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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Transactions of The Korean Institute of Electrical Engineers
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The Korean Institute of Electrical Engineers
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Volume & Issues
Volume 60, Issue 12 - Dec 2011
Volume 60, Issue 11 - Nov 2011
Volume 60, Issue 10 - Oct 2011
Volume 60, Issue 9 - Sep 2011
Volume 60, Issue 8 - Aug 2011
Volume 60, Issue 7 - Jul 2011
Volume 60, Issue 6 - Jun 2011
Volume 60, Issue 5 - May 2011
Volume 60, Issue 4 - Apr 2011
Volume 60, Issue 3 - Mar 2011
Volume 60, Issue 2 - Feb 2011
Volume 60, Issue 1 - Jan 2011
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Development of Wireless Data Acquisition Device for Individual Load to Improve Function of Smart Meter Applied to AMI
Sung, Byung-Chul ; Bae, Sun-Ho ; Park, Woo-Jae ; Jeon, Seung-Wook ; Park, Jung-Wook ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1795~1803
DOI : 10.5370/KIEE.2011.60.10.1795
Advanced Metering Infrastructure (AMI) is one of the important components to form a smart-gird, which is an advanced power system by combining the power system with the communication systems. This AMI makes it possible to exchange information between operators and consumers for the efficient and reliable operation of the power system through a smart meter or a In-Home Display. However, according to the increase of the demanded information such as the power quality, the accurate load-profile, and the billing data to help customers manage their power consumption, it is necessary to gather more accurate analytical data from each house appliances and transfer it to the smart meter for synthesizing the information and controlling each loads. In this paper, the development of the wireless data acquisition device for the individual load data metering, which is connected with the smart meter for advanced functions, is proposed. AVR, a kind of microcontroller, and Bluetooth are used and integrated into the proposed the wireless data acquisition device to transmit the detailed power data (voltage and current) to the smart meter. To verify the effectiveness of the proposed system, a hardware experiment is carried out including the confirmation of the possibility for providing the more various information by applying analysis algorithms to the obtained data. Also, the application structure of the wireless data acquisition device to gather the data from the various house appliances is presented.
Practical Alarm Suppression Rules and their Implementation for Nuclear Power Plants
Hwang, In-Koo ; Kim, Yang-Mo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1804~1810
DOI : 10.5370/KIEE.2011.60.10.1804
It is necessary to adopt some logical techniques and methods of alarm processing for a large complex plant such as nuclear power plants in order to present the occurred alarm messages properly and concisely. Among such alarm processing techniques, the alarm suppressing function is a strong tool to avoid alarm flooding during the sudden transients of plant output power such as turbine trips, reactor trips and other incidents. Unless any suppression or representation technologies are used in an alarm message listing system, it cannot provide quick assistance to plant operators or supervisors during plant upsets because too many alarm messages are presented in an alarm list window. This paper presents the key suppression methods and analysis processes developed for implementing a suppressed alarm message listing function of an integrated alarm system called LogACTs which has been applied to a CANDU nuclear power plant. A simulation testing of the suppressing function conducted with the real plant alarm message list data has demonstrated an effective performance of the developed logics with the high suppression rate.
Switching Surge Analysis and Evaluation in Combined Transmission System with 345kV GIL
Jang, Hwa-Youn ; Lee, Jong-Beom ; Kim, Yong-Kap ; Jang, Tae-In ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1811~1816
DOI : 10.5370/KIEE.2011.60.10.1811
This paper describes switching surge analysis for reclosing decision in 345kV combined transmission line with GIL. Reclosing operation should be decided based on the detailed technical analysis in combined transmission line because this line includes power cable section which is week on insulation. Insulation of power cable can be breakdown at the week point in case of reclosing moment. Therefore the detailed analysis has to be carried out by considering several conditions such as charging rate, inserting resistance, arrester, length ratio of power cable section, grounding resistance, etc. Analysis is performed by EMTP/ATP.
