A composite power management strategy for congregated-storage based multiple voltage-level DC network

This paper proposes a composite power management strategy for a novel multiple voltage-level dc network topology. To realize convenient power management, all storages are congregated to form a storage subsystem which is connected to a common bus. DC network with various nominal voltage levels immensely improves the efficiency and performance of the whole dc system. To realize better dc network operations, the composite power management strategy is necessary. First, with the consideration of trade-off between voltage regulation and power sharing, an adaptive droop control strategy is proposed for storage subsystem to realize voltage recovery and improve power sharing accuracy without any need of common bus voltage variation detection scheme. Besides, the lifetime of storage is extended due to the reduced frequent charging/discharging cycles. Second, a distributed coordinated power control strategy is applied to dc subgrids supported by their neighbors. Third, a dc subgrid with higher share of critical loads or weight factor should sustain small power deviations, for which a coordinated coefficient is applied to the proposed distributed coordinated power control strategy. Finally, hardware-in-loop (HIL) platform is built up to validate the effectiveness of the proposed control strategy.