• Title/Summary/Keyword: Harmonic

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The Development of Real-Time Harmonic Analysis Algorithm in Distribution Transformer (배전용 변압기의 실시간 고조파 분석 알고리즘 개발)

  • Park, Chul-Woo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.3
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    • pp.43-49
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    • 2013
  • Recently harmonics flowing into power system is increasing as the usage of semiconductor equipments and switching mode power equipments are increasing. Harmonics cause problems such as heat increasing and reduction in capacity of transformers, especially the harmonics flowing into a distribution transformer can lead to the lifetime reduction of transformer. In this paper, we are about to develop a device that can monitor harmonics in real-time as it is affixed to a distribution transformer. Unlike the existing expensive harmonic analysis device, a new harmonic analysis algorithm is proposed in order to implement low-cost equipment. The real-time harmonic analysis algorithm proposed in this paper allows implementation on low performance microcontrollers, thus it can monitor the harmonic in real-time as it is individually affixed to the transformer. Therefore, it would improve the reliability of the transformer and stable power system operation would be possible as it can prevent the transformer accidents in advance.

Harmonic Reduction of a Single-Switch Three-Phase Boost Rectifier using Harmonic-Injection Method (고조파 주입법에 의한 3상 부스트 정류기의 고조파 저감)

  • Lee, Joon-Ku;Park, Sok-Ha;Kim, Jin-Sung;Kim, Yang-Mo
    • Proceedings of the KIEE Conference
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    • 1998.11a
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    • pp.134-136
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    • 1998
  • In this paper, we present harmonic reduction of a Single-Switch Three-Phase Boost Rectifier which is operated at 25kHz. A simulation result shows that input current harmonics of Single-Switch Three-Phase Rectifier are reduced by Harmonic-Injection Method. Sixth harmonic is used for Harmonic-Injection Method.

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A Novel Harmonic Identification Algorithm for the Active Power Filters in Non-Ideal Voltage Source Systems

  • Santiprapan, Phonsit;Areerak, Kongpol;Areerak, Kongpan
    • Journal of Power Electronics
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    • v.17 no.6
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    • pp.1637-1649
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    • 2017
  • This paper describes an intensive analysis of a harmonic identification algorithm in non-ideal voltages source systems. The dq-axis Fourier with a positive sequence voltage detector (DQFP) is a novel harmonic identification algorithm for active power filters. A compensating current control system based on repetitive control is presented. A design and stability analysis of the proposed current control are also given. The aim of the paper is to achieve a robustness of the harmonic identification in a distorted and unbalanced voltage source. The proposed ideas are supported by a hardware in the loop technique based on a $eZdsp^{TM}$ F28335 and the Simulink program. The obtained results are presented to demonstrate the performance of the harmonic identification and the control strategy for the active power filter in non-ideal systems.

Harmonic Generation and System Response Characteristics in Electrified Railway(I) - Focused on System Response Characteristics - (전기철도에서의 고조파 발생과 계통응답특성(I) - 계통응답특성을 중심으로 -)

  • 오광해;이장무
    • Journal of the Korean Society for Railway
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    • v.7 no.1
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    • pp.60-64
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    • 2004
  • 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.

COEFFICIENTS OF UNIVALENT HARMONIC MAPPINGS

  • Jun, Sook Heui
    • Journal of the Chungcheong Mathematical Society
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    • v.20 no.4
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    • pp.349-353
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    • 2007
  • In this paper, we obtain some coefficient bounds of harmonic univalent mappings by using properties of the analytic univalent function on ${\Delta}$={z : |z| > 1}.

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BRANCHED SINGULARITIES OF HARMONIC MAPS

  • SHIN, HEAYONG
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.6 no.1
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    • pp.53-57
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    • 2002
  • In this paper we give an example of energy minimizing harmonic maps for which the set of singular points are two or more lines intersecting at a point.

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TYPICALLY REAL HARMONIC FUNCTIONS

  • Jun, Sook Heui
    • Korean Journal of Mathematics
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    • v.8 no.2
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    • pp.135-138
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    • 2000
  • In this paper, we study harmonic orientation-preserving univalent mappings defined on ${\Delta}=\{z:{\mid}z{\mid}>1\}$ that are typically real.

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Planar harmonic mappings and curvature estimates

  • Jun, Sook-Heui
    • Journal of the Korean Mathematical Society
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    • v.32 no.4
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    • pp.803-814
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    • 1995
  • Let $\Sigma$ be the class of all complex-valued, harmonic, orientation-preserving, univalent mappings defined on $\Delta = {z : $\mid$z$\mid$ > 1}$ that map $\infty$ to $\infty$.

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HARMONIC MAPPING

  • Jun, Sook Heui
    • Korean Journal of Mathematics
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    • v.10 no.1
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    • pp.1-3
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    • 2002
  • In this paper, we obtain some coefficient bounds of harmonic, orientation-preserving, univalent mappings defined on ${\Delta}=\{z:{\mid}z{\mid}>1\}$.

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