• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.758-762
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• 1998

Many harmonics components are contained within the stator currents of the high-speed synchronous reluctance motor, SynRM, with salient pole rotor. They cause the power factor of SynRM to get worse. In this paper, the mathematical model of SynRM is investigated, and SV_PWM control method is applied to reduce harmonics components in the stator current. Simulation results show the fast response of speed and the reduction of harmonics components at steady state.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.3
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• pp.43-49
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• 2013

Recently harmonics flowing into power system is increasing as the usage of semiconductor equipments and switching mode power equipments are increasing. Harmonics cause problems such as heat increasing and reduction in capacity of transformers, especially the harmonics flowing into a distribution transformer can lead to the lifetime reduction of transformer. In this paper, we are about to develop a device that can monitor harmonics in real-time as it is affixed to a distribution transformer. Unlike the existing expensive harmonic analysis device, a new harmonic analysis algorithm is proposed in order to implement low-cost equipment. The real-time harmonic analysis algorithm proposed in this paper allows implementation on low performance microcontrollers, thus it can monitor the harmonic in real-time as it is individually affixed to the transformer. Therefore, it would improve the reliability of the transformer and stable power system operation would be possible as it can prevent the transformer accidents in advance.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.58-64
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• 2004

This paper proposes a novel control scheme for the harmonic reduction of DC power regenerating systems, which can regenerate the excessive DC power from DC bus line to AC supply in subway systems. In the developed regenerating systems controlled by MAC(Modified a-Conduction) method, the order of remaining harmonics are 12k$\pm$1. In SHE(Selected Harmonic Elimination) method proposed in this paper, however, the l1th and 13th harmonics are additionally eliminated. And moreover 23rd harmonics, lowest order harmonics among the remaining harmonics, is eliminated by 23rd AC filter furnished at the output terminals of regenerating systems. To verify the validity of the proposed SHE-based harmonic reduction technique, computer simulations are carried out. Simulation results show that the THDs of output voltages are lower than that of the MAC method and the THDs in the control range are in the range of 0.53-0.68 percents.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.333-338
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• 2014

This paper concerns the development of the transformer that can reduce harmonics supplied to the system if the output of photovoltaic inverter in the photovoltaic system is grid-connected, and suggests that problems of harmonics and power factor degradation in the grid-connected photovoltaic system can be improved. In this study, the burden of increasing the investment in new facilities and securing their installation space due to harmonics has been substantially eased through the development of a hybrid transformer possessing unbalanced function and harmonics reduction function using zig-zag coils, and most of all, it is expected that the development of such high efficiency hybrid transformer possessing functions of transformation and reducing harmonics can improve the power quality as well as prevent damages caused by harmonics, leading to suppress unnecessary loss of electric power and thereby contribute to energy savings.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.2
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• pp.68-79
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• 2003

We estimated harmonics on power system of AC railway based on quantitatively measured harmonics and investigated the need of facilities for harmonics reduction. In order to analysis harmonics which inflow into power system due to increase in collector voltages and harmonic currents generated from the train when the railway is in operation, the railway system Is sectioned into power supply, railway line, AT, sectioning Post and subsectioning post. For analysis of extension of currents resulting from the railway loads, PWM converter, VVVF inverter and the feeder system are modeled based on the dynamic node technique(DNT). In order to test the usefulness of the DNT for analysis of harmonic effects, the measured harmonic currents and harmonic magnification ratios at the S/K substation are compared with simulation results using DNT modelling, which include the results for two cases with and without filters for suppression of harmonic currents. When 8 cars(4M4T) are in operation, the total sum of harmonic currents resulting from the train at M and T phases, which inflow into the substation along with the railway line, is calculated. Using the harmonics analysis program for railway feeder system with these data, the total harmonic distortion factor(710) at the outgoing point of KEPCO substation is computed. The calculation shows that when the maximum THD at the receiving point of H/K substation was 0.0443% which is much lower than 1.5% which is the allowable value of KEPCO at 154kV as well as IEEE-519 above 132kV This result indicates that any measure for harmonics reduction in Incheon International Airport Railway is not needed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.138-143
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• 2004

This paper analyzed harmonics from high speed railway traction to high speed railway substation and provide a reduction method of harmonics using the passive filter. A substation supplies the electric power to a train or can supply the electric power to several trains. According to the number of trains covered by a substation, characteristics of harmonics are investigated. These harmonics affect transformer heating and inductive interference. In order to get rid of the damage from the harmonics, this paper presented minimizing method of harmonics. The proposed method is verified in simulation using the PSCAD/EMTDC.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.99-102
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• 1996

In this paper input characteristics of Buck converter to drive small capacity universal motor is analyzed about current harmonics and EMI which is due to a switching effect. And as a strategy for EMI reduction, filter is designed. As a results it is approved that buck converter is adequate method to reduce low order harmonics.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.403-405
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• 1988

Recently, Power change devices using thyristor and transistor have grown with the rapid development of power electronics. But the devices using these semiconductors generate harmonics from the non-linear load, which gives rise to various obstacles. In this paper, therefore, as 3 taps are connected in input line, we can multiply the pulse in input line, by which harmonics is reduced.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.204-207
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• 1998

Many Harmonics components is contained within the stator currents of the High-speed Reluctance Synchronous Motor with salient pole rotor. They cause the power factor of RSM to get worse. In this paper, the mathematical model of RSM is investigated. And SV-PWM control method is applied to reduce Harmonics components in the stator currents. Simulation results shows the fast response of speed and the reduction of Harmonics components at steady state

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1093-1096
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• 2002

In this paper, a novel multi voltage inverter system is proposed for reductions of harmonics, which can compensate reactive power. At first, we remove capacitor at input side for reactive power compensation. Secondly, by adding DC voltage to the filter capacitor, it can control power factors as lead-phase according to alterations of loads at power reception. Thirdly, if winding and single phase-bridge inverter(auxiliary circuit) is installed to DC power for reduction of harmonic, waveform of output voltages become to 36-steps. Thus, SVC(static var compensator) systems which can reduce harmonics are designed.