차량탑재용 온라인 피뢰기 진단장치의 설계 및 제작

정기우(Gi-Woo Jeong),김선재(Sun-Jae Kim),왕국명(Guoming Wang),길경석(Gyung-Suk Kil) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.5

본 논문에서는 누설전류를 측정할 수 있는 전기철도의 차량탑재용 피뢰기 온라인 진단장치에 대하여 기술하였다. 장치는 차량에 탑재되는 측정부와 정비창에 설치되는 서버로 구성된다. 측정부는 내부에 공극(air-gap)과 검출 저항을 설치하여 피뢰기의 보호동작에 영향을 주지 않고, 상시적으로 누설전류를 검출할 수 있다. 측정된 데이터는 무선통신모듈을 통하여 차량 입창 시 마다 서버에 전송된다. 서버 PC에서는 검출모듈로부터 전송된 차량 번호, 누설전류 및 상태를 출력한다. In this paper, we described an on-line analyzer of arresters for use in trains by measurement of leakage current. The analyzer is composed of a detection module and a server which is installed in a railway yard. The detection module consists of an air-gap and a resistor to measure the leakage current flowing an arrester. The magnitude of leakage current is transmitted to the server through a zigbee module when the train arrives a railway yard. The server displays train number, magnitude of leakage current and condition for arresters.

몰드변압기의 보이드 결함 크기 판별

정기우(Gi-woo Jeong),김성욱(Wook-sung Kim) 한국정보통신학회 2022 한국정보통신학회 종합학술대회 논문집 Vol.26 No.2

본 논문에서는 신경망 모델을 적용한 몰드변압기의 보이드 결함 크기 판별에 관한 연구를 수행하였다. PCB 기반의 로고우스키 코일형 부분방전 센서를 제작하여 부분방전 신호를 측정하였고, 보이드에 의한 부분방전 결함을 모의하기 위한 PD 전극계를 제작하였다. 또한 보이드는 원통형 모양의 알루미늄 틀을 제작하여 에폭시가 경화되는 과정에서 실린지를 삽입하고 공기를 주입하여 서로다른 직경을 가지는 4개의 시편을 제작하였다. 보이드 결함 크기 판별을 위해 부분방전 전하량, 방전 펄스 수, 위상 분포의 부분방전 특성 파라미터를 추출하여 Labview 기반의 VI (Virtual Instrument)로 역전파 알고리즘을 설계하였다. 실험 결과로부터 제작된 알고리즘은 90%이상의 판별률로 결함의 직경크기를 구분할 수 있었다. 본 연구의 결과는 현장에서 PD 측정 시 몰드변압기의 유지보수 및 절연물 교체의 근거 자료로 활용될 수 있을 것으로 판단된다. This paper presents the identification of void diameters for a cast-resin transformer using an artificial neural network (ANN) model. A PD signal was measured by the Rogowski coil sensor which has the planar and thin structures fabricated on a printed circuit board (PCB), and the PD electrode system was fabricated to simulate a PD defect by a void. In addition, void samples with different diameters were fabricated by injecting air in a cylindrical aluminum frame using a syringe during the epoxy curing process. To identify the diameter of void defects, PD characteristics such as the discharge magnitude, pulse count, and phase angle were extracted and back propagation algorithm (BPA) was designed using virtual instrument (VI) based on the Labview program. From the experimental results, the BPA algorithm proposed in this paper has over 90% accurate rate to identify the diameter of void defects and is expected to use reference data of maintenance and replacement of insulation for cast-resin transformers in the on-site PD measurement.

LabVIEW 기반 피뢰기 I-V특성 분석장치

정기우(Gi-Woo Jeong),김선재(Sun-Jae Kim),길경석(Gyung-Suk Kil),박희철(Hee-Chul Park) 한국철도학회 2013 한국철도학회 학술발표대회논문집 Vol.2013 No.11

