A statistical model to determine the capacity of battery-supercapacitor hybrid energy storage system in autonomous microgrid

Battery-supercapacitor hybrid energy storage system (BSHS) is a key component for regulating the frequency in autonomous microgrid. The lifetime and capacity are two important aspects for the efficient and economic use of BSHS. In this paper, the above two aspects are investigated in detail. Firstly, a new frequency control strategy based on hysteretic loop is developed for BSHS to extend the battery lifetime by avoiding small charge/discharge cycles. Then a capacity statistical model which is composed of statistical analysis, time-domain simulation and a capacity determination algorithm is proposed. Monte Carlo simulation is implemented to the statistical model to obtain the capacity distributions of BSHS. Finally, a benchmark low voltage microgrid is established as the test system using the commercial software DIgSILENT. Simulation results verify the effectiveness of the hysteretic loop control strategy and the capacity statistical model. The obtained capacity distributions of BSHS are used to determine the optimum capacity according to the needs of operation. The results also show that the hysteretic loop control strategy can reduce the capacity of Battery Energy Storage System (BESS) while increase the capacity of Supercapacitor Storage System (SCSS). (C) 2013 Elsevier Ltd. All rights reserved.