• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.213-215
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• 2002

This paper presents grid connected photovoltaic inverter system using a new Zero-Current-Transition(ZCT) technique. The main switches of the proposed grid connected inverter are turned off under the zero current condition by operating the auxiliary circuit and also all semiconductor devices, switches and diodes, are applied to low rated voltage regardless of the load condition. In additionally, the proposed ZCT scheme has advantages, which are without the additional current stresses and the conduction losses on the main switches during the resonance period of the auxiliary circuit. The simulation was performed to verify the validity of the proposed grid connected photovoltaic ZCT inverter system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2119-2126
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• 2016

In this paper, we developed a smart black box that can monitor and record the information of the sensor from subsystem in the smart grid system. The plant is the complex power system which is integrated by solar power system, grid-connected power systems, and BESS(battery energy storage system). The black box with the web-server application can connect and synchronize to an external monitoring system and a smart phone. We hope that this system is to contribute to improve operational efficiency, reliability, and stability for the smart grid power system.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.161-163
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• 2005

The capability of unity-interactive type in PV generation system depends on its use. In a house, needs such a small capability, a single-phase output of PV can afford. But 3-phase output of PV is required in a case of big capabilities or a PV system directly interactive to 3-phase grid. To verify a validness of a large capable distributed-generation system supplied the proposed method, a 10kW inverter was realized in this paper. And from the results, the system is confirmed its stable operation and validness.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.5
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• pp.48-57
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• 2012

This paper analyzes the characteristic of gird connected photovoltaic power generation system which is available to connect the utility. Renewable energy photovoltaic power system has been linked to the system to analyze the impact of photovoltaic system. It is measured that power data for the Grid connected photovoltaic power plant with instantaneous measuring and 3-sec measuring for 7 days. Harmonic field measurements have shown that the harmonic contents of a waveform varies with time. A cumulative probability approach is the most commonly used method to solve time varying harmonics. So, it is used 50[%] cumulative probability approach. This paper provides an in depth analysis on power quality field measurement of the Grid connected photovoltaic power plant.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.279-285
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• 2007

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.494-497
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• 2004

계통연계형 태양광발전 시스템의 확대보급에 따라 단독운전 검출기법의 검출 성능에 대한 검증의 필요성이 대두되고 있다. 본 논문에서는 단독운전 검출기법의 대표적인 능동적 검출기법인 무효전력 변동기법 (reactive power variation method)과 주파수 쉬프트기법(active frequency drift method)을 IEEE Std 929-2000에서 명시된 단독운전검출 시험 방법을 이용하여 단독운전검출기법의 성능 및 불검출 영역(non-detection zone)에 대하여 비교 분석하였다.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1281-1283
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors a net size, weight, and parts cost saying result compared to the other systems due to elimination of 60Hz transformer.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.519-520
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• 2006

In this paper, to evaluate the grid-connected 120kW class Photovoltaic(PV) system performance, as a consisted of solar cells, PCS, 150kVA transformer station. The paper address modeling and analysis of a grid-connected 120kW class photovoltaic generation system(PV system) PSCAD/EMTD and Psim. A PWM voltage source inverter(VIS) and its current control scheme have been implemented. A P&O(Perturbation and Observation) MPPT algorithms technique modeling has been simulated and analysed.

• 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.