• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 A
• /
• pp.479-481
• /
• 2001

Traditionally, instrument transformer of the ferromagnetic core type have been used for measuring current in GIS(Gas Insulated Switchgear). Recently, with the introduction of digital technology at the protection relay or measurement device level, the use of new current sensor can be foreseen. Current measurement by means of Rogowski coil is just one illustration of this. This paper describes the progress of development of Rogowski-coil type CT for application in 170kV GIS.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
• /
• pp.531-533
• /
• 2000

In compared with air insulated switchgear, GIS has a high efficiency and confidence So the transformer substation can be reduced the size to 1/10. Insulation method using $SF_6$ gas has a very excellent insulation characteristics for high pressure equipment but has a characteristics that insulation heredity is changed for internal unequal electric field. So analysis of electromagnetic field in GIS is very important basic data for structure design and trouble diagnosis process. In compared with established method, SNM in this paper observes variation of the electromagnetic field with real time and get result very similar to measurement. In order to know the variation of electromagnetic field distribution for transient response for time and position, variations are observed when the spacer is bonded and metal particles are moving fast.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 E
• /
• pp.2076-2079
• /
• 1999

This paper describes the analysis results on the PT ferroresonance at 154 kV GIS (gas Insulated substation by EMTP (Electro-magnetic Transient Program). We had simulated the PT ferroresonance between a potential transformer(PT) and an open circuit breaker's grading capacitance. The ferroresonance leads to very large power frequency overvoltages on PT bus and subsequent insulation failure. The large power can be supplied to the PT by the high voltage on the opened circuit due to the grading capacitance and equivalent capacitance of the buses during the ferroresonance. The damping circuit connected on the secondary winding were considered in the model. The actual countermeasure include a saturable inductor and a resistor series-mounted, but the 2 ohms of damping resistance was used in the computational model.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
• /
• pp.418-421
• /
• 2006

현재 국내 외에서 GIS(Gas Insulated Switchgear)용 광 CT(optical current transformer)가 활발히 연구 개발되고 있다. 이러한 광 CT는 전력선에 발생하는 자기장에 의해 레이저 빛의 파장 각도가 변하는 현상인 Faraday Effect를 기련 원리로 한 전류측정용 기기이다. 본 논문에서는 GIS용 광 CT 개발을 목적으로 한 기초적 연구로써 자기장이 발생하는 전력선에 장착되는 센서부가 도선을 중심으로 해서 어떻게 위치하느냐에 따른 광 CT의 출력신호를 측정하여 연구하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.661-662
• /
• 2007

We have carried out the construction of the 154kV intelligent substation with KEPRI. The intelligent substation is built in Gochang testing facility of KEPCO and consists of electronic instruments for GIS(gas insulated switchgear), digital control panel, remote monitoring and diagnosis system, and digital relay system. Rogowski coil type CT(RCT) and capacitive voltage divider(CVD) are introduced compared with the instrument transformer of conventional type. Digital control panel(DCP) replaces the LCP(local control panel) which is drived for mechanical operation. For the monitoring of the condition of GIS and TR, various sensors are used. In this paper, we mention the synopsis and report the progress state of project.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.77-79
• /
• 2005

국내에서도 가스절연 변압기의 개발 및 상용화가 진전됨에 따라 가스절연 변압기의 예방보전기술 연구가 필요하나, 아직 국내에서는 이에 대한 연구가 기초적 수준에 머무르고 있다. 본 논문에서는 우선 $SF_6$ 가스분석을 근거로 한 내부이상 진단기술에 대하여 가스 분석시 이상여부를 결정짓는 지표 성분의 고찰 및 가스절연 변압기 특유의 이상 진단방식에 대하여 현재까지의 국내 외 연구결과를 살펴보고자 한다. 또한 가스절연 변압기에 대한 사고 장해의 미연방지 및 합리화의 관점에서 설비감시 및 이상진단을 위해 그 필요성이 큰 센서기술에 대해서도 검토하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
• /
• pp.153-156
• /
• 2001

The transformer and the OF cable are cooled and insulated by insulating oils in their body. The insulating oil expands or contracts with the heat transfer according to the operating conditions of the electric facilities. So we install the $N_2$ gas tank connected with the insulating oil system to overcome the change. The change of the insulating oil volume for the operation temperature range must be calculated to decide the $N_2$ gas volume and to set the alarm point for safe operation. It is known that this change is proportional to the temperature change and to the insulating oil volume if the temperature change is small enough.[1][11] However this proportional formula has been accepted generally in the design of electric facilities for wide operation temperature range such as $40^{\circ}C{\sim}125^{\circ}C$. Hence, it makes large errors in calculation which car result in serious damage against safe operation of the electric facilities. This paper presents a improved method of calculating the accurate change of the insulating oil volume to insure the safe operation of electric facilities.

