Estudo da proteção diferencial de transformadores.

Abstract

The continuous electric energy supply depends on the proper operation of several systems and equipments, such as transformers and protection systems. The protection of electrical systems is done by relay controlled schemes. Transformers require relays that are dependable (no missing operations), fast and secure (no false tripping), and the differential relays are the ones that best suit these requirements. This work presents the several types of protection available for transformers, focusing on differential protection. Basic functional aspects of the three generations of relays (electromechanical, static and digital) are discussed, along with the advantages of each one over their predecessors. Both differential and overcurrent relays are described, besides the disturbances to which they are subjected. The available techniques to guarantee that differential relays do not operate inappropriately are presented. The work is concluded with a detailed analysis of digital relays, where their basic architecture and a fault detection algorithm are discussed.