CAJ | 학술논문

超高压和特高压变压器组一般由三个单相变压器组成，变压器内部基本上不会发生相间短路，主要的内部故障形式为单相接地和匝间短路。零序差动保护为Y0/Y0或Y0/?接线变压器的Y0侧单相接地主保护，其灵敏度一般很高；但在非常接近中性点处发生单相接地短路时，如果短路的匝数很少，短路电流很小，零序差动保护的灵敏度可能不足，需要校验。该文用多回路分析的方法分析了Y0/?接线变压器Y0侧非常接近中性点处单相接地时零序差动保护的差电流，提供了一种用于工程实践中校验零序差动保护灵敏度的方法。
초고압화특고압변압기조일반유삼개단상변압기조성，변압기내부기본상불회발생상간단로，주요적내부고장형식위단상접지화잡간단로。령서차동보호위Y0/Y0혹Y0/?접선변압기적Y0측단상접지주보호，기령민도일반흔고；단재비상접근중성점처발생단상접지단로시，여과단로적잡수흔소，단로전류흔소，령서차동보호적령민도가능불족，수요교험。해문용다회로분석적방법분석료Y0/?접선변압기Y0측비상접근중성점처단상접지시령서차동보호적차전류，제공료일충용우공정실천중교험령서차동보호령민도적방법。
Extra-high voltage (EHV) and ultra-high voltage (UHV) transformer banks are generally composed of three single-phase transformers, in which interphase fault will not happen basically. The main form of internal fault is single-phase grounding and turn-to-turn fault. Zero-sequence differential protections of transformers are the main protections for single-phase grounding faults of Y0 side of 0 0Y /Y or 0Y /?connected three phase transformers. They usually have high sensitivity. But if the single-phase grounding fault is near the grounded neutral, and the number of short circuit turns is very small, the short-circuit current will be very small. The sensitivity of the zero-sequence differential protection will be very small it may refuse to operate, which needs to be verified. The differential current of zero-sequence differential protection when single-phase grounding faults of Y0 side of 0Y /?connected three phase transformers are close up to the grounded neutral point is analyzed through multi-loop analysis. And a method which may be used in engineering practice for verifying the sensitivity of zero-sequence differential protection is proposed.