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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 8, Issue 6 - Nov 2013
Volume 8, Issue 5 - Sep 2013
Volume 8, Issue 4 - Jul 2013
Volume 8, Issue 3 - May 2013
Volume 8, Issue 2 - Mar 2013
Volume 8, Issue 1 - Jan 2013
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Optimal Hourly Scheduling of Community-Aggregated Electricity Consumption
Khodaei, Amin ; Shahidehpour, Mohammad ; Choi, Jaeseok ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1251~1260
DOI : 10.5370/JEET.2013.8.6.1251
This paper presents the optimal scheduling of hourly consumption in a residential community (community, neighborhood, etc.) based on real-time electricity price. The residential community encompasses individual residential loads, communal (shared) loads, and local generation. Community-aggregated loads, which include residential and communal loads, are modeled as fixed, adjustable, shiftable, and storage loads. The objective of the optimal load scheduling problem is to minimize the community-aggregated electricity payment considering the convenience of individual residents and hourly community load characteristics. Limitations are included on the hourly utility load (defined as community-aggregated load minus the local generation) that is imported from the utility grid. Lagrangian relaxation (LR) is applied to decouple the utility constraint and provide tractable subproblems. The decomposed subproblems are formulated as mixed-integer programming (MIP) problems. The proposed model would be used by community master controllers to optimize the utility load schedule and minimize the community-aggregated electricity payment. Illustrative optimal load scheduling examples of a single resident as well as an aggregated community including 200 residents are presented to show the efficiency of the proposed method based on real-time electricity price.
Coordinated Voltage and Reactive Power Control Strategy with Distributed Generator for Improving the Operational Efficiency
Jeong, Ki-Seok ; Lee, Hyun-Chul ; Baek, Young-Sik ; Park, Ji-Ho ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1261~1268
DOI : 10.5370/JEET.2013.8.6.1261
This study proposes a voltage and reactive coordinative control strategy with distributed generator (DG) in a distribution power system. The aim is to determine the optimum dispatch schedules for an on-load tap changer (OLTC), distributed generator settings and all shunt capacitor switching on the load and DG generation profile in a day. The proposed method minimizes the real power losses and improves the voltage profile using squared deviations of bus voltages. The results indicate that the proposed method reduces the real losses and voltage fluctuations and improve receiving power factor. This paper proposes coordinated voltage and reactive power control methods that adjust optimal control values of capacitor banks, OLTC, and the AVR of DGs by using a voltage sensitivity factor (VSF) and dynamic programming (DP) with branch-and-bound (B&B) method. To avoid the computational burden, we try to limit the possible states to 24 stages by using a flexible searching space at each stage. Finally, we will show the effectiveness of the proposed method by using operational cost of real power losses and voltage deviation factor as evaluation index for a whole day in a power system with distributed generators.
Optimal Coordination of Charging and Frequency Regulation for an Electric Vehicle Aggregator Using Least Square Monte-Carlo (LSMC) with Modeling of Electricity Price Uncertainty
Lee, Jong-Uk ; Wi, Young-Min ; Kim, Youngwook ; Joo, Sung-Kwan ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1269~1275
DOI : 10.5370/JEET.2013.8.6.1269
Recently, many studies have suggested that an electric vehicle (EV) is one of the means for increasing the reliability of power systems in new energy environments. EVs can make a contribution to improving reliability by providing frequency regulation in power systems in which the Vehicle-to-Grid (V2G) technology has been implemented and, if economically viable, can be helpful in increasing power system reliability. This paper presents a stochastic method for optimal coordination of charging and frequency regulation decisions for an EV aggregator using the Least Square Monte-Carlo (LSMC) with modeling of electricity price uncertainty. The LSMC can be used to assess the value of options based on electricity price uncertainty in order to simultaneously optimize the scheduling of EV charging and regulation service for the EV aggregator. The results of a numerical example show that the proposed method can significantly improve the expected profits of an EV aggregator.
Stochastic Modeling of Plug-in Electric Vehicle Distribution in Power Systems
Son, Hyeok Jin ; Kook, Kyung Soo ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1276~1282
DOI : 10.5370/JEET.2013.8.6.1276
This paper proposes a stochastic modeling of plug-in electric vehicles (PEVs) distribution in power systems, and analyzes the corresponding clustering characteristic. It is essential for power utilities to estimate the PEV charging demand as the penetration level of PEV is expected to increase rapidly in the near future. Although the distribution of PEVs in power systems is the primary factor for estimating the PEV charging demand, the data currently available are statistics related to fuel-driven vehicles and to existing electric demands in power systems. In this paper, we calculate the number of households using electricity at individual ending buses of a power system based on the electric demands. Then, we estimate the number of PEVs per household using the probability density function of PEVs derived from the given statistics about fuel-driven vehicles. Finally, we present the clustering characteristic of the PEV distribution via case studies employing the test systems.
An Improvement in Synchronously Rotating Reference Frame-Based Voltage Sag Detection under Distorted Grid Voltages
Sillapawicharn, Yutthachai ; Kumsuwan, Yuttana ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1283~1295
DOI : 10.5370/JEET.2013.8.6.1283
This study proposed an improvement in synchronously rotating reference frame-based voltage sag detection under distorted grid voltages. In the past, the conventional synchronously rotating reference frame (CSRRF)-based voltage sag detection was generally used in the voltage sag compensation applications. Its disadvantage is a long delay of detection time. The modified synchronously rotating reference frame (MSRRF)-based voltage sag detection is able to detect the voltage sag with only a short delay in detection time. However, its operation under distorted grid voltage conditions is unavailable. This paper proposed the improvement of modified synchronously rotating reference frame (IMSRRF)-based voltage sag detection for use in distorted grid voltages with very fast operation of voltage sag detection. The operation of the proposed voltage sag detections is investigated via simulations and experimentations to verify the performance of the IMSRRF-based voltage sag detection.
