Fault Analysis of A 110 kV Substation Total Power Loss Caused by Dead Zone Fault of Main Transformer

The paper describes the relay operation,reason and improvement measures of a 110 kV substation power failure caused by the dead zone fault of a main transformer.By analyzing the protective action report and recorded wave,the high backup protection didn't act,because the compound blocking condition was not open.Then the fault caused distanceⅢ segment action of the lateral line,the protective action of the 110 kV spare power automatic switching device,and the differential action of main transformer,which eventually led to the substation power failure.