New Technology and Benefits of Distribution Automation in Japan

Innovation of distribution automation (DA) including the optimal load transfer and fault restoration began around 20 years ago in Japan. Since then, most distribution feeders are automated, and the aged DA facilities must be considered to be replaced. In replacing the system, new concepts must be introduced to the system. Namely, the small DA systems in business offices are unified and integrated into the ones in the branch of the company, and the supervised area or controlled area of one DA system becomes wider than those of the existing system. The DA functions are also innovated. On the other hand, new trend of distribution system is a connection of such distributed generators (DGs) as solar cells and co-generation systems as gas engines or fuel cells. The functions to cope with DGs are also installed to the new system. Caused by a connection of single phase DGs, 3-phase unbalance must be considered to control distribution systems. A load transfer technology in which 3-phase power flow is implemented is illustrated as a new trend for a future power distribution system. Some beneficial analysis for including 3-phase power flow in distribution automation system is also shown.