Portable fiber-based fluorescence sensor for online assessment of transformer oil ageing

Under smart grid scenario, the penetration of electric vehicles would exacerbate the thermal ageing of insulating oil in distribution transformers. This would threaten the reliable and secure operation of distribution transformers and thus requires timely monitoring of oil conditions. In this work, fluorescence spectroscopy is applied to evaluate the ageing status of transformer oil. The fluorescence spectra were measured for the oil samples thermally aged in laboratory. It is found that the ratio of the two peaks in fluorescence spectrum is well in line with traditional ageing parameters, including colour index and total acid number. The preliminary results imply that it is feasible to apply the portable fibre-based fluorescent probe system in the online assessment of the ageing status of transformer oils.