Determination of Optimal Energy Storage System for Peak Shaving to Reduce Electricity Cost in a University

Abstract This paper presents an approach to determine the optimal capacity of battery energy storage system (BESS) for peak shaving of the electric power load in Naresuan University (NU), Phitsanulok, Thailand. The topology of the system consists of main grid, loads and the proposed BESS. Experimental data are daily load profiles, which were recorded for every 15 minutes over the last year. The consumed electricity energy can well correlate with the temperature as well as the schedules of NU activities for both annual and daily scales. Peak shaving is proposed to reduce the electricity cost contributed from the high load peak during the daytime. Realistic parameters for both AC/DC converter and battery are taken into account. An optimal BESS capacity for saving the electricity cost by peak shaving is calculated by first considering the date when the highest energy demand is recorded. Our results show that the optimal BESS can shave the peak load efficiently. Oversized BESS can further decrease the load peak but the reduced cost per battery capacity is not optimal. In addition, we present and discuss two different management strategies, i.e., time-based and differentiated power criteria, for operating the BESS in this system. BESS with different storage capacity is included into the system and the equivalent electricity cost is estimated. Both time-based and differentiated power criteria can reduce the cost.