Intelligent operations of distribution system with distributed generators

Since the Great East Japan Earthquake, many people had been worried about power shortages in Japan. There has been more focus to installation of Renewable Energy Sources (RES). In Japan, PV system introduction is promoted by national policy of the government in 2012. However, the large amount of distributed generator causes voltage deviation beyond the statutory range in distribution system. Furthermore, supply-demand balance becomes difficult because the generated power is influenced by the weather condition. The current transformer cannot solve the voltage deviation problem which is caused by renewable energy, due to relatively slow behavior. This paper considers using interfaced inverters which are used for distributed generators. This voltage control method can be achieved without introduction of additional reactive power control devices. Recently, isolated operation has been attracted attention. This paper also presents isolated operation method in distribution system. The effectiveness of the proposed distribution system is verified by computer simulations on Matlab/SimPower systems® environment.