• Title, Summary, Keyword: Transformer

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Transformer Design Methodology to Improve Transfer Efficiency of Balancing Current in Active Cell Balancing Circuit using Multi-Winding Transformer (다중권선 변압기를 이용한 능동형 셀 밸런싱 회로에서 밸런싱 전류 전달 효율을 높이기 위한 변압기 설계 방안)

  • Lee, Sang-Jung;Kim, Myoung-Ho;Baek, Ju-Won;Jung, Jee-Hoon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.4
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    • pp.247-255
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    • 2018
  • This paper proposes a transformer design of a direct cell-to-cell active cell balancing circuit with a multi-winding transformer for battery management system (BMS) applications. The coupling coefficient of the multi-winding transformer and the output capacitance of MOSFETs significantly affect the balancing current transfer efficiency of the cell balancing operation. During the operation, the multi-winding transformer stores the energy charged in a specific source cell and subsequently transfers this energy to the target cell. However, the leakage inductance of the multi-winding transformer and the output capacitance of the MOSFET induce an abnormal energy transfer to the non-target cells, thereby degrading the transfer efficiency of the balancing current in each cell balancing operation. The impacts of the balancing current transfer efficiency deterioration are analyzed and a transformer design methodology that considers the coupling coefficient is proposed to enhance the transfer efficiency of the balancing current. The efficiency improvements resulting from the selection of an appropriate coupling coefficient are verified by conducting a simulation and experiment with a 1 W prototype cell balancing circuit.

The Thermal Analysis of Pole Mount Mold Transformer with One-body Molding by Duct Condition (일체형 주상용 몰드 변압기의 덕트에 따른 열해석 특성 연구)

  • 조한구;이운용;박영두
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.3
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    • pp.348-352
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    • 2004
  • The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and ow loss, but it needs some cooling method because heat radiation between each winding is difficult. The life of transformer is significantly dependent on the thermal behavior in windings. Many transformer designers have calculated temperature distribution and hot spot point by finite element method(FEM) to analyze winding temperature rise. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

Fabrication and Characteristic Tests of a 1 MVA Single Phase HTS Transformer with Concentrically Arranged Windings

  • Kim, S.H.;Kim, W.S.;Choi, K.D.;Joo, H.G.;Hong, G.W.;Han, J.H.;Lee, H.G.;Park, J.H.;Song, H.S.
    • Progress in Superconductivity and Cryogenics
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    • v.6 no.4
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    • pp.37-40
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    • 2004
  • A 1 MV A single phase high temperature superconducting (HTS) transformer was manufactured and tested. The rated voltages of primary and secondary of the HTS transformer are 22.9 kV and 6.6 kV respectively. BSCCO-2223 HTS tape was used for HTS windings of 1 MV A HTS transformer. In order to reduce AC loss generated in the HTS winding, the type of concentric arrangement winding was adopted to a 1 MV A HTS transformer. Single HTS tape for primary windings and 4 parallel HTS tapes for secondary windings were used considering the each rated current of the HTS transformer. A core of HTS transformer was fabricated as a shell type core made of laminated silicon steel plate. And a GFRP cryostat with a room temperature bore was also manufactured. The characteristic tests of 1 MV A HTS transformer were performed such as no load test, short circuit test and several insulation tests at 65 K using sub-cooled liquid nitrogen. From the results of tests, the validity of design of HTS transformer was ascertained.

A Study on Temperature Characteristics of Main Transformers using Measurement System (계측시스템을 이용한 변압기의 온도 특성 연구)

  • Han Young-Jae;Kim Ki-Hwan;Kim Seog-Won;Mok Jin-Yong;Choi Jung-Sun;Kim Jung-Su
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.3
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    • pp.240-245
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    • 2006
  • Recently, as the road capacity reaches the limit and environmental problems becomes serious, there is gradually increased a need for railroad vehicles that are environment-friendly and have time regularity, reliability, and safety. Accordingly, in addition to conventional railroad vehicles, lots of vehicles are being newly developed. In this study, temperature sensors were adhered to transformer that is used in KHST(Korean High-Speed Train) to verify variation of temperature characteristics about transformer synthetically and efficiently. In the case that temperature of transformer exceeds reference temperature for running of KHST, overheating of transformer may cause a fatal accident of vehicle. Therefore, after on-line measuring system was constructed in vehicle, oil temperature and tank temperature were measured on real-time. Characteristics and main specifications of transformer in KHST were described in this paper. Also, measuring system for temperature measurement of transformer was explained in brief. Temperature data of transformer was acquired using measuring system, KRRI(Korea Railroad Research Institute) analyzed characteristic in contrast with comparing with temperature of transformer about month, running speed and running time.

Characteristic Analysis of Transformer Temperature for High Speed Train (고속철도차량의 변압기 온도 특성 분석)

  • Han, Young-Jae;Kim, Ki-Hwan;Kim, Yeong-Guk;Park, Chun-Su;Kim, Seog-Won;Mok, Jin-Yong;Lee, Su-Gil;Lee, Seong-Ho;Kim, Jong-Young
    • Proceedings of the KIEE Conference
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    • pp.1595-1597
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    • 2005
  • In this study, temperature sensors were adhered to transformer that is used in KHST(Korean High-Speed Train) to verify variation of temperature characteristics about transformer synthetically and efficiently. In the case that temperature of transformer exceeds reference temperature for running of KHST, overheating of transformer may cause a fatal accident of vehicle. Therefore, after on-line measurement system was constructed in vehicle, oil temperature and tank temperature were measured on real-time. Characteristics and main specifications of transformer in KHST were described in this paper. Also, measurement system for temperature measurement of transformer was explained in brief. Temperature data of transformer was acquired using measurement system, KHRI(Korea Railroad Research Institute) analyzed characteristic in contrast with comparing with temperature of transformer about month, running speed and running time.

