• 전기산업
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• v.7 no.4
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• pp.14-25
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• 1996

• Nuclear industry
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• v.28 no.6
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• pp.17-23
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• 2008

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.282_283
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• 2009

최근 국내계통에서도 중부하 상태로 안정도 한계근처에서 운용되고 있는 실정으로 이미 여러 선진국에서 경험한 전압붕괴로 인한 대규모 정전사태의 확률이 점점 증대되고 있다. 최근 우리나라에서도 전압안정도 측면에서 전압제어시스템의 필요성을 인식하고 이러한 문제를 해결하기 위해 전력IT과제를 통해 지능형 전압제어시스템을 개발하였다. 일반적으로 성공적인 지능형 시스템을 구현하기 위해서는 효과적인 탐색기법을 선정해야 한다. 본 논문에서는 지능형 전압제어시스템의 효과적인 동작을 위한 탐색기법을 선정하기 위해 전압제어문제를 상태공간 표현법을 사용하여 모델링 하였고 이에 적합한 탐색기법을 선정하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.50-51
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• 2008

최근 구미 선진국에서 빈발하고 있는 전압붕괴로 인한 대형 정전사고의 확률이 점증하고 있어 전압관리가 전력계통의 주요관심사로 대두되고 있으며, 이러한 문제들에 대한 대비가 시급한 실정이다. 전압 및 무효전력의 계층적 전압제어는 이러한 문제점들을 경감시킬 수 있는 방법의 일환으로 이미 유럽의 선진국에서는 2차적 전압제어, 3차적 전압제어 시스템을 개발하여 운영하고 있는 실정이다. 이에 따라 본 연구에서는 지능형 전압제어시스템을 개발하였으며, RTDS(Real Time Digital Simulator)를 통하여 성능을 검증하는 단계에 와 있다. 본 논문에서는 정적 모의를 통해 지능형 전압제어시스템의 효과를 검증하였고, 제주계통을 대상으로 개발된 지능형 전압제어시스템의 동적 특성을 검증 할 예정이다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.262-266
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• 2010

During the restoration process of primary restorative transmission system, the over voltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. This over voltage is caused by harmonic resonance and can be prevented by damping loads that are connected before restoration process of primary restorative transmission system. But it is very difficult to predict the occurrence possibility of the harmonic resonance previously. This paper analyzes the relationship between the harmonic resonance and the amount of damping loads to prevent the harmonic resonance. This paper calculates the minimum amount of damping loads to prevent harmonic resonance while changing the length of primary restorative transmission line. And this paper confirmed that the amount of damping loads is not proportional to length of transmission line. The result of this paper will be used as important experiment data to predict the occurrence possibility of harmonic resonance previously.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.944-949
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• 2012

As modern power systems become large and complicated, the automated voltage and reactive power control system is required in most developed countries due to the recent amazing progress of computer net works and information thechnology. So far the voltage control has been depend on human operator in korean power system. This paper presents an intelligent voltage control system based on sensitivity analysis and artificial intelligence technology. Detailed state space modeling technique is discussed and a new performance index is proposed to speed up the searching performance of the expert system. As the searching strategy is very important factor of the speed of expert system the least first search algorithm is applied using this performance index. The intelligent voltage control system is applied to the Jeju power system. As a result, case studies showed a promissing application of the intelligent voltage control system.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.249-251
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• 2004

Harmonic resonant overvoltage during restoration of primary restorative transmission system originates in switching operations and nonlinear characteristics of equipments. Actually it is difficult to predict the occurrence of harmonic overvoltage, since they result from nonlinear characteristics of transformers and other equipments. This paper describes the analysis of domestic primary restorative transmission system using PSCAD/EMTDC. The harmonic resonance is verified and showed the relation with equipments which have nonlinear characteristics such as generator and transformer in this paper. And the solution to prevent harmonic resonance is proposed too. As a result, the PSCAD/EMTDC simulation showed slightly conflictive results that had been presented by IEEE Power System Restoration Working Group report.

• Computational Structural Engineering
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• v.7 no.3
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• pp.41-45
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• 1994

최적화 방법이 구조설계 분야에 사용된지 근30년이 지난 오늘 이론적 측면에서 보면 상당한 발전이 있어 왔다고 해도 과언이 아니다. 실무 입장에 볼 때 과연 얼마만큼 최적화 방법이 현실의 설계업무 속에 자리잡혀 있는가를 곰곰히 되새겨 볼 필요가 있다고 본다. 사실 실제와 이론 사이의 괴리를 줄여보려는 노력에서, 최적호 기술 분야에서도 기존의 확정론적 최적화 방법만이 아니라 확률론적 최적화방법에 대한 연구도 시작되었으리라 본다. 본문에서 언급한 Genetic Algorithm과 Evolutionary Strategy도 기존의 최적화 방법과 마찬가지 이유에서 복잡한 현실문제의 최적해를 추구하기 위한 또 하나의 방법으로 인식 될 필요가 있다고 보아 이 두 방법에 대한 개략적인 내용을 적었다.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.627-632
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• 2003

Squeal noise is generated by railway vehicles transversing tight curves. This squeal has always been noticed as one of the most disturbing noise sourecs of railway systems. At present we cannot predicted squeal noise that is influenced by a large number of dependent parameters. But the application of wheel damping and rail lubrication have successfully reduced wheel squeal. In this study, we measured squeal noise to find out the reduction effectiveness of noise through rail lubricator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.913-917
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• 2013

During the restoration process of primary restorative transmission system, some over voltages may happen due to nonlinear interaction between unloaded transformers and transmission systems. These over voltages caused by harmonic resonance can be suppressed by inserting damping loads before energizing transformers. But it is very difficult to predict the occurrence possibility of harmonic resonance and complex simulation must be repeated to estimate the sufficient damping loads. This paper presents a damping loads prediction system to prevent harmonic resonance. Detailed analysis of the relationship between harmonic resonance and the amount of damping loads is discussed. The prediction system is developed using a curve fitting and a neural network based on this relationship. A curve fitting used a Gaussian function based on non-linear least square method and multi-layer back-propagation neural network is applied. The system is applied to primary restorative transmission lines in korean power system and the result showed satisfactory performance.