• Title, Summary, Keyword: winding change

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Non-linear tension control in a winding process with a contact roll and a nip roll (접압롤 및 보조롤이 있는 권취공정에서의 장력의 비선형 제어)

  • 신기현;김규태;천성민
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.748-753
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    • 1996
  • The contact roll is often used to regulate the winding tension as well as the entrained air in a wound roli by adjusting the contact force to the winding roll. But the contact force generated by other rolls, like assistant nip rolls, in a winding(or roll changing) process may act as disturbance to the control of the winding tension. In this paper, the mechanism of a roll change process is analyzed. And, the behavior of the contact and the assistant nip rolls are mathematically modeled. A nonlinear PID(NPID) controller is designed to control the winding tension and to reject the effect of disturbance generated by the assistant nip roll on the winding tension variation. Computer simulation study showed that the performance of the suggested NPID controller is improved compared with that of the PID controller in con trolling the winding tension and in rejecting the effect of the disturbance.

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Non-linear PID Tension Control in a Winding Process with a Contact Roll and a Nip Roll (접압롤 및 보조닙롤이 있는 권취공정에서의 장력의 비선형 PID제어)

  • 신기현;김규태;천성민
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.2
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    • pp.45-52
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    • 1998
  • The contact roll is often used to regulate the winding tension as well as the entrained air in a wound roll by adjusting the contact force to the winding roll. But the contact force generated by other rolls, like assistant nip rolls, in a winding(or roll changing) process may act as disturbance to the control of the winding tension. In this paper, the mechanism of a roll change process is analysed. Ana, the behavior of the contact and the nip rolls are mathematically modeled. A nonlinear PID(NPID) controller is designed to control the winding tension and to reject the effect of disturbance generated by the nip roll on the winding tension variation. Computer simulation study showed that the performance of the suggested NPID controller is improved compared with that of the PID controller in controlling the winding tension and in rejecting the effect of the disturbance.

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A Study on L.V.I. Diagnosis Field Application of Transformer Winding Deformation (변압기 권선변형 L.V.I. 진단 실적용을 위한 연구)

  • Cho, Kook-Hee;Kang, Dong-Sik;Kim, Kwang-Hwa;Kweon, Dong-Jin
    • Proceedings of the KIEE Conference
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    • pp.1638-1640
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    • 1998
  • We describe the possibility of field application and the diagnosis method of winding deformation in the power transformers using L.V.I. test system. Any winding deformation will result in a change of capacitance between winding parts and passibly some change in the winding inductance. These changes will then result in a change in the responce to the applied pulse in both the magnitude and period of the resulting oscillations. And we discuss with respect to test result of model transformer and commercial transformer, appear good results with application possibility in field.

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Drive Characteristics of 2-Stage Commutated SRM with Auxiliary Winding

  • Lee, Dong-Hee;Ahn, Jin-Woo;Oh, Seok-Gyu;Park, Sung-Jun
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.11B no.4
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    • pp.175-179
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    • 2001
  • The switched reluctance drive exhibits higher levels of vibration and acoustic noise than that of most competing drives. The main source of vibration in the switched reluctance drive is generated by rapid change of radial force when phase current is extinguished by commutation action. A new excitation strategy for a Switched Reluctance Motor with Auxiliary Winding (SRMAW) is described and tested. This scheme has auxiliary winding with one diode which is sound to all th poles in one winding. In this scheme, auxiliary winding is used to reduce magnetic stress during commutations. The abrupt change of a phase excitation produces mechanical stresses and it results in vibration and noise. The acoustic noise is reduced remarkably through 2-stage commutation. The operational principle and a characteristic comparison to that of the conventional SRM show that this scheme has some advantages including noise reduction as well as high efficiency drive.

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Measurement of winding deformation in transformers using low voltage impulse (저압충격을 이용한 변압기에서 권선변형 측정)

  • Cho, Kook-Hee;Kang, Dong-Sik;Kim, Kwang-Hwa;Kweon, Dong-Jin
    • Proceedings of the KIEE Conference
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    • pp.388-390
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    • 1997
  • We describe the characteristic of LVI(Low-voltage Impulse) test system and methods to detect the deformation of windings in the power transformers. Any winding deformation will result in a change of capacitance between winding parts and possibly some change in the winding inductance. These changes will then result in a change in the responce to the applied pulse in both the magnitude and period of the resulting oscillations. A results of measured differential method in stead of typical method, the sensitivity is greatly improved by the use of differential methods where the pulse is applied to two identical windings and the response measured with a differential amplifier.

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Winding Design of Pole Change Motor for Harminics Reduction (고조파 저감을 위한 극변환 전동기의 권선 설계)

  • Nam, Hyuk;Hong, Jung-Pyo;Jeong, Seung-Kyu;Jung, Tae-Uk;Baek, Seung-Myun
    • Proceedings of the KIEE Conference
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    • pp.910-912
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    • 2001
  • The winding design of a capacitor-run single-phase induction motor for changing two poles(2-/4-pole) is proposed for reducing the harmonics of Magneto Motive Force(MMF) in the airgap at 2-role. To improve motor performance, it is important to analyze exactly the harmonics and design the winding pattern for its harmonics reduction. The winding design method to reduce the harmonics is suggested in this paper and its characteristics are analyzed by using equivalent circuit considering harmonic components. The various performances of the pole change motor with the proposed winding pattern are compared with the experimental results.