본 논문에서는 철도용 피뢰기의 관리를 위한 I-V 특성 분석장치에 대하여 기술하였다. 분석장치는 직류 고전압 발생장치, 데이터 수집모듈 및 제어부로 구성되며, LabVIEW 를 이용하여 데이터를 분석하도록 설계하였다. 분석 프로그램은 최대 전류와 시험 전압을 100 V/s 의 비율로 인가하도록 설정할 수 있다. DAQ 에서는 피뢰기의 누설전류와 인가 전압을 측정한다. 그 값으로부터 분석장치에 I-V 특성 곡선을 나타내고, 피뢰기의 상태 진단에 활용될 수 있다. In this paper, we described the I-V characteristic analyzer to diagnose lightning arrester for traction systems. The analyzer is composed of a DC high voltage power supply, a data acquisition module and a control unit, and is designed to analyze measured data using a LabVIEW program. An analysis program set the applied test voltage with the rate of 100 V/s and the maximum current. The DAQ detects leakage current flowing an arrester under test and applied voltage. From the value, the analyzer displays I-V characteristics curve, and we can identify the soundness of the arrester.

SF₆ 압력에 따른 결함별 부분 방전 펄스의 분포 분석

김선재,조향은,정기우,길경석,김성욱,Kim, Sun-Jae,Jo, Hyang-Eun,Jeong, Gi-Woo,Kil, Gyung-Suk,Kim, Sung-Wook 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.1

Electrode systems: a protrusion on conductor (POC), a protrusion on enclosure (POE), a crack in epoxy plate and a free particle (FP) were fabricated to simulate insulation defects in a gas insulated switchgear (GIS). $SF_6$ gas was filled in the electrode systems by 3 bar and/or 5 bar, respectively. Partial discharge (PD) pulses were detected through a $50{\Omega}$ non-inductive resistor. A calibration test was carried out according to IEC 60270, and the sensitivity was 0.25 pC/mV. PD pulses were distributed in the phase of $50^{\circ}{\sim}135^{\circ}$ and over 95% of them existed in the phase of $55^{\circ}{\sim}120^{\circ}$ for the POC. PD pulses were distributed in the phase of $230^{\circ}{\sim}310^{\circ}$ and over 90% of them existed in phase of $220^{\circ}{\sim}300^{\circ}$ for the POE. PD pulses occurred in the phase of $40^{\circ}{\sim}60^{\circ}$ and $220^{\circ}{\sim}300^{\circ}$ for the crack, and pulse counts were 25% higher in negative polarity than in positive polarity. PD pulses were distributed in every phase unlike to other three electrode systems and the peak magnitude was measured at $118^{\circ}$ and $260^{\circ}$ for the FP. As described above, PD pulses were observed in positive polarity for the POC, in negative one for the POE, in both one for the crack and the FP. In conclusion, it is expected that the identification rate of defect type can be improved by considering the polarity ratio of PD pulses on the PRPDA method.

가스절연 구조에서 단일 부분방전펄스 분석에 의한 결함 판별

조향은,김선재,정기우,길경석,Jo, Hyang-Eun,Kim, Sun-Jae,Jeong, Gi-Woo,Kil, Gyung-Suk 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.5

This paper dealt with a defect identification algorithm which is based on single partial discharge (PD) pulse analysis in gas insulated structure. Four types of electrode systems such as a needle-plane, a plane-needle, a free particle and a crack inside spacer were fabricated to simulate defects in gas insulated switchgear (GIS). We measured single PD pulse by an oscilloscope with a sampling rate of 5 GS/s and a frequency bandwidth of 1 GHz. Data aquisition and signal processing were controlled by a LabVIEW program. Physical shapes of PD pulses were compared with kurtosis, skewness and time-based parameters as rising time, falling time and pulse-width. These parameters were analysed by an algorithm with a back propagation algorithm (BPA). By applying the algorithm, the identification rate was 97% for the needle-plane electrode, 96% for the plane-needle electrode, 91% for the free particle and 93% for the crack inside spacer. The results verified that the algorithm could identify the type of defects in GIS.

