• 제목/요약/키워드: Pole interaction

검색결과 22건 처리시간 0.021초

제주 HVDC No. 2의 극간 상호작용 경험과 분석: 무정전 전력 송전을 위한 실용적 해결방안 (Experience and Analysis of Pole Interaction for Jeju HVDC No. 2: Practical Solution for Non-Interruptible Power Transfer)

  • 김희진;김찬기;박창환
    • 전력전자학회논문지
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    • 제25권6호
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    • pp.459-468
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    • 2020
  • The pole interaction of the line-commutated converter high-voltage direct current (HVDC) is analyzed, and a practical solution that uses a surge arrester is proposed. Jeju HVDC No. 2 is a double-monopole HVDC link that has a rated power capacity of 2 × 200 MW and was commissioned in 2012. During normal operation, Jeju HVDC No. 2 is operated in the bipolar mode to minimize the loss caused by the dedicated metallic return. However, when one pole of the inverter valve is bypassed, a commutation failure can occur in the other pole. This phenomenon is called pole interaction in this work. This pole interaction interrupts the HVDC power transfer for almost 2 s and may affect the stability of the power system. This research proposes the installation of a surge arrester at the inverter neutral, which can be an effective and practical solution for pole interaction. The HVDC system is analyzed, and the residual voltage of the surge arrester is determined. Detailed simulation using PSCAD/EMTDC demonstrates that the proposed method eliminates the pole interaction of the bipolar-operated HVDC.

반경방향-축방향 일체형 4극 전자기 베어링의 설계 (II) - 바이어스 자속 공유형 - (Design of Combined Radial and Axial 4-pole Electromagnetic Bearing (II) - with Coupled Bias Flux -)

  • 김하용;김승종
    • 대한기계학회논문집A
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    • 제29권12권
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    • pp.1567-1573
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    • 2005
  • This paper introduces a new active magnetic bearing(AMB) that can provide both radial and axial control functions in one bearing unit without axial disk. It has a structure of double four-pole AMB or a four-pole AMB where each core is split into two axially. The cores have two kinds of coil winding; they independently generate fluxes on the planes perpendicular or parallel to the shaft. For the radial control action, it works just like a conventional four-pole AMB. Meanwhile, for the axial control, it uses the Lorentz force generated by the interaction of the bias flux for radial control and the axial control flux. In this paper, the proposed structure, principle, and design process based on magnetic flux analysis are introduced, and its feasibility is experimentally verified by using a simple PD control algorithm with a feedforward loop to compensate the coupled flux effect.

콘크리트 전주의 극한강도에 관한 해석적 연구 (An Analytical Study on the Ultimate Strength of Concrete Poles)

  • 신동근;윤기용;이승현;이규세;강영종
    • 한국방재학회 논문집
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    • 제7권5호
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    • pp.19-25
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    • 2007
  • 본 연구에서는 전주의 공칭강도를 계산하기 위해 이론적 방법에 의해 P-M상관도 프로그램을 개발하였다. 그리고 이를 바탕으로 기존 연구와 검증하고 전주의 공칭강도$(M_n)$를 산정하였다. 설계기준에 제시된 파괴강도$(M_r)$와 본 연구에서 산정한 전주의 공칭강도$(M_n)$를 비교 분석한 결과 현재 사용하고 있는 전주의 공칭강도가 설계기준$(M_r)$보다 작게 산정되었다. 따라서 공칭강도 증대를 위해 인장근/보강근의 지름 증가, 보강근의 개수 증가, 인장근의 위치변화, 전주의 두께 변화 등의 매개변수를 선정하여 선정된 매개변수를 고려한 전주의 공칭강도$(M_n)$를 설계기준의 공칭강도$(M_n)$와 비교 분석하였다.

