Effects of Moisture on Furfural Partitioning in Oil-Paper Insulation System and Aging Assessment of Power Transformers

Abstract

The furfural concentration in oil is a well-accepted chemical marker indicating the aging condition of power transformers. However, recent researches suggest that the furfural concentration in oil is affected by moisture, because moisture influences the furfural partitioning ratio in oil-paper insulation system. In this study, the correlation of moisture and furfural partitioning ratio was investigated. The accelerated thermal aging test and moisture absorption test were conducted to prepare oil-paper samples with different furfural and moisture concentrations. For samples with different moisture concentrations, the furfural partitioning ratios between oil and paper were compared. Results showed that samples with high humidity exhibited a high furfural mass fraction in oil. This finding implied that high humidity promoted the furfural diffusion from paper to oil. Further, the interference of moisture on aging assessment of insulation paper was analyzed. Results showed that the increase of moisture concentration in oil-paper system would significantly affect the accuracy of insulation paper aging assessment. A corrected equation for aging assessment of insulation paper with different moisture concentrations was established. Verification result showed that the equation could effectively correct the interference of moisture and enhance the accuracy of the aging assessment of insulation paper.

Keywords:

• furfural analysis
• aging assessment
• oil–paper insulation
• power transformer
• moisture effect

Additional information

Notes on contributors

Yuandi Lin

Yuandi Lin was born in Anhui, China, in 1988. He received the B.Sc. degree in electrical engineering in 2012, from China University of Mining And Technology, Jiangsu, China, and the Ph.D. degree in electrical engineering in 2017, from Chongqing University, Chongqing, China. He is currently with State Grid Jiangsu Electric Power Research Institute, Nanjing, China. His major research activities include online detection of insulation condition of electrical devices, and insulation fault diagnosis for high voltage equipment.

Ruijin Liao

Ruijin Liao was born in Sichuan, China in 1963. He received the M.S. and Ph.D. degrees in electrical engineering from Xi’an Jiaotong University, China and Chongqing University, China, respectively. He has been a professor of Electrical Engineering College at Chongqing University, China, since 1999. His research activities include on-line monitoring of insulation condition and fault diagnosis for high voltage apparatus, as well as ageing mechanism and diagnosis for power transformers.

Fengbo Tao

Fengbo Tao was born in Jiangsu, China, in 1982. He received the Ph.D. degree in electrical engineering in 2009, from Xi’an Jiaotong University, Xi’an, China. He is currently with State Grid Jiangsu Electric Power Research Institute, Nanjing, China. His major research activities include status evaluation of high voltage equipment.

Chao Wei

Chao Wei was born in Shandong, China, in 1984. He received the B.Sc. and M.Sc. degrees in electrical engineering in 2007 and 2010, from Chongqing University, Chongqing, China. He is currently with State Grid Jiangsu Electric Power Research Institute, Nanjing, China. His major research activities include on-line monitoring of insulation condition and fault diagnosis for high voltage apparatus, as well as ageing mechanism and diagnosis for power transformers.