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The Energized Aging Property of Pole Mount Mold transformer by Back-to-back Method (반환부하법에 의한 옥외 주상용 몰드변압기의 과전열화 특정)

  • Hwang, Bo-Guk;Cho, Han-Goo;Lee, Un-Yong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.484-487
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    • 2002
  • The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. In this paper, the proto type mold transformer of 50kVA class is investigated by routine, type, special test. The outdoor energized aging test is investigated by back-to-back method to verify the long time performance of pole mold transformer. The aging process of transformer is analyzed by various diagnosis method such as DC voltage-current test, $tan{\delta}$, Meggar measurement, winding temperature and etc.

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Analysis of the Ultrasonic Signals by the Partial Discharge and Noises from the Transformer (변압기 부분방전과 노이즈에 의한 초음파 신호 분석)

  • Gwon, Dong-Jin;Jeong, Gil-Jo;Jin, Sang-Beom;Gwak, Hui-Ro
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.8
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    • pp.354-360
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    • 2002
  • The partial discharge detecting method using the ultrasonic technique has been investigated to monitor the insulation ageing of a transformer. However, the result of the studies on the ultrasonic technique for detecting of partial discharge in the operating transformer is not enough yet to utilize. This paper presents the analysis of the ultrasonic signals due to the partial discharge in a model transformer and the corona in air at a shielded high voltage room. In addition, the ultrasonic signals due to the vibration from the core, operation of the cooling pump, the fan and the OLTC at the 345㎸ power transformer, were analyzed and corona noise from overhead transmission line in 345㎸ substation were measured to remove the electrical and mechanical noises from the transformer. Furthermore, ultrasonic signal due to the partial discharge in the 154㎸ power transformer with in $C_2$$H_2$ gas warning condition was measured. The inside of the transformer was examined with care. which confirms the existence of the partial discharge source.

A Study on the on Line Monitoring Techniques of the Partial Discharge for Transformer (변압기 부분방전 상시 감시기법에 관한 연구)

  • 권동진;박재준
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.12
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    • pp.1032-1040
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    • 2001
  • In order to apply the partial discharge measuring technique utilizing electrical pulse to the transformer at sites, this paper describes the measuring technique obtaining only the signals due to internal partial discharge in the transformer, but the noises due to external corona which has been a major problem so far. At first, partial discharge and corona noise were simultaneously generated in the model transformer by using needle-plane electrodes and rod-sphere electrodes out of it in a high voltage laboratory, respectively. It was verified that only the partial discharge signals in the transformer could be measured by removing the noise signals from the superposed signals of partial discharges and noises on the grounding wire of the model transformer. By application to a 345kV transformer in service, it was also confirmed that the partial discharge could be on-line monitored by removing the noise signals measured by the inductance sensor on the grounding wire of a 154kV lightning arrester from the superposed signals of internal partial discharge and external corona noise measured by bushing tap coupler of the transformer.

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The Study of the Harmonic Currents Effects on the Transformer Vibration (고조파 전류가 변압기 진동에 미치는 영향에 관한 연구)

  • Kim, Su-Yeol;Kim, Yeon-Whan;Kim, Jang-Mok;Lim, Ik-Hun;Lee, Hyun
    • Journal of the Korean Society of Safety
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    • v.15 no.1
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    • pp.106-111
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    • 2000
  • EP(Electrostatic Precipitator) has been used to keep the natural environment from fly-ash in the industrial fields and operated in intermittent PEC(Pulse Energized Control) mode to improve dust-collecting efficiency. Intermittent PEC mode induces low-frequency harmonic currents into power system, therefore EP transformer vibrates. This continuous transformer vibration developes transformer abnormal audio-noise and if it is too much or operates in the region of natural frequency, transformer will be damaged in the end. EP interruption caused by transformer damage results in power generation stopped, power quality down and economic loss. Therefore, this paper explains harmonic currents and transformer vibration-core vibration, winding vibration, and proposes the measures of suppressing the vibration with EP operated in intermittent PEC mode. And this results is proposed to be used for future EP transformer design or EP control method to operate EP-concerned equipment safely keeping from system faults caused by transformer vibration.

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Characteristics of Transformer-Type SFCL according to the Connecting Methods of Secondary Coils (2차 권선의 연결방법에 따른 변압기형 초전도 한류기의 특성)

  • Cho, Yong-Sun;Park, Hyoung-Min;Chung, Soo-Bok;Choi, Hyo-Sang
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.12
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    • pp.2078-2083
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    • 2007
  • We have analyzed operating characteristics of transformer-type superconducting fault current limiter (SFCL) according to the serial or parallel connections of secondary coils with $YBa_2Cu_3O_7$ (YBCO) thin films. The turn ratio between the primary and secondary coils was 63:21. Transformer-type SFCL using a transformer with secondary winding of serial or parallel coils could reduce the unbalanced quench caused by differences of the critical current density between YBCO thin films. We found that transformer-type SFCL having serial or parallel connections induced simultaneous quench between the superconducting units. The limiting current in the transformer-type SFCL with a parallel connection was lowered to 30 % compared to the SFCL with a serial connection. In the meantime, when the currents generated in the superconducting units were similar, the voltage value in the parallel connection was 60 % as low as that in the serial connection. However, the voltage generated in the primary winding was some higher. In conclusion, we found that transformer-type SFCL with parallel connection of secondary coils was more effective in fault current limiting characteristics and in the reduction of the consumption power for superconducting units compared to those of the transformer-type SFCL with serial connection of secondary coils.