• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.48-50
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• 2004

The energization of high voltage transmission lines and transformers, that is an inevitable process in most countries as the first restorative action for wide-area blackout, may induce overvoltages such as sustained overvoltage, transient overvoltage and harmonic resonant overvoltage. And these may cause damages to power system equipments or failure of surge arresters. The harmonic resonant overvoltage 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 the solution to prevent harmonic resonance is proposed in this paper. As a result, the PSCAD/EMTBC simulation showed slightly conflictive results that had been presented by IEEE Power System Restoration Working Group report.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1377-1382
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• 2015

Power system restoration following a massive blackout starts with re-energizing Primary Restorative Transmission (PRT) systems at first. As power systems have been gradually enlarged and become more complex, periodical evaluation and reassignment of PRTs are needed. So far it has been decided by try and error approach by corresponding human experts to analyze and evaluate them. This paper presents an intelligent system that finds optimal primary restoration paths using analytic and heuristic knowledge from PSS/E data, and suggests an optimal PRTs depending on the condition of Ferranti effect or a reactive power capability margin of black-start generator. This system was tested in Korea Electric Power system, and showed a promising result.

• 전기학회논문지
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• 제62권7호
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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.

• 전기학회논문지
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• 제56권1호
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• pp.14-17
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• 2007

Power system restoration following a massive blackout starts with re-energizing primary restorative transmission systems at first. The comparison of the TLCC(transmission line charging capacity) and the RPC(reactive power capability) of related black-start generator should be considered in this stage because overvoltage can be caused by self-excitation at the generator when the RPC is smaller than the TLCC. The RPC can be decided by two criteria. One is stator end core heating, and the other is steady state stability. RPC in steady state stability area has been found based on a synchronous reactance Xd. This paper presents RPC limit of salient pole machine which is different from that of non-salient pole machine in steady state stability area and shows derivation process about that.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.192-194
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• 2005

Power system restoration following a massive blackout starts with reenergizing of primary transmission lines. This paper presents the restoration and training system for Jeju network using RTDS. System operators can simulate the jeju restorative procedures from primary transmission lines to ail the system topology written by KPX in the real time. Owing to the efficient restoration training by the system, It is expected to restore the power system rapidly and accurately when a massive blackout occurs, and also the system helps student understand the restoration method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.31-33
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• 2003

Power system restoration following a partial or complete blackout starts with energizing of primary transmission lines. Because system changed rapidly during early restoration process, transformer energization and load pickup is executed to maintain the power system stability. However unexpected problem such as harmonic overvoltage may be arisen during energizing transformer. The reason of harmonic overvoltage is known as transformer saturation and magnetizing in-rush current and so on, but it is difficult to estimate the condition of occurrence. This paper describes the analysis of the harmonic overvoltage while unloaded transformer is energized using PSCAD/EMTDC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.163-165
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• 2003

In order to improve the power restoration capability of system operators In case that the fault and blackout happen in the power system, Development of the Power Restoration Training System is necessarily required as a simulator tool for training operator. Owing to these reasons, KEPRI has developed the power restoration training system and graphic editor and applied it to Jeju transmission system. This paper presents the design and implementation of the system, and shows a example to simulate the primary restorative line in jeju.