• Title/Summary/Keyword: 고조파 공진

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Case Study of Resonant Interaction with Elevator (고조파 공진으로 인한 엘리베이터 정지사례 분석)

  • Cho, Nam-Hun
    • Proceedings of the KIEE Conference
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    • pp.76-79
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    • 2005
  • 전력품질 저하로 인하여 수용가 설비에 문제가 발생되었을 경우, 전력품질의 유지 및 관리 책임이 있는 전력회사(판매회사)는 전력품질 저하원인을 규명하여야 한다. 이 경우 전력품질 향상에 필요한 소요 비용은 전력품질 저하원인 제공자가 부담하는 것이 원칙이며, 전력품질 원인 제공자가 전력회사로부터 계속 전력을 공급받기 위해서 수용가는 전력품질 향상을 위한 대책들을 전력회사에 제시하여야 하며, 그 중 비용이 가장 적은 방법을 선택할 수 있다. 이 경우 전력회사는 최선을 다하여 수용가 및 전력회사 측면에서 적절한 대책이 수립될 수 있도록 기술적으로 협조하여야 한다.

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A Study on the Outages Due to Voltage Expanding in Closing High Voltage Capacitor (고압 커패시터 투입시 전압확대에 따른 사고 사례 연구)

  • Cho, Nam-Hoon;Jung, Jum-Soo;Park, Yong-Woo;Ha, Bok-Nam;Lee, Hyung-Ho
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.9
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    • pp.94-102
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    • 2008
  • Capacitor switching is essential for the economic operation and proper voltage control of KOREA electric utility distribution system. Voltage transients produced by capacitor switching (around 2.0 per unit at substation and 2.5 or less per unit at customer site, and lasting less then 1[ms]) do not have the magnitude or duration to interfere with the operation of computers, but they do disrupt the operation of adjustable speed drivers. The result of our research, ASD manufacturers should learn from the computer industry and design products that will operate satisfactory In the electrical envelopment in which they will be placed. In this case history, the inductors on the input to ADSs in order to prevent nuisance tripping from capacitor switching(and other causes within the apartment) proved to be an effective, low-cost solution.

Nonlinear Vibrations of Piezoelectric Microactuators in Hard Disk Drives (하드디스크 드라이브용 압전형 마이크로 액추에이터의 비선형 진동 특성)

  • Jeong, Deok-Yeong;Lee, Seung-Yeop;Kim, Cheol-Sun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.12
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    • pp.2002-2008
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    • 2001
  • Nonlinear vibration characteristics of a piezoelectric-type micro actuator used for hard disk drives are experimentally studied. The nonlinear characterisitics include hysteresis, superharmonic resonance, jump phenomenon, and shifting of natural frequencies. The vibration modes and frequencies of the commercial actuator of the Hutchinson's Magnum series are measured using a laser vibrometer. From harmonic excitation to the PZT acturator, we observe interesting hysteresis patterns with 3 times input frequency. It is shown that the micro actuator has the typical 3 times superhamonic resonances coupled to the first torsional and sway modes of the suspension.

A Study on the Analysis of Damping Loads to Prevent Harmonic Resonance (고조파 공진 억제를 위한 완충부하 투입량 분석에 관한 연구)

  • Lim, Chan-Ho;Lee, Kyeong-Seob;Yu, Won-Kun;Lee, Heung-Jae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.2
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    • pp.262-266
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    • 2010
  • During the restoration process of primary restorative transmission system, the over voltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. This over voltage is caused by harmonic resonance and can be prevented by damping loads that are connected before restoration process of primary restorative transmission system. But it is very difficult to predict the occurrence possibility of the harmonic resonance previously. This paper analyzes the relationship between the harmonic resonance and the amount of damping loads to prevent the harmonic resonance. This paper calculates the minimum amount of damping loads to prevent harmonic resonance while changing the length of primary restorative transmission line. And this paper confirmed that the amount of damping loads is not proportional to length of transmission line. The result of this paper will be used as important experiment data to predict the occurrence possibility of harmonic resonance previously.

Analysis of the Harmonic Resonance during Restoration of Primary Restorative Transmission System (시송전계통의 고조파 공진현상에 대한 분석)

  • Lee, Kyeong-Seob;Lee, Heung-Jae
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.55 no.5
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    • pp.191-194
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    • 2006
  • Power system restoration following a wide area or complete blackout starts with energizing primary restorative transmission systems. During this primary restoration process, unexpected over-voltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. This is known as the harmonic resonance phenomenon that may cause burning out of transformer or other devices. Since the harmonic resonance originates from the nonlinear characteristics, it is very difficult to predict the occurrence of this phenomenon. This paper reports the analyses of the harmonic resonance occurred in domestic power system. Various analyses and results of the harmonic over-voltage is presented based on the PSCAD/EMTDC simulations.

