• Title/Summary/Keyword: Harmonic

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A Study on the Analysis of Harmonic Injection and Emission for Power System (전력계통 고조파 유입 유출 분석에 관한 연구)

  • Wang, Yong-Peel;Jeong, Jong-Won;Kim, Se-Dong;Kwak, No-Hong;Jeon, Young-Soo;Park, Sang-Ho
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2007.05a
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    • pp.203-205
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    • 2007
  • A method is proposed in this paper to determine the harmonic contributions of a customer at the point of common coupling. The method can quantify customer and utility responsibilities for limit violations caused by either harmonic source changes or harmonic impedance changes. It can be implemented in current power quality monitors and digital revenue meters. The method is comparison of measurement phase angles between harmonic voltage and current. The proposed method has been applied to the test system. The study results have indicated the accuracy of harmonic injection and emission for customer and utility.

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TRANSVERSE HARMONIC FIELDS ON RIEMANNIAN MANIFOLDS

  • Pak, Jin-Suk;Yoo, Hwal-Lan
    • Bulletin of the Korean Mathematical Society
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    • v.29 no.1
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    • pp.73-80
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    • 1992
  • We discuss transverse harmonic fields on compact foliated Riemannian manifolds, and give a necessary and sufficient condition for a transverse field to be a transverse harmonic one and the non-existence of transverse harmonic fields. 1. On a foliated Riemannian manifold, geometric transverse fields, that is, transverse Killing, affine, projective, conformal fields were discussed by Kamber and Tondeur([3]), Molino ([5], [6]), Pak and Yorozu ([7]) and others. If the foliation is one by points, then transverse fields are usual fields on Riemannian manifolds. Thus it is natural to extend well known results concerning those fields on Riemannian manifolds to foliated cases. On the other hand, the following theorem is well known ([1], [10]): If the Ricci operator in a compact Riemannian manifold M is non-negative everywhere, then a harmonic vector field in M has a vanishing covariant derivative. If the Ricci operator in M is positive-definite, then a harmonic vector field other than zero does not exist in M.

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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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    • 1996.10b
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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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Microwave Incoherent Imaging of a Conducting Cylinder by Using Multi-Frequency Time-Harmonic Field : Part I - Incoherent Intensity Pattern by Using Multi-Frequency Time-Harmonic Field (다중주파수 시간좌화신호를 사용한 도체기중의 초고주파 incoherent 영상:Part I - 다중주파수 시간좌화신호를 사용한 incoherent 전력패턴)

  • 강진섭;라정웅
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.2
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    • pp.47-55
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    • 1996
  • A microwave incoherent imaging method for a conducting cyliner by using multi-frequency tiem-harmonic field is presented in this study. In this paper, an incoherent intensity pattern of th econducting cylinder is obtained by averagin gout the multi-frequency intensities of the coherent field such as the time-harmonic field scattered from this cylinder. This phenomenon is hsown numerically in scattering by a conducting circular cylinder illuminated by the time-harmonic plane wave, and is interpreted analytically by the mutual coherence functon defined as a frequency-averaged intensity of the time-harmonic fields in th frequency domain.

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Development of Measurement System for Harmonic Analysis of Electric Equipment (전기설비의 고조파 분석을 위한 측정 시스템의 개발)

  • Yoo, Jae-Geun;Lee, Sang-Ik;Jeon, Jeong-Chay
    • Proceedings of the KIEE Conference
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    • 2002.07a
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    • pp.259-261
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    • 2002
  • Recently, according to the spread of semiconductor applied technology like motor speed control contrivance, power conversion installation and so on, harmonic ingredients occurred in switching operation flow into a distribution system and increase voltage distortion of distribution system and bring on obstacles like damage, lowering of capability, false operation and so on of various electrical installation. So, in order to consider a countermeasure to limit occurrence quantity of harmonic source, harmonic interception and others, precision measurement and analysis on voltage, current, power, power factor, the each ingredient of harmonic order, the percentage of total harmonic distortion and so forth are needed. In this paper monitoring system to measure and analyze power quality connected with power harmonics was developed and it's performance is verified by measuring and analyzing three-phase voltage and current of R, S, T in the three-phase and four-wire system using the developed measurement system.