An Analysis on Power Demand Reduction Effects of Demand Response Systems in the Smart Grid Environment in Korea
Won, Jong-Ryul ; Song, Kyung-Bin ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1296~1304
DOI : 10.5370/JEET.2013.8.6.1296
This study performed an analysis on power demand reduction effects exhibited by demand response programs, which are advanced from traditional demand-side management programs, in the smart grid environment. The target demand response systems for the analysis included incentive-based load control systems (2 month-ahead demand control system, 1~5 days ahead demand control system, and demand bidding system), which are currently implemented in Korea, and price-based demand response systems (mainly critical peak pricing system or real-time pricing system, currently not implemented, but representative demand response systems). Firstly, the status of the above systems at home and abroad was briefly examined. Next, energy saving effects and peak demand reduction effects of implementing the critical peak or real-time pricing systems, which are price-based demand response systems, and the existing incentive-based load control systems were estimated.
Bus-voltage Sag Suppressing and Fault Current Limiting Characteristics of the SFCL Due to its Application Location in a Power Distribution System
Kim, Jin-Seok ; Lim, Sung-Hun ; Kim, Jae-Chul ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1305~1309
DOI : 10.5370/JEET.2013.8.6.1305
The application of the superconducting fault current limiter (SFCL) in a power distribution system is expected to contribute the voltage-sag suppression of the bus line as well as the fault-current reduction of the fault line. However, the application effects of the SFCL on the voltage sag of the bus line including the fault current are dependent on its application location in a power distribution system. In this paper, we investigated the fault current limiting and the voltage sag suppressing characteristics of the SFCL due to its application location such as the outgoing point of the feeder, the bus line, the neutral line and the 2nd side of the main transformer in a power distribution system, and analyzed the trace variations of the bus-voltage and fault-feeder current. The simulated power distribution system, which was composed of the universal power source, two transformers with the parallel connection and the impedance load banks connected with the 2nd side of the transformer through the power transmission lines, was constructed and the short-circuit tests for the constructed system were carried out. Through the analysis on the short-circuit tests for the simulated power distribution system with the SFCLs applied into its representative locations, the effects from the SFCL's application on the power distribution system were discussed from the viewpoints of both the suppression of the bus-voltage sag and the reduction of the fault current.
Software Resolver-to-Digital Converter for Compensation of Amplitude Imbalances using D-Q Transformation
Kim, Youn-Hyun ; Kim, Sol ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1310~1319
DOI : 10.5370/JEET.2013.8.6.1310
Resolvers are transducers that are used to sense the angular position of rotational machines. The analog resolver is necessary to use resolver to digital converter. Among the RDC software method, angle tracking observer (ATO) is the most popular method. In an actual resolver-based position sensing system, amplitude imbalance dominantly distorts the estimate position information of ATO. Minority papers have reported position error compensation of resolver's output signal with amplitude imbalance. This paper proposes new ATO algorithm in order to compensate position errors caused by the amplitude imbalance. There is no need premeasured off line data. This is easy, simple, cost-effective, and able to work on line compensation. To verify feasibility of the proposed algorithm, simulation and experiments are carried out.
Bulk Micromachined Vibration Driven Electromagnetic Energy Harvesters for Self-sustainable Wireless Sensor Node Applications
Bang, Dong-Hyun ; Park, Jae-Yeong ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1320~1327
DOI : 10.5370/JEET.2013.8.6.1320
In this paper, two different electromagnetic energy harvesters using bulk micromachined silicon spiral springs and Polydimethylsiloxane (PDMS) packaging technique have been fabricated, characterized, and compared to generate electrical energy from ultra-low ambient vibrations under 0.3g. The proposed energy harvesters were comprised of a highly miniaturized Neodymium Iron Boron (NdFeB) magnet, silicon spiral spring, multi-turned copper coil, and PDMS housing in order to improve the electrical output powers and reduce their sizes/volumes. When an external vibration moves directly the magnet mounted as a seismic mass at the center of the spiral spring, the mechanical energy of the moving mass is transformed to electrical energy through the 183 turns of solenoid copper coils. The silicon spiral springs were applied to generate high electrical output power by maximizing the deflection of the movable mass at the low level vibrations. The fabricated energy harvesters using these two different spiral springs exhibited the resonant frequencies of 36Hz and 63Hz and the optimal load resistances of
, respectively. In particular, the energy harvester using the spiral spring with two links exhibited much better linearity characteristics than the one with four links. It generated
of output power and 107.3mV of load voltage at the vibration acceleration of 0.3g. It also exhibited power density and normalized power density of
, respectively. The total volume of the fabricated energy harvesters was
A New Topology of Multilevel Voltage Source Inverter to Minimize the Number of Circuit Devices and Maximize the Number of Output Voltage Levels
Ajami, Ali ; Mokhberdoran, Ataollah ; Oskuee, Mohammad Reza Jannati ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1328~1336
DOI : 10.5370/JEET.2013.8.6.1328
Nowadays multilevel inverters are developing generally due to reduced voltage stress on power switches and low total harmonic distortion (THD) in output voltage. However, for increasing the output voltage levels the number of circuit devices are increased and it results in increasing the cost of converter. In this paper, a novel multilevel inverter is proposed. The suggested topology uses less number of power switches and related gate drive circuits to generate the same level in output voltage with comparison to traditional cascaded multilevel inverter. With the proposed topology all levels in output voltage can be realized. As an illustration, a symmetric 13-level and asymmetric 29-level proposed inverters have been simulated and implemented. The total peak inverse (PIV) and power losses of presented inverter are calculated and compared with conventional cascaded multilevel inverter. The presented analyses show that the power losses in the suggested multilevel inverter are less than the traditional inverters. Presented simulation and experimental results demonstrate the feasibility and applicability of the proposed inverter to obtain the maximum number of levels with less number of switches.
