1. School of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, P. R. China
2. Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, P. R. China
3. School of Electrical Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou 310018, P.R. China
4. Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, P. R. China