• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.64-70
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• 2010

This paper presents how to decide on tuning factor(${\delta}$) and quality factor(Q) values in design of single-tuned passive harmonic filters. Tuning factor(${\delta}$) and quality factor(Q) values have to consider before decision on circuit parameters of passive filters. A Study on these two value has not been scarcely performed and only experienced values has been used in passive harmonic filter design by far. As a experienced value, in cases of 5th and 7th filter, tuning factor(${\delta}$) is about 0.94 and 0.96 respectively and quality factor(Q) is, in all cases of, 50. If Single-tuned passive harmonic filter will be off-tuned, performance of filter will be decreased steeply and occur to parallel resonance between system reactance and filter capacitance. Therefore During the operation, In order not to off-tuning, Filter must be tuned at former order than actual tuning order. This is the same that total impedance of filter must have a reactive impedance. In this paper, Tuning factor(${\delta}$) is decided via example of real system and using the bode-plot and then performance of filters confirmed by filter current absorbtion rate. And Quality factor(Q) decided using the bode plot in example system and then performance of filters confirmed by filter current absorbtion rate also, which makes a calculated filter parameters to satisfy IEEE-519 distortion limits. Finally, Performance of the designed passive harmonic filter using the tuning factor(${\delta}$) and quality factor(Q) values, decided in this paper is verified by experiment and shows that 5th, 7th, 9th, 11th and 13th current harmonic distortions are decreased within IEEE-519 distortion limits, respectively.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.183-184
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• 2008

In this paper, the THD(Total Harmonic Distortion) in distribution systems according to the ratio of non-linear loads was calculated and analyzed. The PCC(Point of Common Coupling) is selected to analyze THD of a 3-phase current and a neutral current.

• 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.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.184-193
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• 2021

Purpose: In this study, since the operation principle of the CCFL Exit light is the same as that of general lighting equipment, the characteristics of the CCFL Exit light were analyzed by deriving test items that can affect the characteristics of the light source from the KS standard, which is the standard for lamp ballast performance certification of general lighting equipment. Method: The samples used in the experiment were performed on products of two manufacturers for each size, such as large, medium, and small, and the test items were power factor, crest factor, and current harmonic distortion. Result: As a result of the experiment, the power factor showed a value between 0.4 and 0.6 in all samples, which was smaller than the 0.9 value set by KS. The crest factor ranged from 3.6 to 3.7 for large, 4.4 to 4.7 for medium, and 3.5 to 3.7 for small. It showed a value more than two times higher than the KS standard of 1.7. Current total harmonic distortion ranged from 81% to 110%, and considering that the KS standard was less than 20%, it could be confirmed that all samples had a value significantly exceeding the KS standard. Conclusion: The crest factor and current total harmonic distortion may affect the temperature rise of the light source and the burnout of the device. When developing an exit light, if this item is developed within the scope of the KS standard, the quality improvement and maintenance of the exit light will be greatly improved.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.147-148
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• 2006

Recently, due to increasing the application of power electronic equipment, harmonics generated from the non-liner load are fairly produced. Harmonics can cause a variety of problems such as the overheating of distribution transformer, the breakdown of device and communication interference. Interest about power quality decline of power system is very increased. In this paper, we are measured the harmonic voltage and current o( power system to analyze harmonic characteristics, and it is analyzed Total Harmonic Distortion(THD). Also, we Ere modeled power system using PSCAD/EMTDC. And it is analyzed harmonic voltage and current in steady-state. The study results have been indicated the utility about harmonics analysis and modelling for power system.

• KIEE International Transactions on Power Engineering
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• v.5A no.3
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• pp.235-243
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• 2005

Line constants of the catenary system are estimated. The harmonic current that the Korean Train Express (KTX) injects into the catenary is measured to precisely analyze the harmonic effects. The Korean high-speed railway system is modeled by estimated and measured results. The system model is applied for predicting the harmonic effects. The simulation results from the system model are compared to field test data concerning the total harmonic distortion (THD). The reliability of the system model is verified.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.47-52
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• 2005

Recently, power conversion equipment increased rapidly makes a lot of harmonics. Thus, it is growing that wrong operation and break down of sensitive devices. There are two kinds of causes of harmonics. One of them is lots of power conversion equipment as modem controller, inverter, converter and SWS(Switching Mode Power Supply). Another is nonlinear operating machines as transformer and motor. The more nonlinear loads like them grow, the more serious problems as harmonic current to source and low power factor because of increasing reactive power grow. It is installed for reactor and L-C Filter to decrease harmonic in general. This paper analysis and compares two of characteristics and harmonic from reactor and L-C Filter with operation of induction motor and power conversion equipment. In the result, L-C Filter more improves unbalance rate and THD than reactor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.733-738
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• 2011

As increase of nonlinear loads and renewable energy generators (REGs) being connected to power distribution system via inverters, the concern on harmonic problems have increased. Recently, the harmonics evaluation method considering TDD (Total Demand Distortion) is used to analyze the effect of harmonics from inverters on power distribution quality. Harmonic current sources are typically used for simulation of nonlinear load. Most inverter type for REGs is voltage source inverter (VSI). So, harmonic voltage sources are more suitable to analyze impact of renewable energy generator on harmonics problem in power distribution system. In this paper, we presented the circuit model to analyze interaction between harmonics from nonlinear load and REGs. We verified that the harmonic analysis using the proposed circuit model is more appropriate than the harmonics evaluation method considering TDD through case study using PSCAD/EMTDC.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.397-402
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• 2013

This paper proposes a new passive type LED driver which satisfies the standard of power factor (PF) and total harmonic distortion (THD). The proposed passive LED driver also has high-efficiency and long-life time characteristics compared to active LED driver which is composed of op-amp, switches and so on. By using just passive components such as inductor, capacitor, and diode, it has resolved extremely short-life time and low-efficiency problems of previous LED drivers. It has achieved PF of 0.99, THD of 16.4 %, and the total efficiency of 95 %. The proposed passive LED driver is fully analyzed and verified by simulations and experiments, which results are in good agreement each other.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1328-1336
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• 2013

Nowadays multilevel inverters are developing generally due to reduced voltage stress on power switches and low total harmonic distortion (THD) in output voltage. However, for increasing the output voltage levels the number of circuit devices are increased and it results in increasing the cost of converter. In this paper, a novel multilevel inverter is proposed. The suggested topology uses less number of power switches and related gate drive circuits to generate the same level in output voltage with comparison to traditional cascaded multilevel inverter. With the proposed topology all levels in output voltage can be realized. As an illustration, a symmetric 13-level and asymmetric 29-level proposed inverters have been simulated and implemented. The total peak inverse (PIV) and power losses of presented inverter are calculated and compared with conventional cascaded multilevel inverter. The presented analyses show that the power losses in the suggested multilevel inverter are less than the traditional inverters. Presented simulation and experimental results demonstrate the feasibility and applicability of the proposed inverter to obtain the maximum number of levels with less number of switches.