A Simplified Modulation Strategy for Three-leg Voltage Source Inverter Fed Unsymmetrical Two-winding Induction Motor
Sinthusonthishat, Saliltip ; Chuladaycha, Nontawat ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1337~1344
DOI : 10.5370/JEET.2013.8.6.1337
This paper presents a simplified modulation strategy for the three-leg VSI fed two-winding induction motor. The strategy provides independent unbalanced voltage control for the main and auxiliary windings. This make the motor can be reversed rotation through the range of motor speed operation without limitation of voltage boost of the auxiliary winding. To study the advantages of the proposed drive, the experimental results such as voltage stresses, hysteresis band of the currents in locus, and also acoustic noise levels of the three-leg VSI are compared with those of the conventional two-leg topology. The results obviously show that the proposed technique achieves superior performance compared with the traditional scheme in case of dramatic increase of DC bus utilization, effective reduction of harmonic voltages content, and also significant enhancement of motor efficiency.
The Iron loss Estimation of IPMSM According to Current Phase Angle
Cho, Gyu-Won ; Kim, Dong-Yeong ; Kim, Gyu-Tak ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1345~1351
DOI : 10.5370/JEET.2013.8.6.1345
Variable iron loss as function of current phase angle of Interior Permanent Magnet Synchronous Motor(IPMSM) was calculated through Curve Fitting Method(CFM). Also, a magnetic flux density distribution of iron core according to current phase angle was analyzed, and an iron loss calculation was performed including harmonic distortion. The experiment was performed by production of non-magnetizing model for the separation of mechanical loss, and the iron loss was calculated by the measurement of input using power analyzer and output power using dynamometer. Some error was generated between experimental results and calculation value, but an iron loss diminution according to current phase angle followed a same pattern. So, errors were generated by measurement, vibration, noise, harmonic distortion loss, etc.
Control of a Single Phase Unified Power Quality Conditioner-Distributed Generation Based Input Output feedback Linearization
Mokhtarpour, A. ; Shayanfar, H.A. ; Bathaee, M. ; Banaei, M.R. ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1352~1364
DOI : 10.5370/JEET.2013.8.6.1352
This paper describes a novel structure for single phase Unified Power Quality Conditioner-Distributed Generation (UPQC-DG) with direct grid connected DC-AC converter for low DC output DG systems which can be used not only for compensation of power quality problems but also for supplying of load power partly. This converter has been composed of one full-bridge inverter, one three winding high frequency transformer with galvanic isolation and two cycloconverters. Proper control based on Input Output feedback Linearization is used to tracking the reference signals. The simulation and experimental results are presented to confirm the validity of the proposed approach.
Numerical Calculations and Analyses in Diagonal Type Magnetohydrodynamic Generator
Le, Chi Kien ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1365~1370
DOI : 10.5370/JEET.2013.8.6.1365
This paper examines the effects of magnetic induction attenuation on current distribution in the exit regions of the Faraday-type, non-equilibrium plasma Magnetohydrodynamic (MHD) generator by numerical calculation using cesium-seeded helium. Calculations show that reasonable magnetic induction attenuation creates a very uniform current distribution near the exit region of generator channel. Furthermore, it was determined that the current distribution in the middle part of generator is negligible, and the output electrodes can be used without large ballast resistors. In addition, the inside resistance of the exit region and the current concentration at the exit electrode edges, both decrease with the attenuation of magnetic flux density. The author illustrates that the exit electrodes of the diagonal Faraday-type, non-equilibrium plasma MHD generator should be arranged in the attenuation region of the magnetic induction, in order to improve the electrical parameters of the generator.
Behaviour Analysis of Self Excited Induction Generator Feeding Linear and No Linear Loads
Moulahoum, Samir ; Kabache, Nadir ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1371~1379
DOI : 10.5370/JEET.2013.8.6.1371
Application of induction machines in wind turbine driven generators is a good alternative due to their good characteristics such as efficiency, reliability and low cost. Nevertheless, when isolated operation is required, the application of external capacitive bank, connected to the stator windings, to provide self-excitation results in a rather complex analysis. This paper presents an analysis of self-excited induction generator connected to a load either directly or by an intermediate of a power converter. At first a dynamic model of the induction generator accounting for magnetic saturation is developed. Then a number of balanced and unbalanced capacitors, passive and active loads are verified. Experimental results obtained from laboratory tests are compared to those simulated; the two are shown to be in good agreement.
Graphical Representation of the Instantaneous Compensation Power Flow for Single-Phase Active Power Filters
Jung, Young-Gook ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1380~1388
DOI : 10.5370/JEET.2013.8.6.1380
The conventional graphical representation of the instantaneous compensation power flow for single-phase active power filters(APFs) simply represents the active power flow and the reactive power flow which flowing between the power source and the active filter / the load. But, this method does not provide the information about the rectification mode and the compensation mode of APFs, especially, the loss for each mode was not considered at all. This is very important to understand the compensation operation characteristics of APFs. Therefore, this paper proposes the graphical representation of the instantaneous compensation power flow for single-phase APFs considering the instantaneous rectification mode and the instantaneous inversion mode. Three cases are verified in this paper - without compensation, with compensation of the active power 'p' and the fundamental reactive power 'q', and with compensation of only the distorted power 'h'. To ensure the validity of the proposed approach, PSIM simulation is achieved. As a result, we could confirm that the proposed approach was easy to explain the instantaneous compensation power flow considering the instantaneous rectification mode and the instantaneous inversion mode of APFs, also, Total Harmonic Distortion(THD)/Power Factor (P.F) and Fast Fourier Transform(FFT) analysis were compared for each case.
