Application of superconducting flywheel energy storage system to inertia-free stand-alone microgrid

Sun Ho Bae, Dong Hee Choi, Jung Wook Park, Soo Hyoung Lee

Research output: Contribution to journalArticle


Recently, electric power systems have been operating with tight margins and have reached their operational limits. Many researchers consider a microgrid as one of the best solutions to relieve that problem. The microgrid is generally powered by renewable energies that are connected through power converters. In contrast to the rotational machines in the conventional power plants, the converters do not have physical rotors, and therefore they do not have rotational inertia. Consequently, a stand-alone microgrid has no inertia when it is powered by the only converter-based-generators (CBGs). As a result, the relationship between power and frequency is not valid, and the grid frequency cannot represent the power balance between the generator and load. In this paper, a superconducting flywheel energy storage system (SFESS) is applied to an inertia-free stand-alone (IFSA) microgrid. The SFESS accelerates or decelerates its rotational speed by storing or releasing power, respectively, based on its rotational inertia. Then, power in the IFSA microgrid can be balanced by measuring the rotor speed in the SFESS. This method does not have an error accumulation problem, which must be considered for the state of charge (SOC) estimation in the battery energy storage system (BESS). The performance of the proposed method is verified by an electromagnetic transient (EMT) simulation.

Original languageEnglish
Pages (from-to)1442-1448
Number of pages7
JournalJournal of Electrical Engineering and Technology
Issue number4
Publication statusPublished - 2017 Jan 1

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

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