• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.899-904
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• 2012

In recent years, a lot of research was done for earth fault protection in ungrounded dc power supply system. As a result, selective-breaking integrated protective relaying system is developed in progress and is currently field-testing are planned. Algorithm on a PC using PSCAD done a lot of testing before performing field tests, but in this study developed algorithms and functions needed to determine whether they were operating normally. Therefore, simulated system is similar to the actual situation was required and made. selective-breaking algorithm verification and validation was performed with simulator.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.351-352
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• 2008

본 논문에서는 변전운영분야 실무능력 강화를 위한 교육시스템 구축을 위한 방법을 도출하였다. 변전운영분야의 전문기술 양성을 위한 체계적인 로드맵을 수립하였고, 변전운영분야 근무직원의 고장대처능력강화를 위해 실설비와 연동되는 모의고장시뮬레이터가 구비된 옥내.옥외 변전종합실습장을 구축하였다. 실습장의 효율성을 극대화하기 위해 변전실습강사를 양성화하는 방안을 제시하였고, 교육과정의 실습비율을 60%이상으로 확대하는 등 실무위주의 교육개편 방안을 수립하였다. 또한, IEC-61850기반의 변전소자동화 기술 확보를 위한 전문기술교육체계 수립 방안을 제시하였으며, 특화된 전문기술 취득을 위한 과정 개발 등 교육수요자의 요구사항이 반영되는 교육시스템을 제시하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.571-572
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• 2015

한국전력공사에서는 2013년도부터 154kV급 변전소를 IEC 61850 기반의 변전소 자동화 시스템을 구축 운영중이다. 현재 구축 운영중인 디지털 변전소는 Station Level의 자동화 시스템이며, Process Level의 Full Digital 디지털 변전소 구축은 연구과제 성과물의 신뢰도 검증과 관련 기술 신뢰성 확보 시 구축예정이다. 본 논문에서는 Full Digital 변전소 구축을 위한 Process Level의 IED 및 엔지니어링 프로그램 개발에 대한 결과와, 개발된 시작품의 현장 실증 환경 구축에 대해 논하고자 한다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.587-589
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• 2015

본 논문에서는 IEC-61850 기반 송전선로 보호용 IED에 대한 실시간 동특성시험 방법을 학습할 수 있는 가상모의시스템을 제안한다. 가상모의시스템은 Qt Creator를 사용하여 구현하였으며, 개인의 PC를 통해서 시험환경을 구성하는 방법과 계통을 모델링하는 방법, 그리고 시험결과 확인 방법에 대하여 학습할 수 있다. 제안된 가상모의시스템을 통해 손쉽게 송전선로 보호용 IED에 대한 실시간 동특성시험 방법을 학습할 수 있음을 보였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.489-490
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• 2007

In order to construct a digital substation based on IEC61850, All of the utility company should used IEDs to be verified and also vendors should get a certification from the international conformance testing organizationsuch as KEMA. So KEPRI in charge of POWER IT project related to SAS was required to IED conformance testing system, which can perform the test previously. The system, KEPCO developed, consists of HMI, IED (Intelligent Electronic Device), network equipment, V/I generator etc

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.31-32
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• 2007

In this paper, a fault section detection method is proposed for ungrounded system in the case of a single line-to-ground fault. A conventional method is used for faulted feeder selection according to the angular relationship between zero-sequence currents of the feeders and zero-sequence voltage of the system. Fault section detection is based on the comparison of phase angle of zero-sequence current. Proposed method has been testified in a demo system by Matlab/Simulink simulations. Based on Distribution Automation System(DAS), Feeder Remote Terminal Unit(FRTU) is used to collect those necessary data, at present a demo system is under developing using Manufacturing Message Specification (MMS) in IEC61850 standard.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.879-881
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• 2013

SCADA 시스템과 같은 제어 시스템의 일반 네트워크와의 연결은 시스템의 제어 및 관리에 효율성을 높여주었으나 일반 네트워크를 사용하기 때문에 고전적인 네트워크의 취약성에 노출되어 취약성을 이용한 사이버 공격이 가능하게 되었다. 따라서 기존 네트워크 환경과는 다른 제어 시스템의 환경과 보안을 고려한 프로토콜이 개발 되었거나 개발 중에 있으며 보안은 이 프로토콜들과 밀접한 관계를 가지게 되었다. 본 논문에서는 제어시스템 프로토콜 중 IEC 61850에서 정의된 GOOSE프로토콜을 대상으로 GOOSE프로토콜의 취약점 분석 및 취약점을 이용한 공격과 이러한 공격을 탐지하기 위한 방법을 제시한다.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2055-2061
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• 2022

In the event of a short-circuit accident on a 4.16 kV non-safety bus, the voltage is temporarily lowered as backflow occurs on the safety bus. In such cases, the undervoltage relay of the safety bus shall not pick up the undervoltage so as not to interfere with the operation of the safety motors. The aim of this study is to develop an adaptive undervoltage protection scheme for the 4.16 kV safety bus considering the faults on the 13.8 kV and 4.16 kV non-safety buses connected to secondary windings of the three winding transformers, UAT and SAT. The result of this study will be the adaptive undervoltage protection scheme for the safety bus of nuclear power plants satisfying functional requirements of the safety related medium voltage motors. The adaptive undervoltage protection scheme can be implemented into an integrated digital protective relay to make user friendly and reliable protection scheme.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.653-661
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• 2012

High-availability seamless redundancy (HSR) is a redundancy protocol for Ethernet networks that provides two frame copies for each frame sent. Each copy will pass through separate physical paths, pursuing zero fault recovery time. This means that even in the case of a node or a link failure, there is no stoppage of network operations whatsoever. HSR is a potential candidate for the communications of a smart grid, but its main drawback is the unnecessary traffic created due to the duplicated copies of each sent frame, which are generated and circulated inside the network. This downside will degrade network performance and might cause network congestion or even stoppage. In this paper, we present two approaches to solve the above-mentioned problem. The first approach is called quick removing (QR), and is suited to ring or connected ring topologies. The idea is to remove the duplicated frame copies from the network when all the nodes have received one copy of the sent frame and begin to receive the second copy. Therefore, the forwarding of those frame copies until they reach the source node, as occurs in standard HSR, is not needed in QR. Our example shows a traffic reduction of 37.5%compared to the standard HSR protocol. The second approach is called the virtual ring (VRing), which divides any closed-loop HSR network into several VRings. Each VRing will circulate the traffic of a corresponding group of nodes within it. Therefore, the traffic in that group will not affect any of the other network links or nodes, which results in an enhancement of traffic performance. For our sample network, the VRing approach shows a network traffic reduction in the range of 67.7 to 48.4%in a healthy network case and 89.7 to 44.8%in a faulty network case, compared to standard HSR.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.179-184
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• 2010

The digital substation automation system has contributed hugely to increasing the stability of power systems by providing not only protection and control of power systems but diagnostic features alongside them. Digital substation automation systems in the scale of substations consist of integrated operation systems and intelligent electronic devices. The main intelligent electronic devices currently in use are digital protection relays and the bay controllers in Gas insulated switchgears. Proficiently accomplishing the coordination of protection within the power system as a means of ensuring reliability and contriving for the stability of power supply through connection of function, the application of bay controllers is crucial, which collectively manage the protection relay at the bay level in order to achieve both. In this research, the bay controllers to be used in high-voltage Gas insulated switchgear has been localized, and in particular, the logic function and editor required in order to minimize the complicated hardware-like cable connections in the local panel have been developed. In addition, to ensure the strength and reliability of the bay controller hardware developed herein, the type tests from KERI have been successfully completed.