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Experimental Study on Prediction and Diagnosis of Leakage and Water Absorption in Water-Cooled Generator Stator Windings by Drying Process Analysis

수냉각 발전기 고정자 권선의 건조 과정 분석을 통한 누설 및 흡습 예측 진단에 관한 실험적 연구

  • Kim, Hee-Soo (Power Generation Lab., Korea Electric Power Corporation Research Institute) ;
  • Bae, Yong-Chae (Power Generation Lab., Korea Electric Power Corporation Research Institute) ;
  • Lee, Wook-Ryun (Power Generation Lab., Korea Electric Power Corporation Research Institute) ;
  • Lee, Doo-Young (Power Generation Lab., Korea Electric Power Corporation Research Institute)
  • Received : 2010.01.21
  • Accepted : 2010.07.26
  • Published : 2010.09.01

Abstract

The failure of water-cooled generator stator windings as a result of insulation breakdown due to coolant water leaks and water absorption often occurs worldwide. Such failure can cause severe grid-related accidents as well as huge economic losses. More than 50% of domestic generators have been operated for over 15 years, and therefore, they exhibit signs of aging. Leaking and water-absorbing windings are often found during an overhaul. In an existing method for evaluating the integrity of generator stator windings, the drying process of the interior of the windings is ignored and only final leak tests are performed. In this study, it is shown that water leaks and water absorption in stator windings can be detected indirectly through vacuum pattern analysis in the vacuum drying mode, which is the used in the preparation stage of the leak test.

수냉각 발전기 고정자 권선에서의 냉각수 누수 및 흡습에 의한 절연파괴 손상사례가 국내 및 국외에서 자주 발생되고 있다. 이러한 사고는 막대한 경제적 피해뿐만 아니라 전력의 안정적 공급 측면에서 매우 심각한 계통 사고로 연결될 수 있다. 특히 국내 발전기는 15년 이상 운전되어 열화가 진행된 발전기가 50% 이상이며, 계획예방정비 기간 중에 권선에서의 누설 및 흡습 권선이 종종 발견되고 있다. 기존에는 누수 시험 전 과정인 권선 건조 과정을 무시한 채 누수 시험 결과만으로 권선 누설 여부를 진단하였으나 본 논문에서는 누수 시험을 위한 준비 단계인 진공 건조 시의 권선 내부의 진공도 패턴 분석을 통해 권선 누설 및 흡습 여부를 예측진단할 수 있는 방법을 실험적으로 증명하였다.

Keywords

References

  1. Lamberg, A. etc., "GE Generator Fleet Experience and Available Refurbishment Options," GE Energy GER-4223.
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