1. Key Laboratory of Engineering Dielectrics and Its Application, Harbin University of Science and Technology, No. 52 Xuefu Road, Harbin 150080, P. R. China
2. School of Electrical Engineering, Northeast Electric Power University, No. 169 Changchun Road, Jilin 132013, P. R. China
3. State Grid Tianjin Training Center, No. 6 Zhongshanmen No. 2 Road, Hedong District, Tianjin 300171, P. R. China
4. State Grid Information and Telecommunication Group Co. Ltd., Beijing 100031, P. R. China
5. School of Computer Science and Information Technology, Northeast Normal University, Changchun 130117, P. R. China
6. State Grid Liaoning Province Power Co. Ltd., Power Research Institute, Shenyang 110181, P. R. China