Implementation of Robust Prediction Observer Controller for DC-DC Converter
Shenbagalakshmi, R. ; Raja, T. Sree Renga ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1389~1399
DOI : 10.5370/JEET.2013.8.6.1389
A discrete controller is designed for low power dc-dc switched mode power supplies. The approach is based on time domain and the control loop continuously and concurrently tunes the compensator parameters to meet the converter specifications. A digital state feedback control combined with the load estimator provides a complete compensation, which further improves the dynamic performance of the closed loop system. Simulation of digitally controlled Buck converter is performed with MATLAB/Simulink. Experimental results are given to demonstrate the effectiveness of the controller using LabVIEW with a data acquisition card (model DAQ Pad - 6009).
Grid-tied Power Converter for Battery Energy Storage Composed of 2-stage DC-DC Converter
Kim, Do-Hyun ; Lee, Yoon-Seok ; Han, Byung-Moon ; Kim, Ju-Yong ; Chae, Woo-Kyu ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1400~1408
DOI : 10.5370/JEET.2013.8.6.1400
This paper proposes a new grid-tied power converter for battery energy storage, which is composed of a 2-stage DC-DC converter and a PWM inverter. The 2-stage DC-DC converter is composed of an LLC resonant converter connected in cascade with a 2-quadrant hybrid-switching chopper. The LLC resonant converter operates in constant duty ratio, while the 2-quadrant hybrid-switching chopper operates in variable duty ratio for voltage regulation. The operation of proposed system was verified through computer simulations. Based on computer simulations, a hardware prototype was built and tested to confirm the technical feasibility of proposed system. The proposed system could have relatively higher efficiency and smaller size than the existing system.
The Estimation Method Comparison of Iron Loss Coefficients through the Iron Loss Calculation
Kim, Yong-Tae ; Cho, Gyu-Won ; Kim, Gyu-Tak ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1409~1414
DOI : 10.5370/JEET.2013.8.6.1409
A new calculation method for iron loss coefficients is proposed by using the Steinmetz equation from Epstein data. The hysteresis loss must have linear characteristic according to the frequency. However, the existing iron loss coefficients are defined by formula of frequency. In this case, the hysteresis loss has non-linear characteristics by frequency. So, in this paper, the iron loss coefficients were defined by a function of the magnetic flux density, and the iron loss calculation is applied for Interior Permanent Magnet Synchronous Motor(IPMSM) of 600(W) and 200(W). The iron loss calculation results and the experimental results are compared according to the various materials.
Characteristic Analysis of an Traveling Wave Ultrasonic Motor using a Cylindrical Dynamic Contact Model
Ro, Jong-Suk ; Yi, Kyung-Pyo ; Chung, Tae-Kyung ; Jung, Hyun-Kyo ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1415~1423
DOI : 10.5370/JEET.2013.8.6.1415
The traveling wave ultra-sonic motor (TWUSM) is operated through the frictional force between the rotor and the stator. Hence, the contact mechanism should be analyzed to estimate the motor performance. However, the nonlinearity of the contact mechanism of the TWUSM makes it difficult to propose a proper contact model and a characteristic analysis method. To address these problems, a novel contact model is proposed and be termed the cylindrical dynamic contact model (CDCM) in this research. An estimation method of the motor performance is proposed using the CDCM, an analytical method, and a numerical method. The feasibility and usefulness of the proposed characteristic analysis are verified through experimental data.
A Study on the Design Procedure of the Eight Pole Magnetic Bearings for the Inner-rotor and the Outer-rotor Type
Lee, Jun-Ho ; Park, Chan-Bae ; Lee, Byung-Song ; Lee, Su-Gil ; Kim, Jae-Hee ; Jung, Shin-Myung ; Lee, Hyung-Woo ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1424~1430
DOI : 10.5370/JEET.2013.8.6.1424
This paper presents design procedure of the magnetic bearings used for high-speed electric machines and flywheel energy storage systems. Magnetic bearing can be categorized by inner-rotor type and outer-rotor type according to the position of the rotary disc. These two types are applicable based on application environments such as application space, required attraction force, and controllability. Magnetic bearing is generally designed based on the ratio (geometrical coefficient or geometrical efficiency) of pole width to rotor journal radius but proper ratio is only decided by the analysis. This is the difficulty of the magnetic bearing design. In this paper, proper design technology of the inner-rotor type and outer-rotor-type eight pole magnetic bearings is introduced and compared with the FEM analysis results, which verifies the proposed design procedure is suitable to be applied to the design of the magnetic bearings for the industrial applications and flywheel energy storage system.
Performance Assessment of a Lithium-Polymer Battery for HEV Utilizing Pack-Level Battery Hardware-in-the-Loop-Simulation System
Han, Sekyung ; Lim, Jawhwan ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1431~1438
DOI : 10.5370/JEET.2013.8.6.1431
A pack-level battery hardware-in-the-loop simulation (B-HILS) platform is implemented. It consists of dynamic vehicle models using PSAT and multiple control interfaces including real-time 3D driving and GPS mode. In real-time 3D driving mode, user can drive a virtual vehicle using actual drive equipment such as steering wheel and accelerator to generate the cycle profile of the battery. In GPS mode, actual road traffic and terrain effects can be simulated using GPS data while the trajectory is displayed on Google map. In the latter part of the paper, several performance tests of an actual lithium-polymer battery pack are carried out utilizing the developed system. All experiments are conducted as parts of actual development process of a commercial battery pack adopting 2nd generation Prius as a target vehicle model. Through the experiments, the low temperature performance and fuel efficiency of the battery are quantitatively investigated in comparison with the original nickel-metal hydride (NiMH) pack of the Prius.
