• Title, Summary, Keyword: Harmonic analysis

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A Study on Harmonics Analysis and Modelling for Distribution System (배전 시스템의 고조파 분석 및 모델링에 관한 연구)

  • Wang, Yong-Peel;Jeong, Jong-Won;Jeong, Dong-Il
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.3
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    • pp.62-68
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    • 2007
  • The increasing use of power electronic equipment in distribution system has been the reason for the greater concern about a harmonic in recent time. Therefore, it is necessary for measurement and modelling to analyze a harmonic level and a transfer characteristic in distribution system. In this paper, the Point of Common Coupling (PCC) is selected to analyze harmonic characteristic of distribution system by IEC 61000-3-6. Harmonic voltage and orient were measured at the PCC of real distribution system Harmonic distribution, nonlinear load component and Total Harmonic Distortion(THD) were verified. The effective and accurate modelling of real distribution system were proved through a analysis of harmonic impedance, voltage and current under steady-state. Harmonic transfer characteristic were investigated through a analysis of harmonic voltage and current under harmonic current source.

Novel Third Harmonic Current Injection Technique for Harmonic Reduction of Controlled Converters

  • Eltamaly, Ali M.
    • Journal of Power Electronics
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    • v.12 no.6
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    • pp.925-934
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    • 2012
  • Three-phase controlled converters have many applications in the utility interfacing of renewable energy sources and adjustable speed drives as a rectifier or inverter. The utility line currents of these converters have a high harmonic distortion, which is more than the harmonic standards. This paper introduces a new technique for circulating the third harmonic currents from the dc-link to the line currents to reduce their harmonic contents. The proposed system uses a single-phase PWM converter to control the angle and amplitude of the injection current for each of the firing angle of a three-phase converter. A detailed analysis is introduced to achieve a relationship between the firing angle of the three-phase controlled converter and the power angle of the PWM converter. In addition, a detailed design for the other injection path components is introduced. A simulation and experimental work is introduced to prove the mathematical derivations. Analysis, simulation and experimental results prove the superiority of the proposed technique.

A Case of the Distribution Power System PQMS Construction & Harmonic Voltage Analysis (배전계통 PQM 시스템 구축 및 고조파전압 분석사례)

  • Park, Yong-Up;Lee, Keon-Hang
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.9
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    • pp.108-117
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    • 2010
  • The main contents of this paper are the PQM system construction case and distribution system harmonic voltage analysis. The PQM system has constructed by KEPCO in order to investigate power quality of distribution power system for new power quality standard of KEPCO. In result, we have confirmed that voltage harmonic measurement value of the high voltage contract customer 8 households is suitable the KEPCO harmonic standard tentative plan. And the voltage harmonic value of distribution line end side is not always more high than source side by harmonic current offset effect. In the future, acquired data by season, region, load from the PQMS will be used on the resonable harmonic standard enactment in KEPCO.

Analysis of Kinematics and Tooth Profile in Harmonic Drive (주속식 감속기의 운동학 및 치형해석)

  • 전완주
    • Tribology and Lubricants
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    • v.4 no.2
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    • pp.60-67
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    • 1988
  • Conventional theory of gear mechanism can't be applied to analyze the harmonic drive due to specific movement of the teeth. This paper deals with an analysis of kinematics and geometry of the tooth engagement of a harmonic drive comprising circular spline, flexspline and wave generator. A theoretical new tooth profile of the flexspline in meshing internal rigid gear with involute profile is obtained. Characteristics of harmonic drive reducer are shown according to parameters such as deviation coefficient, deviation distance, addendum modification coefficient. As an example, the design of harmonic drive with 1:80 reduction ratio is presented.

Harmonic Analysis of a Modular Multilevel Converter Using Double Fourier Series

  • Quach, Ngoc-Thinh;Chae, Sang Heon;Ahn, Jin Hong;Kim, Eel-Hwan
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.298-306
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    • 2018
  • This paper presents a harmonic analysis of the modular multilevel converter (MMC) using a double Fourier series (DFS) algorithm. First, the application of DFS for harmonic calculation in the MMC is made by considering the effect of arm inductor. The analytical results are then confirmed by comparing with the simulation results of using the fast Fourier transform (FFT) algorithm. Finally, distribution of harmonics and total harmonic distortion (THD) in the MMC will be analyzed in three cases: harmonics versus number of levels of MMC, harmonics versus total switching frequency and harmonics versus modulation index. The simulation results are performed in the PSCAD/EMTDC simulation program in order to verify the analytical results obtained by Matlab programming.

