This paper proposes a novel droop control strategy for indirect battery management in DC nanogrids. Droop control as a decentralized control method is a well-recognized method to provide effective power sharing and voltage stability among sources and loads in the DC nanogrid without additional communication links. While most existing droop control methods focus on adjusting each individual battery droop curve directly, the proposed method manipulates the droop curve of the active front-end converter, which connects the nanogrid to the main grid to indirectly influence the state of charge of the battery. The method employs a piecewise linear droop curve with a movable inflection point, which can be adjusted according to different scenarios. The effectiveness of the proposed method is evaluated through simulations using real data from a residential house with rooftop PV panels. The results show that the proposed method not only improves battery utilization but also increases renewable energy self-consumption.
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