Distributed control, load sharing, and dispatch in DC microgrids

Abstract

Due to their compatibility with distributed generation microgrids are a promising operational architecture for future power systems. Here we consider the operation of DC microgrids that arise in many applications. We adopt a linear circuit model and propose a novel decentralized voltage droop control strategy inspired by frequency droop in AC networks. In comparison to conventional DC voltage droop strategies, our novel droop controller is able to achieve load sharing (even in presence of actuation constraints) or an optimal economic generation dispatch. Similar to AC frequency droop control, our voltage droop control induces a steady-state voltage drift as global signal depending on load/generation imbalance. Thus, we augment the primary droop controller with additional secondary regulation and investigate two strategies: a fully decentralized secondary integral control strategy successfully compensates for the steady-state voltage drifts yet it fails to achieve the desired optimal steady-state injections. Next, we propose a consensus filter that requires communication among the controllers, that regulates the voltage drift, and that recovers the optimal injections. The performance and robustness of our controllers are illustrated through simulations.