College of Energy and Electrical Engineering Hohai University Nanjing 211100 China;
State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China;
Xuji Group Co.LTD Xuchang 461001 China;
State Grid Nanjing Power Supply Company Nanjing 210019 China;
