Synchronization of isolated microgrids with a communication infrastructure using energy storage systems

Abstract

There exists an increasing interest in networked systems due to the wide number of applications in distributed and decentralized control of large scale systems, such as smart grids. We address the problem of distributed frequency synchronization of several isolated microgrids, each one described by a linear-time continuous system, composed by different types of generators, whose outputs are measured and sent through a communication infrastructure. We assume that each microgrid possesses renewable resources with storage capabilities that helps to improve stability of the network when small damping ratio is considered. Thus, using the smart grid communication infrastructure and the data flow through the network, we propose a cooperative control strategy based on the consensus algorithm that simultaneously manages the turbine governor input and the amount of energy that the storage devices have to absorb/inject from/into the grid. Nevertheless, physical constraints need to be included, which can be modeled using saturation non-linearities, and conditions to assure synchronization even with saturation are obtained based on multi-agent systems. Additionally, we consider that sensor measurements are sampled and we extend the results of frequency synchronization with saturation to the case of control discretization and sampling-period independence is demonstrated using passivity concepts.