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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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On the Local Identifiability of Load Model Parameters in Measurement-based Approach
Choi, Byoung-Kon ; Chiang, Hsiao-Dong ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 149~158
DOI : 10.5370/JEET.2009.4.2.149
It is important to derive reliable parameter values in the measurement-based load model development of electric power systems. However parameter estimation tasks, in practice, often face the parameter identifiability issue; whether or not the model parameters can be estimated with a given input-output data set in reliable manner. This paper introduces concepts and practical definitions of the local identifiability of model parameters. A posteriori local identifiability is defined in the sense of nonlinear least squares. As numerical examples, local identifiability of third-order induction motor (IM) model and a Z-induction motor (Z-IM) model is studied. It is shown that parameter ill-conditioning can significantly affect on reliable parameter estimation task. Numerical studies show that local identifiability can be quite sensitive to input data and a given local solution. Finally, several countermeasures are proposed to overcome ill-conditioning problem in measurement-based load modeling.
Improved Pre-prepared Power Demand Table and Muller's Method to Solve the Profit Based Unit Commitment Problem
Chandram, K. ; Subrahmanyam, N. ; Sydulu, M. ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 159~167
DOI : 10.5370/JEET.2009.4.2.159
This paper presents the Improved Pre-prepared Power Demand (IPPD) table and Muller's method as a means of solving the Profit Based Unit Commitment (PBUC) problem. In a deregulated environment, generation companies (GENCOs) schedule their generators to maximize profits rather than to satisfy power demand. The PBUC problem is solved by the proposed approach in two stages. Initially, information concerning committed units is obtained by the IPPD table and then the subprob-lem of Economic Dispatch (ED) is solved using Muller's method. The proposed approach has been tested on a power system with 3 and 10 generating units. Simulation results of the proposed approach have been compared with existing methods and also with traditional unit commitment. It is observed from the simulation results that the proposed algorithm provides maximum profit with less computational time compared to existing methods.
Wavelet Transforms: Practical Applications in Power Systems
Akorede, Mudathir Funsho ; Hizam, Hashim ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 168~174
DOI : 10.5370/JEET.2009.4.2.168
An application of wavelet analysis to power system transient generated signals is presented in this paper. With the time-frequency localisation characteristics embedded in wavelets, the time and frequency information of a waveform can be presented as a visualised scheme. This feature is very important for non-stationary signals analysis such as the ones generated from power system disturbances. Unlike the Fourier transform, the wavelet transform approach is more efficient in monitoring fault signals as time varies. For time intervals where the function changes rapidly, this method can zoom in on the area of interest for better visualisation of signal characteristics.
Optimal Measurement Placement for Static Harmonic State Estimation in the Power Systems based on Genetic Algorithm
Dehkordl, Behzad Mirzaeian ; Fesharaki, Fariborz Haghighatdar ; Kiyournarsi, Arash ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 175~184
DOI : 10.5370/JEET.2009.4.2.175
In this paper, a method for optimal measurement placement in the problem of static harmonic state estimation in power systems is proposed. At first, for achieving to a suitable method by considering the precision factor of the estimation, a procedure based on Genetic Algorithm (GA) for optimal placement is suggested. Optimal placement by regarding the precision factor has an evident solution, and the proposed method is successful in achieving the mentioned solution. But, the previous applied method, which is called the Sequential Elimination (SE) algorithm, can not achieve to the evident solution of the mentioned problem. Finally, considering both precision and economic factors together in solving the optimal placement problem, a practical method based on GA is proposed. The simulation results are shown an improvement in the precision of the estimation by using the proposed method.
Photovoltaic System Allocation Using Discrete Particle Swarm Optimization with Multi-level Quantization
Song, Hwa-Chang ; Diolata, Ryan ; Joo, Young-Hoon ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 185~193
DOI : 10.5370/JEET.2009.4.2.185
This paper presents a methodology for photovoltaic (PV) system allocation in distribution systems using a discrete particle swarm optimization (DPSO). The PV allocation problem is in the category of mixed integer nonlinear programming and its formulation may include multi-valued dis-crete variables. Thus, the PSO requires a scheme to deal with multi-valued discrete variables. This paper introduces a novel multi-level quantization scheme using a sigmoid function for discrete particle swarm optimization. The technique is employed to a standard PSO architecture; the same velocity update equation as in continuous versions of PSO is used but the particle's positions are updated in an alternative manner. The set of multi-level quantization is defined as integer multiples of powers-of-two terms to efficiently approximate the sigmoid function in transforming a particle's position into discrete values. A comparison with a genetic algorithm (GA) is performed to verify the quality of the solutions obtained.
