Electrical Transient Interaction between Transformers and Power System – Brazilian Experience

The paper goal is to present the work that has been carried out by the Cigré-Brazil Joint Working Group (JWG) A2/C4–03, called “Electrical Transient Interaction between Transformers and the Power System”. A description of some Brazilian utilities experiences regarding transformer failures related to system transients is presented. It is also presented a proposed methodology for transient system studies, in order to evaluate a range of frequencies and waveforms that appear during circuit breaker or disconnector operations and shortcircuits into the substation incoming lines, for different voltage levels and arrangements. A frequency spectrum (energy spectral density) comparison between standard impulse test curves and voltages curves, found in the electromagnetic transient simulations, is made. Finally, it presents a discussion on how to use the transient studies results to propose a revision of the specifications, design review practices, system planning and operation evaluations.