Performance evaluation and load leveling effect by n atr1u m-salfer battery system based on bms data

Demand for electric power in private sector is increasing year by year in Japan. Especially during summer season, a high demand for electricity exists due to cooling load. Since an excess of capacity reduces the efficiency of electrical power plant, load leveling is needed. Natrium-Sulfur (NaS) energy storage system is a new technology that provides load leveling. In this paper, actual operation performance of NaS energy storage system was evaluated based on real operating data collected from building management system. Efficiency of NaS energy storage system was 73% including power conversion system (PCS). Power consumption of auxiliary machine (mostly electrical heater) was also measured and reported. Total efficiency of NaS storage system was evaluated in a correlation with average outdoor air temperature, and takes value between 50%~65%.