Design of an LCL-Filter for Three-Parallel Operation of Power Converters in Wind Turbines Hae-Gwang Jeong*, Dong-Keun Yoon**, and Kyo-Beum Lee†

Design of an LCL-Filter for Three-Parallel Operation
of Power Converters in Wind Turbines
Hae-Gwang Jeong*, Dong-Keun Yoon**, and Kyo-Beum Lee†
†*Department of Electrical and Computer Engineering, Ajou University, Suwon, Korea
**Research Group, LG Innotek Co., Ltd., Ansan, Korea

This paper proposes a design scheme for an LCL-filter used for the three-parallel operation of the power converters in high-capacity wind turbines. The designs of the power devices and grid connected filter are difficult due to the high level voltages and currents in huge-capacity wind turbines. To solve these problem, this paper presents three-parallel operation and LCL-filter design techniques optimized by parallel operation. Furthermore, the design of an inverter side inductance of the LCL-filter is discussed in detail considering the switching modulation method. Simulation and experimental results demonstrate the validity of the designed filter and wind turbines.
LINK
http://jpe.or.kr/archives/view_articles.asp?seq=744
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GRAU DE PROTEÇÃO IP PARA EQUIPAMENTOS ELÉTRICOS

Parallel Operation of Three-Phase Four wire UPS using Droop Control ( Hyunseob Kim․Jungho Han․Joong-Ho Song )

Parallel Operation of Three-Phase Four wire UPS using Droop Control

* Main author：Dept. of Railway Electrical and
Signaling Engineering, Seoul National
University of Science and Technology,
Candidate of MS
** Corresponding author：Dept. of Electrical and
Information Engineering, Seoul National
University of Science and Technology,
Professor
Tel：02-970-6415, Fax：02-978-2754
E-mail：joongho@seoultech.ac.kr
 Abstract
A new droop control method which can be applied to 3-phase 4-wire uninterruptible power supply is
proposed in this paper. The droop control method for parallel operation is very attractive one as UPS
parallel operation can be carried out without any data communication devices provided among UPS
systems connected, but it reportedly shows a PnP(plug-and-play) problem. A basic reason why a
circulating current could flow among parallel-connected UPS systems is clearly investigated as well
when droop-controlled-ups systems are operated in the manner of PnP. The proposed algorithm is
deduced from the investigated result and is basically structured to keep a balanced frequency and
balanced voltage profile against power variation. This paper shows that balanced parallel operation of
droop control method can be obtained under unbalanced load as well as balanced load conditions .when PnP operation is needed and load change occurs.
LINK
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=JMJGCE_2013_v27n4_88

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Power Factor Correction of Single-phase Boost Converter for Low-cost Type UPS Configuration Jong-Chan Park․Jin-Geun Shon

Power Factor Correction of Single-phase Boost Converter for Low-cost Type UPS Configuration 박 종 찬*․손 진 근† (Jong-Chan Park․Jin-Geun Shon) The Transactions of the Korean Institute of Electrical Engineers Vol. 62P, No. 3, pp. 145～150, 2013

 Abstract -A novel AC to DC PWM converters with unity input power factor are proposed to overcome the above shortcoming. The main function of these converters is to shape the input line current to force it exactly in phase with the input AC voltage. Therefore, the input power factor can be improved to near unity and the input current harmonics can be eliminated. In this paper, half-bridge converter with two active switches and two diodes are utilized for low-cost type UPS configuration. By having only two semiconductors in the current path at any time, losses can be reduced over the conventional boost topology. Also, this converter provides controllable dc-link voltage, high power factor, and low cost type converter by simple power circuits. Simulation results show that the proposed half-bridge converter/inverter control technique can be applied to single-phase low-cost type UPS systems successfully.
LINK
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=DHJGHA_2013_v62n3_145

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LLC Resonant Converter design for Uninterruptible Power Supply Battery Discharger

LLC Resonant Converter design for Uninterruptible Power Supply Battery
Discharger
Kwang-Min Yoo1, Seung-Joo Kim1, Kyoung-Dong Kim1, Seung-Hee Park1, Yong-Seop Byeon,
Seung-Beom Lim, and Jun-Young Lee

Abstract - An Uninterruptible Power Supply(UPS) is a system designed to deliver energy during accidents that the AC mains is out of its acceptable limits, without interruption of power flow through the load. Battery Discharger is the device to supply high quality power to the Inverter, when accidents occur, such as Power Failure. The Battery Discharger should have a fast response characteristics. The LLC resonant converter for UPS battery discharger is proposed. The proposed Battery Discharger offers substantial improvements in efficiency, size and cost. The proposed Battery Discharger of UPS approach is a good solution for high power applications above KW. To verify the validity of proposed Battery Discharger, simulations and experiments are carried out. Paper number: TKPE-2013-18-3-6 ISSN: 1229-2214 ✝ Corresponding author: pdpljy@mju.ac.kr, Dept. of Electrical Engineering, MyongJi University Tel: +82-31-330-6357 Fax: +82-31-330-6977 1 Dept. of Electrical Engineering, Myongji University 2 Eon Co., Ltd Manuscript received Oct. 5, 2012; accepted Feb. 20, 2013 ─ 본 논문은 2012년 전력전자학술대회 외부장학금 수혜논문임
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 http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=JRJJC3_2013_v18n3_240

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