• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.557-559
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• 2004

The study of applying wavelet transform in power cable system fault location has been recognized by many researchers and investigated. For performance of fault location, the fault generated transients can be captured at one end of the cable or both ends. Between two approaches, single-ended approach is less expensive and more reliable as it doesn't need communication link between the ends of the cable. So, we performs the approach based on the one. In this paper, we are going to introduce a new algorithm to discriminate the transient and the reflected signal using wavelet coefficient. For wavelet transform, the stationary wavelet transform(SWT) is applied instead of conventional DWT because SWT has redundancy properties which is more useful in noisy signal processing.

• Transactions on Electrical and Electronic Materials
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• 제7권5호
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• pp.247-251
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• 2006

The traction DC feeder cable is one of the key devices for the safety operation of subway system, but for low voltage DC feeder cable (<3000 V) for subway, little attention has been paid by investigators on its online monitoring technology. With an introduction of cable laying and operation environment for the cable, this paper investigated the on-line monitoring technology of 1500 V DC feeder cable of subway. Firstly, in the text, the fault model of 1500 V DC cable was proposed based on the analysis of the fault type of the DC feeder cable, and then put forward synthetically on-line monitoring discharge signal and DC leakage current signal to assess DC feeder cable insulating state. The results of laboratory experiment prove that the proposed methods are feasible and can be implemented on-line monitor on DC feeder cable of subway.

• 전기학회논문지
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• 제65권9호
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• pp.1583-1589
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• 2016

This paper proposes an improved spread spectrum time domain reflectometry (ISSTDR) using time-frequency correlation and reference signal elimination method in order to have more accurate fault determination and location detection than conventional (SSTDR) despite increased signal attenuation due to the long distance to cable fault location. The proposed method has a two-step process: the first step is to detect a peak location of the reference signal using time-frequency correlation analysis, and the second step is to detect a peak location of the correlation coefficient of the reflected signal by removing the reference signal. The proposed method was validated through comparison with existing SSTDR methods in open-and short-circuit fault detection experiments of low voltage power cables. The experimental results showed that the proposed method can detect correlation coefficients at fault locations accurately despite reflected signal attenuation so that cable faults can be detected more accurately and clearly in comparison to existing methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.446-448
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• 2000

This paper discribes the modeling and transient analysis of cable in combined transmission line under high impedance fault(HIF). And also, transient characterstic analyzed on cable covering protection unit(CCPU) is presented. Modeling of the combined transmission line is established in PSCAD/EMTDC V3. The required data to analyze the transient phenomena is given from the actual system. The results show the HIF modeling in cable, fault current according to the value of fault resistance. And also when the value and method of grounding resistance is changed in CCPU, simulation results are presented.

• 전기학회논문지
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• 제59권7호
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• pp.1194-1198
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• 2010

A high temperature superconducting power cable (HTS power cable) was applied large current capacity by no resistance in normal state. Fault state was risen out of over-current but, it was limited to resistance. this study was modeling equivalence, and unbalanced state analyzed operating charateristics of HTS power cable. The equivalence model was composed superconductor, shield, and former part. This model simulation was appeared conductor and shield current in normal state, but fault state was appeared former current as rise current by resistance. so it need to sufficiently influenced the quench characteristic when the former design.

• 한국산학기술학회논문지
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• 제21권5호
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• pp.84-92
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• 2020

