• Title, Summary, Keyword: Harmonic distortion

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On-line Harmonic Distortion Index for Power Quality Assessment (온라인 고조파 해석 지수의 개발)

  • Jang, Gil-Soo;Song, Hwa-Chang;Lee, Byong-Jun
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.50 no.8
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    • pp.373-378
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    • 2001
  • This paper introduces a new online index to quantify the harmonic distortion. The proposed index based on VI product can represent the harmonic distortion of both voltage and current, and it includes the effect of interharmonic distortion. Also, the new index is suitable to online harmonic distortion evaluation since it only requires the r.m.s. (root mean square) value and fundamental frequency value of the signals. Case studies are presented to show the availability of the proposed index using the comparison with the THD (Total Harmonic Distortion).

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Carrier based SVPWM Method for Multi-Level System Considering Harmonic Distortion Factor

  • Lee, Yo-Han;Kim, Dong-Hyun;Hyun, Dong-Seok
    • Journal of Power Electronics
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    • v.1 no.1
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    • pp.26-35
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    • 2001
  • In most inverter/converter applications SVPWM method is a preferred approach since it shows good characteristics in linear modulation range and waveform quality. In this paper, we propose a new carrier based SVPWM method for multi-level system, First, we survey the conventional carrier based SVPWM method, and investigate the problem of the conventional one for the multi-level system with the focus on the switching frequency harmonic flux trajectories. Finally, we propose a new carrier based SVPWM method that can reduce harmonic distortion. Simulation and experimental results are given for verification of the proposed SVPWM method.

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Harmonic Distortion Control for Electric Propulsion (전기 추진선을 위한 고조파 제어 사례 연구)

  • Kim, Ju-Wan;Lee, Choong-Yeol;Seo, Kun-Kyung
    • Special Issue of the Society of Naval Architects of Korea
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    • pp.38-45
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    • 2008
  • The application of the electric propulsion system to the vessels has recently become common due to the latest technology for controlling the electric motors with variable speed. However it has been found that harmonic distortion exists in the electric propulsion system, which consists of an electric motor, a converter and an inverter, and this harmonic distortion has a harmful effect on the system. In this paper, the definition of the harmonic distortion and problems caused by the harmonic distortion in the electric propulsion of the vessels are introduced and the practical solutions for the problems are investigated.

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Controller design for compensation of nonlinear harmonic distortion in direct-radiator loudspeakers (직접 방사형 스피커의 비선형 고조파 왜곡 보상 제어기의 설계)

  • 김윤선;박영진
    • 제어로봇시스템학회:학술대회논문집
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    • pp.399-402
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    • 1996
  • The electrodynamic loudspeakers should have a wide dynamic range to reproduce various sound levels. When the input signal is small, the radiated sound from the loudspeaker is not so much distorted. However, for large input signal with low frequency component the radiated sound is significantly distorted due to the nonlinearities of the loudspeaker. The suspension, damping, and magnetic flux of loudspeaker are the main sources of the nonlinearity. Such electromechanical parameters related to harmonic distortion have been represented by a polynomial model for diaphragm displacement, while each of the polynomial coefficient is evaluated by using the principle of harmonic balance experimentally. Based on the polynomial model, we designed a compensator for nonlinear harmonic distortion of direct radiator loudspeaker. Than observer is used to estimate the displacement of the loudspeaker diaphragm, which is rather difficult to measure directly in the conventional setting. The usefulness of the designed compensator is demonstrated by numerical simulations. Simulation results show about 30db decrease at the second and third higher harmonic distortions. We carry out an experiment on speaker to verify designed controller and nonlinear observer.

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Estimation of Harmonic Sources in a Power System using Recursive Least-Squares Technique (회귀 최소 자승법을 이용한 고조파 발생원 추정 연구)

  • Han, Jong-Hoon;Lee, Key-Byung;Park, Chang-Hyun;Jang, Gil-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.9
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    • pp.1639-1645
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    • 2011
  • A technique to allocate responsibilities among the interested parties in electric power system with harmonic voltage distortion at the point of common coupling (PCC) has been presented. The recursive least-squares technique has been used to estimate the parameters of the Thevenin equivalent load model. The validity of the technique has been verified using a simulation which considered the voltage waveform distortion at the PCC between the utility and two industrial consumers. With the estimated data from the measured voltage and current waveform at the PCC, the individual contributions to the distortion of voltage waveform at an interested harmonic frequency have been calculated and could provide a flexible solution to identify the source of harmonic pollution in distribution systems.

