Distributed State of Charge-Based Droop Control Algorithm for Reducing Power Losses in Multi-Port Converter-Enabled Solar DC Nano-Grids

This paper aims to address the power loss problem of multi-port converter-enabled solar DC nano-grids (or simply nano-grids) that are designed to provide energy access in rural areas. Nano-grids are low voltage DC energy systems that are built for energy access by gradually interconnecting households that have solar panels, batteries and multi-port converters. Due to low distribution voltage levels (≤120 V), scattered households in rural areas and bidirectional power exchange between the households, power losses such as distribution line losses, battery charge/discharge losses and converter losses are significant in nano-grids. As batteries are distributed in each household and the nano-grid network configuration is dynamic in nature owing to the gradual interconnection of households, addressing the power loss problem using conventional optimization techniques is a challenge. To address the challenge, we propose a novel distributed state of charge-based droop control algorithm that does not require prior knowledge of the nano-grid network configuration. The proposed algorithm minimizes the power losses by reducing the magnitude of power flow in the nano-grid at each time instant through battery state of charge balancing. Numerical and simulation results demonstrate the effectiveness of the proposed algorithm.