Descargas parciais no interior do sistema de isolação de uma barra estatórica: avaliação de criticidade e simulação dinâmica utilizando método de elementos finitos

Abstract

Partial discharges inside cavities within the insulation of stator bars are a leading cause of failures in electrical generators. Consequently, it is of great importance to understand the process surrounding this phenomenon. Computational models are currently being developed to gain a deeper understanding of partial discharges and to use this digital tool as support to prevent significant losses. For this reason, in this work, the Finite Element Method software will be used to study the partial discharge process inside a cavity present in a stator bar. First, one of the conditions for this phenomenon to occur is that the electric field inside the cavity reaches a minimum value known as the inception field. This value will be used as a reference for a proposed methodology aimed at evaluating the critical cavity size, that is, the minimum size of a cavity in the stator bar's insulation at which the existence of partial discharges becomes possible. Following this, a dynamic partial discharge model, which is already well-established in literature and considers the probabilistic nature of the phenomenon, will be adapted for time optimization and implemented in a stator bar. The proposal is to evaluate the levels of charge magnitude generated from a cavity size typically found in newly manufactured electrical generators.