METHOD FOR OFFSET OF MAGNETISATION CURRENT RUSH DURING CONNECTION UNDER VOLTAGE FOR TRANSFORMER DIFFERENTIAL PROTECTION Russian patent published in 2016 - IPC H02H7/45 

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, namely to differential protection, and can be used for differential protection of transformers. Said technical result is achieved by method of offset of magnetisation current rushes during connection under voltage for transformer differential protection consists in analysis of currents on the side of supply, the filters formed voltage direct, reverse and zero-sequence corresponding to symmetrical components of phase currents passing from the side of supply of power system, zero sequence is compared with the first specified value, ratio of zero-sequence voltage to negative-sequence voltage to second specified value, ratio of total voltage reverse and zero-sequence to direct sequence with third preset value, if value of zero sequence is less than the first specified value in case of two previously mentioned ratios corresponding to second and third preset values of differential protection blocking signal is generated.

EFFECT: proposed method is detuning of magnetisation current rush during connection under voltage for differential protection of transformers, which in the transition process does not cause slowing at saturation current transformers in range to fifty percent of current error of CT, as well as higher sensitivity of differential protection of power transformer.

1 cl, 1 dwg