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Vibration and Acoustic Noise Reduction Method of SRM Using Auxiliary Winding (보조권선 활용에 의한 SRM의 진동 및 소음 저감 방안)

  • 정태욱
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.11
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    • pp.548-556
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    • 2003
  • Switched reluctance motor(SRM) has simple magnetic structure, and needs simple power electronic driving circuit. It is very useful for wide range adjustable speed drive system. But, SRM drive generates large vibration and acoustic noise because it is commutated individually by step pulse m.m.f of each phase. In the vibration and acoustic noise characteristics. the considerable vibration and noise is induced by radial deforming of stator, so the frequency of dominant vibration and noise is coincident with the frequency of natural frequency of mechanical structure. This radial vibration force is generated by abrupt change of radial magnetic force in the phase commutation region. This paper studied about simple electromagnetic structure of SRM using auxiliary compensating winding for the reduction of noise and vibration. This auxiliary winding is coupled with all phase windings electromagnetically and absorb and transfer magnetic energy variation from phase to other phase. By this interaction of phase windings and compensating winding can reduce abrupt radial force change and vibration and acoustic noise. In this paper the improvement effect is examined by the test of prototype machine.

Prediction of Change in Equivalent Circuit Parameters of Transformer Winding Due to Axial Deformation using Sweep Frequency Response Analysis

  • Sathya, M. Arul;Usa, S.
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.983-989
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    • 2015
  • Power transformer is one of the major and key apparatus in electric power system. Monitoring and diagnosis of transformer fault is necessary for improving the life period of transformer. The failures caused by short circuits are one of the causes of transformer outages. The short circuit currents induce excessive forces in the transformer windings which result in winding deformation affecting the mechanical and electrical characteristics of the winding. In the present work, a transformer producing only the radial flux under short circuit is considered. The corresponding axial displacement profile of the windings is computed using Finite Element Method based transient structural analysis and thus obtained displacements are compared with the experimental result. The change in inter disc capacitance and mutual inductance of the deformed windings due to different short circuit currents are computed using Finite Element Method based field analyses and the corresponding Sweep Frequency Responses are computed using the modified electrical equivalent circuit. From the change in the first resonant frequency, the winding movement can be quantified which will be useful for estimating the mechanical withstand capability of the winding for different short circuit currents in the design stage itself.

Magnetic Field Analysis of 1 MVA HTS Transformer Windings

  • Park, Chan-Bae;Kim, Woo-Seok;Lee, Sang-Jin;Han, Jin-Ho;Park, Kyeong-Dal;Joo, Hyeong-Gil;Hong, Gye-Won;Hahn, Song-Yop
    • Progress in Superconductivity and Cryogenics
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    • v.5 no.1
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    • pp.66-70
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    • 2003
  • In a HTS transformer, the perpendicular component of magnetic flux density ($B_r$) applied to HTS tapes of pancake windings becomes larger than that of solenoid winding, thereby decreasing the critical current in the HTS tapes. This paper introduces several methods to reduce $B_r$ applied to the HTS tapes in the transformer with double pancake windings by changing winding arrangements and the relative permeability of flux diverters. We have conducted a winding design for a single-phase 1MVA 22.9kV/6.6kV HTS transformer. We observed a change of $B_r$ due to a variation of gap-length between the high voltage windings and the low voltage windings, reciprocal arrangement and an increase of the number of the high voltage pancake. We also observed a change of Br on the HTS tapes due to variation of the relative permeability of flux diverters placed between the high voltage winding and the low voltage winding. Finally, we have designed a 1MVA 22.9kV/6.6kV HTS transformer winding using suggested methods and calculated transformer parameters by the 3D finite element method.

Development of Inter-Turn Short Circuits Sensor for Field Winding of Synchronous Generator

  • Nam J-H;Jeon Y-S;Choe G-H;Lee S-H;Jeong S-Y;Yoo B-Y;Ju Y-H;Lee Y-J;Shin W-S
    • Proceedings of the KIPE Conference
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    • pp.56-59
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    • 2001
  • An effective method of detecting inter-turn short circuits on round rotor windings is described. Shorted-turns can have significant effects on a generator and its performance. A method of detecting inter-turn short circuits on rotor windings is described. The approach used is to measure the rate of change of the air-gap flux density wave when the rotor is at operating speed and excitation is applied to the field winding. The inter-turn short circuits sensor for synchronous generator's field winding has been developed. The sensor, installed in the generator air-gap, senses the slot leakage flux of field winding and produces a voltage waveform proportional to the rate of change of the flux. For identification of reliability for sensor, a inter-turn short circuits test was performed at the West-Inchon combined cycle power plant on gas turbine generator and steam turbine generator. This sensor will be used as a detecting of shorted-turn for field winding of synchronous generator. The purpose of this paper is to describe the design and operation of a sensitive inter-turn short circuits detector. In this paper, development of inter-turn short circuits sensor for field winding of synchronous generator and application in a field.

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