• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.212-213
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• 2016

본 논문에서는 옵셋 전압을 이용한 Random PWM 기법을 제안한다. 제안된 Random PWM은 일정 스위칭 주파수 하에서 유효벡터를 랜덤하게 위치시켜 고조파 스펙트럼(Spectrum)을 확산한다. 제안된 기법과 일반적인 PWM 기법의 고조파 스펙트럼 분포, Harmonic Spread Factor(HSF), Total Harmonic Distortion(THD)를 통해 제안된 Random PWM의 유효성을 확인하였다. 3.7kW 유도 전동기에 대한 실험을 통해 제안된 기법의 타당성을 검증하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.319-324
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• 2002

This paper describes analysis of power quality in distribute network system. EDSA is used for simulations to the teal model system. Harmonic load flow, harmonic frequency scan studies, distortion levels, and filter design method. Through this paper, minimized injected harmonic by computating the capacitor of optimal filter satisfied with IEEE Std-519 applying to distribute system are analysed through detailed simulation.

• Transactions on Electrical and Electronic Materials
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• v.14 no.6
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• pp.283-290
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• 2013

This paper illustrates the possibilities of using the program ATP-Draw (Alternative Transient Program) for the modeling of power networks to study power quality problems with highly detailed analyses. The Program ATP-Draw is one of the most widespread and oldest programs. A unique characteristic of this program is its public domain and the existence of forums and study committees where new application cases and modification are presented and shared publicly. In this paper, to study the propagation of harmonics through a power network, a part of an industrial power network was modeled. The network contains different types of electric components, such as transformers, transmission lines, cables and loads, and there is a source of harmonics that injects $3^{rd}$, $5^{th}$, $7^{th}$, $9^{th}$ and $11^{th}$ harmonic currents into the network, causing a distortion of the wave form of the currents and voltages through the power network.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.257-262
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• 2009

Capacitor is basically used for the power-factor compensation and sometimes as the passive filter to reduce harmonics of nonlinear load. Since the impedance of capacitor is inversely proportional to the frequency. The harmonic current may result in the problems of voltage distortion and resonance. Capacitor has easily fall under by two harmonic components, a nonlinear load and a distorted utility voltage. The amplified harmonic current and voltage may damage power capacitor. Hence the pre-investigation of harmonic is needed before designing and application the power factor for reducing fault rate. In this paper, we analyzed that voltage and current with harmonics components act on the capacitor under the resonance condition. we concluded that both voltage and current harmonics have an bad effect on the capacitor and current harmonics is a bitter rather than effect by voltage harmonics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1100-1103
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• 2004

The paper presents the results of using the fundamental and the low frequency harmonic components of leakage current to study aging of EPDM insulator for contaminated condition by kaolin. The largeer the leakage current during 200ms, the higher harmonic component at 60hz. The harmonic component at 60hz and the odd order harmonics is increase relation without Kaolin Conent. Arcing on the surface was always associated with distortion in the leakage current; hence the low frequency components of the leakage currnent can be used as a means to evaluate the surface degration. Both the fundamental and 3rd & 5th harmonics increase dry-band activity.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.782-787
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• 2005

Magnitude of generated harmonic currents along with the operation of AC traction has nonlinear characteristics, and generated harmonic currents for high speed traction are more and more in high speed railroad(HSR) systems, especially. This paper presents probabilistic approximation method for the harmonic currents analysis about the operating speed of AC traction. To use probabilistic method for HSR system, probability density function(PDF) for collected operating speed based measure data is calculated. Mean and variance of harmonic currents of single traction are obtained based on the operating speed PDF and electrical traction model. The results of Monte Carlo Simulation(MCS) are in well accordance with the experimental and analytic methods. The harmonics of different number of trainloads are systematically investigated. It is assessed by the total demand distortion(TDD) for the HSR system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.265-266
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• 2008

The interest on harmonics which is one of the matters related with power quality problem is not limited in only the system where the large scale industrial load is connected. The harmonics phenomenon not only causes the malfunction of devices, but also lowers the energy efficiency of power system. This paper focuses on the harmonic analysis process to establish the harmonic mitigation method, considering the harmonics distortion as a major cause to reduce the energy efficiency of a skyscraper. A system diagram of building is modelled with PSCAD simulator. Based on the harmonic analysis results of it, the electrical locations with the high priority to install the mitigating devices are selected. Finally, the result of PSCAD simulations and the site-measured data are compared, verifying that they reach a common conclusion.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.754-755
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• 2008

This paper presents a method for reducing the Total Harmonic Distortion(THD) of line-line back_EMF of the IPMSM with distributed winding under the no-load condition. Firstly, the specific harmonic components of line-line back EMF are reduced considering with winding factor. Secondly, THD of line-line back EMF is minimized according to change of pole angle using by Space harmonic Analysis. Finally, the optimal design for minimizing the THD is conducted using response surface methodology with finite element analysis. The validity of the design method dealt with in this paper is demonstrated by comparison between the THD of optimal model and initial model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2161-2166
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• 2008

This paper deals with a Z-source active power filter(Z-AFU) for mitigation voltage THD(total harmonic distortion) due to voltage harmonic propagation(amplification) in 6.6kv power distribution system. Bus voltage harmonic signal is detected by 60Hz butterworth BPF(band pass filter). As an ESS(energy storage system) of the proposed system, PEM fuel cells(Ballard NEXA, 1.2kw) is employed. Test results based on PSIM(power electronics simulation tool) validate the proposed approach.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.35-41
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• 2007

This paper presents the results of investigating harmonic levels on medium voltage motors at loading conditions in air separation plant. The essential results of the measurements of the medium voltage motor harmonics are summarized in the values for the total harmonic distortion (THD). Motors loading case is used to assess the current and voltage harmonic distortions. Proper system analysis is important when adding a new motor starting and controlling the equipment. With the result of the paper it is possible to suggest the most appropriate starting and control method. Two medium voltage motors of air separation unit measurement results and simulations are summarized. Both current and voltage harmonic distortions are fitted by using a linear and exponential regression model. The prediction of THD values can be used for this kind of process for future planning by utilities.