Comparison of ESS configurations and IC control technologies in islanded hybrid AC/DC microgrids

Abstract

Due to the Hybrid AC/DC microgrids(HMG) structure merges the advantages of AC microgrid and DC microgrid, it is a key step towards the future smart grid. In the isolated hybrid AC/DC microgrid (IHMG), keeping the power balance and voltage/ frequency regulation is challenging task mainly because the absence of a dominating source and the low physical inertia of the limited DG units. The use of the energy storage systems (ESS) and interlinking converter (IC) technologies for meeting the above challenges is a widely accepted idea. This paper examines connection topologies of the ESS and the corresponding control approaches of IC and defines and explains five typical operation modes for IHMG. The unified power equations are proposed. The different operation modes can be represented through different assignment of input parameters of the equations. The operating characteristics of the IHMG are obtained by solving the equations. Finally, the accuracy and effectiveness of the proposed scheme are verified against the time domain simulation result. The quasi-steady-state behaviors of multi-DC subgrids IHMG in different modes are investigated. The results show that the location of the ESS device and the control scheme adopted by IC is closely related to the operating characteristics of the IHMG.