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Identification of Nonlinear Parameters of Electrodynamic Direct-Radiator Loudspeaker with Output Noise (출력 소음을 고려한 직접방사형 라우드스피커의 비선형 매개변수 규명)

  • 박석태;홍석윤
    • Journal of KSNVE
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    • v.8 no.5
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    • pp.887-899
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    • 1998
  • It has been resulted that Lagrange multiplier method with statistical approach was superior to traditional harmonic balance method in identifying the nonlinear loudspeaker parameters when output signals were contaminated with Gaussian random noise. We have known that the displacement-dependent characteristic values of nonlinear parameters identified by traditional harmonic balance method were estimated less than original values by the increase of output noise and the stiffness coefficients were very sensitive to output noise. Also, by the sensitivity analysis we have verified that the harmonic distortions in acoustic radiation was mainly due to nonlinearity of force factor caused by uneven magnetic fields and that reducing the nonlinearity of damping coefficients were very effective for improving second harmonic distrotion of acoustic radiation.

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Study of viscoelastic model for harmonic waves in non-homogeneous viscoelastic filaments

  • Kakar, Rajneesh;Kaur, Kanwaljeet;Gupta, Kishan Chand
    • Interaction and multiscale mechanics
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    • v.6 no.1
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    • pp.31-50
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    • 2013
  • A five parameter viscoelastic model is developed to study harmonic waves propagating in the non-homogeneous viscoelastic filaments of varying density. The constitutive relation for five parameter model is first developed and then it is applied for harmonic waves in the specimen. In this study, it is assumed that density, rigidity and viscosity of the specimen i.e., rod are space dependent. The specimen is non-homogeneous, initially unstressed and at rest. The method of non-linear partial differential equation has been used for finding the dispersion equation of harmonic waves in the rods. A simple method is presented for reflections at the free end of the finite non-homogeneous viscoelastic rods. The harmonic wave propagation in viscoelastic rod is also presented numerically with MATLAB.

Rotation-Invariant Pattern Recognition of the Multiple Circular Harmonic Filter Using Proper Center (적정의 중심점을 이용한 다중 원형 고조 필터의 회전 불변적 형태 인식)

  • 김종찬;도양회;김수중
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.1
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    • pp.130-136
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    • 1990
  • For the rotation-invariant pattern recognition, we propose multiple circular harmonic filter which is expanded about the proper center. The proper centerm when input image is given, is the circular harmonic expansion center of the filter which yields a maximum center correlation peak in the output plane. In this paper, we founded the circular harmonic components that the proper center superposes on the same position and then designed multiple circular harmonic filter using these components. Also the proposed filter is compared with conventional multiple circular harmonic filter and shows that it can maximize the center correlation peak for the rotated input image by the computer simulation.

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A Study on the Realization of X-Band Harmonic Generator (X-밴드 고조파 발생기의 구현에 관한 연구)

  • 김영범;홍헌진;박동철;오승협
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.4
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    • pp.513-519
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    • 1990
  • In order to realize an efficient and stable X-band harmonic generator, a 100 MHz frequency multiplier, an impulse generator using SRD(Step Recovery Diode) module, and a narrow-band bandpass waveguide filter have been designed and tested. By properly combining these devices an X-band harmonic generator has been realized. The output power of the harmonic generator was measured to be -1.5 dBm at 9 GHz which is the 90th harmonic of the 100MHz input. The power fluctuation of the harmonic generator due to temperature variation was observed to the about 0.15 dB during 24 hours of 4\ulcorner temperature variation.

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Performance Improvement of an Active Neutral Harmonic Suppressor System Under Unbalanced Load Conditions

  • Choi, Se-Wan;Jang, Min-Soo
    • Journal of Power Electronics
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    • v.3 no.3
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    • pp.151-158
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    • 2003
  • Three-phase four-wire electrical distribution systems are widely employed in manufacturing plants, commercial and residential buildings Due to the nonlinear loads connected to the distribution system, the neutral conductor carries excessive harmonic currents even under balanced loading since the triplen harmonics in phase currents do not cancel each other This may result in wiring failure of the neutral conductor and overloading of the distribution transformer In response to these concerns, a cost-effective neutral current harmonic suppressor system has been proposed. This paper proposes an improved control method for the harmonic suppressor system under unbalanced load conditions The proposed control method compensates for only the harmonic components in the neutral conductor, and the zero-sequence fundamental component due to unbalanced loading is prevented from flowing through the harmonic suppressor system This remedies overloading and power loss of the system The experimental results on a prototype validate the proposed control approach.