• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2106-2117
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• 2017

An effective statistical feature extraction approach of data sampling of fault in the combined transmission system is presented in this paper. The proposed algorithm leads to high accuracy at minimum cost to predict fault location and fault type classification. This algorithm requires impedance measurement data from one end of the transmission line. Modal decomposition is used to extract positive sequence impedance. Then, the fault signal is decomposed by using discrete wavelet transform. Statistical sampling is used to extract appropriate fault features as benchmark of decomposed signal to train classifier. Support Vector Machine (SVM) is used to illustrate the performance of statistical sampling performance. The overall time of sampling is not exceeding 1 1/4 cycles, taking into account the interval time. The proposed method takes two steps of sampling. The first step takes 3/4 cycle of during-fault and the second step takes 1/4 cycle of post fault impedance. The interval time between the two steps is assumed to be 1/4 cycle. Extensive studies using MATLAB software show accurate fault location estimation and fault type classification of the proposed method. The classifier result is presented and compared with well-established travelling wave methods and the performance of the algorithms are analyzed and discussed.

• 전기학회논문지
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• 제60권3호
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• pp.492-499
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• 2011

This paper describes that the evaluation on operation practicality of Al conductor cable will be used instead of Cu conductor cable. Analysis is divided into two kinds of cases as transmission and distribution. To evaluate that Al conductor line has the insulation strength indeed safely, various analysis and calculation such as single line-to-ground fault current, lightning surge and allowance current were carried. Model was established based on real combined transmission and distribution is being used in utility with EMTP. The analysis results on Al and Cu conductor line were compared each other. It was proved that Al conductor line can be operated instead of Cu conductor line without special insulation problem in transmission and distribution, in electrical view point such as overvoltage and allowance current.

• 대한전기학회논문지:전력기술부문A
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• 제52권10호
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• pp.602-609
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• 2003

This paper describes the fault location calculation using neuro-fuzzy systems in combined transmission lines with underground power cables. Neuro-fuzzy systems used in this paper are composed of two parts for fault section and fault location. First, neuro-fuzzy system discriminates the fault section between overhead and underground with normalized detail coefficient obtained by wavelet transform. Normalized detail coefficients of voltage and current in half cycle information are used for the inputs of neuro-fuzzy system. As the result of neuro-fuzzy system for fault section, impedance of selected fault section is calculated and it is used as the inputs of the neuro-fuzzy systems for fault location. Neuro-fuzzy systems for fault location also consist of two parts. One calculates the fault location of overhead, and the other does for underground. Fault section is completely classified and neuro-fuzzy system for fault location calculates the distance from the relaying point. Neuro-fuzzy systems proposed in this paper shows the excellent results of fault section and fault location.

• 한국산학기술학회논문지
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• 제14권7호
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• pp.3474-3481
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• 2013

본 논문에서는 결함접지구조와 가유전체 기판구조를 이용하여 새로운 초고주파 대역 전송선로 구조가 제안된다. 결함접지구조는 전송선로의 단위길이당 등가의 인덕턴스를 증가시켜 동일한 선폭일 때 전송선로의 특성 임피던스를 키우면서 선로의 길이를 줄여준다. 가유전체 기판구조는 전송선로의 단위길이당 등가의 커패시턴스를 증가시켜, 동일한 선폭일 때 전송선로의 특성 임피던스를 낮추면서 선로의 길이를 줄여준다. 따라서 결함접지구조와 가유전체 기판구조는 모두 전송선로의 길이를 줄이면서 선폭에 대해서는 상보적인 역할을 한다. 그러므로 두 구조가 결합되면 전송선로의 특성 임피던스는 크게 변하지 않은 채 길이만 더욱 줄일 수 있으므로, 초고주파 회로의 소형화에 크게 유리하다. 본 논문에서는 결함접지구조와 가유전체 기판구조를 모두 결합시킨 $35{\sim}100{\Omega}$ 전송선로를 설계하고, 실제로 제작 및 측정하여 그 결과를 제시하는데, 특성 임피던스의 예측값과 측정값이 잘 일치함을 보인다. 동일한 전기적 길이에 대하여 제안한 전송선로는 Fig.준형 마이크로스트립 전송선로에 비하여 불과 55.4~76.9% 물리적 길이를 갖는다.

• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1202-1209
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• 2014

A novel integrated optimization method is proposed to combine both generation and transmission line expansion problem considering bus voltage limit. Most of the existing researches on the combined generation and transmission expansion planning cannot consider bus voltages and reactive power flow limits because they are mostly based on the DC power flow model. In this paper the AC power flow model and nonlinear constraints related to reactive power are simplified and modified to improve the computation time and convergence. The proposed method has been successfully applied to Garver's six-bus system which is one of the most frequently used small scale sample systems to verify the transmission expansion method.

• 전기학회논문지
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• 제64권6호
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• pp.857-863
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• 2015

OF cable with excellent reliability and economic efficiency, has been used as the main cable of underground transmission in Korea. However, as XLPE cable is excellent in view points such as reduction of loss, convenience on the construction/operation, and manufacturing technology, it has been replaced as instead of OF cable. Also, when the aging occurs in some sections of OF cable, the section is replaced as XLPE cable without changing of whole cable line. However, there are some differences like electrical constants between both types of cables. Therefore if underground transmission system will be operated as combined connection composited of both cables, it should be proved that overvoltage is stable in steady and transient state. This paper describes the effectiveness of connection operation in combined OF and XLPE cable. For the evaluation of effectiveness, some important analysis such as sheath component voltage, lightning and switching overvoltage, single line-to-ground fault are carried out in steady and transient state. EMTP/ATPDraw is used for modeling and analysis of system.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1002-1008
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• 2014

This paper describes insulation design and its reliability evaluation of ${\pm}80kV$ HVDC XLPE cable. Recently, the construction of HVDC transmission system, which is combined overhead line with underground cable, has been completed. This system is installed with existing 154 kV AC transmission line on the same tower. In this paper, the lightning transient analysis is firstly reviewed for selection of basic impulse insulation level and nominal insulation thickness. Then the electrical performance tests including load cycle test and superimposed impulse test based on CIGRE TB 496 are performed to evaluate the reliability of newly designed HVDC cable. There is no breakdown for ${\pm}80kV$ HVDC XLPE cable during electrical performance test. Finally, this system is installed in Jeju island based on successful electrical performance test (Type test). After installation tests are also successfully completed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.319-322
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• 2002

Distance relay is operated in calculating line impedance. It can be worked accurately in overhead line. However, power cables or combined transmission lines need compensation for calculated impedance because cable systems have sheaths, grounding wires and sheath voltage limiters(SVLs) Neuro-fuzzy can be viewed either as a fuzay system, a neural network or fuzzy neural network and it can estimate the location of the fault accurately. In this paper, fault section and fault location can be classified and estimated in neuro- fuzzy inference system and neural network.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.491-493
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• 2001

This paper describes the effect of lightning current on combination transmission line. In the paper, an lightning current which can generate 2/80[${\mu}s$]. 20[kA] - 40[kA] waveform is modeled in ATPDraw. The lightning current invaded to the overhead power transmission line propagates to the underground power cable. The simulation was performed to analyze the effect of arrester location and overvoltage occurred in power cable.

• 한국산학기술학회논문지
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• 제7권4호
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• pp.616-624
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• 2006

본 논문은 집중소자가 결합된 결함접지구조를 갖는 초고주파 전송선로의 전기적 특성에 관하여 기술하고 있다. 주기구조의 일종인 결함접지구조를 전송선로에 삽입하면, 등가의 부가적인 인덕턴스와 캐패시턴스에 의하여 표준형 전송선로에는 없던 저역통과, 대역차단 또는 대역통과 특성이 발생하며, 전송선로의 전기적 길이가 늘어나는 지연파 특성이 나타난다. 여기에 다시 저항, 캐패시터, 인덕터와 같은 집중소자가 결합되면 공진주파수의 변화를 포함한 다양한 전송특성의 변화가 발생한다. 본 논문에는 결합되는 집중소자들의 값에 따른 DGS 전송선로의 특성 변화를 예측하고 실험적으로 검증하였다.