1. School of Electrical Engineering, Beijing Jiaotong UniversityBeijing100044People's Republic of China
2. School of Automation, Beijing Information Science & Technology UniversityBeijing100192People's Republic of China
3. China Electric Power Research InstituteBeijing100192People's Republic of China
4. State Grid Shanxi Electric Power CompanyTaiyuan030001ShanxiPeople's Republic of China