1. Faculty of Intelligent Manufacturing, Nanning University, Nanning 530200, China
2. School of Mechanical and Electrical Engineering, Liuzhou Vocational & Technical College, Liuzhou 545000, China
3. School of Electrical Engineering, Guangxi University, Nanning 530004, China
4. Liuzhou Power Supply Bureau of Guangxi Power Grid Co., Ltd., Liuzhou 545000, China