• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.18-23
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• 2010

As the increasing of Non-linear load, we have been growing interest for the harmonics. Harmonics has been focused on the current component rather than voltages. Voltage harmonics can be mainly generated at the PCC with non-linear load and act on voltage unbalance. Voltage harmonics can be enlarged at the capacitor with low impedance as frequency increases. Capacitor is basically used for the power-factor compensation and sometimes as the passive filter. Small voltage of low-order acts on quite a few at the capacitor by the current increase. Capacitor has easily fall under by harmonic components. In this paper, we measured the magnitude and phase angle of asymmetrical voltage with harmonics components at the PCC and calculated with the same condition. we concluded that voltage harmonics of higher order increase each current component but have a little effect on capacitor rating.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.15-17
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• 2004

Most of LV customer has been composed the 3-phase four wire system distribution system which is supplying simultaneously at the 1-phase & 3-phase load. In this system, the composition of the power apparatus system is simple rather than conventional separation mode of the 1-phase & 3-phase, But due to uneven load unbalance or unclean power quality, various kinds such as derating or power losses become an issue. In this paper, we measured and analyzed voltage and current waveform in the field, compared with internationally allowable voltage unbalance limits.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.419-421
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• 1997

Three-phase system has many problems because of the unbalance load. So we propose two control algorithms using active power filter to dissolve these problems. One is three-leg inverter topology in which ac neutral line is connected directly to the midpoint of two series dc capacitors. The other is four-leg inverter topology in which ac neutral line is provided through a fourth leg. The three-phase unbalance is considered by connecting the load to one-phase. It is show that the proposed control algorithms give good performances.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.325-329
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• 2010

Capacitor has been used principally for the power factor compensation long ago. However now it does as passive filter to reduce harmonics of nonlinear load with reactor. Most of the customer's low-voltage feeder has been designed with approximately balanced and connected at the 3 phase four wire system. But voltage and current unbalance is appeared by the mixing operation of single or three phase load etc. The addition of reactor at the condenser may rise its terminal voltage. Voltage and current values above rating can act on electrical stress on the condenser. In this paper, we calculated and measured that voltage, current and capacity of condenser are changed under the voltage balance. We conclude that magnitude and deviation of phase voltage act on major point of electrical stress.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.1
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• pp.86-93
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• 1999

It is necessary to calculate the system's factor for reasonable operation and security enhancerrent of large scale distribution system This paper presents an effective three phase load flow calculation for distribution system unbalance evaluation. It takes into account an untranspoed transmission line, the core loss as a functioo of voltage on the serondary side of the transformer, and a generator unbalance mxle1 which is also suitable for a salient pole machine. The load flow algorithm is used Newton-RaiDson method of load flow equations in bus phase voltage.oltage.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.43-47
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• 2004

Most of LV customer has been composed the 3-phase four wire system distribution system which is supplying simultaneously at the 1-phase & 3-phase load. In this system, the composition of the power apparatus system is simple rather than conventional separation mode of the 1-phase & 3-phase, But due to uneven load unbalance or unclean power quality, various kinds such as do-rating or power losses become an issue. In this paper, we measured and analyzed voltage and current waveform in the field, compared with internationally allowable voltage unbalance limits.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.91-99
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• 2004

Most of LV customer have applied the 3-phase four wire system distribution system because it has advantage of supplying both of 1-phase at 3-phase loads simultaneously. Due to its structural simplicity, it is more convenient for use rather than the conventional separated scheme. But once in a while uneven load unbalance or unclean power quality lead some problems such as do-rating or power losses. In this paper, voltage and current waveform in the actual fields have been measured and analyzed in relation with intermationally allowable voltage unbalance limits.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.2
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• pp.82-86
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• 2012

Recently, due to the expansion of electric power demands, nonlinear load such as converters and inverters connected to the electric power distribution system, and extensive application of harmonic generation sources with power electric devices, disturbance of the electric power system and its influences on industries have been continuously increasing. In this research, power quality was analyzed for 11 extra-high voltage customers by considering voltage unbalance condition, power factor, THD and TDD. This research will be utilized as fundamental data to improve power quality for power utility.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1062-1064
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• 2005

3 phase 4-wire system has been widely used in the customer's application due to merit of 1 bank construction of loads such as 1-phase lighting, heat and 3-phase motor. But if the load distribution is not uniformed by the operation conditions, voltage unbalance is highly appeared by the difference of each phase current value. Especially, if the linear load such as resistance or inductive load has different power factor value, voltage unbalance factor is not the same due to the phase angle and magnitude of each phase voltage. In this paper, we composed the measurement device and analyzed by varying of load pattern.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.155-161
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• 2005

Nonlinear electronic loads used at office buildings distort the voltage and current waveform that cause the overheating of transformer losses, ELB(Electrical Leakage Breaker) tripping, and so on. This paper analyzed waveform distortion characteristics at several once buildings by comparing with magnitude of voltage and current harmonics, crest factor of voltage and current, phase voltage and current unbalance. As a consequence, severe current waveform distortion in phase and neutral line by harmonics and high current unbalance rates by unbalanced using of single loads among the three phases are investigated. The results of the study can be used in making decisions regarding reasonable and economical operating of loads at office buildings.