PV GENERATION-ENERGY STORAGE COORDINATION WITH ADAPTIVE DROOP CONTROL IN ISOLATED DC MICROGRID

Photovoltaic (PV) generators and energy storages are critical components for supplying electricity and ensuring system stability, particularly in isolated DC mi-crogrid. Coordination of PV generators and energy storages plays an important role to avoid voltage instability, overcharge and overdischarge of energy storages. To develop PV generators-energy storage coordination, this paper proposes a distributed control method based on the SoC (state of charge) battery level and the DC bus voltage signalling. The proposed control method is equipped with adaptive droop control for both energy storage system and PV generators. Droop control for energy storage is responsible for ensuring the balance of stored energy, which can avoid overcharging or deepdischarging of certain energy storage units. Meanwhile, droop control for PV is used to minimize load sharing error when line resistance is considered. To restore the DC bus voltage due to the use of droop control, secondary control is also proposed in this paper. The results of the proposed technique are simulated completely using Matlab/Simulink, even under fluctuating PV power and the load changes.