• Title/Summary/Keyword: Power main transformers

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A Study on the Application of SFCL on 22.9 kV Bus Tie for Parallel Operation of Power Main Transformers in a Power Distribution System (배전계통에 전력용 변압기 병렬운전시 22.9 kV SFCL Bus Tie 적용방안에 관한 연구)

  • On, Min-Gwi;Kim, Myoung-Hoo;Kim, Jin-Seok;You, Il-Kyoung;Lim, Sung-Hun;Kim, Jae-Chul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.1
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    • pp.20-25
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    • 2011
  • This paper analyzed the application of Superconducting Fault Current Limiter (SFCL) on 22.9 [kV] bus tie in a power distribution system. Commonly, the parallel operations of power main transformers offer a lot of merits. However, when a fault occurs in the parallel operation of power main transformer, the fault currents might exceed the interruption capacity of existing protective devices. To resolve this problem, thus, the SFCL has been studied as the fascinating device. In case that, Particularly, the SFCL could be installed to parallel operation of various power main transformers in power distribution system of the Korea Electric Power Corporation (KEPCO) on 22.9 [kV] bus tie, the effect of the resistance of SFCL could reduce the increased fault currents and meet the interruption capacity of existing protective devices by them. Therefore, we analyzed the effect of application and proposed the proper impedance of the R-type SFCL on 22.9 [kV] bus tie in a power distribution system using PSCAD/EMTDC.

Design requirements for Generator Circuit Breaker (원자력발전소의 발전기차단기 설계요건 검토)

  • Chi, Mun-Goo;Han, Sung-Heum
    • Proceedings of the KIEE Conference
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    • 2001.07a
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    • pp.371-373
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    • 2001
  • Main functions of Generator Circuit Breaker(GCB) is cut the generator off from the main transformers and the aux. transformers when plant trip or startup. In this paper, the design requirements For GCB of nuclear power plant is examined. NRC presented the area of review, acceptance criteria and review procedures of GCB in the SRP(Standard Review Plan). In Korea, APR1400 adapted the GCB in main power system.

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A New Phase Shift Full Bridge Converter with Serially Connected Two Transformers (직렬 연결된 두 개의 트랜스포머를 갖는 새로운 위상 천이 풀 브릿지 컨버터)

  • 구관본;김태성;문건우;윤명중
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.5
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    • pp.443-452
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    • 2002
  • A new phase shift full bridge (PSFB) converter with serially connected two transformers for telecommunication equipments of several hundred watts is proposed. The main features of the proposed converter are a wide input voltage range, an easiness to meet the requirement for zero voltage switching (ZVS) condition at a light load, and a small output voltage ripple. Furthermore, the serially connected two transformers can replace both a main transformer and an output inductor since the two transformers act as not only a main transformer but an output inductor by turns. Therefore, there is no need to use an output inductor, then the proposed converter features high power density. A mode analysis, design equations through a large signal modeling, and experimental results are presented to verify the validity of the proposed converter.

Magnetostriction Modeling for the Analysis of Electromagnetically Induced Vibration of Transformers (전자기력에 의해 유도된 변압기의 진동 해석을 위한 자왜 현상 모델링)

  • Yoo, Seong-Yeol;Lee, Jun-Sin;Lee, Uk-Ryun;Noh, Myoung-Gyu
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.1
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    • pp.108-114
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    • 2008
  • Recently, there have been several instances that the nuclear power plants were shut down due to the mechanical faults in the main transformer of the plants. These mechanical faults are primarily originated from the electromagnetically induced mechanical vibrations. Magnetostriction is identified to be the main cause of the mechanical vibration after analyzing the vibration data of the main transformers in nuclear power plants. In this study, we derived a mathematical model of the magnetostriction based on the Jiles-Atherton hysteresis model. The validity of the model is checked by matching the simulations with the experimental observations. The magnetostriction model used in this study will be the first step toward developing a design tool far the transformers that have minimal mechanical vibrations and are robust to mechanical faults.

A New Phase Shift Full Bridge Converter with Serially Connected Two Transformers (직렬 연결된 두개의 트랜스포머를 갖는 새로운 위상천이 풀 브릿지 컨버터)

  • Koo Gwan-Bon;Kim Tae-Sung;Moon Gun-Woo;Youn Myung-Joong
    • Proceedings of the KIPE Conference
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    • 2002.07a
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    • pp.370-373
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    • 2002
  • A new phase shift full bridge converter(PSFB) with serially connected two transformers is proposed. It is well suited for applications in the communication equipment of a few hundred watts. The main features of the proposed converter are a wide input voltage range, an easiness to meet the requirement for zero voltage switching (ZVS) condition at a light load, and a small output voltage ripple. Furthermore, it features high power density since serially connected two transformers can replace both a main transformer and an output inductor. A mode analysis and experimental results are presented to verify the validity of the proposed converter.

