• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1093-1101
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• 2015

Partial Discharge (PD) is a physical phenomenon, which causes defects and damages to the insulation. This phenomenon is regarded as the most important source of fault and defect in power transformers. Therefore, methods of high speed and precision are considered of special importance for the maintenance of transformers in localization of the origin of partial discharge. In this paper, the transformer winding is first modeled in a transient state by using RLC ladder network and multiconductor transmission line (MTL) models. The parameters of the two models were calculated by Ansoft Maxwell software, and the simulations were performed by Matlab software. Then, the PD pulses were applied to the models with different widths of pulses. With regard to the fact that the signals received after the application of PD had a variable frequency nature over time, and based on the wavelet transform and signal energy, a new method was presented for the localization of PD. Ultimately; the mentioned method was implemented on a 20 kV winding distribution transformer. Then, the performances of the models used in this paper, including RLC and MTL models, were compared in different frequency bands for the correct distinction of partial discharge location.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.27-27
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• 2010

The exact partial discharge pulse should be measured in order to estimate the discharge source in the solid insulation and diagnose the degree of deterioration. Partial discharges generated in the insulation occur in the internal voids or at the edge of the insulation, have unique characteristics following the type and location. When external voltage is applied, Partial discharges occurred in the restrictively presented voids increase the quantity of electrical charge at the discharge onset voltage. The discharge characteristics have remained constant as space is filled by the impurity such as a compound of gases accompanied with discharge. In this study, How to design the insulation about the problems of the built-in diagnostics in the transformer is discussed by the interpretation of electric field.

• 조명전기설비학회논문지
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• 제18권4호
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• pp.112-117
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• 2004

본 논문에서는 GIS내에 존재할 수 있는 부분방전원을 추정하기 위하여 모의 GIS를 제작하고 부분방전의 원천으로 모의된 코로나방전, 연면방전, 파티클의 자유운동, 보이드(void) 방전, 그리고 플로팅(floating) 전극으로부터 발생하는 UHF신호의 특성을 분석하였다. UHF 신호의 특성 분석의 결과로써 각 부분방전원에 대한 UHF 신호의 주파수 스팩트럼과 위상 특성을 도출하였다. 이 결과를 실제 GIS 내의 부분방전원을 분석하는데 체계적으로 적용하기 위하여 취득된 모든 UHF 신호의 특성을 정량화하고 다층구조를 갖는 역전파학습 신경회로망에 기초한 알고리즘의 데이터로 활용하였다. 구축된 알고리즘의 인식률은 학습과 테스트 데이터에서 각각 약 94(%)와 82(%) 정도로 양호하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1748-1750
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• 2002

Partial discharge is attendant physical phenomenon on electromagnetic, sounds, lightning and mechanical vibration. In this paper, we simulated GIS and measured the radiated electromagnetic wave emitted from partial discharge in $SF_6$ gas using antenna(30[MHz] ${\sim}$ 2[GHz]) and spectrum analyzer. This paper describes characteristics of radiated electromagnetic waves with distance 1 [m] between antenna and discharge source.

• Journal of Electrical Engineering and Technology
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• 제2권3호
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• pp.396-400
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• 2007

A novel technique has been proposed and related experimental works have been performed in order to detect the partial discharges and the location of the possible defects introduced into the Gas Insulated Switchgear. For this purpose, a prototype HY Pockels sensor has been developed and then employed in order to investigate its field applicability for finding the location of the defects using a 170kV GIS mock-up. Our proposed sensor enables us to measure the electric field variation due to the PD occurrence. In addition, the different PD patterns are observed, which might be dependant on the location and the distance of the sensor with respect to the PD source. Throughout this work, its linear response has been proved to be admissible as a function of the applied voltage. And also the position of the PD source might be distinguished by comparing the PD patterns.

• 한국전기전자재료학회논문지
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• 제21권5호
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• pp.481-485
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• 2008

In stator windings of 6.6 kV rotating machine, corona discharge, surface discharge and internal discharge are caused mainly by internal voids and insulation degradation. Also, if partial discharge occurs in inner-part of stator windings, it will be happened electromagnetic pulses at wide frequency range. In case of discharge spark, electromagnetic pulse generated from discharge source, and we can detect it by using various RF resonators as an EM sensor. In order to detect these kind of electromagnetic sources, we have designed and fabricated planar patch sensor using CST MWS simulation, and also PD signals from artificial defected cable were measured by our proposed sensor. Furthermore, HFCT was used as a reference sensor and compared with our proposed new planar patch sensor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.136-138
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• 2000

This paper describes an efficient location detection algorithm for a partial discharge(PD) source in the transformer. The algorithm is previously proposed is not suitable for PD source detection because ultrasonic signal is diminished through the inner structure. In this paper, the proposal algorithm find PD source using geometry method and 3th sensor on the one side of transformer without diminution of ultrasonic signal. The proposed algorithm demonstrates the effectiveness and validity on model transformer.

• 한국전기전자재료학회논문지
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• 제21권4호
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• pp.348-353
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• 2008

Most of the high voltage insulation systems, such as the power cable joint having hetero interface, are composed of more than two different insulators to improve insulating performance. The partial discharge(PD) in these hetero interface is expected to affect the total insulation performance. Thus, it is important to study electrical properties on these interfaces. This study described the influence of copper and semiconductive substance defects on $\Phi$-q-n distribution between the interface of the model cable joints to classify PD source. PD was sequentially detected for 600 cycles of the applied voltage. The K-means cluster analysis has been analyzed to investigate the $\Phi$-q-n distribution. The skewness-kurtosis(Sk-Ku) plot from K-means clustering results was defined to quantify cluster distribution and classify distribution patterns. The Sk-Ku plot is composed of skewness and kurtosis along abscissa and ordinate which indicate the asymmetry and the sharpness of distribution. As a result of the Sk-Ku plot, it was confirmed that the data was distributed in 1st 2nd and 3rd quadrant at copper foreign substance defect, but in case of semiconductive foreign substance, the data was distributed in 2nd quadrant only.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.197-198
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• 2007

We studied the partial discharge detecting by sensing electromagnetic pulse emitted from the partial discharge source in the stator winding of HV Rotating Machine with UWB sensor. In this study, we designed new type of compact low frequency UWB sensor based on micro-strip technology and made experiments of offline dismantled testing compare with the traditional HFCT as a reference sensor in the laboratory. We investigated internal discharge, surface discharge, corona discharge and non-defected state normal stator on pre-made stator winding by using UWB patch sensor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.95-96
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• 2008

We constructed an on-line PD monitoring system for the 380kV U/G Cable project at the Riyad 9012 substation in Saudi-arabia. The system will be monitoring the termination of the two 380kV XLPE Cables to prevent unexpected failure of the cable insulation. The system had been tested in the laboratory and on-site for detection of various PD signals and reliability of operation. The system distinguish the existence and nonexistence of the partial discharge and then judge the source of partial discharge using automatic PD pattern recognition software.