Contribution of an Energy Storage System for Stabilizing a Microgrid during Islanded Operation
Kim, Jong-Yul ; Kim, Seul-Ki ; Park, June-Ho ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 194~200
DOI : 10.5370/JEET.2009.4.2.194
In this paper, the cooperative control scheme of micro sources and an ESS (Energy Storage System) during islanded operation is presented and evaluated by a simulation study. The ESS handles the frequency and voltage as a primary control. Then, the secondary regulation control returns the cur-rent power output of ESS into a pre-planned value. The simulation's results show that the proposed co-operative control scheme can regulate the frequency and voltage and reduce the consumption of the stored energy of ESS.
A Lookup Table Based Loss Minimizing Control for FCEV Permanent Magnet Synchronous Motors
Lee, Jung-Gi ; Nam, Kwang-Hee ; Lee, Sun-Ho ; Choi, Soe-Ho ; Kwon, Soon-Woo ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 201~210
DOI : 10.5370/JEET.2009.4.2.201
A loss minimizing controller is developed for a fuel cell electric vehicle (FCEV) permanent magnet synchronous motor (PMSM). The PMSM losses are modeled by some experimental equations. Applying Lagrangian to the loss function, a necessary condition for the optimality appears to be a fourth order polynomial, and the loss minimizing solutions are obtained by a simple numerical approach. On the other hand, the loss minimizing solutions are found by scanning the motor loss in the entire operating region. The two results agree well. The loss minimizing current sets for given torque and speed are made into a table, which is utilized as a look-up in the current control loop.
Three-Phase 4-Wire Isolated Wind Energy Conversion System Employing VSC with a T-Connected Transformer for Neutral Current Compensation
Kasal, Gaurav Kumar ; Singh, Bhim ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 211~218
DOI : 10.5370/JEET.2009.4.2.211
This paper presents a voltage and frequency controller (VFC) for a 4-wire stand-alone wind energy conversion system (WECS) employing an asynchronous generator. The proposed VF con-troller consists of a three leg IGBT (Insulated Gate Bipolar Junction Transistor) based voltage source converter and a battery at its DC bus. The neutral terminal for the consumer loads is created using a T-connected transformer, which consists of only two single phase transformers. The control algorithm of the VF controller is developed for the bidirectional flow capability of the active power and reactive power control by which it controls the WECS voltage and frequency under different dynamic conditions, such as varying consumer loads and varying wind speeds. The WECS is modeled and simulated in MATLAB using Simulink and PSB toolboxes. Extensive results are presented to demonstrate the capability of the VF controller as a harmonic eliminator, a load balancer, a neutral current compensator as well as a voltage and frequency controller.
Rotor Failures Diagnosis of Squirrel Cage Induction Motors with Different Supplying Sources
Menacer, Arezki ; Champenois, Gerard ; Nait Said, Mohamed Said ; Benakcha, Abdelhamid ; Moreau, Sandrine ; Hassaine, Said ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 219~228
DOI : 10.5370/JEET.2009.4.2.219
The growing application and the numerous qualities of induction motors (1M) in industrial processes that require high security and reliability levels has led to the development of multiple methods for early fault detection. However, various faults can occur, such as stator short-circuits and rotor failures. Traditionally the diagnosis machine is done through a sinusoidal power supply, in the present paper we study experimentally the effects of the rotor failures, such as broken rotor bars in function of the ac supplying, the load and show the impact of the converter from diagnosis of the machine. The technique diagnosis used is based on the spectral analysis of stator currents or stator voltages respectively according to the types of induction motor ac supplying. So, four different ac supplying are considered:
the IM is directly by the balanced three-phase network voltage source,
the IM is fed by a sinusoidal current source given the controlled by hysteresis,
the IM is fed (in open loop) by a scalar control imposing through ratio V/f=constant,
the IM is controlled through a vector control using space vector pulse width modulation (SVPWM) technique inverter with an outer speed loop.
Correction of the Approximation Error in the Time-Stepping Finite Element Method
Kim, Byung-Taek ; Yu, Byoung-Hun ; Choit, Myoung-Hyun ; Kim, Ho-Hyun ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 229~233
DOI : 10.5370/JEET.2009.4.2.229
This paper proposes a correction method for the error inherently created by time-step approximation in finite element analysis (FEA). For a simple RL and RLC linear circuit, the error in time-step analysis is analytically investigated, and a correction method is proposed for a non-linear system as well as a linear one. Then, for a practical inductor model, linear and non-linear time-step analyses are performed and the calculation results are corrected by the proposed methods. The accuracy of the corrected results is confirmed by comparing the electric input and output powers.