SF₆ 가스 중 직류 고전압 하에서 부분방전 특성

김민수,김선재,정기우,조향은,길경석,Kim, Min-Su,Kim, Sun-Jae,Jeong, Gi-Woo,Jo, Hyang-Eun,Kil, Gyung-Suk 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.4

This paper dealt with the measurement and analysis of partial discharge (PD) under high voltage direct current (HVDC) in SF6 gas. Electrode systems such as a protrusion on conductor (POC), a protrusion on enclosure (POE), a crack on epoxy plate and a free particle (FP) were fabricated to simulate the insulation defects. The analysis system was designed with a Time-Frequency (T-F) map algorithm programed based on LabVIEW. This can arrange the acquired PD pulses into frequency and time domain. A HVDC power source is composed of a transformer (220 V/50 kV), a diode (100 kV) and a capacitor (50 kV, 0.5 ${\mu}F$). The gap between the electrodes is 3 mm, and the $SF_6$ gas was set at 5 bar. PD pulses were detected by a 50 ${\Omega}$ non-inductive resistor. In the analysis, PD pulses were distributed below 0.5 MHz and 20 ns ~ 35 ns for the POC, 0.7 MHz ~ 1.7 MHz, below 0.6 MHz and 10 ns ~ 40 ns and 60 ns ~125 ns for the POE, below 0.1 MHz and 135 ns ~ 215 ns for the crack, and below 1.6 MHz and 250 ns for the FP.

동봉과 탄소블록의 접지 임피던스의 경년변화

김선재(Sun-Jae Kim),정기우(Gi-Woo Jeong),왕국명(Guoming Wang),길경석(Gyung-Suk Kil) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.5

본 논문에서는 동봉과 탄소블록을 매설하여 접지 임피던스의 경년변화에 관하여 기술하였다. 접지 임피던스는 IEEE Std. 81의 전위강하법으로 급준파, 8/20us 표준 뇌임펄스 및 구형파로 2년 동안 주기적으로 측정하였다. 접지 임피던스는 지난 2년간 큰 변화는 없었으며, 탄소블록의 접지 임피던스는 동봉에 비해 구형파에서는 낮게, 그리고 급준파에서는 높게 나타났다. This paper described the seasonal variation of ground impedance for a copper-rods and a carbon block buried in the ground. Ground impedance was measured by the fall of potential method specified in IEEE Std. 81 and by the application of a fast-rise step impulse, a 8/20us standard lightning impulse and a square waveform for 2 years periodically. Comparatively, ground impedance as ages showed no difference for the last 2 years, and ground impedance of the carbon block was lower at the square waveform and was higher at the fast-rise step impulse than that of the copper-rods.

침-평판 전극계에서 SF₆ 가스 압력에 따른 부분방전 패턴 분석

김민수(Min-Su Kim),정기우(Gi-Woo Jeong),길경석(Gyung-Suk Kil),박대원(Dae-Won Park) 한국철도학회 2013 한국철도학회 학술발표대회논문집 Vol.2013 No.11

본 논문에서는 침-평판 전극계에서 SF₆ 가스 압력에 따른 부분방전 패턴에 대하여 기술하였다. 전극계는 곡률반경이 10 μm인 침 전극과 지름 80 mm, 두께 10 mm인 평판 전극으로 구성되며, 침 전극과 평판 전극의 거리는 3 mm로 제작하였다. 정밀저항을 전극계와 접지선 사이에 삽입하여 부분방전 펄스를 검출하였으며, 1 bar에서부터 5 bar까지 SF₆ 가스를 봉입시키고 각각의 압력에서 120주기 동안 부분방전 펄스의 위상분포를 분석하였다. 실험결과, 1 bar에서는 48°~128°, 222°~312°에 부분방전 펄스가 분포하였으며, 발생횟수는 1,622회로 측정되었다. 3 bar에서는 53°~120°, 5 bar에서는 45°~123°에 분포하였고, 발생횟수는 각각 214회와 123회로 측정되었다. This paper described the partial discharge (PD) pattern as a function of SF₆ gas pressure on needle-plane electrode system. Electrode system is consisted of a needle electrode with a radius curvature of 10 μm, and a plane electrode with diameter of 80 mm and thickness of 10 mm, and its gap between the needle and the plane electrode is 5 mm. We detect PD pulses by a 50ohm resistor which is located between the electrode system and a ground. Phase distributions of PD pulses were analyzed at 1 bar, 3 bar and 5 bar of SF₆ gas pressure. From the experimental results, PD pulses were appeared in ranges of 48°~128°, 222°~312° at 1 bar, in ranges of 53°~120° at 3 bar and in ranges of 45°~123° at 5 bar, respectively.