A SoC based voltage control strategy for DC microgrid

In this paper, two control algorithms for maintaining constant DC bus voltage under wide variations in generation and loading conditions in a DC micro-grid are discussed. They are: the traditional voltage based control and a modified voltage plus SoC (state-of-charge)-based control. The DC micro-grid consists of a photovoltaic (PV) system, a wind energy system based on permanent magnet synchronous generator (PMSG), a fuel cell system, an energy storage system (battery), an electrolyzer as a dump load, and DC loads. It has been observed that the voltage plus state of charge (SOC) based control method gives better performance than the traditional voltage based control method in terms of effective maintenance of constant DC bus voltage as well as power balance of the power management system (PMS). The control strategies for the battery, fuel cell, electrolyzer, PV system and wind energy systems are also discussed. The complete DC micro-grid and all the associated control algorithms are simulated and evaluated using MATLAB/SIMULINK.