Analysis and optimization of the battery energy storage systems for frequency control in autonomous microgrids, by means of hardware-in-the-loop simulations

This paper presents an original hardware-in-the-loop (HIL) solution for real-time testing and optimization of the frequency control mechanism in autonomous microgrids (MG), when battery energy storage systems (BESS) are integrated along classical and RES-based generators to stabilize the frequency. The focus is on autonomous MGs that dynamically should perform similarly to the conventional power systems. During MG autonomous operation, the generators should accomplish the frequency control process, by means of their automatic generation control. However, RES-based generators have poor controllability in terms of active power, and therefore the need of improving the MG power reserve by adding energy storage systems is often demanded. The proposed HIL solution aims to improve the design of the BESS frequency control systems according to the MG characteristics, being based on aggregated models of the involved mechanisms in the MG dynamics. An experimental test bench including a real-time digital simulator with BESS controller in the HIL structure is used for assessing the proposed system performances.