This paper proposes a new convex model predictive control strategy fordynamic optimal power flow between battery energy storage systems distributedin an AC microgrid. The proposed control strategy uses a new problemformulation, based on a linear d-q reference frame voltage-current model andlinearised power flow approximations. This allows the optimal power flows to besolved as a convex optimisation problem, for which fast and robust solversexist. The proposed method does not assume real and reactive power flows aredecoupled, allowing line losses, voltage constraints and converter currentconstraints to be addressed. In addition, non-linear variations in the chargeand discharge efficiencies of lithium ion batteries are analysed and includedin the control strategy. Real-time digital simulations were carried out for anislanded microgrid based on the IEEE 13 bus prototypical feeder, withdistributed battery energy storage systems and intermittent photovoltaicgeneration. It is shown that the proposed control strategy approaches theperformance of a strategy based on non-convex optimisation, while reducing therequired computation time by a factor of 1000, making it suitable for areal-time model predictive control implementation.
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