Transformer hot spot temperature prediction based on basic operator information

A power transformer is an important component in power trains and electrical distribution networks. Predicting its life time is desirable, especially, if a zero downtime policy is applied. However, end customers often have to deal with a lack of information and cannot always use the established methods for life time prediction. Therefore, the present paper provides an alternative way to calculate the hot spot temperature and thus, the life time of power transformers based on limited information, i.e. transformer rating information and rms current and voltage measurements (including phase angles). The transformer hot spot temperature is derived from the transformer losses and a virtual twin. Therefore, the paper provides methods i) to evaluate the separate transformer losses, i.e. core, winding and stray losses, ii) to create a simple virtual transformer twin and iii) to calculate the temperature distribution in the transformer windings and thus, the hot spot temperature. The methods are applied to one phase of a 154kV, 15MVA power transformer. It is shown that the calculated losses and hot spot temperature matches with winding measurements available in literature.