Neuro-Fuzzy Control of Interior Permanent Magnet Synchronous Motors: Stability Analysis and Implementation
Dang, Dong Quang ; Vu, Nga Thi-Thuy ; Choi, Han Ho ; Jung, Jin-Woo ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1439~1450
DOI : 10.5370/JEET.2013.8.6.1439
This paper investigates a robust neuro-fuzzy control (NFC) method which can accurately follow the speed reference of an interior permanent magnet synchronous motor (IPMSM) in the existence of nonlinearities and system uncertainties. A neuro-fuzzy control term is proposed to estimate these nonlinear and uncertain factors, therefore, this difficulty is completely solved. To make the global stability analysis simple and systematic, the time derivative of the quadratic Lyapunov function is selected as the cost function to be minimized. Moreover, the design procedure of the online self-tuning algorithm is comparatively simplified to reduce a computational burden of the NFC. Next, a rotor angular acceleration is obtained through the disturbance observer. The proposed observer-based NFC strategy can achieve better control performance (i.e., less steady-state error, less sensitivity) than the feedback linearization control method even when there exist some uncertainties in the electrical and mechanical parameters. Finally, the validity of the proposed neuro-fuzzy speed controller is confirmed through simulation and experimental studies on a prototype IPMSM drive system with a TMS320F28335 DSP.
Robust Zero Power Levitation Control of Quadruple Hybrid EMS System
Cho, Su-Yeon ; Kim, Won-Ho ; Jang, Ik-Sang ; Kang, Dong-Woo ; Lee, Ju ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1451~1456
DOI : 10.5370/JEET.2013.8.6.1451
This paper presents the improved zero power levitation control algorithm for a quadruple hybrid EMS (Electromagnetic Suspension) system. Quadruple hybrid EMS system is a united form of four hybrid EMS systems one on each corner coupled with a metal plate. Technical issue in controlling a quadruple hybrid EMS system is the permanent magnet's equilibrium point deviation caused by design tolerance which eventually leads to a limited zero power levitation control that only satisfies the zero power levitation in one or two hybrid EMS system among the four hybrid EMS system. In order to satisfy a complete zero power levitation control of the quadruple hybrid EMS system, the proposed method presented in this paper adds a compensating algorithm which adjusts the gap reference of each individual axe. Later, this paper proves the stability and effectiveness of the proposed control algorithm via experiment and disturbance test.
Liquid Crystal Orientation Mechanism: Competition Between Rubbing and Ion-beam Method
Kim, Ji-Ho ; Han, Jeong-Min ; Shon, Jin-Geun ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1457~1461
DOI : 10.5370/JEET.2013.8.6.1457
The effect of liquid crystal (LC) alignment on a homeotropic polyimide (PI) surface induced by ion beam (IB) irradiation and rubbing process was studied. LC alignment was not affected by IB irradiation with an exposure time of 10 s, and an IB irradiation with an exposure time of 60 s more effectively oriented the LCs on the PI layer than the rubbing process. It was assumed that the LC alignment depended on the C-O bonds created from the C=O bonds on the PI surface broken by IB irradiation after an exposure time of 60 s, which resulted in a strong surface energy that transformed the homeotropic LC alignment to homogeneous states.
Pseudo 480-Hz Driving Method for Digital Mode Grayscale Displays
Ryeom, Jeongduk ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1462~1467
DOI : 10.5370/JEET.2013.8.6.1462
A pseudo 480-Hz drive method has been proposed to reduce the dynamic false contour noise that occurs on flat panel displays with displaying grayscale image in the digital mode, such as plasma display panels. The proposed method makes the image movements nearly continuous by rearranging the 8-bit image data displayed for 1 TV field into 8 subfields. The position of the image data rearranged in subfields has been optimized on the basis of the speed of the moving image by computer simulations for the dynamic false contour noise. It is verified that a significant reduction in the dynamic false contour noise is achieved with the proposed method as compared to the conventional noise reduction technologies. Moreover, to reduce the noise in digital mode displays, the proposed technology requires only 8 subfields. Therefore, there is no reduction in the brightness of the image.
Characteristic Analysis and Origin Positioning of Acoustic Signals Produced by Partial Discharges in Insulation Oil
Park, Dae-Won ; Jo, Hyang-Eun ; Kim, Sun-Jae ; Kil, Gyung-Suk ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1468~1473
DOI : 10.5370/JEET.2013.8.6.1468
This paper dealt with the propagation characteristics of acoustic signals produced by partial discharges and the positioning of PD origin in insulation oil to develop insulation diagnostic techniques of oil-immerged transformers. Electrode systems such as needle to plane, plane to plane, and particle electrodes were fabricated to simulate some defects of power transformers. In addition, the frequency spectrum and propagation characteristics of acoustic signals with partial discharge (PD) in insulation oil were analyzed. Although there were differences based on the type of defect, the frequency spectra of the acoustic signals measured by wide and narrow band acoustic emission (AE) sensors were distributed in the range of 50 kHz-400 kHz. Therefore, a narrowband AE sensor is suitable for the diagnosis of oil-immersed power transformers. We could find the position of the PD source with an error margin of 10% in the experiments by calculating the position of the PD occurrence using the time difference of arrival measured by five AE sensors.
Effects of SPS Mold on the Properties of Sintered and Simulated SiC-ZrB
Lee, Jung-Hoon ; Kim, In-Yong ; Kang, Myeong-Kyun ; Jeon, Jun-Soo ; Lee, Seung-Hoon ; Jeon, An-Gyun ; Shin, Yong-Deok ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1474~1480
DOI : 10.5370/JEET.2013.8.6.1474
Silicon carbide (SiC)-zirconium diboride (
) composites were prepared by subjecting a 60:40 vol% mixture of
-SiC powder and
matrix to spark plasma sintering (SPS) in 15
molds. The 15
compacts were sintered for 60 sec at
under a uniaxial pressure of 50 MPa and argon atmosphere. Similar composites were simulated using
3D computer simulation software. The current and power densities of the specimen sections of the simulated SiC-
composites were higher than those of the mold sections of the 15
mold simulated specimens. Toward the centers of the specimen sections, the current densities in the simulated SiC-
composites increased. The power density patterns of the specimen sections of the simulated SiC-
composites were nearly identical to their current density patterns. The current densities of the 15
mold of the simulated SiC-
composites were higher than those of the 20
mold in the center of the specimen section. The volume electrical resistivity of the simulated SiC-
composite was about 7.72 times lower than those of the graphite mold and the punch section. The power density, 1.4604
, of the 15
mold of the simulated SiC-
composite was higher than that of the 20
distributions in the 20
mold in the sintered SiC-
composites were more uniform than those of the 15
mold on the basis of energy-dispersive spectroscopy (EDS) mapping. The volume electrical resistivity of the 20
mold of the sintered SiC-
, was lower than that of the 15
, at room temperature.
