• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.540-541
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• 2013

본 논문에서는 PSCAD/EMTDC를 이용하여 MMC(Modular Multi-level Converter)를 기반으로 한 HVDC 시스템 시뮬레이션 모델을 개발하였다. 스위칭 레벨의 동작을 분석하기 위해 각 ARM당 10개의 SM(Sub-Module)과 2개의 RM(Redundancy-Module)을 구성하여 11-level의 MMC 출력 전압을 형성하였다. SM 동작시 발생하는 전압 불균등 문제를 해결하기 위하여 밸런싱 알고리즘을 적용하였으며, SM의 출력 전압에 발생하는 Ripple을 고려하여 Capacitor의 용량을 설계하고 이를 검증하였다. 또한 시뮬레이션을 이용하여 HVDC 성능 분석과 MMC의 성능개선을 위한 순환전류 알고리즘 및 Redundancy 투입 알고리즘을 구현하고 그 결과를 확인하였다.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.890-892
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• 1998

TCSC is a FACTS device that can control the active power flow and current of transmission lines by adjusting line impedances. In this paper, we study the effect of TCSC on power transfer capability. A static model of TCSC is implemented in the continuation power-flow(CPF) Program and the power transfer capability is measured using the CPF. The site of TCSC is selected to increase power transfer capability by the sensitivity information provided from the CPF. The effect of TCSC with various control mode is tested in IEEE New England 30-bus system.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.795-797
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• 2000

The analysis model of voltage-sag compensator is achieved in synchronous rotating coordinates. Inverter's LC filter and DC-link capacitor is designed in order to reduce THD of output voltages and LC filter's size And the circuit parameters of voltage-sag compensator is presented for 3-phase Customer.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.571-573
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• 1995

This paper presents a method for optimal dispatch which minimizes transmission losses and improves voltage profile of power systems using genetic algorithm based on the mechanism of natural genetics and natural selection. The constraints are VAR sources(transformer tap, generator voltage magnitude and shunt capacitor/reactor), load bus voltages and generator reactive power. Real variable-based genetic algorithms which can save coding times and maintain the accuracy are applied for optimal dispatch of reactive power. The genes of genetic algorithm consisted of integers for considering discrete VAR sources. A efficient operator for crossover is proposed to consider the effect of close genes. The algorithm proposed can apply to problems for large scale power systems with multi-variables and complex nonlinear functions efficiently. The proposed method is applied to IEEE 30 buses model system to show its effectiveness.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.493-498
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• 2003

Harmonic current originating from electric locomotives can be magnified due to the impedance characteristics of power supply circuit and bring about various problems. That is, electromagnetic interference with communication lines, operational trouble in signaling, overheat and/or vibration in power capacitor, mis-operation in protection relay and so on. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. For these reasons, this study propose a new approach to model and to analyse traction power feeding system focused on system response to current and voltage harmonic(PART I ). Measurements of harmonics are also performed for railway power supply systems under normal operation. Spectrum and distortion analyses in measurement data are variously described in PART II

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.499-504
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• 2003

Harmonic current originating from electric locomotives can be magnified due to the impedance characteristics of power supply circuit and bring about various problems. That is, electromagnetic interference with communication lines, operational trouble in signaling, overheat and/or vibration in power capacitor, mis-operation in protection relay and so on. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. For these reasons, this study propose a new approach to model and to analyse traction power feeding system focused on system response to current and voltage harmonic(PART I ). Measurements of harmonics are also performed for railway power supply systems under normal operation. Spectrum and distortion analyses in measurement data are variously described in PART II

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.8
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• pp.420-426
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• 2003

This paper deals with the effect of exciter parameters on the torsional stress of turbine-generator. The excitation system effects on the AC network stability and the turbine-generator stress. However. it, until now, have not reported that any parameter among exciter parameters is related to the stability and the stress. In order to verify those CIGRE HVDC model was used. Since the AC network with HVDC has the voltage stability problem due to big capacitor, the worst condition to analyze the stress can considered. The EMTDC program is used for the simulation studies.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.945-947
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• 2003

Various kinds of practical machines using single phase induction motor(SPIM) are necessary to control speed and torque. In particular, capacitor-run type SPIM has constitutional characteristics, the motor torque is changed by auxiliary capacitance variation. In this study, we manifest equivalent model having more simplicity, and study the relation between torque and capacitance value of SPIM. And analyze Magnetic vibration for FEM(Finite Element Method) simulation. Also, We design the experimental controller which is able to speed control accurately by phase angle control of AC input voltage. Through the simulation and experimental results, we confirmed validity of this study.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.11
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• pp.720-728
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• 2000

This paper describes the calculation of the equivalent circuit parameters and the characteristic analysis of a capacitor-run type single-phase induction motor by means of the finite element method in coupled with the conventional equivalent circuit model. The circuit parameters of the stator are calculated form the lumped parameter and the slot leakage reactance of the rotor with the closed slot can be obtained by the use of slot pitch boundary condition. From the analysis result this combined equivalent circuit and finite element method which is used slot pitch boundary condition is compared with the experimental results, the validity of the method is proved.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.2
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• pp.119-126
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• 2010

An integrated magnetic (IM) transformer is proposed for a phase shifted full bridge (PSFB) converter with zero voltage switching (ZVS). In a proposed IM transformer, the transformer is located on the center leg of E-core and the output inductor is wound on two outer legs with air gap. The proposed IM transformer is analyzed by using the magnetic capacitor model. For reducing the core size, EE core is redesigned. The proposed IM transformer is experimentally verified on a 1.2 kW prototype converter. The converter efficiency with the proposed IM transformer is about 93 % at full load and its volume size can be reduced. It can be expected that the power density can be largely increased with the proposed IM transformer.