1. Gifu Renewable Energy System Research Center Gifu University 1‐1, Yanagido Gifu 501‐1193 Japan
2. Advanced Collaborative Research Organization for Smart Society Waseda University 513, Wasedatsurumakicho, Shinjuku‐ku Tokyo 162‐0041 Japan
3. Department of Electrical, Electronic and Computer Engineering, Faculty of Engineering Gifu University 1‐1, Yanagido Gifu 501‐1193 Japan