METHOD AND DEVICE FOR PREVENTING UNDERSTABILIZATION OF LONGITUDINAL DIFFERENTIAL PROTECTION IN CASE OF EXTERNAL FAULT AND CURRENT TRANSFORMER SATURATION

摘要

A method and a device for preventing understabilization of longitudinal differential protections in case of external faults and current transformer saturation. The invention comprises an extension of the state of the art with regard to stabilization of longitudinal differential protections in such a way that the values (A1, A2, ... An), (ζ1, ζ2, ... ζn), obtained via current measurement (C1, C2, ... Cn) and Fourier filters (4, 5, 6), for determining the function characteristic of the protection under certain conditions as regards current amplitude and current transformer saturation are given corrected values (A1k, A2k, ... Ank), (ζ1k, ζ2k, ... ζnk).