Power management of hybrid energy storage system in a standalone DC microgrid

Abstract

Abstract Standalone microgrids with renewable energy sources (like solar photovoltaic and wind systems) utilize energy storage devices (ESDs) to supply uninterrupted power to their system loads. To utilize the characteristic advantages of different ESDs, they are combined to form a hybrid energy storage system (HESS). Efficient control algorithms are necessary for power sharing among the multiple ESDs in a HESS to ensure maximum utilization of all the storage devices in the microgrid. Conventional fuzzy logic controllers (FLCs) are used to decide the power output of an ESD considering state of charge (SoC) of the fuzzy controlled ESD and the overall power demand (or availability) in the microgrid. However in a standalone DC microgrid with multiple ESDs, such conventional FLC algorithms cause over or under utilization of the ESDs since the instantaneous SoC status of other ESDs are not considered in its control logic. Thus a novel adaptive FLC (AFLC) algorithm is proposed in this paper to dynamically change the controlling rules of the AFLC as per the average SoC of other ESDs of the microgrid. The performance of the proposed AFLC algorithm is compared with the conventional FLC algorithm on the basis of duration of discharge, average power delivered and utilization factor of the ESDs in a DC microgrid using real time simulation study in OPAL RT 4510 simulator. The merits of using the AFLC for power sharing among multiple ESDs are further validated through experimental study performed on a microgrid hardware setup at Indian Institute of Technology Kharagpur, India.