낙서의 유희성을 반영한 '미디어 폴' 디자인 (The Media Pole Design Applying the Playfulness of Scribbling)

  • 김희은;류한영
    • 디자인융복합연구
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    • 제14권5호
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    • pp.103-115
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    • 2015
  • 본 연구는 서울 강남역 유비쿼터스 거리에 설치된 미디어 폴의 발전 방안으로 유희적인 기능을 강조하여 낙서의 형태적, 경험적, 내용적, 커뮤니케이션적 측면을 고려한 디자인을 제안한다. 미디어 폴은 디지털 미디어 공공시설물로서 주변 장소와 관련된 다양한 편의 정보를 제공한다. 미디어 폴의 이용 행태를 분석한 연구에 의하면 미디어 폴이 제공하는 여러 기능 중 사진 촬영 및 포토 메일 등의 유희적인 기능을 사용자가 가장 많이 이용하는 것으로 나타났다. 본 연구는 이러한 이용자의 행태를 고려하여 유희적인 도구로서의 미디어 폴을 강조하고 낙서의 유희성을 반영한 새로운 디자인을 제안하려 한다. 문헌 연구를 통해 고찰한 낙서의 유희적 특성을 미디어 폴의 인터페이스 형태, 인터랙션 경험, 애플리케이션 내용 및 커뮤니케이션 기능적 측면에 각각 대입한 디자인 결과물을 제안한다. 본 연구 결과를 통해 미디어 폴의 이용이 이전보다 재밌어진다면 이용자 수도 더 증가할 것이라고 기대한다. 낙서는 인간 본연의 유희적 추구이자 행동이기 때문에 이를 디지털 기기에 반영한다면, 보다 자연스러운 이용을 유도할 수 있을 것이다. 이는 미디어 폴에서뿐만 아니라 다른 디지털 기기에서도 확대·적용이 가능할 것이다.

가속열화 방법에 의한 주상변압기 절연물의 열 열화 특성 평가 (The Evaluation of Thermal Aging Characteristics in Insulating Materials of the Pole Transformers)

  • 이병성;송일근;이재봉;한상옥
    • 한국전기전자재료학회논문지
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    • 제16권12호
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    • pp.1136-1141
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    • 2003
  • The primary insulation materials used in an oil filled transformer are kraft paper, wood, porcelain and oil. Modern transformers use chemically treated paper to improve its tensile strength and resistance to aging caused by immersion in oil. But these insulation papers are mainly aged by thermal stress. Over the life time of the insulation paper and oil, it is exposed to high temperatures, oxygen and water. Its interaction with the steel of the tank and core plus the copper and aluminium of the windings will eventually cause the chemical properties of the oil to decay. High temperature have an effect on mechanical strength of cellulous paper used in the layer insulation. We made two aging cells in which insulation papers and mineral oil are conducted to test thermal properties. It is measured dielectric strength, number of acid, moisture, etc. of insulation paper and oil aged in the aging cells.

Influence of time delay and saturation capacity to the response of controlled structures under earthquake excitations

  • Pnevmatikos, Nikos G.;Gantes, Charis J.
    • Smart Structures and Systems
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    • 제8권5호
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    • pp.449-470
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    • 2011
  • During the last thirty years many structural control concepts have been proposed for the reduction of the structural response caused by earthquake excitations. Their research and implementation in practice have shown that seismic control of structures has a lot of potential but also many limitations. In this paper the importance of two practical issues, time delay and saturation effect, on the performance of controlled structures, is discussed. Their influence, both separately and in interaction, on the response of structures controlled by a modified pole placement algorithm is investigated. Characteristic buildings controlled by this algorithm and subjected to dynamic loads, such as harmonic signals and actual seismic events, are analyzed for a range of levels of time delay and saturation capacity of the control devices. The response reduction surfaces for the combined influence of time delay and force saturation of the controlled buildings are obtained. Conclusions regarding the choice of the control system and the desired properties of the control devices are drawn.

Macroscopic Nonlinear Optical Properties of Tricyanopyrrolidene Chromophore Containing Amorphous Polycarbonate: Effect of Molecular Lateral Moiety in the Conjugative Structure

  • Cho, Min-Ju;Lee, Sang-Kyu;Jin, Jung-Il;Choi, Dong-Hoon
    • Macromolecular Research
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    • 제14권6호
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    • pp.603-609
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    • 2006
  • Tricyanopyrrolidene chromophores were prepared in order to compare their macroscopic nonlinear optical (NLO) properties with a conjugated structure through the long molecular axis. A thiophene or phenyl ring was tethered to an ethylenic bond; it may act as a lateral moiety to disrupt the planarity of a chromophore and lessen the electrostatic interaction. Thin film composites of these chromophores dissolved in amorphous polycarbonate (APC) were fabricated. Real time pole and probe method was employed to investigate the change of electro-optic (EO) signal during poling. The EO properties and their relaxation behaviors of the guest-host systems containing newly synthesized chromophores were investigated in detail.