Analytical Modeling and Simulation of Dual Material Gate Tunnel Field Effect Transistors
Samuel, T.S.Arun ; Balamurugan, N.B. ; Sibitha, S. ; Saranya, R. ; Vanisri, D. ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1481~1486
DOI : 10.5370/JEET.2013.8.6.1481
In this paper, a new two dimensional (2D) analytical model of a Dual Material Gate tunnel field effect transistor (DMG TFET) is presented. The parabolic approximation technique is used to solve the 2-D Poisson equation with suitable boundary conditions. The simple and accurate analytical expressions for surface potential and electric field are derived. The electric field distribution can be used to calculate the tunneling generation rate and numerically extract tunneling current. The results show a significant improvement of on-current and reduction in short channel effects. Effectiveness of the proposed method has been confirmed by comparing the analytical results with the TCAD simulation results.
A Novel AE Based Algorithm for PD Localization in Power Transformers
Mehdizadeh, Sina ; Yazdchi, Mohammadreza ; Niroomand, Mehdi ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1487~1496
DOI : 10.5370/JEET.2013.8.6.1487
In this paper, a novel algorithm for PD localization in power transformers based on wavelet de-noising technique and energy criterion is proposed. Partial discharge is one of the main failures in power transformers. The localization of which could be very useful for maintenance systems. Acoustic signals due to a PD event are transient, irregular and non-repetitive. So wavelet transform is an efficient tool for this signal processing problem that gives a time-frequency demonstration. First, different wavelet based de-noising methods are analyzed. Then, a reasonable structure for threshold value determining and applying manner on signals is presented. Evaluated errors are good evidences for choices. Next, applying the elimination low energy frequency bands is discussed and developed as a de-noising method. Time differences between signals are used for PD localization. Different ways in time arrival detection are introduced and a novel approach in energy criterion method is presented. At the end, the quality of algorithm is verified through the different assays in lab.
Design Optimization of Silicon-based Junctionless Fin-type Field-Effect Transistors for Low Standby Power Technology
Seo, Jae Hwa ; Yuan, Heng ; Kang, In Man ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1497~1502
DOI : 10.5370/JEET.2013.8.6.1497
Recently, the junctionless (JL) transistors realized by a single-type doping process have attracted attention instead of the conventional metal-oxide-semiconductor field-effect transistors (MOSFET). The JL transistor can overcome MOSFET's problems such as the thermal budget and short-channel effect. Thus, the JL transistor is considered as great alternative device for a next generation low standby power silicon system. In this paper, the JL FinFET was simulated with a three dimensional (3D) technology computer-aided design (TCAD) simulator and optimized for DC characteristics according to device dimension and doping concentration. The design variables were the fin width (
), fin height (
), and doping concentration (
). After the optimization of DC characteristics, RF characteristics of JL FinFET were also extracted.
Investigation on Flashover Development Mechanism of Polymeric Insulators by Time Frequency Analysis
Muniraj, C. ; Krishnamoorthi, K. ; Chandrasekar, S. ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1503~1511
DOI : 10.5370/JEET.2013.8.6.1503
This paper deals with the analysis of leakage current characteristics of silicone rubber insulator in order to develop a new condition monitoring tool to identify the flashover of outdoor insulators. In this work, laboratory based pollution performance tests are carried out on silicone rubber insulator under ac voltage at different pollution levels and relative humidity conditions with sodium chloride (NaCl) as a contaminant. Min-Norm spectral analysis is adopted to calculate the higher order harmonics and Signal Noise Ratio (SNR). Choi-Williams Distribution (CWD) function is employed to understand the time frequency characteristics of the leakage current signal. Reported results on silicone rubber insulators show that the flashover development process of outdoor polymer insulators could be identified from the higher order harmonics and signal noise ratio values of leakage current signals.
Influence of Electrical Aging on Space Charge Dynamics of Oil-Impregnated Paper Insulation under AC-DC Combined Voltages
Wang, Yan ; Li, Jian ; Wu, Sicheng ; Sun, Peng ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1512~1519
DOI : 10.5370/JEET.2013.8.6.1512
Oil-impregnated paper is a major type of insulation used in oil-filled converter transformers for both traditional and new energy systems. This paper presents and analyzes the results of the experiment conducted on the electrical aging of oil-impregnated paper under AC-DC combined voltages using the pulsed electro-acoustic (PEA) technique. The formation and dynamics of space charge affected the performance of insulation material. The electrical aged oil-paper insulation was obtained through electrical aged experiments under the voltages. Based on the PEA technique, measurements were carried out when the oil-paper insulation system was subjected to different stressing and aging times. The space charge dynamics in the bulk of the oil-paper insulation system with different aging times were measured and analyzed. Characteristic parameters such as the total charge injection amount, the total charges of fast moving and slow moving, and the distortion factor of electric field were calculated and discussed. Results show that the longer electrical aging time, the more charges trapped in the bulk of aging sample. It leads to larger distortion factor of electric field in the bulk of aging samples and accelerate degradation of oil-paper insulation under AC-DC combined voltages.
