Influence of sympathetic current on transformer differential protection with inner bridge connection

The mechanism of transformer sympathetic interaction with parallel connection is analyzed in this paper.The substation internal bridge connection and current transformer secondary connection are introduced.The effect of the magnetizing inrush current on transformer different protection is discussed,and the influence of sympathetic current on the different protection is also investigated in detail with the saturation characteristics of current transformer,the brake principle of differential protection and the load of transformer considering.At last,some measures have been put forward to improve the differential protection performance.