• Title/Summary/Keyword: harmonic generation

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A Study of High Power Microwave Output by K-band Waveguide (K-band 도파관을 이용한 대전력 마이크로파 출력장치 연구)

  • Kim, Won-Sop
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.4
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    • pp.588-591
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    • 2009

  • We had experimental studies of microwave output generator. We experimented with a corrugate-shped K-band slow wave guide in the backward wave oscillator. It generated output 표 interaction between electron beam's generation and magnetic field. We estimated oscillation frequency at 24GHz by changing propagation velocity and group velocity. We identified movement by second harmonic of Cherencov interaction and slow cyclotron mode. In our study we achieved oscillation stabilization, generation of long pulse, improvement of oscillation efficiency and output.

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UV ultra-short laser pulse generation and amplification (UV 극초단 레이저 펄스의 발생과 증폭)

  • 이영우
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.324-326
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    • 2004

  • We have obtained ultra-short pulses with a wavelength of 616 nm from a Distributed Feedback Dye Laser pumped by excimer laser. Using the second harmonic generation, we obtained ultra-short pulse at 308nm in ultraviolet region and also performed amplification in 3 stages of XeCl amplifiers.

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Analysis of Reduction Effect of Three Harmonic Currents by Zigzag Wiring of Single Phase Transformer (단상 변압기 지그재그 결선에 의한 3고조파 전류 저감 효과 분석)

  • Kim, Jong-Gyeum;Kim, Ji-Myeong
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.66 no.3
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    • pp.99-104
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    • 2017

  • The three-phase four-wire power distribution system can be used to supply power to single-phase and three-phase loads at the same time. There are linear loads and nonlinear loads as single-phase loads connected to each phase. The nonlinear load generates a harmonic current during the power energy conversion process. In particular, the single-phase nonlinear load has a higher proportion of generation of the third harmonic current than the harmonics of the other orders. In a three-phase four-wire system, the third harmonic current flows through the neutral wire to the power supply side, affecting the power supply side and the line. Furthermore, the magnitude of the current flowing in the neutral line can be higher than the current flowing in the individual phase. If the neutral current is higher than the phase current, the breaker may be blocked. Therefore, it is necessary to reduce the amount of current flowing in the neutral line by harmonics. There is a method of zigzag connecting a single phase transformer by a method of reducing 3 harmonic current. In this study, the method of reducing the magnitude of the three harmonic currents flowing through the zigzag wire by comparing the polarity and the negative polarity characteristics of the single phase transformer was compared through measurement and simulation.

  • https://doi.org/10.5370/KIEEP.2017.66.3.099 인용 PDF KSCI

An Enhanced Instantaneous Circulating Current Control for Reactive Power and Harmonic Load Sharing in Islanded Microgrids

  • Lorzadeh, Iman;Abyaneh, Hossein Askarian;Savaghebi, Mehdi;Lorzadeh, Omid;Bakhshai, Alireza;Guerrero, Josep M.
    • Journal of Power Electronics
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    • v.17 no.6
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    • pp.1658-1671
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    • 2017

  • To address the inaccurate load demand sharing problems among parallel inverter-interfaced voltage-controlled distributed generation (DG) units in islanded microgrids (MGs) with different DG power ratings and mismatched feeder impedances, an enhanced voltage control scheme based on the active compensation of circulating voltage drops is proposed in this paper. Using the proposed strategy, reactive power and harmonic currents are shared accurately and proportionally without knowledge of the feeder impedances. Since the proposed local controller consists of two well-separated fundamental and harmonic voltage control branches, the reactive power and harmonic currents can be independently shared without having a remarkable effect on the amplitude or quality of the DGs voltage, even if nonlinear (harmonic) loads are directly connected at the output terminals of the units. In addition, accurate load sharing can also be attained when the plug-and-play performance of DGs and various loading conditions are applied to MGs. The effects of communication failures and latency on the performance of the proposed strategy are also explored. The design process of the proposed control system is presented in detail and comprehensive simulation studies on a three-phase MG are provided to validate the effectiveness of the proposed control method.

  • https://doi.org/10.6113/JPE.2017.17.6.1658 인용 PDF KSCI