Area backup protection based on substation's secondary-DC-loss

A scheme of substation SDL (secondary-DC-loss) protection based on the regional grid information is proposed, which can quickly isolate the fault when the in-substation or outlet-line fault occurs in a substation with SDL. With the substations as the objects, the concept of regional master-slave station protection system and its construction modes are proposed, which realizes the effective detection of the SDL of substation protection system by the aid of the regional process-level communication network and the communication power-supply independent of the protection power-supply, and a complete scheme of SDL protection is further proposed. The results of RTDS test show that, the proposed method and scheme can correctly detect the status of substation SDL and quickly isolate the faults in the SDL area.