A Study on Optimal Sizing and Control for Hybrid Energy Storage System with SMES and Battery**This work was supported in part by the National Research Foundation (NRF) of Korea grant funded by the Korea government (MEST) (No. 2011-0028065) and in part by the Power Generation & Electricity Delivery Core Technology Program of the Korea Institute of Energy Technology Evaluation and

Abstract

This paper proposes the new hybrid energy storage system with the superconducting magnetic energy storage (SMES) and a lead-acid battery. The SMES is the most effective energy storage device due to its high power density, fast response, and high efficiency. However, its energy density is not higher than that of other batteries. Therefore, the proposed hybrid energy storage system combines these two energy storage devices. The optimal sizes of the SMES and battery are determined by considering the system cost, output power reference, and their proper efficiencies. Also, the new control algorithm is applied to share the charging and discharging powers effectively and therefore to manage the state-of-charge (SOC) in each energy storage device. Then, the performance of proposed hybrid energy storage system is evaluated on a residential photovoltaic (PV) system with respect to energy capacity, peak load leveling, and system efficiency.