Análise das perdas no núcleo de um transformador trifásico de distribuição considerando fluxo de potência reverso usando o método de elementos finitos

Abstract

Photovoltaic generation has been experiencing rapid growth in Brazil, particularly in terms of small-scale residential and commercial installations, known as distributed photovoltaic generation. One characteristic of this energy source is the intermittency of generation since it can only inject power into the grid when there is sunlight incident on the solar panels. Consequently, there is a new behavior in power flow within the grid, where excess generation results in reverse power flow, flowing through the transformer towards high voltage. In order to better understand the effects of this phenomenon on the distribution transformer, specifically in terms of core losses, this study develops a methodology that encompasses the analysis of various possible reverse power flow scenarios, both balanced and unbalanced (in which one phase has conventional power flow while the other exhibits reverse power flow). Additionally, a simulation model is developed using the finite element method in the Ansys Electronics software, and the results are analyzed. Through this analysis, it is possible to conclude that reverse power flow increases core losses in the transformer compared to conventional power flow, although this effect depends heavily on the equipment’s characteristics. Unbalanced reverse flow did not show any additional adverse effects on core losses compared to balanced reverse flow, with the latter being the worst-case scenario.