Coordinated control for battery and supercapacitor in hybrid energy storage system in Microgrid

Abstract

In an island Microgrid (MG), energy storage system (ESS) is required to balance the power generation and load demand. Battery is the most commonly used energy storage device, but it has its longevity adversely affected by accumulated depth of discharge (DOD). This paper presents a cooperative control strategy for a battery-supercapacitor based hybrid ESS (HESS) for both improving the transient performance of MG bus voltage and reducing the battery loss. In this control strategy, the power generated by different devices in HESS are distributed as that battery is controlled to provide the balanced power in steady-state, while supercapacitor (SC) is controlled to generate transient and unbalanced power for a single phase load demand. Simulations are implemented in the PSCAD/EMTDC software environment, and the results show that the transient response of MG bus voltage has been improved under the unbalanced load disturbance. Simultaneously, the battery loss is reduced by the proposed control strategy with lower DOD, less internal power loss, and higher entire efficiency than the conventional control method for battery on the base of frequent charging and discharging conditions in MG applications.