths. As a result, an increase of the length of ground rod is not always followed by a decrease of grounding impedance, at least at a high frequency. The results obtained using the newly proposed simulation method considering multi-layered soil structures are in good agreement with the measured results.
The Development of an Electroconductive SiC-ZrB
Ceramic Heater through Spark Plasma Sintering
Ju, Jin-Young ; Kim, Cheol-Ho ; Kim, Jae-Jin ; Lee, Jung-Hoon ; Lee, Hee-Seung ; Shin, Yong-Deok ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 538~545
DOI : 10.5370/JEET.2009.4.4.538
composites were fabricated by combining 30, 35, 40 and 45vol.% of Zirconium Diboride (hereafter,
) powders with Silicon Carbide (hereafter, SiC) matrix. The SiC-
composites, the sintered compacts, were produced through Spark Plasma Sintering (hereafter, SPS), and its physical, electrical, and mechanical properties were examined. Also, the thermal image analysis of the SiC-
composites was examined. Reactions between
were not observed via X-Ray Diffractometer (hereafter, XRD) analysis. The relative density of the SiC+30vol.%
, and SiC+45vol.%
composites were 88.64%, 76.80%, 79.09% and 88.12%, respectively. The XRD phase analysis of the sintered compacts demonstrated high phase of SiC and
but low phase of
. Among the SiC-
composites, the SiC+35vol.%
composite had the lowest flexural strength, 148.49MPa, and the SiC+40vol.%
composite had the highest flexural strength, 204.85MPa, at room temperature. The electrical resistivities of the SiC+30vol.%
at room temperature, respectively. The electrical resistivities of the SiC+30vol.%
composites had Positive Temperature Coefficient Resistance (hereafter, PTCR) in the temperature range from
. The V-I characteristics of the SiC+40vol.%
composite had a linear shape. Therefore, it is considered that the SiC+40vol.%
composite containing the most outstanding mechanical properties, high resistance temperature coefficient and PTCR characteristics among the sintered compacts can be used as an energy friendly ceramic heater or electrode material through SPS.
Fabrication of a Bottom Electrode for a Nano-scale Beam Resonator Using Backside Exposure with a Self-aligned Metal Mask
Lee, Yong-Seok ; Jang, Yun-Ho ; Bang, Yong-Seung ; Kim, Jung-Mu ; Kim, Jong-Man ; Kim, Yong-Kweon ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 546~551
DOI : 10.5370/JEET.2009.4.4.546
In this paper, we describe a self-aligned fabrication method for a nano-patterned bottom electrode using flood exposure from the backside. Misalignments between layers could cause the final devices to fail after the fabrication of the nano-scale bottom electrodes. A self-alignment was exploited to embed the bottom electrode inside the glass substrate. Aluminum patterns act as a dry etching mask to fabricate glass trenches as well as a self-aligned photomask during the flood exposure from the backside. The patterned photoresist (PR) has a negative sidewall slope using the flood exposure. The sidewall slopes of the glass trench and the patterned PR were
, respectively. The negative sidewall enables an embedment of a gold layer inside
wide glass trenches. Gold residues on the trench edges were removed by the additional flood exposure with wet etching. The sidewall slopes of the patterned PR are related to the slopes of the glass trenches. Nano-scale bottom electrodes inside the glass trenches will be used in beam resonators operating at high resonant frequencies.
A Semi-blind Digital Watermarking Scheme Based on the Triplet of Significant Wavelet Coefficients
Chu, Hyung-Suk ; Batgerel, Ariunzaya ; An, Chong-Koo ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 552~558
DOI : 10.5370/JEET.2009.4.4.552
We proposed a semi-blind digital image watermarking technique for copyright protection. The proposed algorithm embedded a binary sequence watermark into significant wavelet coefficients by using a quantization method. The main idea of the quantization method was to quantize a middle coefficient of the triplet of a significant wavelet coefficient according to the watermark`s value. Unlike an existing algorithm, which used a random location table to find a coefficient in which the watermark bit will be embedded: the proposed algorithm used quad-tree decomposition to find a significant wavelet coefficient for embedding. For watermark detection, an original host image was not required. Thanks to the usage of significant wavelet coefficients, the proposed algorithm improved the correlation value, up to 0.43, in comparison with the existing algorithm.
A Novel High Performance Scan Architecture with Dmuxed Scan Flip-Flop (DSF) for Low Shift Power Scan Testing
Kim, Jung-Tae ; Kim, In-Soo ; Lee, Keon-Ho ; Kim, Yong-Hyun ; Baek, Chul-Ki ; Lee, Kyu-Taek ; Min, Hyoung-Bok ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 559~565
DOI : 10.5370/JEET.2009.4.4.559
Power dissipation during scan testing is becoming an important concern as design sizes and gate densities increase. The high switching activity of combinational circuits is an unnecessary operation in scan shift mode. In this paper, we present a novel architecture to reduce test power dissipation in combinational logic by blocking signal transitions at the logic inputs during scan shifting. We propose a unique architecture that uses dmuxed scan flip-flop (DSF) and transmission gate as an alternative to muxed scan flip-flop. The proposed method does not have problems with auto test pattern generation (ATPG) techniques such as test application time and computational complexity. Moreover, our elegant method improves performance degradation and large overhead in terms of area with blocking logic techniques. Experimental results on ITC99 benchmarks show that the proposed architecture can achieve an average improvement of 30.31% in switching activity compared to conventional scan methods. Additionally, the results of simulation with DSF indicate that the powerdelay product (PDP) and area overhead are improved by 28.9% and 15.6%, respectively, compared to existing blocking logic method.
Robust Model Predictive Control Using Polytopic Description of Input Constraints
Lee, Sang-Moon ;
Journal of Electrical Engineering and Technology, volume 4, issue 4, 2009, Pages 566~569
DOI : 10.5370/JEET.2009.4.4.566
In this paper, we propose a less conservative a linear matrix inequality (LMI) condition for the constrained robust model predictive control of systems with input constraints and polytopic uncertainty. Systems with input constraints are represented as perturbed systems with sector bounded conditions. For the infinite horizon control, closed-loop stability conditions are obtained by using a parameter dependent Lyapunov function. The effectiveness of the proposed method is shown by an example.