72.5 kV GIS 스페이서 내장형 LPCT의 설계 및 제작 = Design and Fabrication of a Low-power Current Transformer embedded in a 72.5 kV-GIS Spacer

다국어 초록 (Multilingual Abstract)

In this thesis, a study on the design and fabrication of Low-power current transformer (LPCT) embedded in Gas insulated switchgear (GIS) spacer was conducted. LPCT based on IEC 61869-10 was consisted of Rogowski current sensor (RCS) and Low voltage part (LV part). The RCS was designed with consideration of the radius, cross-sectional area, coil thickness, and number of turns to achieve the desired rated secondary output. The LV part was used for impedance matching and output adjustment. The fabricated LPCT was evaluated at 5%, 20%, 100% and 120% of rated current, and the maximum ratio error was – 2.546% and phase error 5,650.65 min. According to IEC standard correction factors were calculated and applied, the maximum corrected ratio error was – 0.207% and corrected phase error was 25.65 min, satisfied accuracy class 0.5. Changes in ambient temperature affects the LPCT output, a study on temperature correction was conducted. The LPCT temperature-output characteristics were analyzed at the maximum range of – 40 ℃ ~ 40 ℃, a mathematical correction in merging unit (MU) and passive circuit method were deviesed. For the mathematical correction, the correction coefficient was calculated by linear regression analysis, and as a result, the output fluctuation decreased to 0.02%. The passive circuit was configured through a thermistor, and its simulation results, the output was fluctuated at – 0.023% ~ 0.023%. The LPCT proposed in this thesis is expected to be able to replace the conventional iron-core current transformers, providing a stable and accurate measurement of the load current with an output voltage level in the range of hundreds of millivolts. Additionally, it is anticipated that the reduction in installation area and SF6 usage will enable the miniaturization, eco-friendly, and digitalization of GIS, leading to performance improvements. keywords : Gas insulated switchgear, Low-power current transformer, Rogowski curr ent sensor, IEC 61869-10, Spacer, Temperature compensation

목차 (Table of Contents)

• 1. 서 론 1
• 2. 이 론 4
• 2.1 계기용 변류기 4
• 2.2 로고우스키 전류 센서 9
• 3. 설계 및 제작 13
• 3.1 로고우스키 전류 센서 15
• 3.2 저전압부 18
• 3.3 저전력 변류기 21
• 4. 평가 및 분석 25
• 4.1 실험계 25
• 4.2 결과 및 분석 30
• 4.3 LPCT 온도 보상 35
• 5. 결 론 40
• 참 고 문 헌 41