• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.57-60
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• 2008

As the technology of a large scale battery have advanced, it's application to the electric power network have been active in foreign country. By providing the electric power energy stored in the electric power storage system when needed, there are many advantages that it is able to reduce the gap between the electric power demand and supply for day and night to increase capacity factor, to upgrade the electric power quality degraded from the unbalance between power demand and supply and to compensate the fluctuation of wind power plant and photovoltaic power generation. In this study, the current application of electric power storage system using battery is introduced in detail, and I have thought out it's application fields based on the foreign examples. These are demand side response, upgrade of the power quality, stabilization of fluctuation of renewable energy and distributed generation for filling elapse.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.125-127
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• 2005

In this paper, the control algorithm of DC source device for inverter starting is proposed and the control method for compensating unbalance system source on operating time in the voltage type PWM converter with driving and regenerative faculty is suggested. The maintaining way of balancing condition for converter of AC source is used the compensating unbalanced status by current control loop. Because it is possible that the unbalanced System control is used to leakage transformer not equaled reactance by each phase in rectifier system, the proposed H/W and control algorithm of rectifier system is contributed to minimize of device and rising efficiency.

• 전력전자학회논문지
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• 제20권5호
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• pp.464-470
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• 2015

In this paper, a non-isolated three-level high step-up boost converter with output voltage balancing is proposed. By adding one extra inductor to the conventional three-level boost converter, the proposed converter is derived. Compared with the traditional boost converter and the three-level boost converter, the proposed converter can obtain very high voltage conversion ratio, and the voltage and current stress of switching devices and diodes are reduced. A 2.7 kW prototype converter is built and tested to verify performances of the proposed converter.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권6호
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• pp.372-379
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• 2004

Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, in the user power distribution systems, most of the loads are single ＆ three phase and unbalanced, generating voltage unbalance. Rotating machines operating on an unbalanced voltage will draw a highly unbalanced current. As a result, the three-phase currents may differ considerably, thus resulting in an increased temperature rise in the machine. This paper presents a scheme on steady states of a three-phase induction motor under unbalanced voltages. The three-phase voltages applied to the stator winding of the studied induction motor are controlled by respectively adjusting the magnitude and phase angle of each phase. The voltage unbalanced factor(VUF) of the three-phase source voltages can then be varied to examine the different values of VUF on machine's operation characteristics.

• 한국정보통신학회논문지
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• 제3권1호
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• pp.223-228
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• 1999

A five-level VSI(Voltage Source Inverter) is introduced as a SVC(Static Vu Compensator) like a large scale power source. The problems in using SVC are that the power device can easily be destroyed by voltage unbalance and accurate reactive power control is difficult because of voltage variation. A asymmetrical PAM(Pulse Amplitude Modulation) switching pattern is proposed to solve this problem and analyze both fundamental component and harmonic current in the system. Through experimental results of 3.5 kVA experimental test system, It is confirmed that DC capacitor voltage can be controlled by asymmetrical PAM switching pattern control.

• KIEE International Transactions on Power Engineering
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• 제3A권2호
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• pp.79-84
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• 2003

Unbalanced systems, such as distribution systems, have difficulties in fault locations due to single-phase laterals and loads. This paper proposes new fault locations developed by the direct three-phase circuit analysis algorithms using matrix inverse lemma for the line-to-ground fault case and the line-to-line fault case in unbalanced systems. The fault location for balanced systems has been studied using the current distribution factor, by a conventional symmetrical transformation, but that for unbalanced systems has not been investigated due to their high complexity. The proposed algorithms overcome the limit of the conventional algorithm using the conventional symmetrical transformation, which requires the balanced system and are applicable to any power system but are particularly useful for unbalanced distribution systems. Their effectiveness has been proven through many EMTP simulations.

• Journal of Power Electronics
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• 제15권1호
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• pp.288-297
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• 2015

This paper presents a novel approach to diagnose interturn insulation faults in three-phase transformers that operate at different loading conditions. This approach is based on the loci of instantaneous symmetrical components and requires the measurement of three input primary winding currents and voltages to diagnose faults in the transformer. The effect of unbalance supply conditions, load variations, constructional imbalance, and measurement errors when this methodology is used is also investigated. Wing size or length determines the loading on the transformer. Wing travel and area determine the degree of severity of fault. Experimental results are presented for a 400/200 V, 7.5 kVA transformer to validate this method.

• 전력전자학회논문지
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• 제14권5호
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• pp.406-414
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• 2009

본 논문에서는 전원장치의 고집적화와 저가격화를 위해 두 개의 공진커패시터와 두 개의 변압기로 구성된 독립된 공진탱크회로를 갖는 LLC 공진 컨버터를 제안하였다. 제안된 공진회로에 적용된 두개의 변압기는 각 변압기에 흐르는 전류 불평형문제를 저감하기 위해 1차 측은 병렬 연결되어 있고 2차 측은 상호 직렬 연결되어 있다. 300W 시제품을 제작 실험한 결과를 통해 제안된 LLC 공진컨버터가 적용 가능함을 나타냈다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.76-80
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• 2001

Voltage harmonics resulting from current harmonies produced by the nonlinear loads have become a serious problems in many systems. Moreover momentary interruptions and voltage sags are responsible for many of the power quality problems found in typical industrial plants. In this paper, proposed power quality compensate system using photovoltaic system is not only for harmonic compensation but also for harmonic isolation between supply and load, and for voltage regulation and unbalance compensation. Through computer simulations, we have verified the effectiveness of the proposed system.

• 한국안전학회지
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• 제20권3호
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• pp.47-52
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• 2005

Recently, power conversion equipment increased rapidly makes a lot of harmonics. Thus, it is growing that wrong operation and break down of sensitive devices. There are two kinds of causes of harmonics. One of them is lots of power conversion equipment as modem controller, inverter, converter and SWS(Switching Mode Power Supply). Another is nonlinear operating machines as transformer and motor. The more nonlinear loads like them grow, the more serious problems as harmonic current to source and low power factor because of increasing reactive power grow. It is installed for reactor and L-C Filter to decrease harmonic in general. This paper analysis and compares two of characteristics and harmonic from reactor and L-C Filter with operation of induction motor and power conversion equipment. In the result, L-C Filter more improves unbalance rate and THD than reactor.