1. Qingyuan Yingde Power Supply Bureau, Guangdong Electric Power Co., Ltd., Yingde 513000, China
2. School of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, China
3. Foshan Power Supply Bureau, Guangdong Electric Power Co., Ltd., Foshan 528000, China
4. Electric Power Science Research Institute, Guangdong Electric Power Co., Ltd., Guangzhou 510080, China