Dynamic optimal power flow for DC microgrids with distributed battery energy storage systems

Abstract

This paper proposes a model predictive control strategy for power flow optimisation between battery energy storage systems distributed in a DC Microgrid. The proposed control strategy uses a new convex formulation of the DC microgrid dynamic optimal power flow problem, based on a static voltage-current model and linear power flow approximations. Unlike optimisation strategies based on a single bus model, line losses and line voltage drops are included in the optimisation. The availability of fast and robust solvers for convex optimisation problems makes this a scalable solution for a real-time model predictive control implementation. To verify the performance of the proposed control strategy, real-time simulations were carried out for a DC microgrid with distributed lead-acid batteries and intermittent photovoltaic generation. The simulations were completed on an RTDS Technologies real-time digital simulator, using switching converter models and non-linear battery models.