Análise comparativa entre estratégias de chaveamento controlado na energização de transformadores.

Abstract

Several techniques have been used to reduce inrush currents in transformers, among them, controlled switching techniques and pre-insertion resistors (PIR). However, the literature lacks studies that evaluate and compare the performance of these techniques. The objective of this work is to fill this gap by performing a comparative analysis between the application of PIR and the main controlled switching strategies applied to reduce inrush currents. Case studies involving re-energization maneuvers of transformers were performed by means of digital simulations using an electromagnetic transients program (EMTP). The dispersion in the operating time of the circuit breakers, the magnetic coupling and the residual flux in the transformer core were considered, admitting several forms of winding connections. Controlled switching strategies presented a performance similar to PIR for a 0.5 ms operating dispersion time of the circuit breaker contacts. Techniques that consider the residual flux are most effective in reducing the inrush currents to values below 1.0 pu.