Analysis on Current Limiting Characteristics of a Hybrid SFCL with the First Half Cycle Limiting Operation Due to Resistance of Superconducting Element
Kim, Jin-Seok ; Lim, Sung-Hun ; Kim, Jae-Chul ; Choi, Jong-Soo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1817~1822
DOI : 10.5370/KIEE.2011.60.10.1817
The fault current has been increasing due to expansive substation facilities for meeting the increase of demand. To limit increasing fault current in a power system, among methods the superconducting fault current limiter (SFCL) has been considered to be adopted in the power grid. However, in case of adopting SFCL in the power system, most of SFCLs need to solve problems such as recovery, cost. With efforts to solve those problems, the novel fault current limiting device which is called hybrid SFCL is developed. To apply the hybrid SFCL, it has to be needed to analyze application possibility and itself operation characteristics. In this paper, the fault current limiting and operation characteristics of hybrid SFCL with first half cycle the limiting operation in case of various resistances of superconducting element were analyzed through experiment.
Correlation Analysis of Wind and Solar Power Generation Pattern for Modeling of Renewable Energy
Kim, Min-Jeong ; Park, Young-Sik ; Park, Jong-Bae ; Roh, Jae-Hyung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1823~1831
DOI : 10.5370/KIEE.2011.60.10.1823
When the RPS(Renewable Portfolio Standards) becomes effective in 2012, the use of renewable energy will be dramatically increased. However, there are no production simulations and demand supply programs that reflect the characteristics of the renewable energy. This paper analyzes correlations of the domestic wind power and solar power generation pattern in different areas and those of these sources` output and load pattern. Based on the regional correlation analysis, an appropriate method that uses a average output of the renewable energy or another modeling that takes account of uncertainty could be selected. Because it`s output is dependent on weather condition, we can not control the generation of renewable energy, that is the reason why the correlation between the load and output pattern of sources can be helpful to determine whether the renewable energy is modeled as a generator or load modifier. Through this analysis, a basis will be provided in order to properly model the renewable energy source.
Analysis on the Protective Coordination with Hybrid Superconducting Fault Current Limiter
Kim, Jin-Seok ; Lim, Sung-Hun ; Kim, Jae-Chul ; Choi, Jong-Soo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1832~1837
DOI : 10.5370/KIEE.2011.60.10.1832
The fault current has increased due to the large power demand in power distribution system and network distribution system. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) has been notified. However, the conventional SFCL has some problems such as cost, operation, recovery, loss. To solve some problems, the hybrid superconducting fault current limiter using the fast switch was proposed. However, hybrid SFCL also has a problem that is protection coordination in power distribution system with hybrid SFCL. In this paper, the fault current limiting characteristics of hybrid SFCL with first half cycle non-limiting operation according to the fault angle, the resistance of superconducting element, and the magnitude of Current Limit Resistor (CLR) which are the components of hybrid SFCL were analyzed through the experiments.
A Study of Coupled Electromagnetic-Thermal Field Analysis for Temperature Rise Prediction of Power Transformer
Ahn, Hyun-Mo ; Kim, Min-Soo ; Song, Jae-Sung ; Hahn, Sung-Chin ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1838~1845
DOI : 10.5370/KIEE.2011.60.10.1838
This paper deals with coupled electromagnetic-thermal field analysis for thermal fluid analysis of oil immersed power transformer. Electric power losses are calculated from electromagnetic field analysis and are used as input source of thermal field analysis based on computational fluid dynamics(CFD). Particularly, In order to accurately predict the temperature rise in oil immersed power transformer, the thermal problem should be coupled with the electromagnetic problem. Moreover, to reduce analysis region, the heat transfer coefficient is applied to boundary surface of the power transformer model. The coupling method results are compared with the experimental values for verifying the validity of the analysis. The predicted temperature rises show good agreements with the experimental values.
Design and Analysis of Surface-Mounted PM Motor of Compressor for Electric Vehicles Applications according to Slot/Pole Combinations
Choi, Jang-Young ; Park, Hyung-Il ; Jang, Seok-Myeong ; Lee, Sung-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1846~1857
DOI : 10.5370/KIEE.2011.60.10.1846
This paper deals with design and analysis of surface-mounted PM (SPM) motor for compressor of air-conditioning system for electric vehicle applications according to slot/pole combination. First, required torque-speed curve characteristics are determined from operating conditions of the compressor. Restricted conditions such as motor size limit and current density are also determined. And then, under same rated and restricted conditions, twelve models which have different slot/pole combinations each other are designed for various pole arc/pitch ratio using simple equations and 2-d finite element (FE) analyses. Designed models are analyzed and compared in terms of back-emf THD, cogging torque, torque ripple, power losses, efficiency, etc. On the basis of analysis results, it is found that the motor with a 6-pole PM rotor and a 27-slot stator has most outstanding performances in electromagnetic aspects. Finally, through the mechanical modal analysis and demagnetization analysis, it is concluded that the determined motor is most suitable for the compressor of air-conditioning system for electric vehicles.
