• JOURNAL OF ELECTRICAL WORLD
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• no.12 s.96
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• pp.86-92
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• 1984

최근의 전자계산기, 각종 제어장치 또는 컬러TV등 전자기기의 보급에 따라 공급전압의 고도의 안전성, 즉 전력의 질적 향상에 대한 요구는 더욱 높아지고 있다. 한편 전압변동 발생원인 아크로, 암정기 및 용접기 등은 합리화, 생산성의 향상을 위해 대형화됨에 따라 공장내 뿐만 아니라 일반 전력계통에 전압변동장해를 야기하는 경우가 많아지고 있다. 이같은 전압변동은 조명에 플리커가 발생하여 인간의 눈에 불쾌감을 주거나 각종 전기기기의 오동작이나 정지 등을 야기하여 생산, 연구, 의료관계에 악영향을 미친다. 여기서 전압변동이 전기기기에 미치는 영향과 대책에 대하여 해설하기로 한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.132-139
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• 2004

Unsymmetrical faults are classified into single line-to-ground faults, line-to-line faults, or double line-to-ground faults in receiving and distribution power systems. Many of overhead distribution-line faults are single line-to-ground faults, and lightning surge arresters are stressed by system frequency overvoltages due to unsymmetrical faults. In this work, the unsymmetrical faults in receiving and distribution systems were experimentally simulated, and the characteristics of total leakage current flowing through lightning surge arresters due to various unsymmetrical faults were investigated. As a result, a little variations of the leakage current flowing through Zinc oxide (ZnO) surge arresters in the range of $\pm$10[%] voltage regulations were observed. It could be concluded that the unsymmetrical faults have no effect on the long-term life performance of ZnO surge arresters in effective grounding systems. On the other hand, the magnitude of the leakage current flowing through ZnO surge arrester elements under single line-to-ground faults was more than 140 times as compared with that under normal operating voltages in ineffective grounding systems. But abnormal voltages caused by line-to-line faults and double line-to-ground faults have a little effect on total leakage current of ZnO surge arrester elements.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.95-104
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• 2003

The electric traction systems are quite differ from general power systems which is single-phase and heavy load. Therefore, there are inevitably power quality problems such as steady state or transient voltage drop, voltage imbalance and harmonic distortion. Among these problems, since steady-state volatge drop is the one of most important factor in electric power quality, many researches about on the compensation of volatge drop by using SVC(Static Var Compensator) and/or STACOM(Static Compensator) have been studied and proposed Also, it is expected that transient voltage drop(voltage sag) could affect the control and safety of high speed traction load. In this paper, voltage sag compensation of AT(Auto Transformer) feeding system are studied The detailed transient models of utility source, scott transformer, AT, and traction load are estabilished. The application of DVR(Dynamic Voltage Restorer) in electric traction system is proposed to compensate the voltage sag of traction network which is occured by the fault of utility source. It can be shown that application of the DVR in electric traction system is very useful to compensate the volatge sag from the result of related simulation works.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.71-79
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• 2008

High voltage distribution lines in the electric railway system placed according track with communication lines and signal equipments. Case of the over head lines is occurrence the many fault because lightning, rainstorm, damage from the sea wind and so on. According this fault caused protection device to wrong operation. One line ground fault that occurs most frequently in railway high voltage distribution lines and sort of faults is line short, three line ground breaking of a wire, and so on. For this reason we need precise maintenance for prevent of the faults. The most important is early detection and fast restoration in time of fault for a safety transit. In order to develop an advanced fault location device for 22.9[kV] distribution power network in electric railway system this paper deals with new fault locating algorithm using flow technique which enable to determine the location of the fault accurately. To demonstrate its superiorities, the case studies with the algorithm and the fault analysis using PSCAD/EMTDC (Power System Computer Aided Design/Electro Magnetic Transients DC Analysis Program) were carried out with the models of direct-grounded 22.9[kV] distribution network which is supposed to be the grounding method for electric railway system in Korea.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.3
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• pp.56-63
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• 1999

