Distributed Finite-Time Multiagent Control for DC Microgrids With Time Delays

This paper proposes a novel distributed multi-agent finite-time control strategy with time delays for the state of charge balancing and voltage restoration in a dc microgrid with distributed battery energy storage systems. The delays can be different and theoretically unbounded for each battery system. Feedback linearization method is applied to convert the state of charge balancing and voltage restoration problems to double-integrator and single-integrator systems with input time delays, respectively. Then, the Artstein transformation is applied to reduce the time delayed systems to delay-free systems. Based on the reduced models, the finite-time control is modified to achieve the state of charge balancing and voltage restoration. Only the state of charge and its derivative and voltage information are required to be transmitted over a sparse communication network to generate the control signals. The finite-time Lyapunov method ensures accurate convergence and finite-time stability. The proposed secondary control strategy can be integrated with conventional primary droop control. The proposed control strategy is resilient to communication link failures and features plug-and-play capability. The performance is verified with an RTDS Technologies real-time digital simulator, using switching converter models and nonlinear lead-acid battery models.