• Tribology and Lubricants
• /
• 제35권3호
• /
• pp.151-157
• /
• 2019

Insulated oil degradation produces charged by-products, such as acids and hydro-peroxides, which tend to reduce the insulating properties of the oil. In this study, UV-vis spectroscopy measurement technology is developed and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate its ability to monitor the degradation of electrical insulating paper. The degradation characteristics of the insulating paper are appropriately represented through various types of measurement methods, such as the Tan (delta) method, $CO_2$ gas production measurement, the titration method, and IR spectroscopy. The results are demonstrated to be well comparable to a change in the fluorescence emission ratio (FER), which is defined as the shift in fluorescence intensity in the measured wavelength range, and also to the chromatic ratio, which is defined as a color shift to longer wavelength ranges. The results also show that, by using UV-vis spectroscopy, it is possible to detect the degradation of the insulating paper. This study suggests that UV-vis spectroscopy can be applied as an alternative to high-performance liquid chromatography, which is the internationally recognized measurement technology for cellulose paper degradation. The FER detector is also verified to be useful as an effective condition-monitoring device for power transformers.

• Progress in Superconductivity
• /
• 제10권1호
• /
• pp.60-67
• /
• 2008

We present domestic efforts for superconducting fault current limiter (SFCL) application in the Korea Electric Power Corporation (KEPCO) grid and pending points at issue. KEPCO's decision to upgrade the 154 kV/22.9 kV main transformer from 60 MVA to 100 MVA cast a problem of high fault current in the 22.9 kV distribution lines. The grid planners supported adopting an SFCL to control the fault current. This environment friendly to SFCL application must be highly dependent upon the successful development of SFCL having specifications that domestic utility required. The required conditions are (1) small size of not greater than twice of 22.9 kV gas insulated switch-gear (GIS), (2) sustainability of current limitation without the line breaking by circuit breakers (CB) for maximum 1.5 seconds. Also, optionally, recommended is (3) the reclosing capability. Conventional resistive SFCLs do not meet (1) $\sim$ (3) all together. A hybrid SFCL is an excellent solution to meet the conditions. The hybrid SFCL consists of HTS SFCL components for fault detection and line commutation, a fast switch (FS) to break the primary path, and a limiter. This characteristic structure not only enables excellent current limiting performances and the reclosing capability, but also allows drastic reduction of HTS volume and small size of the cryostat, resulting in economic feasibility and compactness of the equipment. External current limiter also enables long term limitation since it is far less sensitive to heat generation than HTS. Semi-active operation is another advantage of the hybrid structure. We will discuss more pending points at issues such as maintenance-free long term operation, small size to accommodate the in-house substation, passive and active control, back-up plans, diagnosis, and so on.

• 조명전기설비학회논문지
• /
• 제29권8호
• /
• pp.98-103
• /
• 2015

Power plant is that very high reliability when industrial and economic impact on the overall electric power system is required, it is essential to improve the reliability, especially the fault prediction diagnosis. Since an accident caused by the partial discharge in the power plant is above state has a faster response characteristic than the other indications in the case of any, the partial discharge generated in the power plant immediately detect the deterioration of insulation due to the accident of the power plant and the non-drawn It should prevent or reduce. Partial Discharge Measuring Systems for UHV SF6 Gas Insulated Switchgear and power transformer on site installed has some probability of abnormal recognition in case of non-flexible deal with on site noise. Many methode to eliminate these kinds of noises, UHF Detection System is chosen as purchase description in Korea, but this system having a bandwidth between 500MHz 1.5GHz wide band. Initial install periods(about 20 years ago), this band had no strong signal source, but in these days this wide band have strong signals, such as LTE. So, module described in this paper is designed as simultaneously use with wide and narrow band for solve this noise problem, and introduce this system.