• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.946-954
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• 2016

Energy industry is undergoing a paradigm shift in customer participation in the smartgrid. Customers traditionally consume electrical power. But nowadays not only do they generate electricity from private distributed generations, they can participate in demand response programs with their negawatt power which means a theoretical unit of power representing an amount of energy saved. Therefore development of decision-making criteria for electric load aggregation becomes a greater consideration as an amount of energy saved from demand response resources increases. This paper proposes load aggregators' decision-making criteria in the industrial sector where it made up the largest portion in demand response portfolio in order to assure reliability performance for demand response resources.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.89-92
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• 2011

본 연구에서는 전력계통(특히 배전계통)의 해석분야에서 가장 일반적으로 사용되고 있는 상용 S/W인 PSCAD/EMTDC를 이용하여, 분산전원이 배전계통에 연계되어 운용되는 상태(정상, 사고, 품질상태)를 모의할 수 있는 계통연계 시험장치를 모델링하는 방법을 제시하였다. 이 모델링에 의한 다양한 시뮬레이션 결과를 바탕으로 분산전원 계통연계 시험장치의 기능을 확인하여, 분산전원이 연계된 배전 계통의 모의 시험장치를 제작하는데 기초적인 데이터로 활용할 수 있도록 하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1547-1553
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• 2017

Due to the high penetration ratio of dispersed generations, overvoltage problem of the feeder has become more an important issue in distribution system operation. This paper proposes a new method for the smart inverter to control reactive power to mitigate voltage rise by the reverse power flow from the DGs. The proposed method controls reactive power based on current measurement while conventional methods use voltage measurement which include unacceptably large errors. Various case studies using MATLAB simulation have been performed to verify effectiveness of proposed method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.500-508
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• 2011

In the distribution systems, the maximum power transportation capacity is restricted within 40MW based on two lines, because of the thermal current limit of a distribution line. Recently it has been continuously required to expand the abilities of the power transportation in distribution systems, as the number of large scale industrial complexes and distributed generations are growing. In this paper, we suggested the five alternatives combining two methods, laying the two bundle lines and adding another voltage between the 22.9kV and 154kV in distribution systems. This paper implemented the economic evaluations of proposed alternatives from national and customer perspectives. And then we compare the results with those of 154kV transmission system.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.60-62
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• 2010

최근 태양광, 풍력 등의 분산전원이 배전계통에 도입되어 운영되고 있다. 현재의 배전계통에 스마트 그리드 연계 시 전력 공급의 신뢰성 및 안정성, 전력 품질의 확보를 위한 계통 계획이나 해석을 위해 가장기본적으로 역 조류를 고려한 전압강하 계산이 필요하다. 본 논문에서는 기존의 역 조류 전압강하 계산방법을 개선하여, 분산전원의 출력변동(역 조류)을 고려하여, 간편하게 전압강하를 계산할 수 있는 분산전원 대응형 전압강하 해석법을 제안하고자 한다.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.36-38
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• 2008

본 논문에서는 여러 대의 인버터를 동시에 사용하는 분산전원 환경하에서 Anti-islanding을 효과적으로 할 수 있는 방안을 제안한다. 제안하는 Anti-islanding기법은 SMS(Sliding Mode Frequency Shift)를 근간으로 하면서 공진 Q가 높을 때 검출이 어려운 단점을 해결하는 방법을 제시한다. SMS위상의 변동 값을 판단근거를 사용하지 않고 SMS위상의 적분 값을 판단근거로 사용한다. Run on시간이 0.5초 이내로 국내외 규격을 모두 만족시킨다. 여러 대의 인버터를 병렬로 접속해도 islanding 검출이 탁월하다. 출력전력의 품질 면에 있어서도 다른 Anti-islanding기법에 비해 우수하다. 본 알고리즘의 우수성을 시뮬레이션과 실험을 통해 검증하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2089-2094
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• 2009

The fault current has increased due to growth of distributed generations for the large power demand in power distribution system. To solve some problem such as excess of the circuit breaker's cut-off ratings, the superconducting fault current limiter(SFCL) has been progressed. However, the operational characteristics of the relay is changed by SFCL. Therefore, the proper impedance for the SFCL should be selected to keep protective coordination with the SFCL when SFCL is introduced on the neutral line of main transformer in distribution system. In this paper, the proper normal conducting resistance was suggested to solve the problem in case of the protection coordination with SFCL.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.147-150
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• 2004

본 논문에서는 분산전원 계통을 모의하기 위한 시뮬레이터의 설계와 시험에 대한 내용을 제시하고자 한다. 제시하고자 하는 시뮬레이터는 RTDS(Real Time Digital Simulator)와 전력 증폭기(power amplifier)로 구성된다. RTDS 부분은 분산전원이 적용되는 계통의 모의와 분산전원의 전원부 모의를 위해 사용되며 전력 증폭기는 RTDS에 의해 모의된 전력 계통의 모선 전압 출력과 분산전원 전원부의 전압 출력을 증폭하기 위하여 사용된다. 시뮬레이터 구성을 위해 사용되는 RTDS의 구성과 제작된 전력 증폭기의 사양과 동작시험에 대한 결과를 제시하고자 한다. 개발된 시뮬레이터는 분산전원의 동적 및 정적 성능 평가를 위한 시험 시스템 개발에 적용될 수 있다.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.32-33
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• 2010

This paper describes a droop control method for the autonomous operation of DC distribution system using distributed generations and energy storage. The method suppress the circulating current, and each unit could be controlled autonomously without communication system. Detailed model of wind power generation, photo-voltaic generation, fuel-cell generation and battery was implemented with the user-defined model of PSCAD/EMTDC software that is coded with C-language. The simulation and experimental results confirms that the proposed DC distribution system make it feasible to provide power to the load stably and verify effectiveness of the proposed method.

• Proceedings of the KIEE Conference
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• summer
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• pp.257-259
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• 2004

This paper proposes the identification method for the faulted feeder, where it identify whether the faulted feeder is the DG-connected feeder or the neighboring feeder (but sharing the same bus of the substation). In general, DG has to be disconnected from the grid when the fault occurs on the interconnected distribution feeder as soon as possible. However, the faults occured on the neghboring feeder would mistakenly cause the disconnection of the DG. For reliable operation of DG, DG should be sustained at the fault occurred on neighboring distribution feeders. The proposed identification method utilizes the impedance monitored from the DG and examines the coordination of overcurrent relay of the distribution system. This paper describes how the proposed method to identify the faulted feeder and how the method can be utilized.