코깅력이 저감된 3상 9극 10슬롯 구조의 영구자석 선형 전동기 (A Low Cogging Force Permanent Magnet Linear Motor Having 3 Phase 9 Pole 10 Slot Structure)

  • 연승환;이종진;고창섭
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제55권11호
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    • pp.547-554
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    • 2006
  • The detent force of a permanent magnet linear motor(PMLM) consists of the end force and cogging force, and should be reduced for high precision purpose applications. The cogging force comes from the electromagnetic interaction between the permanent magnets and interior teeth(or the slots) of the stator, and of which the magnitude depends on the ratio of the numbers of the armature and permanent magnet poles as well as the geometrical shape of the permanent magnet and armature pole. In order to reduce the cogging force of a PMLM, this paper proposes a new configuration which has 9 permanent magnet poles and 10 armature winding slots. By theoretical investigation of the principle of cogging force generation and simulating using finite element method, the proposed PMLM configuration is proven to give much less cogging force than the conventional configuration which has 8 permanent magnet poles and 12 armature winding slots. A proper winding algorithm, modified (A, A, A) winding method, for the proposed configuration is also suggested when the proposed PMLM is operating as a 3 phase synchronous machine. A theoretical and numerical calculation shows that the proposed configuration makes slightly bigger back-emf and thrust force under same exciting current and total number of winding turns condition.

가속열화 방법에 의한 주상변압기 절연물의 열열화 특성 평가 (The Evaluation of Thermal Aging Characteristics in Insulating Paper for the Use of the Pole Transformers)

  • 이병성;송일근;이재봉;박동배;한상옥
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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    • pp.100-103
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    • 2003
  • The primary insulation system used in an oil-filled transformer is kraft paper, wood, porcelain and oil. Modern transformers use paper that is chemically treated to improve its tensile strength properties and resistance to aging caused by immersion in oil. But these insulation papers are mainly aged to thermal stress. Over the course of the insulation paper and oil's life it is exposed to high temperatures, oxygen and water. Its interaction with the steel of the tank and core plus the copper and aluminium of the windings will eventually cause the chemical properties of the oil to decay. High temperature have an effect on mechanical strength of cellulous paper using the layer insulation. We made two aging cell in which thermal aging tests of insulation papers and mineral oil are conducted. It is measured dielectric strength, number of acid, moisture, etc. of insulation paper and oil aged in the aging cells.

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중국 유아교육의 질 보장제도 변천에 관한 연구: 역사적 제도주의 관점에서의 분석 (Study on the Institutional Change of Early Childhood Education Quality Assurance in China: From the Perspective of Historical Institutionalism)

  • 왕정;이승미
    • Human Ecology Research
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    • 제58권1호
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    • pp.87-103
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    • 2020
  • This study discusses the institutional change of Chinese early childhood education quality assurance institution (ECEQAI) from the three dimensions of the perspective of historical institutionalism of that refer to the external environment, dynamic mechanism containing with nation-market-society, and the invisible ideology of the institutional change. Chinese ECEQAI was divided into five historical periods, which were 17 years after the founding of China (1949-1966), the Great Cultural Revolution (GCR) period (1966-1976), the early stage of Reform and Opening-up (RO) (1976-1995), the social change period (1995-2010) and the new period (2010-now). This study also concludes five separate change models for Chinese ECEQAI that correspond to the five periods. The first was a compulsory and gradual institutional change model influenced by the Soviet model and dominated by national power. The second was compulsory and radical change model controlled by the counter-revolutionary group. The third was a compulsory and gradual institutional change model dominated by national power. The fourth was induced and gradual institutional change model driven by market power and forced by society power. The fifth was a compulsory and gradual institutional change model led by national power and forced by society power. Finally, the future change direction of China's ECEQAI was further pointed out, that was the government-leading and tend to balanced three-pole power model of "Nation-Market-Society", as well as the "three-pole power relationship" of indepth communication and positive interaction.