1. Associate Professor, State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power Univ., Beijing 102206, China (corresponding author).
2. Master Degree Candidate, School of Electrical and Electronic Engineering, North China Electric Power Univ., Beijing 102206, China.
3. Ph.D. Student, School of Electrical and Electronic Engineering, North China Electric Power Univ., Beijing 102206, China.
4. Engineer, State Grid Energy Conservation Service Co. Ltd., 8 Nanhengdongjie Rd., Xicheng District, Beijing 100052, China.