Detecção das correntes de inrush em sistemas elétricos de potência

Abstract

It is well known that the differential protection is the most suitable for protection of power transformers. However, during the energization of the transformer, a large amplitude magnetization current known as the inrush current arises, which may appear to be a fault from the point of view of the differential protection relay. To improve safety while maintaining the necessary levels of sensitivity, many methods for detecting this current have been proposed in order to inhibit the operation of the differential element. This work presents, first, a brief review of the principles of differential protection in transformers, for a better understanding of how the inrush currents can interfere in the correct functioning of these equipments. Afterwards, the main concepts regarding inrush currents, their causes and consequences for the protection of the Electric Power Systems, as well as an approach regarding the events and switching conditions in the emergence of this phenomenon are presented. Finally, a new method for the detection of inrush currents is proposed, as well as the test systems used in the simulations using the ATP Draw software and the results obtained.