Multi-agent consensus design for heterogeneous energy storage devices with droop control in smart grids

This paper proposes a distributed control architecture for battery energy storage systems (BESSs) based on multi-agent system framework. The active/reactive power sharing, the frequency/voltage, and the energy of BESSs are synchronized by exchanging local information with a few other neighboring BESSs. Two consensus algorithms namely leaderless and leader-follower are proposed. The proposed control architecture offers unique features. First, the heterogeneous nature of BESSs is explicitly taken into account in BESS models and consensus designs, while it is usually ignored in the literature. Second, the proposed designs bring the plug-and-play capability to the smart grid system by operating in both islanded and grid-connected modes. Next, the nominal frequencies and nominal voltage magnitudes of BESSs are used in the consensus design instead of their frequencies and voltage magnitudes. This makes the proposed structure much easier to be implemented in the real power grids. Lastly, an additional control input is designed to synchronize the energy levels of BESSs directly, whereas the energy levels of BESSs are synchronized indirectly through their powers in other existing research. Time-domain simulations on a modified IEEE 57-bus power system are then carried out to validate the proposed control structure and the consensus designs.