Power management of energy storage system with modified interlinking converters topology in hybrid AC/DC microgrid

Abstract

This paper develops a power management strategy (PMS) that improves the power quality in a hybrid AC/DC microgrid with an energy storage system (ESS) applying a modified interlinking converters topology. To create the DC microgrid, an interlinking converter (ILC) operates as a grid-forming unit. Moreover, other interfacing device is employed, consisting of a bidirectional DC-DC half-bridge converter coupled with a voltage source converter (VSC). The energy storage device (ESD) is connected to the DC bus between the two converter stages. Such modified topology is called Two Stages Interlinking Converter with Energy Storage Device (TSILC-ESD). The PMS applied in the hybrid AC/DC microgrid is based on the ILC control responsible for the DC microgrid formation, and the TSILC-ESD control, which provides ancillary services to the utility grid. Therefore, the electric current’s harmonic specter injected into the utility grid is mitigated at the point of common coupling (PCC). Besides, a droop-based power-sharing between the ESD and the power grid is implemented, aiming to achieve voltage regulation in the DC link. Different source and load profiles are considered to analyze both sub-grids’ proposed strategy to explore the modified interlinking converters in different operation conditions. Simulations are carried out in the MatLab/Simulink software. The results show that the interlink converter improves the flexibility of the hybrid microgrid and, in addition, the power quality of the energy supplied in the utility grid is improved.