Current line ground fault directional-detection device for three-phase network in ground protection relay, has calculation device to calculate average and standard deviation, and comparison device to compare average and deviation

摘要

The device (20) has a signal processing module (30) comprising a calculation device (34) for calculating standardized correlation coefficients (rA-rC) between a signal representative of a homopolar current and signals representing phase currents (I-A-I-C) in a predetermined duration. The module includes another calculation device (36) for calculating an arithmetic average (mu) and a standard deviation (sigma) between absolute values of the calculated correlation coefficients. An interpretation module (40) comprises a comparison device (38) for comparing the average and the standard deviation. Independent claims are also included for the following: (1) a ground fault passage indicator comprising current sensors (2) a ground protection relay comprising an activation unit (3) a method for directional-detection of a ground fault in a multiphase electrical network (4) a method for protecting a current line during appearance of a ground fault.