Influence of Grid-Tied PV Systems and EV Charging Stations on Power Transformers Failure Rate Behaviour

This document presents the analysis of the failure rate of an oil-inmmersed header distribution transformer due to the presence of current harmonics produced by a Grid-Tied PV system and slow charging stations. Monte-Carlo simulations were performed to generate harmonic profiles in order to calculate the accelerated aging factor that along with the transformer health index determine the behavior of the transformer's failure rate. The results show that harmonic distortion does not have a significant influence on the transformer life reduction, and that degradation of solid and liquid insulation is one of the cause of increase in the failure rate in long-term as they have a high relative weight in the health index.