The Identification Method of Transformer Excitation Inrush Current Based on the Decay Characteristics of Aperiodic Component

Abstract

Focusing on the optical current transformer secondary side current aperiodic component decay characteristics, a novel identification method of excitation inrush current based on aperiodic component dynamic decay characteristics was proposed, and the traditional transformer excitation inrush current identification method based on the various static characteristics were break through. First, considering the transformer losses were exist and the truth of characteristics of excitation inrush current was not a periodic function, the aperiodic component was calculated by taking different cycles of the excitation inrush current derivation. Second, taking the (k+1)th cycle of excitation inrush current integration as an example, the five different forms excitation inrush current integration were found, and the five forms aperiodic component function expression were written. Then, taking derivation of five-stage aperiodic component and the aperiodic component decay speed expression was got. Compared with the normal operation and short circuit faults occurred, using the aperiodic component decay dynamic time constant to identity the excitation inrush current. Combined with the related simulation, not only verified this novel identification method was effective, but also provides a new way for the application of dynamic characteristics in excitation inrush current identification and relay protection.