Distributed cooperative control of a flywheel array energy storage system

Abstract

Flywheel energy storage systems (FESSs) such as those suspended by active magnetic bearings have emerged as an appealing form of energy storage. An array of FESS units form a flywheel array energy storage system (FAESS) that expands the storage capacity of an individual FESS unit. This article establishes a discharging/charging model of the FESS units and, based on this model, develops distributed control algorithms that cause all FESS units in an FAESS to collectively deliver the total power desired of the FAESS while dynamically balancing the state-of-charge among the FESS units as long as the undirected graph representing the communication network is connected and at least one flywheel has the knowledge of the desired power. We also carry out an extensive simulation study to demonstrate the functionality of our proposed algorithms, examine their performance with respect to the communication topology and establish their robustness property against disruption of the communication network connectivity.