• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1882-1884
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• 2003

This paper introduced the characteristics of fiber-optic Mach-Zehnder interferometer to detect ultrasonic waves by discharges in oil. Noise-reduction method with wavelet and frequency-domain analysis was performed.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.143-145
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• 1996

This paper presents the hybrid type based expert system for fault diagnosis in transformers. The proposed system uses the novel fault diagnostic technique based on dissolved gas analysis(DGA) in oil-immersed transformers. The uncertainty of key gas analysis, norm threshold, and gas ratio boundaries are managed by using a fuzzy set. Also, the uncertainty of the fault diagnostic rules are handled by using fuzzy measures. Finally, kohnen's feature map performs fault classification in transformers. To verify the effectiveness of the proposed diagnosis technique, the hybrid type based expert system for fault diagnosis has been tested by using KEPCO's transformer gas records.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1694-1697
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• 2002

KEPCO is planing to adopt a preventive diagnostic system to obtain the reliability of transformer and GIS in 765kV substation. KEPRI has developed the preventive diagnostic system for 765kV substation since 1997. We used various sensors and fault detecting devices such as a dissolved gas analyzer in oil, a ultrasonic detector and LA leakage current detector, etc., and carried out adaptation tests at the both a laboratory and a site. We developed a data acquisition system, a communication control unit and a server system as well. Furthermore, monitoring program and diagnostic expert system were also developed. This paper describes the preventive diagnostic system for 765kV Sin-Ga-Pyong and Sin-Tae-Baek substations which will be operated from 2004.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.114-119
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• 2006

In this paper, measurement of hydrogen gas using three kinds of gas sensors were studied for improving selectivity and quantification on hydrogen gas. Output characteristics for each sensors were analyzed to some concentrations of hydrogen gas. It was illustrated that the wide range of hydrogen gas concentrations upto 10,000[ppm] can be reliably measured from investigation of concentration ranges with high amplitudes and good resolutions. Also, the combinations of outputs from three kinds sensors were able to improve the selectivity of hydrogen gas.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.69-75
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• 2008

This paper presents an algorithm robust to error for estimating partial discharge (PD) location using acoustic emission sensors. In operating transformers, the velocity computing of the acoustic signal is difficult because the temperature of the Insulation oil is not homogeneous. So, some error occurs in the process. Therefore, the algorithm estimating PD location must consider this error to provide maintenance person with useful information. The conventional algorithm shows the PD position as a point, while the new algorithm using LookUp-Table(LUT) shows PD position as error-map visually. The error-map is more useful than the conventional result because of robustness to error. Also, we compared performance of them, by adding error to data on purpose.