• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.103-105
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• 2004

In this paper, a novel control scheme compensating for source voltage unbalance and current harmonics and power factor simultaneously in unified active power filter systems combined with shunt passive filters is proposed, where no low/high-pass filter are used in deriving the reference voltage for compensation. Using digital all-pass filters, the phase angle and the reference voltages compensating for harmonic current and unbalanced voltage are derived from the positive sequence component of the unbalanced voltage. The amplitude of d-axis current in a series filter is controlled as zero for power factor correction. The validity of the proposed control scheme has been verified by experimental results.

• 전기학회논문지P
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• 제56권3호
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• pp.123-128
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• 2007

Hydro power supplies no pollution energy, mainly induction generator has been applied at the small capacity power station. The generating power of small hydro-electric power station connects on the 22.9kV distribution system or low voltage system in the case of three-phase four-wire supply system. There are side effects of various kinds in the 3-three phase 4-wire distribution system mixing 1-phase load and 3-phase load. This system generates the voltage unbalance by unbalanced load operating condition. They have various serious effects on generator and connection system. In this paper, we analyzed what kind of operation characteristic are happened in the induction generator by customer load variation at the 3-three phase 4-wire distribution system.

• 산업기술연구
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• 제25권B호
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• pp.203-210
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• 2005

The PWM(Pulse Width Modulated) converter for the AC to DC rectification has become attractive in the industrial variable-speed drive application and the electric utilities due to the following benefits: Nearly the sinusoidal input current with unity power factor; Controllable DC link voltage; Bidirectional power flow. This paper presents a quantitative analysis of single and three phase PWM converter's input and output characteristics as a function of the input filter inductance under balanced and unbalanced conditions. Also, its performance under the supply voltage including harmonics is investigated by simulation with Matlab Simlulink and experiments. These results provide a reference for selecting the reasonable converter's input filter inductance for given harmonics or power factor criterion.

• 전기학회논문지
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• 제56권4호
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• pp.716-723
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• 2007

This paper suggests of a 3-phase 3-wire unified active power filter. The system is composed of a series active power filter and a parallel active power filter. The proposed series active power filter compensating unbalance source voltage and current harmonics of the parallel active power filter improves power factor. The proposed algorithm which improves for power factor and harmonic reduction are calculated by the performance function, and which compensates for the unbalanced source voltage is calculated based on the symmetrical component analysis. We composed a combined system of the series active power filter and parallel active power filter to confirm a validity of the proposed control methods. The effectiveness of the proposed algorithm is confirmed by the experiments.

• 전기학회논문지P
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• 제61권2호
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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.

• 조명전기설비학회논문지
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• 제18권6호
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• pp.91-99
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• 2004

대부분의 저압 수용가는 단상 및 3상 부하를 동시에 공급할 수 있는 장점을 지닌 3상 4선식 배전시스템을 적용하고 있다. 이 시스템은 구조적인 간단함 때문에 종래의 단상 및 3상 부하를 분리하는 방식보다 편리하다. 그러나 고르지 못한 부하 불평형이나 낮은 전기품질은 출력저하나 손실과 같은 문제를 발생하고 있다. 본 논문에서는 실제현장에서 전압 및 전류 파형을 측정하여 국제적으로 허용되고 있는 전압불평형 기준과 비교 분석을 실시하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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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.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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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.

• 조명전기설비학회논문지
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• 제19권1호
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• pp.155-161
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• 2005

사무용 빌딩의 비선형 전자부하에 기인한 전압 및 전류파형의 왜곡은 중성선의 과열, 변압기 손실, 누전차단기 오동작 등을 야기 시킨다. 본 논문에서는 사무용 빌딩에서의 전압 및 전류 고조파의 크기, 전압 및 전류 파고율(Crest Factor : CF), 전압 및 전류 불평형 등을 비교함으로써 파형왜곡 특성을 분석하였다. 분석 결과, 고조파에 의한 상 및 중성선에서의 심각한 파형 왜곡 문제와 삼상에서의 단상 부하의 부적절한 분배로 인한 전류 불평형이 심한 빌딩이 조사되었다. 본 연구 결과는 사무용 빌딩에서 합리적이고 경제적인 부하운용을 위해 사용될 수 있을 것이다.