• KIEE International Transactions on Electrophysics and Applications
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• 제11C권2호
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• pp.12-17
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• 2001

In this work, the correlation between the PD Patterns and the electrical tree propagation has been investigated by use of the specimen removed from the insulation of the real 154 kV XLPE underground power cables. As a result, it could be deduced that the PD pattern regarding electrical trees depends on their type which could be classified into three different distinct groups such as branch-bush mixed. Considering the results of our investigation, if the partial discharge magnitude is only considered for the diagnosis of the cable system, it is possible to draw a wrong decision. Therefore, it is possible to propose that the time characteristics of PD pattern should be taken into account for the diagnosis of the cable system in addition to the conventional $\Phi$-q-n characteristics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.96-100
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• 2001

We have measured the space charge distribution and PD patterns simultaneously in XLPE under AC voltages by modified PEA method in order to investigate the effect of space charge on PD patterns in XLPE with air-gap. From the experimental results, we found that the dynamic space charge accumulated on the surface of XLPE due to the PD dominantly affects the PD pattern in the dielectric-barrier structure and governs the voltage across the air-gap. Moreover, the space charge formed by applying DC voltage still remained after applying AC voltage, which means that the space charge formed during DC strength test is likely to be fatal to the long-time AC insulating characteristics of HV equipments. On the other hand, the PD patterns was much influenced by the pre-formed space charge by DC application. Therefore, it is possible to detect the effects of space charge by monitoring the infinitesimal change of PD patterns before and after DC strength.

• 한국전기전자재료학회논문지
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• 제19권10호
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• pp.976-983
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• 2006

Multi-resolution Signal Decomposition (MSD) Technique of Wavelet Transform has interesting properties of capturing the embedded horizontal, vertical and diagonal variations within an image in a separable form. This feature was exploited to identify individual partial discharge sources present in multi-source PD pattern, usually encountered during practical PD measurement. Employing the Daubechies wavelet, feature were extracted from the third level decomposed and reconstructed horizontal and vertical component images. These features were found to contain the necessary discriminating information corresponding to the individual PD sources and multi-PD soruces.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2093_2094
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• 2009

오늘날 국내 지중선로는 주로 XLPE케이블과 OF케이블로 구성된다. 기존 사용되던 OF케이블의 화재 위험성 및 환경오염 문제 등으로 인해 XLPE케이블의 비중이 점차 높아지고 있지만 XLPE케이블의 경우 운전 중 케이블의 열화나 절연진단 등이 쉽지 않은 점이 문제로 제기되고 있다. 그나마 XLPE케이블에 대한 PD측정은 현재로서는 가장 유용한 케이블 진단기법으로 알려져 있으며 그 활용성과 신뢰성을 높이기 위한 연구가 국내외적으로 계속되고 있는 실정이다. 본 논문에서는 실제 운전 중인 154kV 지중송전선로에 대해 PD측정을 수행하고 그 결과로 취득된 Pattern의 분석을 통해 선로내부에서 PD가 발생하고 있는지 판별하는 과정을 소개하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1673-1675
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• 2001

In this paper, Partial Discharge(PD) patterns are compared by means of Low Frequency PD(LFPD, based on the IEC 270) and recently proposed High Frequency PD(HFPD). For this purpose, three different types of artificial defects are provided such as corona in air, void in epoxy insulator and needle defect in XLPE cable insulation. PD were generated from each defect and then detected respectively by two different methods such as LFPD and HFPD. As a result, remarkable resemblance in PD pattern for differ detecting method have been observed from each defect. Accordingly, it could be deduced that the pattern recognition by LFPD could be regarded as the reference for the investigations by HFPD.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.183-187
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• 2000

This paper deals with multiresolution analysis of wavelet transform for partial discharge(PD), both corona and surface discharge. Multiresolution analysis was used for performing discrete wavelet transform. PD signals was decomposed into "approximation" and "detail" components until 4 levels by using discrete wavelet analysis. In this paper, daubechies family is adopted for the research of the characteristics of PD signals. The results show that in corona discharge the segment 7, 8, 9, 10, 11 values of defined variable is increased with discharge process, so phase distribution is characterized by 210~330 ranges. In case surface discharge in expoxy insulator inserted, defined variable values is fairly symmetric discharge pattern because coupled both corona and dielectric bounded discharges. We can confirmly discriminate the type PD source. the type PD source.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1535-1537
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• 2006

Recently, the noise discrimination method using PD pulse waveshape analysis has been suggested to be very effective method which can improve the reliability of the on-site PD measurement. In this method, the data clusters due to PD pulses or noises can be distinguished on the PA map. And for the automatic recognition of the PD clusters, it is necessary to adopt the adaptable pattern recognition method. In this study, as for the algorithm which can recognize data clusters, the data mining method has been adopted and the result of the analysis has been reported.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.192-199
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• 2016

With changes in insulated defects, the environment, and so on, new partial discharge (PD) data are highly different from the original samples. It leads to a decrease in on-line recognition rate. The UHF signal and pulse current signal of four kinds of typical artificial defect models in gas insulated switchgear (GIS) are obtained simultaneously by experiment. The relationship map of ultra-high frequency (UHF) cumulative energy and its corresponding apparent discharge of four kinds of typical artificial defect models are plotted. UHF cumulative energy and its corresponding apparent discharge are used as inputs. The support vector machine (SVM) incremental method is constructed. Examples show that the PD SVM incremental method based on simulated annealing (SA) effectively speeds up the data update rate and improves the adaptability of the classifier compared with the original method, in that the total sample is constituted by the old and new data. The PD SVM incremental method is a better pattern recognition technology for PD on-line monitoring.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.699-706
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• 2016

Partial discharges (PD) lead to the degradation of high voltage cables and accessories. PD activities occur due to the existence of impurities, voids, contaminants, defects and protrusions during the manufacture and installation of power cables. Commonly, insulation failures occur at cable joints and terminations, caused by inhomogeneous electric field distributions. In this work, a blend of natural rubber (NR) and linear low density polyethylene (LLDPE) was investigated, and the optimal formulation of the blend that could resist PD was discussed. The experiments were conducted under a constant high voltage stress test of 6.5 kV AC and the magnitude of partial discharge activities was recorded using the CIGRE method II. Pattern analysis of PD signals was performed along with the interpretation of morphological changes. The results showed that the addition of 10 wt% of NR and 5 wt% of Alumina Trihydrate (ATH) provided promising results in resisting PD activities. However, as the NR content increased, more micropores existed, thus resulting in increased PD activities within the samples.

• 전기전자학회논문지
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• 제22권2호
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• pp.356-361
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• 2018

고온에서 이용 가능한 수소 센서에 관해 연구하였다. 센서는 $Pd/Ta_2O_5/SiC$으로 구성된 MOS 구조로 제작되었으며, $Ta_2O_5$ 박막은 급속 열 산화법(RTO)법으로 형성하였다. 본 연구에서는 3가지 다른 패턴의 팔라듐(Pd) 전극으로 만든 센서를 제작하여, Pd 전극의 형태가 응답 특성에 미치는 영향을 고찰하였다. 그 결과, 센서는 Pd 전극의 채워진 면적이 클수록, 정전용량의 응답특성이 개선됨을 확인하였다.