METHOD FOR PREVENTING MAL-OPERATION OF TRANSFORMER DIFFERENTIAL PROTECTION

摘要

The invention discloses a technical unproved solution of transformer differential protection. A ratio braking unit is formed by using the positive-sequence or negative-sequence current of the fundamental wave of three-phase differential current in transformer longitudinal differential protection and the zero-sequence current in Y0 side, a three-phase braking signal is outputted so that the ratio differential portion of transformer longitudinal differential protection is braked when. The ratio value is less than the correcting value K. It can prevent the mal-operation. of transformer longitudinal differential protection caused by ground fault outside the Y0 side region, while the normal operation of longitudinal differential protection in the region under the fault is not affected. It is suitable for the longitudinal differential. protection of power transformer.