AN APPARATUS AND METHOD FOR COMPENSATING SECONDARY CURRENTS USED IN DIFFERENTIAL PROTECTION TO CORRECT FOR A PHASE SHIFT INTRODUCED BETWEEN HIGH VOLTAGE AND LOW VOLTAGE TRANSFORMER WINDINGS

摘要

Provided is an apparatus and method for providing to a differential relay anoperational vector-group compensation setting pair that automatically providescorrection for a phase shift occurring between currents of at least twowindings of a power transformer. The method includes calculating a first andsecond plurality of phasors using secondary currents derived from respectivefirst and second winding of the at least two windings. The method alsoincludes selecting one pair of vector-group compensation settings based onoperate current values calculated using different pair combinations of thevector-group compensation settings applied to the first and second pluralityof phasors. The method further includes comparing phase angles of like-phasephasors to determine if the phase angles are within a pre-determined anglerange, and enabling application of the selected pair of vector-groupcompensation settings as the operational vector-group compensation settingpair if the phase angles are within the pre-determined angle range.