Control Techniques of Sensorless BLDC Motor Drive for a Vehicle Fuel Pump Application
Tran, Quang-Vinh ; Chun, Tae-Won ; Lee, Hong-Hee ; Kim, Heung-Geun ; Nho, Eui-Cheol ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1858~1864
DOI : 10.5370/KIEE.2011.60.10.1858
This paper suggests a control technique of the sensorless brushless DC (BLDC) motor drive for a vehicle fuel pump application. The sensorless technique based on a comparator and a potential start-up method with high starting torque are proposed. The comparator is used to generate the commutation signals in phase with the three-phase back-EMFs. The rotor position is aligned at standstill for maximum starting torque without an additional sensor and any information of motor parameters. Also, the stator current can be easily adjusted by modulating the pulse width of the switching devices during alignment. Some experiments are implemented on a single chip 16-bit DSP controller to demonstrate the feasibility of the sensorless techniques.
A Novel MPPT Control of Photovoltaic Generation Using NFC Algorithm
Jang, Mi-Geum ; Choi, Jung-Sik ; Chung, Dong-Hwa ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1865~1874
DOI : 10.5370/KIEE.2011.60.10.1865
This paper proposes a novel maximum power point tracking(MPPT) using a new fuzzy control(NFC) algorithm for robust in insolation variation. Maximum power point(MPP) of solar cell has to achieve for improving output efficiency because it is changed with insolation and temperature. Conventional MPPT controller such as constant voltage(CV), perturbation and observation(PO) and incremental conductance(IC) are researched. But these controller have the problem that is failure to MPP with environment changing. The proposed NFC controller is based the fuzzy control algorithm and able to robust control with environment changing. Also the proposed controller of PV system is modeled by PSIM and the response characteristics according to the parameter variation is compared and analyzed. The validity of this controller is proved through response results.
Experiment and Implementation of NiMH Battery Model for Autonomie Environment
Lee, Jong-Kyung ; Kim, Jae-Eon ; Cha, Han-Ju ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1875~1880
DOI : 10.5370/KIEE.2011.60.10.1875
This paper proposes a battery model applicable to Autonomie environment. Also, a various of experiment is implemented for validation. The proposed battery model modifies Randles equivalent circuit and battery parameters are extracted from pulsed current tests. The parameters are two-dimensional function of current and SOC(State of Charge). The battery model is developed in the Matlab/Simulink and is implemented for NiMH Panasonic HHR650D and compared with pulsed current discharge curves. The simulation results validate the accuracy of the proposed model and the model is also tested by adding it on Autonomie for HEV application. Constant current charge/discharge, pulsed current test that can be used to extract battery parameter are performed and test results are used to build up the proposed battery model for Autonomie.
Temperature Dependence of Conductivities of Recyclable Polyethylene and Polypropylene and its Effects on Electric Field Distribution in Power Cable
Lee, June-Ho ; Kong, Tae-Sik ; Kim, Seong-Jung ; Kwon, Ki-Hyung ; Cho, Kyu-Cheol ; Hozumi, Naohiro ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1881~1887
DOI : 10.5370/KIEE.2011.60.10.1881
In this work the recyclable new polyethylene(PE) and polypropylene(PP), which are thermoplastic, have been investigated as the eco-friendly insulating candidates to replace the cross-linked polyethylene (XLPE). The temperature dependence of conductivities of these materials has been measured and its effects on electric field and space charge distribution in polymeric insulated power cable under temperature gradient have been calculated. It is shown that the sensitivity of conductivity to temperature change has more critical influence to determine the electric field distribution in the power cable than the absolute value of conductivity does and it can be said that the temperature dependence is one of most important factors for the power cable design.
