1. School of Engineering, Anhui Agricultural University, Hefei, China
2. College of Electrical and Automation Engineering and Anhui Province Key Laboratory of Renewable Energy Utilization and Energy Saving, Hefei University of Technology, Hefei, China
3. Economic Research Institute of State Grid Hebei Electric Power Company, Ltd., Shijiazhuang, China
4. College of Electrical and Information Engineering, Hunan University, Changsha, China
5. Institute of Energy Technology, Aalborg University, Aalborg, Denmark