1. School of Electrical EngineeringWuhan UniversityWuhan430072Hubei ProvincePeople's Republic of China
2. Changsha Power Supply Company, State Grid Hunan Electric Power CompanyChangsha410015Hunan ProvincePeople's Republic of China
3. State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing UniversityChongqing400044People's Republic of China