A Study on the Design and Fabrication of High Performance Large Current Mica Capacitor for Energy Storage Facility Applications
Jung, Myung-Hee ; Yun, Eui-Jung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1888~1894
DOI : 10.5370/KIEE.2011.60.10.1888
In this study, large-current (75 - 400 A), high-voltage (500 - 1000
), reliable capacitors with capacitances (C) of 100 - 1000 nF were developed for energy storage facility applications. Mica was used as the dielectric of the capacitors. In order to form a parallel stack of a capacitor element, 50
thick mica sheets with a size of
were used with lead foils for the plate lead type of mica capacitors (HCM-L), while the same sizes of mica sheets coated by Ag paste were employed with lead foils for the parallel plate terminal type (HCM-C). The developed capacitors exhibited well behaviored device characteristics which meet the requirements of the capacitors. The developed capacitors also showed excellent characteristics for thermal shock test. The stability characteristics of developed capacitors for large current stress was superior to those measured for the capacitors prepared recently by CDETm.
A Study on the Measurement of Vibrational and Rotational Temperature Using the Atmospheric Ar Plasma Torch
Choi, Kwang-Ju ; Jang, Mun-Gug ; Han, Sang-Bo ; Park, Jae-Youn ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1895~1902
DOI : 10.5370/KIEE.2011.60.10.1895
This work was carried out for the measurement of vibration and rotation temperature using the optical emission spectroscopy of nitrogen second positive system in the small plasma torch. Among emissions
SP systems, the emission of
SP(0-0) was so strong. Emission peaks of SP system increased until the position of 12.5[mm] from the end of plasma torch, after that it decreased. However, vibration temperature decreased from 1540[K] to 1000[K] at the position of 12.5[mm]. In addition, rotational temperature was about 400[K] at the position of 10[mm] and it increased a little as much of 420[K] at 12.5[mm]. Consequently, the plasma torch discussed in this work is possible to apply in the surface treatment process under the low temperature.
Vehicle Running Characteristic Simulator using Induction Motor
Byun, Yeun-Sub ; Kim, Young-Chol ; Mok, Jei-Kyun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1903~1914
DOI : 10.5370/KIEE.2011.60.10.1903
In this paper, we propose vehicle running characteristic simulator. The developed simulator is configured by two induction motors which are directly coupled with each other. One motor is to simulate the vehicle drive and another motor is to simulate the vehicle dynamic load including running resistance, gradient resistance and adhesive characteristics between rail and wheel. The running characteristics of vehicle are modeled by numerical formulas. These are programed by software of embedded controller. Thus, it is possible to change several running characteristics during the running test freely and instantly. To evaluate the feasibility of the simulator, the experiments on slip and adhesion coefficient are performed. Additionally the adhesion control and speed control of vehicle are tested with simulator. Experimental results show that the simulator can produce the driving characteristics similar to the vehicle system.
Position and Orientation Estimation of a Maneticalluy Guided-Articulated Vehicle
Yun, Kyong-Han ; Kim, Young-Chol ; Min, Kyung-Deuk ; Byun, Yeun-Sub ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1915~1923
DOI : 10.5370/KIEE.2011.60.10.1915
For automated guidance control of a magnetically guided-all wheel steered vehicle, it is necessary to have information about position and orientation of the vehicle, and deviations from the reference path in real time. The magnet reference system considered here consists of three magnetic sensors mounted on the vehicle and magnetic markers, which are non-equidistantly buried in the road. This paper presents an observer to estimate such position and orientation at the center of gravity of the vehicle. This algorithm is based on the simple kinematic model of vehicle and uses the data of wheel velocity, steering angle, and the discrete measurements of marker positions. Since this algorithm requires the exact values of initial states, we have also proposed an algorithm of determining the initial position and orientation from the 16 successive magnet pole data, which are given by the magnetic measurement system(MMS). The proposed algorithm is capable of continuing to estimate for the case that the magnetic sensor fail to measure up to three successive magnets. It is shown through experimental data that the proposed algorithm works well within permissible error range.