In power system, substation facilities have become too complex and large according to extended power system. Also, some facilities becorre old and often break down unexpectedly. In order to improve the sectrity of transformer out of substation facilities, the development of diagnosis technique to transformer is very needed. In this paper, we developed a method to be analysis the origin and degree of aging by KSOM based on the dissolved gases in power transfonrer. KSOM can do topological mapping for the multi-dimensional pattern based on the dissolved gases to two dimensional plane. And potential possibility and degree of aging for nonna1 transfonrer are presented using the proposed quantitative criterion. Furtherrrore, the aging process of transfonrer is analyzed based on the proposed criterion to special transfonrer. To demonstrate the validity of peoposed method, case study is performed and its results are presented.sented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.6
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• pp.15-19
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• 2001

This paper presents an modelling and analysis of SSSC and UPFC in static analysis of power systems. SSSC is used to control active power flow in transmission lines by controlling the phase angle of the injected voltage source which is in rectangular to the line current. UPEC is used to control the magnitude and phase of the injected voltage sources which are connected both in series and in parallel with the transmission line to control power flow and bus voltage. To compare the effect of SSSC and UPFC in power system static analysis, the PSS/E simulation program is used. As the FACTS device model such as SSSC and UPFC is not provided in PSS/E yet, an equivalent load model is used. This procedure is implemented by IPLAN which is an external macro program of PSS/E. The simulation results show that UPFC is more effective to improve bus voltage than SSSC in power system static analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.5
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• pp.120-125
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• 2007

Burning the fossil fuel in the thermal power plants causes green house gas emission. Monitoring of CO2 emission of the thermal power plants is growing more important because the amount produced by them is more than 20 percent of national total emission. This paper proposes a method to calculate the amount of the CO2 emission w.r.t. generator[MW] output using the input-output coefficients of the thermal power plants. The power flow computation together with the CO2 emission calculation are demonstrated in a sample power system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.130-138
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• 2008

The tendency of lightning surge to propagate is a eared variously depend on the power system and subject equipment of protection. However, looking into the subject equipment with the lightning surge, the invasion route of lightning surge can be divided in between the two lines of power, between the power line and the ground, the power line and the PE conductor, between the neutral line and the ground and the like. In addition, in the event of the communication equipment, there exists the route of lightning surge incoming from between the communication lines, the communication line and the ground in addition to the power lines. In this study, the tendency of propagation of lightning surge penetrated on to the subject equipment is analyzed through the empirical experiment in accordance with the ground method by using the independent ground, common ground and bypass arrester ground for safety improvement in power lines.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.85-91
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• 2009

This paper proposes a simulation method of the internal winding fault to calculate the short-circuit current, electromagnetic force and vibration mode in a distribution power transformer by using FEM program(FLUX2D) and analytic algorithm. A usage of the Transfer matrix method is also presented for the vibration mode analysis of the cable-type winding of power transformer. The equations of the winding are approximated by the series expansions of the distributed mass mode and Timoshenko's beam theory. The simulation examples are provided for the cable type winding of the transformer(22.9[kV]/220[V], 1,000[kVA]) to verify the method. The proposed Transfer Matrix Method is also verified by the ANSYS program for the vibration mode of the transformer winding. The method presented may serve as one of the useful tools in the electromagnetic force and vibration analysis of the transformer winding under the short circuit condition.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.2
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• pp.9-15
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• 2010

Grounding insures a reference potential point for electric devices and also provides a law resistance path for fault or transient currents in the earth. The grounding impedance as a function of frequency is necessary for determining its performance since fault or transient currents could contain a wide range of frequencies. A concrete rod electrode is one of the commonly used grounding electrodes in electric distribution systems. In this paper, the grounding impedance of concrete rods has been measured in frequency raging from 60[Hz] up to 100[kHz] and an equivalent model of the grounding impedance is identified from the measured values. The grounding impedance under study when a typical lightning surge is injected into the grounding system was simulated numerically and graphically through the use of the EDSA software program.