Operational simulation of PV generation system with hybrid batteries

An intermittent nature of the solar generation affects the micro-grid system noticeably when the micro-grid is disconnected from the power system through a fault, etc., and islanding operation is compulsory forced. So as to prevent anticipated problems, batteries are sometimes used for compensating surplus and shortage of the PV power output fluctuation. Two kinds of battery connections have been proposed: namely, AC side connection through an inverter and DC side direct connections to the PV system. In this paper, the authors propose a hybrid type battery connection which consists of both AC and DC side batteries to compensate a control delay of the AC side battery. So as to grasp the operational characteristics of the hybrid battery system, and to determine the necessary capacity of the DC side battery, the authors carried out a computer simulation of the hybrid battery system. Successful simulation results and several new findings are shown in this paper.