Evaluations of the Robustness of Guidance Controller for a Bimodal Tram
Yun, Kyong-Han ; Lee, Yong-Sang ; Min, Kyung-Deuk ; Kim, Young-Chol ; Byun, Yeun-Sub ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1924~1934
DOI : 10.5370/KIEE.2011.60.10.1924
This paper is concerned with the robustness evaluations of the guidance controller for a bimodal tram which is being developed by the Korea Railroad Research Institute (KRRI). The bimodal tram is an all-wheel steered multiple-articulated vehicle as a new kind of transportation vehicle. This vehicle has to be equipped with an automatic guidance system. In , such a controller has been recently proposed. However, since the performance is affected by weight change of the vehicle due to number of the passenger, model parameter uncertainties depending on the state of friction and the elasticity of the tire, and a typhoon, the controller designed must be examined with these conditions. As expected, because the vehicle dynamics is highly nonlinear, for the sake of investigating the robustness of the controller we compose two simulation ways based on the vehicle models which are implemented by the ADAMS and the MATLAB/LabVIEW toolboxes. Different uncertainties and a typhoon disturbance have been considered for the simulation conditions. Simulation results are shown.
The Steam Temperature Control of Renovated Boiler in 100MW Power Plant
Lim, Geon-Pyo ; Lee, Heung-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1935~1940
DOI : 10.5370/KIEE.2011.60.10.1935
The control logic of steam temperature was redesigned, tested and applied to the power plant after its steam temperature equipments had been revised. This power plant use the ancillary gas gotten in the process of making iron in the steel mill. The boiler of power plant has the superheater and reheater to make the superheated steam. The superheater and reheater have the spray valve to control their temperature. The reheater has the gas bypass damper additionally in this plant. The control logics were redesigned in cascade forms and the initial parameters of control logics were calculated from the several step tests. The final parameters could be obtained through the several repeated tests and the feedforward functions were added by temperature deviation and air flow. The power plant is being commercially-operated normally by improved control logics and It is expected that this improved controls help the efficiency improvement and safe operation of plant.
Human-Livestock Classifier by Using Fuzzy Bayesian Algorithm
Oh, Myung-Jae ; Joo, Young-Hoon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1941~1945
DOI : 10.5370/KIEE.2011.60.10.1941
In this paper, we propose a real-time classifier to distinguish humans from livestock by using the spatial integral. The image-difference method and the Expectation Maximization are used to reduce noises in input image. A histogram analysis based on Simulated Annealing and the fuzzy-Bayesian algorithm are used to classify human and livestock. Finally, the experiment results show the validity of the proposed method.
Input Device of Non-Touch Screen Using Vision
Seo, Hyo-Dong ; Joo, Young-Hoon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1946~1950
DOI : 10.5370/KIEE.2011.60.10.1946
This paper deals with an input device without the touch. The existing touch screens have some problems such as the week durability by frequent contact and the high cost by complex hardware configuration. In this paper, a non-touch input device is proposed to overcome these problems. The proposed method uses a skin color generated by the HCbCr color model and a hand region obtained by the labeling technique. In Addition, the skeleton model is employed to improve the recognition performance of the hand motion. Finally, the experiment results show the applicability of the proposed method.
A Selection Method of Optimal Digital Low-pass Differentiator for Spike Detection of Surface Motor Unit Action Potential
Lee, Jin ; Kim, Sung-Hwan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1951~1958
DOI : 10.5370/KIEE.2011.60.10.1951
The objective of this study is to analyze the performance of digital low-pass differentiators(LPD) and then to provide a method to select effective LPD filter, for detecting spikes of surface motor unit action potentials(MUAP). The successful spike detection of MUAPs is a first important step for EMG signal decomposition. The performances of simple and weighted LPD(SLPD and WLPD) filters are analyzed based on different filter lengths and varying MUAPs from simulated surface EMG signals. The SNR improving coefficient and effective MUAP duration range from the analysis results can be used to select proper LPD filters under the varying conditions of surface EMG.
Angular Displacement Measurement Using Optical Sensor
Jung, Gu-In ; Kim, Ji-Sun ; Hur, Dong-Hun ; Yu, Hwan-Dong ; Lim, Sung-Hwan ; Choi, Ju-Hyeon ; Lee, Jeong-Hwan ; Eom, Gwang-Moon ; Jun, Jae-Hoon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1959~1965
DOI : 10.5370/KIEE.2011.60.10.1959
Measuring the movement of joint angle of human body is very important clinically. Human joint angle displacement can be used to evaluate the degree of disease and disability. Also, we can determine the rehabilitation process with angular information. Conventional methods for measuring angular displacement are many weakness. The purpose of this study is to overcome the limitations of existing equipments by using optical method. For this reason, optical sensor system was used to correlate detected light signal with joint angle. Experimental results of the applied joint model in this study showed that joint angular displacement can be measured by optical signals. The suggested method is simple, durable, small, lightweight, convenient, and cost effective.
