• Journal of Power Electronics
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• 제12권6호
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• pp.925-934
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• 2012

Three-phase controlled converters have many applications in the utility interfacing of renewable energy sources and adjustable speed drives as a rectifier or inverter. The utility line currents of these converters have a high harmonic distortion, which is more than the harmonic standards. This paper introduces a new technique for circulating the third harmonic currents from the dc-link to the line currents to reduce their harmonic contents. The proposed system uses a single-phase PWM converter to control the angle and amplitude of the injection current for each of the firing angle of a three-phase converter. A detailed analysis is introduced to achieve a relationship between the firing angle of the three-phase controlled converter and the power angle of the PWM converter. In addition, a detailed design for the other injection path components is introduced. A simulation and experimental work is introduced to prove the mathematical derivations. Analysis, simulation and experimental results prove the superiority of the proposed technique.

• Journal of Power Electronics
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• 제17권5호
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• pp.1223-1230
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• 2017

The back emf harmonics of a permanent magnet (PM) synchronous motor is a major source of torque ripple. For torque control applications including column fitted MDPS (motor driven power steering) systems, it is essential to reduce the mechanical vibrations due to torque ripples at low speeds. In this paper, a torque ripple reduction algorithm for interior PM synchronous motors is proposed. The harmonic currents that cancel the $6^{th}$ order torque harmonic are added to the nominal dq currents for MTPA (maximum torque per ampere) operation. The compensated harmonic currents are derived from flux linkage harmonics based on a FFT analysis of the back emf harmonics. Simulation and experimental results verify that the $6^{th}$ order torque harmonic and THD of the torque ripple are reduced by compensating the dq harmonic currents.

• 조명전기설비학회논문지
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• 제17권1호
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• pp.103-111
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• 2003

교육용 건물에는 개인용 컴퓨터와 같은 비선형 부하가 증가하여, 중성선에는 많은 고조파 전류가 흐른다. 3상 4선식 배전 계통을 채용하는 중성선에 과다한 고조파 전류가 흐르면 중성선 도체 과열과 보호 시스템의 오동작등 많은 고조파 장해를 일으킨다. 본 논문에서는 현장에서 실측한 고조파 전류와 전압으로 고조파 해석용 3상 등가회로를 구성하였다. 실측한 값과 MATLAB으로 시뮬레이션한 값을 수치와 그래프로 비교 검토 하였다. 또한 중성선 고조파 전류 저감 대책으로 동조 수동 필터를 사례연구 시스템에 적용하여 고조파 저감 효과도 알아 보았다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.688-692
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• 1988

The active filter system for harmonic current compensation is presented in this paper. The active filter, composed of a three-phase voltage-type PWM inverter and the capacitor, compensates both the harmonic currents and the reactive power by injecting the PWM current to the ac line. This paper describes the principle of harmonic current compensation, the calculation circuits for the harmonic currents to be injected, the several compensation characteristics. Also the experimental results are shown to verify the theory proposed in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.715-719
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• 2002

Recently, Dangers due to harmonics emanated from all sorts of machinery have been on the increase with the development in industry. One of them is that Zero Sequence harmonic currents flow from the neutral wires in 3 phases - 4 wire systems. The flowing of harmonic currents in neutral wires brings about the superheating and falloff in output of transformer, the overheating of them, a rise in ground potential and the wrong movement of machinery, so has a bad influence on this system. To develop the machinery to decrease neutral wires Zero sequence harmonic currents and apply it help solve these problems and bring about the effects of a improvement in power factor and energy savings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.304-306
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• 2005

This paper presents the RTDS training course on using passive filters for control of harmonic currents. The course can show harmonic currents in porer system, which is occurred by function generators, with Fourier analysis function of RTDS and the effect of passive filters implemented in RTDS to eliminate harmonics. In addition to, With Jeju-Haenam HVDC system, we have simulated the effect of passive filters on harmonic currents occurred by massive power conversion system of HVDC.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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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.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권2호
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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.

• 조명전기설비학회논문지
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• 제18권3호
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• pp.120-127
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• 2004

스위칭 모드 전원 공급 장치와 같은 비선형 부하의 증가로, 3상 4선식 배전계통을 채용하는 중성선에 많은 고조파 전류가 흐른다. 중성선은 접지 시스템과 연결되어 있기 때문에 접지 임피던스는 중성선 고조파 전류에 영향을 끼친다고 알려져 있다. 현장에서 실측한 고조파 전류와 전압으로 고조파 해석용 3상 등가 회로를 구성하였다. 실측한 값과 MATLAB으로 시뮬레이션 한 값을 수치와 파형으로 비교 검토하였다. 또한 본 논문에서는 중성선 고조파 전류와 접지 임피던스와의 관계를 시뮬레이션을 통해 검증하였다.

• 조명전기설비학회논문지
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• 제19권5호
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• pp.23-29
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• 2005

비선형 부하의 증가는 변압기에 고조파 전류를 증가시키는 요인이 되고 있다. 변압기에 고조파 전류가 유입되면 손실이 증가되고, 변압기 출력이 감소되어야 한다. 본 논문에서는 고조파를 고려한 부하의 변압기 용량 산정법을 제시하고, 직렬리액터가 연결된 커패시터 뱅크와 고조파 필터의 적용으로 변압기 출력을 증가시킬 수 있음을 검증하였다. 사례연구의 시뮬레이션은 EDSA 프로그램을 사용하였다.