Harmonic Distortion Level of Special loads and Method of Harmonic Distortion Management (특수수용가의 고조파전압 왜형현황과 고조파 관리 방안)

  • Hwang, Chi-U;Seung, Ki-Cheul
    • Proceedings of the KIEE Conference
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    • pp.875-877
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    • 1997
  • Due to the development of electric energy conversion technology and need for energy saving most of the electric machinery and equipments are using power semiconductor switching elements, On the contrary semiconductor switching device is more sensitive to the voltage instability and voltage distortion. In order to manage the voltage distortion following foundation should be settled down in advance. First, reasonable and objective technical guidelines should be established. Second, monitoring network for power quality should be operated. In this paper measurement results of the harmonic distortion of the special loads are given and method for harmonic pollution management is discussed.

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Comparison of the harmonic reduction by using harmonic passive fitters and technique of intervene firing method at the pulse of the 6-pulse phase controlled converter.

  • Wongtongdee, Surached W.;Laohasongkram, Pipat
    • 제어로봇시스템학회:학술대회논문집
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    • pp.782-785
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    • 2005
  • This article introduces technique to reduce harmonic by using the $5^{th}$ and $7^{th}$ harmonic tune filter and line reactor in the comparison to the technique of intervening firing method at the pulse of the 6-pulse phase-controlled converter in every 1/6 period. The design of the technique introduced in this article is to reduce the harmonic distortion of the current and the voltage resulted from three-phase thyristor phase-controlled converter. The waveform obtained from the experiment was analyzed on the spectrum of the current, voltage and the total harmonic distortion. The double firing method causes zero vectors of output voltage and input current. Designing the mechanism of the converter based on the idea of Park Vector Theory, the number of harmonic distortion in the intervening firing method were compared to those in normal firing method.

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The Control Technique of 3 Phase NPC PWM Inverter to control fixed Total Harmonic Distortion (종합 고조파 왜율 일정 제어를 위한 삼상 NPC PWM 인버어터의 제어 기법)

  • Song, Eon-Bin
    • Proceedings of the KIEE Conference
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    • pp.565-567
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    • 1994
  • This paper presents a software based NPC PWM inverter control technique to eliminate the harmonics in the output waveforms of inverter. The proposed control technique is able to keep down total harmonic distortion and significantly improve the performance of the inverter. In the control node where the frequency ratio is 36 and the modulation index is $1.2\sim2.0$, the proposed inverter has been operated wi thin 5% Total Harmonic Distortion.

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A Study of Reducing Harmonics using Passive Filter in Distribution System (배전계통에서 수동필터를 이용한 고조파 저감에 관한 연구)

  • Jun, Fu;Park, Keon-Woo;Kim, Chul-Hwan
    • Proceedings of the KIEE Conference
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    • pp.547-548
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    • 2007
  • Recently, harmonic distortion becomes a very important problem of power quality in distribution system. This paper discusses the procedure of passive filter design, and presents the harmonic study of reducing harmonic distortion in distribution system using passive filters.

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Theoretical Analysis of Second Harmonic Distortion for Threshold Current in DH Laser Diode (DH Laser Diode의 Threshold Current에 대한 2차 고조파 왜곡의 이론적 해석)

  • 김성일;박한규
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.17 no.2
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    • pp.10-14
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    • 1980
  • In this paper, the second harmonic distortion of the DH L.D. is analyzed using dynamic and static rate equations. In this analysis the modulation current Jm is changed by varang the iinjection current with the relation of where m stands for modulation index. It is showed that relative harmonic distortion ( ) has a peak exactly at the threshold current. It is also confirmed that this method is simople and more accurate than previously reported methods in the decision of the threshold current.

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