1. Power Science Research Institute of Yunnan Power Grid Co., Ltd, Kunming 650214, China
2. College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China
3. Qujing Power Supply Bureau of Yunnan Power Grid Co., Ltd, Qujing 655099, China
4. Electric Power Research Institute, China Southern Power Grid, Guangzhou 510623, China
5. School of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, China