1. State Grid Corporation Limited 1 , Beijing 100031, China
2. Nanrui Group (State Grid Electric Power Research Institute) Co., LTD 2 , Nanjing 211106, China
3. State Grid Electric Power Research Institute Wuhan Nanrui Co., LTD 3 , Wuhan 430074, China
4. Tbea Hengyang Transformer Co., LTD 4 , Hengyang 421007, China