• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.149-151
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• 2000

This paper compares the measurement values of harmonics to the analysis results in railroads testing system. Therefore, in this paper, new program to calculate THD(Total Harmonic Distortion) and measuring system of harmonics are developed. The harmonic measurement point is PCC(Point of Common Coupling), the primary side(154kV) of scott transformer, and the analysis is performed based on real KEPCO system data. As a result of this study, it is possible to present basic data and informations about harmonic problems which can be occurred in the future commercial railroad systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1751-1758
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• 2003

This paper describes speed control of a permanent split capacitor single phase induction motor using SHE PWM inverters. The inverter is controlled by V55 microprocessor and its range is larger than other systems. Due to the V/F control with SHE(Selected Harmonic Elimination) PWM, continuously variable speed is attained and THD(Total Harmonic Distortion) is decreased. This is verified by simulations and experimental results.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.779-781
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• 1987

In phase controlled rectifier(PCR), harmonica are changed according to the variation of a firing angle. These harmonics are supplied with the input of the inverter. And then, inverter output comes about the harmonics combined with the switching frequency of the inverter. Hence the efficiency of the induction motor ia decreased by the harmonic of the inverter output. In this paper, it analyzed about an effect of these harmonics ia analyzed by a computer simulation. The total harmonic distortion (THD) in the case of PCR containing the ripple was considerably larger than THO of the DC source. Therefore, it was proved that the firing angle variation of PCR had to be limited.

• The Transactions of the Korean Institute of Power Electronics
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• v.28 no.1
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• pp.15-21
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• 2023

With the development of technology, a new class of smaller and more sensitive electrical systems have emerged, requiring higher quality power system. Improving the quality of the power system requires removing harmonics as much as possible to ensure better efficiency. We should first collect information on what harmonic frequencies are included in the current power system to remove the harmonics. In this paper, a new frequency analysis algorithm is introduced for a three-phase and a 1-phase power system. MTE PRS 600.3 is used to generate any harmonics to ensure that the algorithm performs well. Typing any harmonics on the Windows GUI program shows the analyzed result from the board developed for the algorithm.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2193-2194
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• 2006

This paper presents the results of a grid-connected photovoltaic (PV) system modeling that contain incremental conductance MPPT(Maximum Power Point Tracking) controller by PSCAD/EMTDC simulator and investigates the influence that can occur in the grid-connected PV system from aspect of power quality, i.e. voltage drop, total harmonic distortion(THD) and total demand distortion(TDD). The measured data the PV array modeling of PSCAD/EMTDC in Cheongwadae, Seoul, Korea is used in the paper.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.561-562
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• 2006

This paper presents the results of a grid-connected photovoltaic(PV) system modeling that contain incremental conductance MPPT(Maximum Power Point Tracking) controller by PSCAD/EMTDC simulator and investigates the influence that can occur in the grid-connected PV system from aspect of power Quality, i.e. voltage drop, total harmonic distortion(THD) and total demand distortion(TDD) The measured data the PV array modeling of PSCAD/EMTDC in Cheongwadae, Seoul, Korea is used in the paper.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1227-1228
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• 2006

This paper presents the results of a grid-connected photovoltaic(PV) system modeling that contain incremental conductance MPPT(Maximum Power Point Tracking) controller by PSCAD/EMTDC simulator and investigates the influence that can occur in the grid-connected PV system from aspect of power quality, i.e. voltage drop, total harmonic distortion(THD) and total demand distortion(TDD). The measured data the PV array modeling of PSCAD/EMTDC in Cheongwadae, Seoul, Korea is used in the paper.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1687-1688
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• 2006

This paper presents the results of a grid-connected photovoltaic (PV) system modeling that contain incremental conductance MPPT(Maximum Power Point Tracking) controller by PSCAD/EMTDC simulator and investigates the influence that tan occur in the grid-connected PV system from aspect of power quality, i.e. voltage drop, total harmonic distortion(THD) and total demand distortion(TDD). The measured data the PV array modeling of PSCAD/EMTDC in Cheongwadae, Seoul, Korea is used in the paper.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.6
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• pp.478-485
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• 2012

In this paper, a new PWM method is proposed to reduce the input current harmonics of 3 phase PWM rectifier. In the conventional carrier comparison PWM method, a triangular wave is generally used as the carrier wave. However, the large d-axis current ripple by the triangle carrier wave may be a source of large input current THD(Total Harmonic Distortion). In this paper, a new carrier comparison PWM method with saw tooth wave is proposed. Depending on the sector where the voltage command vector places, one of the rising or falling saw tooth wave is selected. To reduce the switching losses of the saw tooth carrier PWM, the discontinuous PWM is also presented. The proposed PWM method can reduce the d-axis current ripple as well as the switching losses. The performance of the conventional and proposed PWM methods is verified by the simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.8
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• pp.405-412
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• 2003

This paper presents a three-phase Line-Interactive uninterruptible power supply (UPS) system with series-parallel active power-line conditioning capabilities, using synchronous reference frame (SRF) based controller, which allows an effective power factor correction, source harmonic voltage compensation, load harmonic current suppression, and output voltage regulation. The three-phase UPS system consists of two active power compensator topologies. One is a series active compensator, which works as a voltage source in phase with the source voltage to have the sinusoidal source current and high power factor under the deviation and distortion of the source voltage. The other is a parallel active compensator which works as a conventional sinusoidal voltage source in phase with the source voltage, providing to the load a regulated and sinusoidal voltage with low THD (total harmonic distortion). The control algorithm using SRF method and the active power flow through the Line-interactive UPS systems are described and studied. The simulation and experimental results are depicted in this paper to show the effect of the proposed algorithm.