A New Assessment for the Total Harmonic Contributions at the Point of Common Coupling

  • Han, Jong-Hoon;Lee, Kyebyung;Song, Chong Suk;Jang, Gilsoo;Byeon, Gilsung;Park, Chang-Hyun
    • Journal of Electrical Engineering and Technology
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    • v.9 no.1
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    • pp.6-14
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    • 2014
  • A new method to determine the total harmonic contributions of several customers and the utility at the point of common coupling is presented. The proposed method can quantify the individual harmonic impact of each suspicious harmonic source at the point of common coupling. The individual harmonic impact index is then used to assess the total harmonic contribution of each harmonic source. This index can be calculated by the results processed from instantaneous harmonic voltage and current phasor values. The results demonstrate the performance of the proposed method in terms of steady-state accuracy and response to time-varying operating conditions. The proposed index can be used for billing purposes to control harmonic distortion levels in power systems.

A Study on the Bicoherence Analysis of Visual Evoked Potential based on AR Model (AR 모델에 의한 견학 유발전위의 Bicoherence분석에 관한 연구)

  • 유병욱;정명진
    • Journal of Biomedical Engineering Research
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    • v.8 no.2
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    • pp.223-230
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    • 1987
  • In this paper the harmonic degrees between $\alpha$ wave and $\beta$ wave in visual evoked potential are analyzed by the bicoherence. The bicoherence analysis is based on an AR model which provides significantly better resolution than that of Fourier transform. The analysis results of visual evoked pope ntial are compared with the analysis results of background EEC. From the comparison results it is found that the harmonic degree of visual evoked potential is less than she harmonic degree of background EEG and the $\beta$ wave of visual evoke potential unlike the background EEC contains the non harmonic property of a wave more than the harmonic properity

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Influence of Different Frequency Harmonic Generated by Rectifier on High-speed Permanent Magnet Generator

  • Qiu, Hongbo;Wei, Yanqi;Yang, Cunxiang;Fan, Xiaobin
    • Journal of Electrical Engineering and Technology
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    • v.13 no.5
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    • pp.1956-1964
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    • 2018
  • Since the stator winding of High-Speed Permanent Magnet Generator (HSPMG) has few winding turns and low inductance value, it is more prone to be influenced by harmonic current. Moreover, the operation efficiency and the torque stability of HSPMG will be greatly influenced by harmonic current. Taking a 117 kW, 60 000 rpm HSPMG as an example, in order to analyze the effects of harmonic current on HSPMG in this paper, the 2-D finite element electromagnetic field model of the generator was established and the correctness of the model was verified by testing the generator prototype. Based on the model, the losses and torque of the generator under different frequency harmonic current were studied. The change rules of the losses and torque were found out. Based on the analysis of the influence of the harmonic phase angle on torque ripple, it is found that the torque ripple could be weakened through changing the harmonic phase angle. Through the analysis of eddy current density in rotor, the change mechanism of the rotor eddy current loss was revealed. These conclusions can contribute to reduce harmonic loss, prevent demagnetization fault and optimize torque ripple of HSPMG used in distributed power supply system.

Controllable Harmonic Generating Method for Harmonic Impedance Measurement of Traction Power Supply Systems Based on Phase Shifted PWM

  • Liu, Qiujiang;Wu, Mingli;Li, Jing;Zhang, Junqi
    • Journal of Power Electronics
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    • v.18 no.4
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    • pp.1140-1153
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    • 2018
  • The harmonic impedance characteristic of a traction power supply system (TPSS) is necessary for taking actions to suppress the high-order harmonic resonances caused by AC electric locomotives. This paper proposes a controllable harmonic generating method (CHGM) for measuring the TPSS harmonic impedance by injecting harmonic disturbances of different frequencies and amplitudes into the TPSS. This method applies phase shifted pulse-width modulation (PSPWM) and ensures that the undesired sideband harmonics can be negligible while the desired harmonic is both controllable and adjustable. Multiple harmonics can be emitted at the same time. The implementation of the method is also presented. Simulations are carried out to validate the performance of the proposed method. Finally, experimental results on a 5 H-bridge converters platform verified the effectiveness and feasibility of the proposed method.

Harmonic Generation and System Response Chartcteristics in Electrified Railway(II) - Focused on Measurement and Analysis - (전기철도에서의 고조파 발생과 계통응답특성(II) - 고조파 측정분석을 중심으로 -)

  • Oh Kwang-Hae;Lee Han-Min
    • Proceedings of the KSR Conference
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    • pp.499-504
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    • 2003
  • Harmonic current originating from electric locomotives can be magnified due to the impedance characteristics of power supply circuit and bring about various problems. That is, electromagnetic interference with communication lines, operational trouble in signaling, overheat and/or vibration in power capacitor, mis-operation in protection relay and so on. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. For these reasons, this study propose a new approach to model and to analyse traction power feeding system focused on system response to current and voltage harmonic(PART I ). Measurements of harmonics are also performed for railway power supply systems under normal operation. Spectrum and distortion analyses in measurement data are variously described in PART II

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