Induction Motor Direct Torque Control with Fuzzy Logic Method
Chikhi, Abdessalem ; Chikhi, Khaled ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 234~239
DOI : 10.5370/JEET.2009.4.2.234
In this article we present the simulation results of induction motor speed regulation by direct torque control with a classic PI regulator. The MATLAB Simulink programming environment is used as a simulation tool. The results obtained, using a fuzzy logic, shows the importance of this method in the improvement of the performance of such regulation.
Position Control for Interior Permanent Magnet Synchronous Motors using an Adaptive Integral Binary Observer
Kang, Hyoung-Seok ; Kim, Cheon-Kyu ; Kim, Young-Seok ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 240~248
DOI : 10.5370/JEET.2009.4.2.240
An approach to control the position for an interior permanent magnet synchronous motor (IPMSM) based on an adaptive integral binary observer is described. The binary controller with a binary observer is composed of a main loop regulator and an auxiliary loop regulator. One of its key features is that it alleviates chatter in the constant boundary layer. However, steady state estimation accuracy and robustness are dependent upon the thickness of the constant boundary layer. In order to improve the steady state performance of the binary observer and eliminate the chattering problem of the constant boundary layer, a new binary observer is formed by adding extra integral dynamics to the existing switching hyperplane equation. Also, the proposed adaptive integral binary observer applies an adaptive scheme because the parameters of the dynamic equations such as the machine inertia and the viscosity friction coefficient are not well known. Furthermore, these values can typically be easily changed during normal operation. However, the proposed observer can overcome the problems caused by using the dynamic equations, and the rotor position estimation is constructed by integrating the rotor speed estimated with a Lyapunov function. Experimental results obtained using the proposed algorithm are presented to demonstrate the effectiveness of the approach.
Study of Hydrodynamic-Magnetic-Thermal Coupling in a Linear Induction MHD Pump
Kadid, Fatima Zohra ; Drid, Said ; Abdessemed, Rachid ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 249~254
DOI : 10.5370/JEET.2009.4.2.249
This article deals with the analysis of a coupling between stationary Maxwell's equations, the transient state Navier-Stokes and thermal equations. The resolution of these equations is obtained by introducing the magnetic vector potential A, the vorticity
, the stream function
and the temperature T. The flux density, the electromagnetic thrust, the electric power density, the velocity, the pressure and the temperature are graphically visualized. Also, the influence of the frequency is presented.
Acoustic Noise and Vibration Reduction of Coreless Brushless DC Motors with an Air Dynamic Bearing
Yang, lee-Woo ; Kim, Young-Seok ; Kim, Sang-Uk ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 255~265
DOI : 10.5370/JEET.2009.4.2.255
This paper presents the acoustic noise and mechanical vibration reduction of a coreless brushless DC motor with an air dynamic bearing used in a digital lightening processor. The coreless brushless DC motor does not have a stator yoke or stator slot to remove the unbalanced force caused by the interaction between the stator yoke and the rotor magnet. An unbalanced force makes slotless brushless DC motors vibrate and mechanically noisy, and the attractive force between the magnet and the stator yoke increases power consumption. Also, when a coreless brushless DC motor is driven by a
conduction type inverter, high frequency acoustic noise occurs because of the peak components of the phase currents caused by small phase inductance and large phase resistance. In this paper, a core-less brushless DC motor with an air dynamic bearing to remove mechanical vibration and to reduce power consumption is applied to a digital lightening processor. A
conduction type inverter drives it to reduce high frequency acoustic noise. The applied methods are simulated and tested using a manufactured prototype motor with an air dynamic bearing. The experimental results show that a coreless brushless DC motor has characteristics of low power consumption, low mechanical vibration, and low high frequency acoustic noise.
