1. School of Electrical Engineering Southeast University Sipailou 2# Nanjing 210096 Jiangsu China
2. State Grid Ningxia Electric Power Company Eastern Changcheng Road 288# Yinchuan 750001 China
3. Department of Electrical and Electronics Engineering Aichi Institute of Technology 1247 Yachigusa, Yakusa‐cho Toyota Aichi 470‐0392 Japan