A Target Tracking Based on Bearing and Range Measurement With Unknown Noise Statistics
Lim, Jaechan ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1520~1529
DOI : 10.5370/JEET.2013.8.6.1520
In this paper, we propose and assess the performance of "H infinity filter (
, HIF)" and "cost reference particle filter (CRPF)" in the problem of tracking a target based on the measurements of the range and the bearing of the target. HIF and CRPF have the common advantageous feature that we do not need to know the noise statistics of the problem in their applications. The performance of the extended Kalman filter (EKF) is also compared with that of the proposed filters, but the noise information is perfectly known for the applications of the EKF. Simulation results show that CRPF outperforms HIF, and is more robust because the tracking of HIF diverges sometimes, particularly when the target track is highly nonlinear. Interestingly, when the tracking of HIF diverges, the tracking of the EKF also tends to deviate significantly from the true track for the same target track. Therefore, CRPF is very effective and appropriate approach to the problems of highly nonlinear model, especially when the noise statistics are unknown. Nonetheless, HIF also can be applied to the problem of timevarying state estimation as the EKF, particularly for the case when the noise statistcs are unknown. This paper provides a good example of how to apply CRPF and HIF to the estimation of dynamically varying and nonlinearly modeled states with unknown noise statistics.
On the Stability of Critical Point for Positive Systems and Its Applications to Biological Systems
Lee, Joo-Won ; Jo, Nam Hoon ; Shim, Hyungbo ; Son, Young Ik ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1530~1541
DOI : 10.5370/JEET.2013.8.6.1530
The coexistence and extinction of species are important concepts for biological systems and can be distinguished by an investigation of stability. When determining local stability of nonlinear systems, Lyapunov indirect method based on the Jacobian linearization has been widely employed due to its simplicity. Despite such popularity, it is not applicable to singular systems whose Jacobian has at least one eigenvalue that is equal to zero. In such singular cases, an appropriate Lyapunov function should be sought to determine the stability of systems, which is rather difficult and quite involved. In this paper, we seek for a simple criterion to determine stability of the equilibrium that is located at the boundary of the positive orthant, when one of eigenvalues of the Jacobian is zero. The goal of the paper is to present a generalized condition for the equilibrium to attract all trajectories that starting from initial condition in the positive orthant and near the equilibrium. Unlike the Lyapunov direct method, the proposed method requires just a simple algebraic computation for checking the stability of the critical point. Our approach is applied to various biological systems to show the effectiveness of the proposed method.
Novel Results for Global Exponential Stability of Uncertain Systems with Interval Time-varying Delay
Liu, Yajuan ; Lee, Sang-Moon ; Kwon, Oh-Min ; Park, Ju H. ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1542~1550
DOI : 10.5370/JEET.2013.8.6.1542
This paper presents new results on delay-dependent global exponential stability for uncertain linear systems with interval time-varying delay. Based on Lyapunov-Krasovskii functional approach, some novel delay-dependent stability criteria are derived in terms of linear matrix inequalities (LMIs) involving the minimum and maximum delay bounds. By using delay-partitioning method and the lower bound lemma, less conservative results are obtained with fewer decision variables than the existing ones. Numerical examples are given to illustrate the usefulness and effectiveness of the proposed method.
Design of Decoupled Control Systems Based on Directional Interpolations
Park, Kiheon ; Kim, Jin-Geol ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1551~1558
DOI : 10.5370/JEET.2013.8.6.1551
design of decoupled control systems is treated in the generalized plant model. The existence condition of a decoupling controller is stated and a parameterized form of all achievable decoupled closed loop transfer matrices is presented by using the directional interpolation approaches under the assumption of simple transmission zeros. The class of all decoupling controllers that yield finite cost function is obtained as a parameterized form and an illustrative example to find the optimal controller is provided.
Energy Efficient Wireless Data Transmission for Personal Health Devices
Kim, Sang-Kon ; Kim, Tae-Kon ; Koh, Jin-Hwan ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1559~1570
DOI : 10.5370/JEET.2013.8.5.1559
The family of ISO/IEEE11073 standards is the basis of the e-health system and provides interoperability for personal health devices. In the early stage of e-health business, it was expected that people would use a health device individually. In this case, a measurement datum was episodically acquired and generally transmitted for one person at a time. Recently, a health device is expected to be used by multiple people, and large amounts of measurement data are gathered in a short time interval. In addition, mobile health devices have become more popular, so that energy efficient measurement data transmission is required, to prolong the use of a device. In IEEE11073 PHD standards, data transmission is classified into three different types: immediate individual transfer, small block transfer, and large block transfer. The large block transfer using PM-store concept provides efficient transmission. However, an existing PM-store has problem when a device is used by multiple people. To address the defined problem, a modified PM-segment that is in compliance with 11073 standards is proposed in this paper. In particular, the proposed PM-segment is designed to minimize the additional complexity of an agent instead of a manager and it is interoperable with the existing manager. The proposed PM-segment shows better performance than the existing PM-segment, in terms of memory requirements and expected queue time. Also, performance comparison among the three transfers is performed in regard to the delay time and communication power consumption points of view.
Dynamic Analysis of a Maglev Conveyor Using an EM-PM Hybrid Magnet
Kim, Ki-Jung ; Han, Hyung-Suk ; Kim, Chang-Hyun ; Yang, Seok-Jo ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1571~1578
DOI : 10.5370/JEET.2013.8.6.1571
With the emergence of high-integration array and large area panel process, the need to minimize the generation of particles in the field of semiconductor, LCD and OLED has grown. As an alternative to the conventional roller system, a contactless magnetic conveyor has been proposed to reduce the generation of particles. An EM-PM hybrid which is one of magnetic levitation types is already proposed for the conveyor system. One of problems pointed out with this approach is the vibration caused by the dynamic interaction between conveyor and rail. To reduce the vibration, the introduction of a secondary suspension system which aims to decouple the levitation electromagnet from the main body is proposed. The objective of this study is to develop a dynamic model for the magnetically levitated conveyor, and to investigate the effect of the introduced suspension system. An integrated model of levitation system and rail based on 3D multibody dynamic model is proposed. With the proposed model, the dynamic characteristics of maglev conveyor system are analyzed, and the effect of the secondary suspension and the stiffness and damping are investigated.
