• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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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

• 한국철도학회논문집
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• 제7권1호
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• pp.60-64
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• 2004

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.

• 대한전자공학회논문지
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• 제26권11호
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• pp.1728-1735
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• 1989

A design procedure for microstrip bandpass filters using step impedance resonators (SIR's) and tapped input/output to a conventional parallel coupled line bandpass filter is presented. The filter configuration consisting of both half-wavelength and SIR's suppreses to spurious resonance response near the second harmonics, while tapping techniques offer benefit in situations where the impractical. The measured frequency responses of the designed filter are in close agreement with the computed responses.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1714-1728
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• 2016

This paper presents improved harmonics extraction based on Adaptive Linear Neuron (ADALINE) algorithm for single phase photovoltaic (PV) shunt active power filter (SAPF). The proposed algorithm, named later as Improved ADALINE, contributes to better performance by removing cosine factor and sum of element that are considered as unnecessary features inside the existing algorithm, known as Modified Widrow-Hoff (W-H) ADALINE. A new updating technique, named as Fundamental Active Current, is introduced to replace the role of the weight factor inside the previous updating technique. For evaluation and comparison purposes, both proposed and existing algorithms have been developed. The PV SAPF with both algorithms was simulated in MATLAB-Simulink respectively, with and without operation or connection of PV. For hardware implementation, laboratory prototype has been developed and the proposed algorithm was programmed in TMS320F28335 DSP board. Steady state operation and three critical dynamic operations, which involve change of nonlinear loads, off-on operation between PV and SAPF, and change of irradiances, were carried out for performance evaluation. From the results and analysis, the Improved ADALINE algorithm shows the best performances with low total harmonic distortion, fast response time and high source power reduction. It performs well in both steady state and dynamic operations as compared to the Modified W-H ADALINE algorithm.

• 조명전기설비학회논문지
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• 제21권3호
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• pp.96-106
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• 2007

동기발전기의 출력전압은 여자 시스템의 계자 전류 제어에 의해 일정하게 유지된다. 현재 대부분의 발전기 여자기의 여자전류제어를 위해 사용되는 AVR 시스템의 AC/DC 컨버터 부는 출력전압 제어가 가능한 위상제어 컨버터나 출력전압을 제어할 수 없는 다이오드 정류기와 DC/DC 컨버터를 결합하여 사용하고 있다. AC/DC 전력 변환장치로서 위상제어 컨버터나 출력전압을 제어할 수 없는 다이오드 정류기의 경우, AVR시스템의 전력을 공급하는 모선의 역률저하 및 저차 고조파 발생의 문제점을 야기 시키게 된다. 본 논문에서는 동기발전기의 여자전류 제어를 위해 사용되는 AVR 시스템 설계에 있어 단위역률 동작이 가능한 Boost형 AC/DC 컨버터와 모선의 부하변동에 속응성 있게 동작할 수 있는 전류 제어형 Buck 컨버터를 결합한 2단 3상 PWM AC/DC 컨버터에 대해 연구하였다. 제안된 AC/DC 컨버터를 시뮬레이션 한 결과 Boost 컨버터의 경우 단위 역률 동작 및 출력 DC 전압의 Boost 동작이 원할히 이루어졌으며, Buck 컨버터의 경우 다른 위상제어 컨버터에 비해 응답시간이 개선되었음을 알 수 있었다.

• 전력전자학회논문지
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• 제7권2호
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• pp.137-148
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• 2002

직접토크제어 기법은 벡터제어계 설계 및 운전시 요구되는 복잡한 좌표변환과 전류제어루프가 불필요하며, 빠른 토크응답을 얻을 수 있기 때문에 벡터제어 기법에 버금가는 유도전동기의 고성능 제어기법으로 인정되고 있다. 본 논문에서는 직접토크제어 기법 적용시 중요한 어려움의 하나로 지적되고 있는 저속영역에서의 자속저하 및 이로 인한 전류고조파의 증가 문제를 해결하기 위한 대책으로서 퍼지 가변 스위칭섹터 기법과 이 기법의 실시간 적용을 위한 실현방법을 제안하였다. 제안된 스위칭섹터 기법을 포함한 유도전동기 제어시스템의 실험적 성능을 고찰하기 위하여 DSP를 이용한 제어보드를 제작하였다. 시뮬레이션과 실험 결과는 제안된 퍼지 가변스위칭 섹터 기법을 도입함으로서 유도전동기 드라이브의 성능이 현저히 개선됨을 보여준다.

• 전력전자학회논문지
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• 제18권3호
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• pp.279-288
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• 2013

This paper proposes a improved speed control system for five-phase squirrel-cage induction motor(IM) injecting 3rd. current harmonic components with field oriented control (FOC) A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation at low frequency and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings. The produced back-electromotive force is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents. There is necessary to controlled 3rd harmonic current in order to high response characteristics. For presenting the superior performance of the proposed the speed control system, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[kW] induction motor.

• Journal of Power Electronics
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• 제18권3호
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• pp.863-870
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• 2018

The traditional power control theories for the harmonic reduction methods in multilevel inverters are found to be unreliable under unbalanced load conditions. The unreliability in harmonic mitigation is caused by voltage fluctuations, non-linear loads, the use of power switches, etc. In general, the harmonics are reduced by filters. However, such devices are an expensive way to provide a smooth and fast response to secure power systems during dynamic conditions. Hence, the Decoupled Double Synchronous Reference Frame (DDSRF) theory combined with a State Delay Controller (SDC) is proposed to achieve a harmonic reduction in power systems. The DDSRF produces a sinusoidal harmonic that is the opposite of the load harmonic. Then, it injects this harmonic into power systems, which reduces the effect of harmonics. The SDC is used to reduce the delay between the compensation time for power injection and the generation of a reference signal. The proposed technique has been simulated using MATLAB and its reliability has been verified experimentally under unbalanced conditions.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권12호
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• pp.691-700
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• 1999

This paper proposes a novel switching strategy of 1Mvar STATCON using cascade multilevel H-bridge inverter(HBI) for FACTS application. To control the reactive power instantaneously, the d-q dynamic system model is described and analyzed. A single pulse pattern based on the SHEM(Selective Harmonic Elimination Method) technique is determined from the look-up table to reduce the line current harmonics and a rotating fundamental frequency switching scheme is presented to adjust the DC voltage of each inverter capacitor at the same value. So the voltage unbalance problem between separately DC bus voltage is improved by using the proposed switching scheme. As a result, the presented inverter configuration not only reduces the system complexity by eliminating the isolation at the AC input side transformer but also improves the dynamic response to the step change of reactive power.

• Journal of Power Electronics
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• 제12권5호
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• pp.800-812
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• 2012

This paper analyses the mathematical model and control strategies of a Hybrid Active Power Filter with Injection Circuit (IHAPF). The control strategy based on the load harmonic current detection is selected. A novel control method for a IHAPF, which is based on the analyzed control mathematical model, is proposed. It consists of two closed-control loops. The upper closed-control loop consists of a single fuzzy logic controller and the IHAPF model, while the lower closed-control loop is composed of an Adaptive Network based Fuzzy Inference System (ANFIS) controller, a Neural Generalized Predictive (NGP) regulator and the IHAPF model. The purpose of the lower closed-control loop is to improve the performance of the upper closed-control loop. When compared to other control methods, the simulation and experimental results show that the proposed control method has the advantages of a shorter response time, good online control and very effective harmonics reduction.