• 한국정보통신학회논문지
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• 제16권10호
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• pp.2230-2236
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• 2012

현재 대형선박에서 다이오드 정류기를 이용한 AC-DC 전력변환장치를 주로 사용하고 있으며 이는 총고조파왜형율을 줄이기 위하여 다중펄스를 출력할 수 있는 상치환변압기가 추가적으로 설치되어야 한다. 이 경우 상치환변압기의 설치로 인해 공간적, 경제적 손실이 발생한다. 본 논문에서는 LNG 운반선 등과 같은 대형선박에서 현재 운용중인 다이오드 정류기를 대신하여 SCR, IGBT등의 소자를 이용하는 새로운 능동형 정류방식을 제안하여 저전압 전원의 이용이 가능하고 전력선 부하에 의해 발생하는 고조파 발생을 줄이며 또한, 기존의 방식에서 사용하는 상치환변압기를 제거하여 경제적인 이점도 얻고자 하였다. 현재 대형선박에서 운용중인 전기추진시스템에 제안한 시스템을 시뮬레이션 한 결과, 추진전동기 입력 전류 및 전압 파형에 포함된 총고조파왜형율이 개선됨을 나타내었다.

• 대한전자공학회논문지TC
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• 제37권3호
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• pp.43-48
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• 2000

본 논문에서는 본딩와이어를 이용한 수직형 트랜스포머를 제안하고, FEM (Finite Element Method)을 이용한 완전 해석법 (Full-waye analysis)으로 20 GHz 까지 해석하였다 나선형 트랜스포머와 전기적인 특성을 비교하였고, 구해진 S-파라미터로부터 상호 인덕턴스를 추출하였다. 본딩와이어를 이용한 트랜스포머는 낮은 삽입손실을 가지며, 본딩와이어의 대부분이 손실이 없는 공기중에 위치하므로 정전용량 및 유전 손실을 줄일 수 있는 구조이다. 또한, 자동화된 와이어 본딩 장비를 이용하여 쉽게 제작할 수 있다. 본딩와이어를 이용한 트랜스포머는 Impedance matching, Phase shifting등 다양한 범위에 응용되어 MMIC의 성능 향상을 이룰 것으로 기대된다.

• Journal of Power Electronics
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• 제18권6호
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• pp.1920-1929
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• 2018

In order to provide a source for nine phases suitable for 18-pulse ac to dc power, this paper proposes a new structure for a step-up asymmetrical delta-connected transformer for converting three-phase ac power to nine-phase ac power. The design allows for symmetry between the nine output voltages to improve the power quality of the supply current and to minimize the THD. The results show that this new structure proves the equality between the output voltages with $40^{\circ}-{\alpha}$ and $40^{\circ}+{\alpha}$ phase shifting and produces symmetrical output currents. This result in the elimination of harmonics in the network current and provides a simulated THD that is equal to 5.12 %. An experimental prototype of the step-up asymmetrical delta-autotransformer is developed in the laboratory and the obtained results give a network current with a THD that is equal to 5.35%. Furthermore, a finite element analysis with a 3D magnetic field model is made based on the dimensions of the 4kVA, 400 V laboratory prototype three-phase with three-limb delta-autotransformer with a six-stacked-core in each limb. The magnetic distribution flux, field intensity and magnetic energy are carried out under open-circuit operation or load-loss.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.262-263
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• 2006

This paper presents a scheme to solve the congestion problem with phase-shifting transformer(PST) and power generation using linear programming method. A good design of PST and power generation control can improve total transfer capability(TTC) in interconnected systems. This paper deals with an application of optimization technique for TTC calculation. linear programming method is used to maximize power flow of tie line subject to security constraints such as voltage magnitude and real power flow. The proposed method is applied to 10 machines 39 buses model systems to show its effectiveness.

• 전력전자학회논문지
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• 제6권1호
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• pp.21-26
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• 2001

본 논문에서는 전압원 인버터의 출력전압 파형을 개선하기 위한 새로운 이중접속 3상 전압원 인버터를 제안한다. 보조회로의 단상인버터로 리플전압을 발생시키고 이를 기존의 12-스템 인버터에 주입함으로서 12-스템 동작이 36 스템 동작으로 전환된다. 한편, 출력 측의 결합용 위상 변압기로서 커플링 리액터를 도입하여 변압기의 KVA용 량을 감소시킨다. 또한 본 방식을 포함한 전체의 정류기-인버터 시스템을 제안하고, 실험에 의해 본 방식의 타당성을 입증한다.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.65-75
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• 2016

Aiming at analyzing the power flow of the distribution systems with distribution transformer (DT) branches and PV nodes, a hybrid three-phase power flow methodology is presented in this paper. The incidence formulas among node voltages, loop currents and node current injections have been developed based on node-branch incidence matrix of the distribution network. The method can solve the power flow directly and has higher efficiency. Moreover, the paper provides a modified method to model DT branches by considering winding connections, phase shifting and off-nominal tap ratio, and then DT branches could be seen like one transmission line with the proposed power flow method. To deal with the PV nodes, an improved approach to calculate reactive power increment at each PV node was deduced based on the assumption that the positive-sequence voltage magnitude of PV node is fixed at a given value. Then during calculating the power flow at each iteration, it only needs to update current injection at each PV node with the proposed algorithm. The process is very simple and clear. The results of IEEE 4 nodes and the modified IEEE 34 nodes test feeders verified the correctness and efficiency of the proposed hybrid power flow algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2010-2012
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• 1997

A cascade multilevel voltage source inverter is introduced to apply the advanced static var compensator(ASVC) for large scale power application. This cascade M-level inverter consists of (M-1)/2 single-phase full bridges. This inverter is suitable to the flexible ac transmission systems(FACTS) including SVC, series compensation and phase shifting. It can solve the problems of conventional transformer -based multipulse inverters and multilevel diode-clamped inverters. From the simulation results, the validity of ASVC with cascade multilevel inverter is shown for high power application.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.415-418
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• 1994

In this paper, a parallel operation of two single-phase GTO PWM converters is presented. The current ripples on the primary side of the transformer can be much reduced by shifting one modulation period from the other one by a half period. Also, a simple power factor control scheme is presented by which the reactive component of converter input current is controlled. Simulations and experimental results for a laboratory system confirm the validity of the purposed algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.1925-1927
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• 1998

D-STATCON using the multilevel voltage source inverters is presented for voltage regulation and reactive power compensation in distribution system. This cascade M-level inverter consists of (M-1)/2 single phase full bridge inverter(FBI). This multilevel inverter is a natural fit to the flexible ac transmission systems(FACTS) including STATCON, SVC, series compensation and phase shifting, It can solve the problems of conventional transformer-based multipulse inverters and multilevel diode-clamped inverters. From the simulation results, the superiority of D-STATCON with cascade multilevel inverter is shown for high power application.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.223-225
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• 2005

This paper presents a scheme to solve the congestion problem using hybrid control with phase-shifting transformer(PST) and power generation in power systems. A good design of PST and power generation control can improve total transfer capability(TTC) in interconnected systems. This paper deals with an application of optimization technique for TTC calculation. The optimization method is used to maximize power flow of tic line subject to security constraints such as voltage magnitude and real power flow. The proposed method is applied to 10 machines 39 buses model systems to show its effectiveness.