Wide　area　information　is　easily　lost　and　distorted　caused　by　disturbance,　which　is　not　fully　considered　in　current　wide　area　protection　principle.　A　wide　area　backup　protection　algorithm　with　high　fault-tolerance　performance　is　proposed　to　implement　the　centralized　substation　backup　protection　system　(CSBPS)　.　CSBPS　can　locate　the　fault　element　with　fault-tolerance　judgment　according　to　fault　direction　and　fault　distance　information　calculated　with　currents　and　voltages　measured　from　electric　elements　of　local　substation　and　collected　from　the　adjacent　substations.　The　results　of　a　case　study　show　that　no　uncorrected　judgment　happens　to　CSBPS　in　case　any　one　of　protection　elements　mal-operates,　fails　to　operate　or　loss　of　fault　information.　The　proposed　algorithm　is　simple　and　reliable　with　good　fault-tolerance　capability.　©2010　State　Grid　Electric　Power　Research　Institute　Press.