• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권2호
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• pp.103-110
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• 2003

With significant development of power electronics technology, the proliferation of nonlinear loads such as static power converters has deteriorated power quality in power transmission and distribution systems. Notably, voltage harmonics resulting from current harmonics produced by the nonlinear loads have become a serious problem in many countries. Many photovoltaic power generation systems installed in building systems have harmonics that are the worst object for distribution systems as a utility interactive system, and it tends to spread out continuously. Proposed and implemented in this paper is a multi-function inverter control strategy that allows a shunt active filter function to the power inverter of the photovoltaic power generation system established on a building system. The effectiveness of the proposed system is demonstrated through the simulation of a hypothetical power system using PSCAD/EMTDC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.89-91
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• 1999

The use of electronic power unit essentially result in serious problems by harmonics. To reduce the effect by harmonics, we propose passive filter system which can control each harmonic filters individually. So, additional devices to detect and analyze harmonics were installed to filter system. According to measured data in the field, we calculated the values of filter components and verified them by computer simulation. After installation of filter system in the field, we could reduce harmonics and improve power factor.

• Journal of electromagnetic engineering and science
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• 제6권3호
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• pp.171-175
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• 2006

In this paper, a new semi-lumped low-pass filter with three finite attenuation poles at stopband is presented. The new structure is composed of a pair of symmetrical parallel coupled-line and a shunted capacitor. With this configuration, three finite attenuation poles can be available for 2nd, 3rd, and 4th harmonics suppression. The research method is based on transmission-line model for tuning the attenuation poles. In order to examine the feasibility of the proposed structure, a low-pass filter based on microstrip structure with harmonics suppression is designed, fabricated, and measured. The experimental results of the fabricated circuit agree well with the simulation and analytical ones.

• Journal of Power Electronics
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• 제16권3호
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• pp.960-969
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• 2016

High-power three-level voltage-source converters are widely utilized in high-performance AC drive systems. In several ultra-power instances, the harmonics on the grid side should be reduced through multiple rectifications. A combined harmonic elimination method that includes a dual primary-side series-connected winding transformer and selective harmonic elimination pulse-width modulation is proposed to eliminate low-order current harmonics on the primary and secondary sides of transformers. Through an analysis of the harmonic influence caused by dead time and DC magnetic bias, a synthetic compensation control strategy is presented to minimize the grid-side harmonics in the dual primary side series-connected winding transformer application. Both simulation and experimental results demonstrate that the proposed control strategy can significantly reduce the converter input current harmonics and eliminates the DC magnetic bias in the transformer.

• 대한전기학회논문지
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• 제41권1호
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• pp.24-31
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• 1992

A 24 pulse current source inverter for reducing the harmonics in output currents is presented in this paper. The proposed system operates a 24 pulse inverter by adding only tap changing circuit which consists of several taps and static switching elements to the 12 pulse inverter, which is the double connected 3 phase 6 pulse inverter with an auto transfomer. Also to optimize the effectiveness of the harmonic reduction, the optimum turn ratio and tap changing control angle of auto transfomer are decided by digital simulation and its validity is verified with experiment. And under the optimum condition, it is clarified that the harmonics components involved in the output current of the proposed inverter are nearly equal to those of the conventional 24 pulse inverter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1236-1238
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• 2000

This paper considers the problem of eliminating harmonics in the inverter output waveforms. The approach is based on the minimization of the current harmonics in the induction motor by space vector modulation method. Reference voltage is compensated with injection of controlled current harmonics which are calculated to reduce current harmonics through sampled current harmonic analyzing algorithm. The theoretical analysis is carried out using computer simulation. It is verified that proposed SVM technique could reduce current harmonic component and improve THD.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.305-307
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• 1996

Because most LIM is driven by inverter, input voltage is involved with the time harmonics. Therefore the equiLlQ/ent circuit for an inverter-fed LIM has to be modified to represent every harmonics present in supply voltage. This paper analyzes the characteristics and loss of LIM to construct the equivalent circuit for each time harmonics through the static test and theoretical analysis. To make an analysis of nonsinusoidal supply waveforms, it is developed the simulation program to calculate the RMS, peak value and THD for any waveforms expressing Fourier series.

• Journal of Power Electronics
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• 제15권2호
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• pp.497-503
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• 2015

This paper analyses the harmonic pollution to power grids caused by several high-power rectifiers, summarizes the requirements for rectifiers in suppressing grid-side current harmonics and optimizes a new-type of current source PWM rectifier with a hybrid switch. The rectifier with a hybrid switch boasts significant current characteristics and cost advantages in the high-power area. To further enhance the working frequency of the current source rectifier with a hybrid switch for suppressing grid-side harmonics and reducing the inductance size, this paper proposes an optimal control strategy based on space vector. It also verifies that the optimal control strategy based on space vector can reduce the total harmonic distortion of the grid-side current of the rectifier with a hybrid switch via circuit simulation and experimental results.

• ETRI Journal
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• 제44권2호
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• pp.260-273
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• 2022

This study presents a novel multilayer structure of parallel coupled-line bandpass filtercentered at 2.42 GHz with a fractional bandwidth value of approximately 19.4%. The designed filter can suppress harmonics with an appropriate frequency response by incorporating different techniques based on the multilayer technique. A combination of different techniques such as radial microstrip stubs and defected ground structure (DGS) and defected microstrip structure techniques are employed to suppress harmonics up to 5f₀. These techniques are used in two layers to suppress up to 5f₀. In addition, in this study, the effects of different parameters, such as the width of slot-line DGS, the angle of diagonal line slots in the upper layer, and the air gap between the two layers on the filter performance, are investigated. To verify the correct circuit operation, the designed filter is implemented and tested. The measurement results of the proposed filter are compared with the simulation results.

• 해양환경안전학회지
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• 제21권6호
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• pp.770-777
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• 2015

본 논문에서는 전동기 구동장치를 선정하여 리액터 용량 및 종류, 부하의 크기에 따라 고조파 왜형률 변화추이를 검토하여 선박 및 해양플랜트에 적용 가능한 최적의 용량선정 근거를 마련하였다. AC라인 리액터와 DC링크 리액터는 가변주파수 구동장치 입력전류의 고조파를 크게 저감시키는 역할을 하며, 동일한 효과를 얻기 위한 DC링크 리액터의 인덕턴스가 AC라인 리액터 인덕턴스의 약 1.7배가 되어야 한다는 것을 시뮬레이션을 통하여 고찰하였다. 소프터웨어 PSIM을 활용하여 각 상황에 따른 전류 고조파 왜형률을 분석하였다.