학술논문
지지 애자형 저전력 측정용 변압기의 설계 및 제작
Design and Fabrication of Post-Insulator type Low Power Voltage Transformer
Design and Fabrication of Post-Insulator type Low Power Voltage Transformer
Document Type
Article
Source
한국철도학회논문집, 27(4), 178, pp.271-279 Apr, 2024
Subject
Language
한국어
ISSN
2288-2235
1738-6225
1738-6225
Abstract
본 논문에서는 고압 수배전반에 사용되는 기존 철심형 계기용 변압기(PT)를 대체하기 위한 24 kV급 지지 애자형 저전력 측정용 변압기(LPVT)를 제안하였다. 용량성 검출 전극을 내장한 애자의 전계 분포를 유한 요소법으로 해석하여 최적 구조의 LPVT를 도출하였다. 최대 전계는 2.8 kV rms /cm로 공기 중 절연 파괴 강도 21 kV rms /cm의 약 1/7, 적용된 에폭시 절연물의 절연 파괴 강도 250 kV rms /cm의 1/90 이하로 상용주파수 과전압과 뇌충격 전압에 대해서 충분한 절연 내력을 갖는다. 시제작 LPVT의 성능은 IEC 61869-11에 따라 정격 전압( )의 80%, 100% 및 120%에서 분압비와 위상을 평가하였다. 분압비 보정 계수( )와 위상 오프셋 보정 계수( ) 적용 후, 분압비 최대 오차는 0.09%, 그리고 위상 오차는 0.76 min.으로 정확도 0.2급을 만족하였다. 동일 정격의 기존 철심형 PT와 비교 시, 본 LPVT는 높이 1/2, 단면적 1/6 및 중량 1/20로 소형화가 가능하므로, 고압 배전반과 변전소 디지털화에 따른 높은 정확 도와 소형·경량화의 요구 사항에 충분히 대응할 수 있어 광범위한 활용이 기대된다.
In this paper, for use in high-voltage switchboards, we propose a 24 kV post-insulator type low-power voltage transformer (LPVT) to replace the iron core potential transformer (PT). Using the finite element method (FEM), an LPVT of optimal structure was derived by analyzing the electric field distribution of an insulator equipped with a capacitive voltage detection electrode. The maximum electric field intensity was 2.8 kVrms/cm, about 1/7 of the insulation breakdown strength of 21 kVrms/cm in air, and less than 1/90 of the insulation breakdown strength of the epoxy. These levels are sufficient to withstand commercial frequency overvoltage and the lightning impulse voltage. The performance of the prototype LPVT was analyzed for voltage ratio and phase error at 80%, 100%, and 120% of the rated voltage according to IEC 61869-11. The maximum error of the voltage ratio was 0.09%, and the phase errorwas 0.76 min. after applying the voltage ratio correction coefficient ( ) and the phase offset correction coefficient ( ), which satisfied the accuracy class of 0.2. Compared to conventional PTs of the same voltage rating, the LPVTis miniaturized by 1/2 in height, 1/6 in cross-sectional area, and 1/20 in weight. The LPVT is expected to be widely used as it can sufficiently meet the high precision and compact-light weight requirements of high voltage switchboards and substation digitization.
In this paper, for use in high-voltage switchboards, we propose a 24 kV post-insulator type low-power voltage transformer (LPVT) to replace the iron core potential transformer (PT). Using the finite element method (FEM), an LPVT of optimal structure was derived by analyzing the electric field distribution of an insulator equipped with a capacitive voltage detection electrode. The maximum electric field intensity was 2.8 kVrms/cm, about 1/7 of the insulation breakdown strength of 21 kVrms/cm in air, and less than 1/90 of the insulation breakdown strength of the epoxy. These levels are sufficient to withstand commercial frequency overvoltage and the lightning impulse voltage. The performance of the prototype LPVT was analyzed for voltage ratio and phase error at 80%, 100%, and 120% of the rated voltage according to IEC 61869-11. The maximum error of the voltage ratio was 0.09%, and the phase errorwas 0.76 min. after applying the voltage ratio correction coefficient ( ) and the phase offset correction coefficient ( ), which satisfied the accuracy class of 0.2. Compared to conventional PTs of the same voltage rating, the LPVTis miniaturized by 1/2 in height, 1/6 in cross-sectional area, and 1/20 in weight. The LPVT is expected to be widely used as it can sufficiently meet the high precision and compact-light weight requirements of high voltage switchboards and substation digitization.