• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.510-512
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• 2000

This paper describes the voltage induced at neutral line and the proper location of lightning arrester in combined 22.9 kV class distribution line jointed overhead line and cable each other Modeling is established in ATP Draw to perform simulation. Simulated distribution line at this paper consists of distribution line 4.2km and underground distribution line 2km. Overvoltage and induced voltage are analyzed at several point of combined line. Analysis results was compared to select the best point to install arrester. Such analysis technology will be applied to obtaining capacity and location of arrester in the similar combined distribution line.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.205-207
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• 2005

In this paper, the Point of Common Coupling (PCC) is selected to analyze harmonic characteristic of distribution system by IEC 61000 - 3 - 6 in Electromagnetic Compatibility(EMC). Harmonic voltage and current were measured at the PCC of real distribution system. Harmonic distribution, nonlinear load component and Total Harmonic Distortion(THD) were verified by measurement. The effective and accurate modelling of real distribution system were proved through a analysis of harmonic impedance, voltage and current in steady-state. Harmonic transfer characteristic in distribution system were summarized and investigated through a analysis of harmonic voltage and harmonic current in harmonic current source.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권5호
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• pp.391-395
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• 1999

In this paper, we have obtained the Electron Energy Distribution Function(EEDF) in plasma by using two differentiators and investigated the EEDFs by sawtooth and triangle waveform voltages with the working pressures and the positions of single probe. It is found that as the working pressure is decreased, the EEDFs approach to theMaxwellian distribution independent of the waveforms of probe voltage. On the otherhand, as the position of probe is moved from the center of the plasma to its edge, the EEDF of sawtooth waveform probe voltage approaches to the Maxwellian distribution, but the EEDF of triangle waveform probe voltage deviates from the Maxwellian distribution.

• 조명전기설비학회논문지
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• 제27권11호
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• pp.69-75
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• 2013

This paper proposes a new algorithm for the optimal placement of a step voltage regulator(SVR) in distribution system with Distributed Generators(DG) using a Particle Swarm Optimization(PSO). The objective function of this algorithm is to find optimal placement for minimum loss while maintaining each node voltage fluctuations within upper and lower limits. In the objective function of proposed algorithm, the deviations to reference voltage and the distribution loss are considered. To verify effectiveness of the proposed method, simulation is implemented using MATLAB.

• KIEE International Transactions on Power Engineering
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• 제3A권4호
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• pp.206-213
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• 2003

The main purpose of this paper is to present a simulation model for assessing the impacts of a variable speed wind turbine (VSWT) on the distribution network and perform a simulation analysis of voltage profiles along the wind turbine installed feeder using the presented model. The modeled wind energy conversion system consists of a fixed pitch wind turbine, a synchronous generator, a rectifier and a voltage source inverter (VSI). Detailed study on the voltage impacts of a variable speed wind turbine is conducted in terms of steady state and dynamic behaviors. Various capacities and different modes of variable speed wind turbines are simulated and investigated. Case studies demonstrate how feeder voltages are influenced by capacity and control modes of wind turbines and changes in wind speed under different network conditions. Modeling and simulation analysis is based on PSCAD/EMTDC a software package.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.156-162
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• 2013

This paper measures the hot spot temperatures in a single-phase, 154 kV, 15/20 MVA power transformer filled with natural ester fluid using optical fiber sensors and compares them with those calculated by conventional heat run tests. A total of 14 optical fiber sensors were installed on the high-voltage and low-voltage windings to measure the hot spot temperatures. In addition, three thermocouples were installed in the transformer to measure the temperature distribution during the heat run tests. In the low-voltage winding, the hot spot temperature was $108.4^{\circ}C$, calculated by the conventional heat run test. However, the hot spot temperature measured using the optical fiber sensor was $129.4^{\circ}C$ between turns 2 and 3 on the upper side of the low-voltage winding. Therefore, the hot spot temperature of the low-voltage winding measured using the optical fiber sensor was $21.0^{\circ}C$ higher than that calculated by the conventional heat run test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.888-890
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• 2003

In the distribution networks, it is required to develop compact and smart current and voltage sensors for compact and digital switchgears. The sensor developed newly adopt the priciple of rogowski coil for current sensing and resistive voltage divider for voltage sensing. The sensing characteristics and reliabilities were improved compared to conventional ones. In the near future, these voltage and current sensing apparatus will be widely used with electronic protection units for the distribution switchgear.

• 한국산학기술학회논문지
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• 제21권11호
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• pp.746-752
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• 2020

환경문제가 세계적으로 심각하게 다뤄지면서 우리나라도 태양광발전 설비가 급속도로 증가하였다. 특히 소용량 태양광발전을 저압배전으로 연계하는 계통에서 인버터 출력단의 전압상승으로 인하여 저압배전계통 품질저하 및 부하설비에 악영향을 주고 있다. 또한 과전압에 의한 인버터 가동중지로 인하여 발전소의 경제적 손실을 줄 수 있다. 본 논문에서는 저압배전계통 연계에 따른 태양광 인버터 출력단 전압 상승 해결방안을 연구 하였다. 첫째, 역률제어 및 능동전압제어 인버터를 사용하여 무효전력을 제어하면 출력단 전압이 230.91V에서 208.99V로 단자전압 비율이 약 10%가 내려갔다. 둘째, 배전전압용 변압기 2차 Tap을 조정하면 약 15V의 전압조정이 가능하지만, 한전배전규정전압이 220±13V의 범위가 벗어나지 않는 한 Tap을 조정해 주지 않는 문제점이 있다. 셋째, 인버터의 댓 수를 제한하면 인버터 과전압 범위 안에서 인버터를 기동할 수 있다. 넷째, 단상이 아닌 삼상으로 연계하면 전압이 분배되어 전압상승을 방지 할 수 있다. 4가지 중 현장 적용이 용이한 것은 역률제어 및 능동전압제어 인버터를 사용하는 것임을 확인하였다.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.176-183
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• 2014

Three-phase four-wire distribution systems are used for both three-phase three-wire loads and single-phase two-wire consumer appliances in South Korea, Myanmar and other countries. Unbalanced load conditions frequently occur in these distribution systems. These unbalanced load conditions cause unbalanced voltages for three-phase and single-phase loads, and increase the loss in the distribution transformer. In this paper, we propose constant DC capacitor voltage control based strategy for the active load balancer (ALB) in the three-phase four-wire distribution systems. Constant DC capacitor voltage control is always used in active power line conditioners. The proposed control strategy does not require any computation blocks of the active and reactive currents on the distribution systems. Balanced source-side currents with a unity power factor are obtained without any calculation block of the unbalanced active and reactive components on the load side. The basic principle of the constant DC capacitor voltage control based strategy for the ALB is discussed in detail and then confirmed by both digital computer simulations using PSIM software and prototype experimental model. Simulation and experimental results demonstrate that the proposed control strategy for the ALB can balance the source currents with a unity power factor in the three-phase four-wire distribution systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.223_224
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• 2009

This paper investigates a normal induced voltage according to earth resistivity from distribution lines using calculation method of the normal induced voltage on telecommunication line. The induced voltage according to earth resistivity from distribution lines is verified by vector analysis and EMTP(Electro-Magnetic Transients Program).