• 한국산학기술학회논문지
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• 제13권11호
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• pp.5397-5402
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• 2012

고조파와 관련한 전력품질저하로 발생하는 전기설비사고 및 경제적 손실은 증가하고 있다. 수동필터는 고조파 문제를 해결하는데 경제적이고 효과적이지만 많은 엔지니어들은 그들의 전력시스템과의 직병렬 공진 문제 및 고조파 증폭 문제로 인해 사용하기를 꺼려한다. 본 논문은 수동필터가 잘 설계될 경우 고조파 문제를 해결하는데 매우 유용하다는 것을 보여준다. 고조파 수동필터 설계의 방법과 과정을 서술하였다. 그리고 100HP DC 모터, 압출 기계, 에어 압력기 등과 같은 비선형 부하로 인해 고조파 문제를 갖는 계통에 적용할 수 있는 수동필터를 설계하였다. 제시된 설계 방법과 절차에 대한 검증을 실험을 통해 입증하였다.

• 전기학회논문지
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• 제60권2호
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• pp.279-284
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• 2011

Harmonic distortions in current waveform may cause significant problems in electric power system facility and operation. This paper presents an adaptive parameter estimation method to detect harmonic current components caused by nonlinear loads. In addition, a coordination strategy for multiple inverter-interfaced distributed generators to compensate the harmonic currents is discussed. The coordination strategy is realized by distributing the harmonic compensation participation index to individual distributed generators. The harmonic compensation participation index can be determined by the amount of remaining power generation capacity of each distributed generator. Simulation results based on switching-level inverter models show that the proposed harmonic detection method has good performance and the coordination strategy can improve harmonic problems efficiently.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2225_2226
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• 2009

An increasing of non-linear loads such as power electronic equipment in distribution systems is the reason for the greater concern about harmonics in recent time. A harmonic current and voltage in distribution systems can cause many problems such as malfunction of protective equipment. In this paper, Total Harmonic Distortion(THD) of voltage according to magnitudes and measurement locations of the non-linear loads was calculated and analyzed with Electro-Magnetic Transients Program(EMTP).

• 한국산업융합학회 논문집
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• 제4권4호
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• pp.379-386
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• 2001

The lower toughness or brittle materials for mechanical test lead to the additional requirement that applied displacements be controlled with high resolution. Biaxial tension and shear tester using stepper motor with harmonic driver is shown. The device had to be high resolution so that the crack initiation process of slow extension and steady growth could be examined, Grip plates were connected to a linear bearing and actuator. The actuators consisted of stepper motors with harmonic driver connected to pre-loaded ball screw and nut assemblies. The encoders and motor controllers were connected to a personal computer so that arbitrary displacements histories could he prescribed in normal and tangential directions. The linear bearings were used to react loads perpendicular to their axes while allowing low friction, parallel movement of the attached grips. Load cells measured the reactions normal and tangential. the loads measured the reactions were recorded by the computer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.840-841
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• 2008

Power capacitors are widely used to compensate the low power factor of the linear load and/or nonlinear load. Especially, nonlinear loads generates the harmonic current and it gives an undesirable effect on the power capacitors. In this paper, harmonic current from nonlinear load to the power capacitors is calculated by the computer simulation and it is compared with the experimental results.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.43-48
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• 2006

This paper presents a scheme on the characteristics of induction motor under the combination of linear & non-linear loads at the three phase 4-wire power distribution system. Under the combination operation of single & three phase load, voltage unbalance will be generated and current unbalance will be more severe by the dropped voltage quality. All power electronic converters used in different types of electronic systems can increase harmonic disturbances by injecting harmonic currents directly into the feeder grid of three phase 4-wire. Harmonic current may cause torque to decrease. Moors may also overheat or become noisy and torque oscillation in the rotor can lead to mechanical resonance and vibration.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.75-82
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• 2015

This paper presents a new technique for enhancing power quality by reducing harmonics in the neutral conductor. Three-Phase Four-Wire (3P4W) system is commonly used where single and three phase loads are connected to Point of Common Coupling (PCC). Due to unbalance loads, the 3P4W distribution system becomes unbalance and current flows in the neutral conductor. If loads are non-linear, then the harmonic content of current will flow in neutral conductor. The neutral current that may flow towards transformer neutral point is compensated by using a series active filter. In order to reduce the harmonic content, the series active filter is connected in series with the neutral conductor by which neutral and phase current harmonics are reduced significantly. In this paper, solar PV based inverter circuit is proposed for compensating neutral current harmonics. The simulation is carried out in MATLAB/SIMULINK and also an experimental setup is developed to verify the effectiveness of the proposed method.

• 조명전기설비학회논문지
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• 제20권1호
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• pp.91-99
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• 2006

규모가 큰 제철소는 전기로를 포함한 비선형 부하를 가지고 있고, 고조파 측정 결과 시간에 따라 변하는 고조파 파형이 관측 되었다. 부하 용량이 매우 크기 때문에 전력회사에 미치는 영향이 클 뿐만 아니라 이웃 수용가의 전력시스템에 주는 충격도 고려하여야 한다. 본 논문에서는 시간에 따라 변하는 고조파를 국제 기준인 IEEE 519와 IEC 61000-3-6에 의해 누적확률을 사용하여 평가하였다.

• Journal of Power Electronics
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• 제8권1호
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• pp.1-9
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• 2008

This paper presents the design and analysis of a new input AC current wave shaping AC-DC converter for cost effective harmonic mitigation under varying loads. The proposed converter consists of a delta-polygon connected autotransformer based twelve-pulse AC-DC converter and a small rating passive shunt filter tuned at $11^{th}$ harmonic frequency. The proposed AC-DC converter eliminates the most dominant $5^{th},\;7^{th}$ and $11^{th}$ harmonics and reduces higher order harmonics; thereby, resulting in an improved power quality at AC mains. Moreover, the design of the autotransformer is modified to make it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. To validate the proposed approach, various power quality indices are presented under varying loads. Experimental results obtained on the developed converter are given to validate the model and design of the proposed converter.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.236-241
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• 2011

An active trailing-edge flap blade named as Seoul National University Flap (SNUF) blade is designed for reducing helicopter vibratory loads and the relevant aeroacoustic noise. Unlike the conventional rotor control, which is restricted to 1/rev frequency, an active control device like the present trailing-edge flap is capable of actuating each individual blade at higher harmonic frequencies i.e., higher harmonic control (HHC) of rotor. The proposed blade is a small scale blade and rotates at higher RPM. The flap actuation components are located inside the blade and additional structures are included for reinforcement. Initially, the blade cross-section design is determined. The aerodynamic loads are predicted using a comprehensive rotorcraft analysis code. The structural integrity of the active blade is verified using a stress-strain recovery analysis.