Lifetime Improvement of Liquid-Immersed Power Transformers Based on Novel Nanofluids and Water Scavenger

Abstract

Liquid-immersed power transformers are an integral part of the electrical grid. Long and reliable service life is of crucial importance in the design and operation of these power apparatuses. Transformer lifetime is mainly determined by the winding insulation system, which ages faster at high temperature. Nanofluid is a new type of oil with enhanced thermal and dielectric properties. Adding nano particles to the cooling oil increases its thermal conductivity, leading to more effective thermal conduction of the transformer. Therefore, hotspot temperature in the transformer windings decreases and hence the lifetime of the transformer is improved. On the other hand, utilization of nanofluids enhances the withstanding capability of the insulation material by scavenging the moisture in the transformer oil. In this paper, various laboratory oil samples will be introduced to serve as the next-generation transformer coolant. In order to understand and verify the behavior of the newly developed oils, finite element analysis and finite volume methods are used for the multi-physics simulations. A comparative study and experimental validation are conducted to show the superiority of nanofluid with respect to the state of the art mineral oil in terms of hotspot temperature and dielectric insulation strength which lead to lifetime improvement.