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This paper analyzes the problems of the relay protections and secondary circuits of traditional substations, and introduces the hierarchical protection and control system of smart substations based on the technologies like IEC 61850 Standard, electronic instrument transformer, process level network, and wide area optical fiber communication network, etc. The hierarchical protection and control system includes three levels: local area protection, substation area protection and control, and wide area protection and control. These three levels are combined to solve the problems of the relay protections in traditional substations, thus improving protection performance and control capability of the system.