Four Representative Applications of the Energy Shaping Method for Controlled Lagrangian Systems
Ng, Wai Man ; Chang, Dong Eui ; Song, Seong-Ho ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1579~1589
DOI : 10.5370/JEET.2013.8.6.1579
We provide a step-by-step, easy-to-follow procedure for the method of controlled Lagrangian systems. We apply this procedure to solve the energy shaping problem for four benchmark examples: the inertial wheel pendulum, an inverted pendulum on a cart, the system of ball and beam and the Furuta pendulum.
A Design on Reduction Cogging Torque of Dual Generator Radial Flux Permanent Magnet Generator for Small Wind Turbine
Lee, Gyeong-Chan ; Jung, Tae-Uk ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1590~1595
DOI : 10.5370/JEET.2013.8.6.1590
In this paper, the design for an electromagnetic structure and reduction cogging torque of a dual generator structured RFPM generator, which is a combination of the inner- and outer-rotor types, has been proposed. We call this a dual generator radial flux permanent magnet generator. To reduce the cogging torque, firstly, stator tooth pairing was designed; secondly, stator displacement was designed and finally, stator tooth pairing and stator displacement were carried out simultaneously. We found the optimal design condition about stator tooth pairing angle combination and stator displacement angle for cogging torque minimization. As a result, a cogging was reduced by 93.3[%] by this study.
Study on Multi-scale Unit Commitment Optimization in the Wind-Coal Intensive Power System
Ye, Xi ; Qiao, Ying ; Lu, Zongxiang ; Min, Yong ; Wang, Ningbo ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1596~1604
DOI : 10.5370/JEET.2013.8.6.1596
Coordinating operation between large-scale wind power and thermal units in multiple time scale is an important problem to keep power balance, especially for the power grids mainly made up of large coal-fired units. The paper proposes a novel operation mode of multi-scale unit commitment (abbr. UC) that includes mid-term UC and day-ahead UC, which can take full advantage of insufficient flexibility and improve wind power accommodation. First, we introduce the concepts of multi-scale UC and then illustrate the benefits of introducing mid-term UC to the wind-coal intensive grid. The paper then formulates the mid-term UC model, proposes operation performance indices and validates the optimal operation mode by simulation cases. Compared with day-ahead UC only, the multi-scale UC mode could reduce the total generation cost and improve the wind power net benefit by decreasing the coal-fired units' on/off operation. The simulation results also show that the maximum total generation benefit should be pursued rather than the wind power utilization rate in wind-coal intensive system.
A Probabilistic Approach to Small Signal Stability Analysis of Power Systems with Correlated Wind Sources
Yue, Hao ; Li, Gengyin ; Zhou, Ming ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1605~1614
DOI : 10.5370/JEET.2013.8.6.1605
This paper presents a probabilistic methodology for small signal stability analysis of power system with correlated wind sources. The approach considers not only the stochastic characteristics of wind speeds which are treated as random variables with Weibull distributions, while also the wind speed spatial correlations which are characterized by a correlation matrix. The approach based on the 2m+1 point estimate method and Cornish Fisher expansion, the orthogonal transformation technique is used to deal with the correlation of wind farms. A case study is carried out on IEEE New England system and the probabilistic indexes for eigenvalue analysis are computed from the statistical processing of the obtained results. The accuracy and efficiency of the proposed method are confirmed by comparing with the results of Monte Carlo simulation. The numerical results indicate that the proposed method can actually capture the probabilistic characteristics of mode properties of the power systems with correlated wind sources and the consideration of spatial correlation has influence on the probability of system small signal stability.
Modelling and Simulating the Spatio-Temporal Correlations of Clustered Wind Power Using Copula
Zhang, Ning ; Kang, Chongqing ; Xu, Qianyao ; Jiang, Changming ; Chen, Zhixu ; Liu, Jun ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1615~1625
DOI : 10.5370/JEET.2013.8.6.1615
Modelling and simulating the wind power intermittent behaviour are the basis of the planning and scheduling studies concerning wind power integration. The wind power outputs are evidently correlated in space and time and bring challenges in characterizing their behaviour. This paper provides a methodology to model and simulate the clustered wind power considering its spatio-temporal correlations using the theory of copula. The sampling approach captures the complex spatio-temporal connections among the wind farms by employing a conditional density function calculated using multidimensional copula function. The empirical study of real wind power measurement shows how the wind power outputs are correlated and how these correlations affect the overall uncertainty of clustered wind power output. The case study validates the simulation technique by comparing the simulated results with the real measurements.
Hybrid Communication Network Architectures for Monitoring Large-Scale Wind Turbine
Ahmed, Mohamed A. ; Kim, Young-Chon ;
Journal of Electrical Engineering and Technology, volume 8, issue 6, 2013, Pages 1626~1636
DOI : 10.5370/JEET.2013.8.6.1626
Nowadays, a rapid development in wind power technologies is occurring compared with other renewable energies. This advance in technology has facilitated a new generation of wind turbines with larger capacity and higher efficiency. As the height of the turbines and the distance between turbines increases, the monitoring and control of this new generation wind turbines presents new challenges. This paper presents the architectural design, simulation, and evaluation of hybrid communication networks for a large-scale wind turbine (WT). The communication network of WT is designed based on logical node (LN) concepts of the IEC 61400-25 standard. The proposed hybrid network architectures are modeled and evaluated by OPNET. We also investigate network performance using three different technologies: Ethernet-based, WiFi-based, and ZigBee-based. Our network model is validated by analyzing the simulation results. This work contributes to the design of a reliable communication network for monitoring and controlling a wind power farms (WPF).