Análise de Perdas Eletromagnéticas de um Transformador de Distribuição a Seco sob Desequilíbrio via Modelagem por Elementos Finitos

This article presents an analysis of the electrothermal performance of a transformer to be installed in a new concept of underground substation. Underground substations are an alternative for the storage and distribution of electric power in urban areas, but they have limitations in terms of available space, cooling and operation under non-ideal conditions. The transformer is the main source of heat in an underground substation and can suffer the effects of voltage and/or current imbalance generated by the load or by the electric system itself. The objective of this work is to evaluate the electrical and thermal behavior of the transformer under different scenarios of voltage imbalance, using numerical simulation based on the finite element method. The results show that imbalances from the electric system reduce the total losses of the transformer, but concentrate losses in the central column of the core, which can compromise its useful life. On the other hand, load imbalances increase winding losses and cause an unequal distribution among phases. The analysis performed is essential to preserve equipment’s useful life and properly size substation’s cooling system.