Surface and Component Analysis of Deteriorated ACSR due to a Flame
Kim, Young-Dal ; Shim, Jae-Myung ; Park, Keun-Seok ; Jeong, Yun-Mi ; Kim, Jae-Kwang ; Byun, Jeong-Seop ; Lee, Dae-Dong ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1966~1971
DOI : 10.5370/KIEE.2011.60.10.1966
Generally, the characteristics of the conductor that was affected by forest fire can be analyzed only when the forest fire is accurately modeled and its effect is identified. Few studies have been conducted with a forest fire model for transmission lines, and no results of the examination of the actual test specimens that were exposed to forest fire have been reported. As the deterioration characteristics of a forest fire are difficult to analyze in the actual field, an environment that was similar to that in the field was used in this study. Deterioration was deposited on a wire using an artificial flame experiment device, to analysis the temperature, surface and component characteristics. It seems that this analysis data in this study can be used as the basic data for the database that can be utilized to analyze wires exposed to forest fire and deterioration and to predict the ACSR wire refurnishment life.
Water Absorption Sensor of Generator Stator Bar Insulation using Cross Capacitance
Bae, Yong-Chae ; Kim, Hee-Soo ; Lee, Doo-Young ; Lee, Wook-Ryun ; Lee, Rae-Deok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1972~1977
DOI : 10.5370/KIEE.2011.60.10.1972
The mechanical integrity of generator stator windings is one of the critical point because the electric power is generated and conducted to power system through these windings. To cool down the heat emitted from generator winding during its operation, a majority of generators use de-mineralized water characterized by high cooling efficiency. Contrary to such the excellent cooling efficiency, however, the damaged bar insulations attributed to the absorption of cooling water in the generator stator winding lead to highly time- and cost consuming efforts as well as to service deterioration due to unexpected forced outage of generator. It is described that the new design of water absorption sensor using cross capacitance for generator in power plant in order to increase the reliability of water absorption diagnostics for generator stator bar insulation.
The Characteristic of Control Response of BLDC using a Fuzzy PI Controller
Yoon, Yong-Ho ; Kim, Jae-Moon ; Kim, Duk-Heon ; Won, Chung-Yuen ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1978~1983
DOI : 10.5370/KIEE.2011.60.10.1978
BLDC motor is used in a wide variety of industrial and servo applications. Its features and advantages mainly consist in high value of torque/inertia ratio, high efficiency with speed range and high dynamic performance. This paper deals with the speed control of a trapezoidal type brushless DC motor using Fuzzy PI controller. The conventional PI controller has been widely used in industrial applications. If we select a optimal PI control gain, the PI controller shows very good control performance. But it is very difficult to find the optimal PI control gain. Fuzzy control does not need any model of plant and is basically adaptive and gives robust performance for plant parameter variation. Therefore the combinations of conventional PI controller and fuzzy controller seem to be very effective. This paper deals with PI controller with 4-rule based fuzzy controller. The proposed fuzzy PI controller increases the control performance of the conventional PI controller. Simulation and experimental results show that fuzzy PI controller has a good robustness regarding the improper tuned PI controller.
Placement Standard Research of Auxiliary Probes when Measuring Ground Impedance
Kim, Dong-Woo ; Gil, Hyoung-Jun ; Kim, Dong-Ook ; Lee, Ki-Yeon ; Moon, Hyun-Wook ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 10, 2011, Pages 1984~1991
DOI : 10.5370/KIEE.2011.60.10.1984
Among ground impedance measurement methods, the fall-of-potential method is the most thorough and reliable method. In the fall-of-potential method, ground electrode and auxiliary probes are placed in a straight line, and then, auxiliary potential probe is moved away from the ground electrode. The point at which plotted resistance curve flattens out is taken as right position of auxiliary potential probe. However, in some cases, it is hard to place ground electrode and auxiliary probes in a straight line. Therefore, we provided alternative placement method in this research. The method can be easily applicable to placing auxiliary probes. Also, this paper analyzed and compared ground impedance measurement standards of large grounding systems. Based on the analysis, practical measurement method using an earth tester was proposed. The proposed methods presented in this paper will be useful when determining locations of auxiliary probes in alternative positions, and the methods can be applied practically and easily.