Analysis of the Harmonic Resonance of Primary Restorative Transmission System Using PSCAD/EMTDC (PSCAD/EMTDC를 이용한 시송전계통의 고조파 공진현상 분석)

  • Lee, H.J.;Cho, B.K.;Lee, K.S.;Park, S.M.;Bae, J.C.;Hwang, B.H.;Lee, N.H.;Song, I.J.
    • Proceedings of the KIEE Conference
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    • pp.31-33
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    • 2003
  • Power system restoration following a partial or complete blackout starts with energizing of primary transmission lines. Because system changed rapidly during early restoration process, transformer energization and load pickup is executed to maintain the power system stability. However unexpected problem such as harmonic overvoltage may be arisen during energizing transformer. The reason of harmonic overvoltage is known as transformer saturation and magnetizing in-rush current and so on, but it is difficult to estimate the condition of occurrence. This paper describes the analysis of the harmonic overvoltage while unloaded transformer is energized using PSCAD/EMTDC.

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A Study on the Harmonic Resonance during Restoration of Primary Restorative Transmission System (부하투입이 고조파 공진에 미치는 영향에 대한 고찰)

  • Lee, H.J.;Lee, K.S.;Park, S.M.;Yu, W.K
    • Proceedings of the KIEE Conference
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    • pp.249-251
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    • 2004
  • Harmonic resonant overvoltage during restoration of primary restorative transmission system originates in switching operations and nonlinear characteristics of equipments. Actually it is difficult to predict the occurrence of harmonic overvoltage, since they result from nonlinear characteristics of transformers and other equipments. This paper describes the analysis of domestic primary restorative transmission system using PSCAD/EMTDC. The harmonic resonance is verified and showed the relation with equipments which have nonlinear characteristics such as generator and transformer in this paper. And the solution to prevent harmonic resonance is proposed too. As a result, the PSCAD/EMTDC simulation showed slightly conflictive results that had been presented by IEEE Power System Restoration Working Group report.

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Analysis of the Harmonic Resonance during Restoration of Primary Restorative Transmission System (시송전계통 탁구과정에서의 고조파 공진 현상에 대한 고찰)

  • Lee, H.J.;Lee, K.S.;Park, S.M.
    • Proceedings of the KIEE Conference
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    • pp.220-222
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    • 2005
  • Power system restoration following a wide area or complete blackout starts with energizing primary restorative transmission systems. During this primary restoration process, unexpected over-voltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. This is known as the harmonic resonance phenomenon that may cause burning out of transformer or other devices. Since the harmonic resonance originates from the nonlinear characteristics, it is very difficult to predict the occurrence of this phenomenon. This paper reports the possible existence of the harmonic resonance in Korean power system. Analysis of the harmonic over-voltage is presented based on the various simulations using PSCAD/EMTDC.

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A Study on the Damping Loads Prediction to prevent Harmonic Resonance during the Power System Restoration (전력계통의 정전복구시 고조파 공진억제를 위한 완충부하투입량 예측에 관한 연구)

  • Lee, Heung-Jae;Yu, Won-Kun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.7
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    • pp.913-917
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    • 2013
  • During the restoration process of primary restorative transmission system, some over voltages may happen due to nonlinear interaction between unloaded transformers and transmission systems. These over voltages caused by harmonic resonance can be suppressed by inserting damping loads before energizing transformers. But it is very difficult to predict the occurrence possibility of harmonic resonance and complex simulation must be repeated to estimate the sufficient damping loads. This paper presents a damping loads prediction system to prevent harmonic resonance. Detailed analysis of the relationship between harmonic resonance and the amount of damping loads is discussed. The prediction system is developed using a curve fitting and a neural network based on this relationship. A curve fitting used a Gaussian function based on non-linear least square method and multi-layer back-propagation neural network is applied. The system is applied to primary restorative transmission lines in korean power system and the result showed satisfactory performance.

Analysis of the Harmonic Resonance of Primary Restorative Transmission System Using PSCAD/EMTDC PART II (PSCADI/EMTDC를 이용한 시송전계통의 고조파 공진현상 분석 II)

  • Lee H. J.;Yoo W. K.;Lee K. S.;Park S. M.
    • Proceedings of the KIEE Conference
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    • pp.48-50
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    • 2004
  • The energization of high voltage transmission lines and transformers, that is an inevitable process in most countries as the first restorative action for wide-area blackout, may induce overvoltages such as sustained overvoltage, transient overvoltage and harmonic resonant overvoltage. And these may cause damages to power system equipments or failure of surge arresters. The harmonic resonant overvoltage originates in switching operations and nonlinear characteristics of equipments. Actually it is difficult to predict the occurrence of harmonic overvoltage, since they result from nonlinear characteristics of transformers and other equipments. This paper describes the analysis of domestic primary restorative transmission system using PSCAD/EMTDC. The harmonic resonance is verified and the solution to prevent harmonic resonance is proposed in this paper. As a result, the PSCAD/EMTBC simulation showed slightly conflictive results that had been presented by IEEE Power System Restoration Working Group report.

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