Modified Direct Torque Control System of Five Phase Induction Motor
Kim, Nam-Hun ; Kim, Min-Huei ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 266~271
DOI : 10.5370/JEET.2009.4.2.266
In this paper, improved direct torque control(DTC) of five-phase induction motor(IM) is proposed. Due to the additional degrees of freedom, five-phase IM drives present unique characteristics. One of them is the ability of enhancing the torque producing capability of the motor. Also five-phase motor drives possess many others advantage compared with the traditional three-phase motor drives. Such as, reducing the amplitude and increasing of frequency of torque pulsation, reducing amplitude of current per phase without increasing the voltage per phase and increasing the reliability. The direct torque control method is advantageous when it is applied to the five-phase IM. Because the five-phase inverter provides 32 space vectors in comparison to 8 space voltage vectors by the three-phase inverter. The 32 space voltage vectors are divided into three groups according to their magnitudes. The characteristics and dynamic performance of traditional five-phase DTC are analyzed and new DTC for five-phase IM is proposed. Therefore, a more precise flux and torque control algorithm for the five-phase IM drives can be suggested and explained. For presenting the superior performance of the pro-posed direct torque control, experimental results is presented using a 32 bit fixed point TMS320F2812 digital signal processor
Analysis of a Gas Circuit Breaker Using the Fast Moving Least Square Reproducing Kernel Method
Lee, Chany ; Kim, Do-Wan ; Park, Sang-Hun ; Kim, Hong-Kyu ; Jung, Hyun-Kyo ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 272~276
DOI : 10.5370/JEET.2009.4.2.272
In this paper, the arc region of a gas circuit breaker (GCB) is analyzed using the fast moving least square reproducing kernel method (FMLSRKM) which can simultaneously calculate an approximated solution and its derivatives. For this problem, an axisymmetric and inhomogeneous formulation of the FMLSRKM is used and applied. The field distribution obtained by the FMLSRKM is compared to that of the finite element method. Then, a whole breaking period of a GCB is simulated, including analysis of the arc gas flow by finite volume fluid in the cell, and the electric field of the arc region using the FMLSRKM.
The Effect of a High Temperature Superconducting Patch on a Rectangular Microstrip Antenna
Chebbara, Fouad ; Amir, Mounir ; Fortaki, Tarek ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 277~281
DOI : 10.5370/JEET.2009.4.2.277
The complex resonant frequency problem of a superconductor patch is formulated in terms of an integral equation which is the kernel of a dyadic Green's function. To include the effect of the superconductivity of the microstrip patch, the surface complex impedance of the superconductor film is introduced using the two fluids model of Gorter and Casimir. The Galerkin procedure is used in the resolution of the electric field integral equation. Numerical results concerning the effect of the operating temperature of a superconductor patch on the characteristics of the antenna are presented.
Design of a High Performance Patch Antenna for GPS Communication Systems
Hamedi-Hagh, Sotoudeh ; Chung, Joseph ; Oh, Soo-Seok ; Jo, Ju-Ung ; Park, Noh-Joon ; Park, Dae-Hee ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 282~286
DOI : 10.5370/JEET.2009.4.2.282
This paper presents the design of a patch antenna for GPS portable devices. The antenna is designed to operate at Ll band on an FR4 PCB with a thickness of 1.6mm, a dielectric constant of 3.8 and two metallization layers. The antenna has a dimension of 49mm
36mm and operates at 1.5754GHz with a return loss of -36dB and a measured bandwidth of 250MHz.
Mach-Zehnder Type Tandem Optical Switch/Modulator using a Single-Mode Interconnecting Waveguide and Its Switching Characteristics
Choi, Young-Kyu ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 287~291
DOI : 10.5370/JEET.2009.4.2.287
In this paper, an optical switch/modulator is designed and its light propagating characteristics analyzed using a simplified BPM. The distinctive feature of this switch/modulator is that all its waveguide branches are designed as single-mode. The principle of the device is based on the coupled mode theory in the Y-junction interconnecting waveguide. In spite of the fact all waveguides are designed as single-mode, by adjusting the interconnecting waveguide length'of the device the same characteristics as existing up to date devices are obtainable. Numerical results show that the switching characteristics periodically depend upon an interconnecting waveguide length with a spatial of about
step index waveguide. The design concept would therefore be utilized effectively in fabricating a monolithic high density optical integrated circuit.
Robust Adaptive Control for a Class of Nonlinear Systems with Complex Uncertainties
Seo, Sang-Bo ; Back, Ju-Hoon ; Shim, Hyung-Bo ; Seo, Jin-H. ;
Journal of Electrical Engineering and Technology, volume 4, issue 2, 2009, Pages 292~300
DOI : 10.5370/JEET.2009.4.2.292
This paper considers a robust adaptive stabilization problem for a class of uncertain nonlinear systems which include an unknown virtual control coefficient, an unknown constant parameter, and a time-varying disturbance whose bound is unknown, We propose a new estimator for an un-known virtual control coefficient and present a robust adaptive backstepping design procedure which results in a smooth state feedback control law, a new two-dimensional parameter update law, and a
Lyapunov function which is positive definite and proper.