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Analysis of a Harmonics Neutralized 48-Pulse STATCOM with GTO Based Voltage Source Converters

  • Singh, Bhim;Saha, Radheshyam
    • Journal of Electrical Engineering and Technology
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    • v.3 no.3
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    • pp.391-400
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    • 2008
  • Multi-pulse topology of converters using elementary six-pulse GTO - VSC (gate turn off based voltage source converter) operated under fundamental frequency switching (FFS) control is widely adopted in high power rating static synchronous compensators (STATCOM). Practically, a 48-pulse ($6{\times}8$ pulse) configuration is used with the phase angle control algorithm employing proportional and integral (PI) control methodology. These kinds of controllers, for example the ${\pm}80MVAR$ compensator at Inuyama switching station, KEPCO, Japan, employs two stages of magnetics viz. intermediate transformers (as many as VSCs) and a main coupling transformer to minimize harmonics distortion in the line and to achieve a desired operational efficiency. The magnetic circuit needs altogether nine transformers of which eight are phase shifting transformers (PST) used in the intermediate stage, each rating equal to or more than one eighth of the compensator rating, and the other one is the main coupling transformer having a power rating equal to that of the compensator. In this paper, a two-level 48-pulse ${\pm}100MVAR$ STATCOM is proposed where eight, six-pulse GTO-VSC are employed and magnetics is simplified to single-stage using four transformers of which three are PSTs and the other is a normal transformer. Thus, it reduces the magnetics to half of the value needed in the commercially available compensator. By adopting the simple PI-controllers, the model is simulated in a MATLAB environment by SimPowerSystems toolbox for voltage regulation in the transmission system. The simulation results show that the THD levels in line voltage and current are well below the limiting values specified in the IEEE Std 519-1992 for harmonic control in electrical power systems. The controller performance is observed reasonably well during capacitive and inductive modes of operation.

Design of A High Energy Density Pulse Transformer (고 에너지 밀도 펄스 변압기 설계)

  • Nam, S.H.;Park, S.S.;Ha, K.M.
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2186-2188
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    • 1999
  • A high frequency and energy density pulse transformer is a critical component of a high voltage power supply in a traveling wave tube (TWT) amplifier system. In this paper, processes of design, manufacturing, and test of the transformer are discussed. Primary voltage of the transformer is 240 V. The transformer secondary have two outputs which are 4100 V (Helix) and 2050 V (Collector). Total output power is 860 W. Normal operating frequency of the transformer is 10 kHz. In high energy density pulse transformers, temperature rise is a main problem during its operation. From our study, it was found that resonant current due to leakage inductance and stray capacitance was the main cause of temperature rise. This happens because of the inherently high turn-ratio in high voltage transformers. Solutions to reduce stray components are presented.

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A Study on the Vibration Reduction of the SPR(sudden pressure relay) in the Single Phase Main Power Transformers(345kV) (단상(345kV) 주변압기 압력 계전기의 진동절연에 관한 연구)

  • Park, Chul-Jun;Lee, Seong-Wook;Choi, Won-Ho;Lee, Wook-Ryun;Kweon, Ki-Young
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.5
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    • pp.486-491
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    • 2010
  • In this paper, it is identified that high-level vibration of the single phase main power transformers shut down due to the mechanical fault. vibration sources of the SPR in the transformer's are identified and the SPR vibrations are reduced by structural modification. For vibration characteristic identification, vibration signals were measured with an accelerometer when the transformer is driving. These signals are presented in a FFT analysis in order to find the dependency of frequency components on the transformer. From finite element analyses and some experiments, it is also found that resonances occur because the natural frequencies of the SPR exist in usual driving range. To shift the natural frequencies outside the driving range, the SPR is modified by increasing stiffness. It is verified that considerable amounts of vibration are reduced by the structural modification.

A Novel AE Based Algorithm for PD Localization in Power Transformers

  • Mehdizadeh, Sina;Yazdchi, Mohammadreza;Niroomand, Mehdi
    • Journal of Electrical Engineering and Technology
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    • v.8 no.6
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    • pp.1487-1496
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    • 2013
  • In this paper, a novel algorithm for PD localization in power transformers based on wavelet de-noising technique and energy criterion is proposed. Partial discharge is one of the main failures in power transformers. The localization of which could be very useful for maintenance systems. Acoustic signals due to a PD event are transient, irregular and non-repetitive. So wavelet transform is an efficient tool for this signal processing problem that gives a time-frequency demonstration. First, different wavelet based de-noising methods are analyzed. Then, a reasonable structure for threshold value determining and applying manner on signals is presented. Evaluated errors are good evidences for choices. Next, applying the elimination low energy frequency bands is discussed and developed as a de-noising method. Time differences between signals are used for PD localization. Different ways in time arrival detection are introduced and a novel approach in energy criterion method is presented. At the end, the quality of algorithm is verified through the different assays in lab.

The effectiveness of noise reduction devices for transformer noise control of Power Plants (발전소 변압기 소음저감 대책의 유효성)

  • Kim, Yeon-Whan;Kim, Hee-Soo;Bae, Yong-Chae;Lee, Hyun;Kim, Sung-Hwi
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1823-1828
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    • 2000
  • Power transformers, air-intakes, stacks in a combined thermal power plant are the main noise sources. Power transformer noise among them has being get a target of public complaint due to 480Hz component of its pure tone. The source is mainly magnetostrictive vibration of the transformer core. The first countermeasures was installing sound barrier on the front of transformer. However, 500Hz, center of the frequency is not reduced. This paper includes the measurements of noise level at the near resident apartment, the identification of noise transfer and the countermeasures for noise sources. Cavity resonance type of noise reduction devices was installed on enclosuring wall of transformers. As a result, the noise level from transformer is reduced about 3dB.

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