본 논문은 M시퀀스 신호를 이용하여 로켓 추진기관의 케이블 결함 위치 추정 기법에 관한 논문이다. 케이블 내부 결함 위치를 추정하기 위해서 다양한 방법이 연구되어왔는데, 이 중에서 TDR(Time Domain Reflectometry), FDR(Frequency Domain Reflectometry), TFDR(Time-Frequency Domain Reflectometry) 등이 가장 널리 사용되어 왔다. 이 방법들은 케이블 결함 상태를 진단하기 위해 주로 사용되지만 사용자가 시험환경에 접근하여 수행해야하기 때문에 리스크가 매우 크다. 따라서 시험안전을 확보하고 기존의 방법 대비 동등 이상의 성능을 지니는 M시퀀스 신호를 이용한 케이블 결함 위치 추정 방법을 제안한다. 제안된 방법은 로켓 추진기관 시험에 사용되고 있는 DAS(Data Acquisition System)를 활용하도록 하고, 주로 물리량 계측에 이용되는 RG-58 케이블을 적용하여 기존의 방법인 TDR, TFDR과 비교하여 성능을 검증하였다. 시험 결과 40 m 이내 근거리 케이블 결함 추정에서는 기존의 방법보다 낮은 오차율을 나타났고, 50 m에서는 기존의 방법과 비슷한 오차율을 확인하였다. 따라서 무기체계에 사용되는 DAS를 활용하고 일반적으로 사용되는 M시퀀스 신호를 응용하여 작업자가 시험환경에 접근하지 않고 안전하게 케이블 결함을 추정할 수 있음을 확인하였다.

• 한국통신학회논문지
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• 제40권2호
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• pp.325-333
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• 2015

본 연구는 광케이블 고장이 발생하였을 때 예상 피해 고객과 고장 처리 지연시간이 고객 불만 증가에 미치는 영향을 분석하고자 한다. 광케이블 고장을 복구시키는데 소요되는 시간, 근무 요일여부, 계절성을 함께 고려하였고, 작업자 부주의로 인한 고장, 외부 공사, 코어 단선 및 밴딩 등 관리 가능 항목 고장과 자연재해, 차량추돌, 화재 등 관리 불가능한 변수를 구분하였다. 광케이블 고장 증가의 실증 분석 결과는 다음과 같다. 첫째, 광케이블 고장에 의한 피해 고객수와 복구 시간에 대해서 생산 함수를 이용하였을 때 고객 불만이 무차별하게 증가 하는 것을 알 수 있었다. 둘째, 광케이블 고장처리 뿐만이 아니고 현장에서 관리 가능한 변수인 작업 장애, 외부 공사, 코어 단선이 발생하면 고객 불만을 증가 시켰다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.868-870
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• 1996

This paper describes the faun phenomena by the simulation in power system including underground transmission power cable. Studying on fault phenomena is a very important part to decide the circuit breaker, protective relay and system configuration. Simulation was carried out in several different model system depended upon cable kinds using PSCAD/EMTDC, which is one of the transient program. The simulated results show the possibility to analyze transient phenomena for the cable system.

• 대한전기학회논문지:전력기술부문A
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• 제54권6호
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• pp.267-273
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• 2005

This paper proposes a line-to-ground fault location algorithm for underground cable system. A feature of the proposed method is a new algorithm based on the analytic research which has not been tried until now. The proposed method firstly makes voltage and current equations using analysis of distributed parameter circuit for each of cores and sheathes respectively, and then establishes an equation of the fault distance according to the analysis of the fault conditions. Finally the solution of this equation is calculated by Newton-Raphson iteration method. The effectiveness of this proposed algorithm has been proven through PSCAD/EMTDC(Ver. 4.1) simulations.

• 전기학회논문지
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• 제65권10호
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• pp.1780-1785
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• 2016

This paper presents few case studies of state diagnosis of XLPE cables using very low frequency techniques. The power cables of 22.9kV which have installation fault were assessed using VLF technique in addition to other techniques like insulation resistance and DC voltage withstand test. From the experimental results, The dielectric loss($tan{\delta}$) values of degradation of the cable(joint, knife, needle) at $U_0$ were 5.839, 5.526 and 6.251, respectively and all values were "further study advised". VLF PD measurement was also found defective portion. These method was effective in defect to fault in the degradation of the cable. However, the breakdown did not occur in the degradation of the cable because of properties of XLPE insulation. Few case studies of using VLF $tan{\delta}$ diagnosis for fault are measured and analyzed. The $tan{\delta}$ values at $U_0$ were "further study advised" or "action required".