An approach to aging assessment of power transformer based on multi-parameters

As the population of transformers in service increases and becomes older, more attentions are focused on their availability and reliability. Through decades´ progress, it is undeniable that considerable advances have been achieved on the techniques of fault diagnosis and condition assessment for oil-immersed transformer, for its great importance in the whole transmission and distribution (T&D) system. However, still insufficient research work focused on how to evaluate transformer´s aging condition. This paper represents Aging Index (AI) which is a practical tool that combines the results of routine inspections, and site and laboratory testing to estimate the aging condition. This Aging Index calculation considers not only typical test results such as dissolved gas analysis (DGA), oil quality, furan, and dissipation factor, but also other parameters such as top oil temperature and hot spot temperature estimating. And further, Frequency Domain Spectroscopy (FDS) is also introduced as a novel non-destructive testing technique to estimate remained life expectancy. Moreover, a software system based on transformer´s electrical and thermal parameters is developed correspondingly, by using a multi-parameters analytic approach. This system is expected to help to decision-making and replacement planning and to have good application prospects.