Control Strategy for DC Microgrids with Photovoltaic Energy Storage Based on Multi-port Bidirectional Converters

Due to the increasing DC loads and excessive energy losses during AC-DC conversion in substations, this paper proposes control strategy for the DC microgrid system with photovoltaic (PV) energy storage in substations based on multi-port bidirectional converters. The microgrid can directly supply DC loads through the shared DC bus. For the low-voltage devices, the voltage can be converted to DC24V and DC12V through DC/DC conversion to meet the power requirements. In situations where the generation power is insufficient, the system can supple energy from the AC grid. Conversely, when the solar energy is abundant and the energy storage devices are fully charged, a constant voltage droop control strategy is employed to regulate PV generation and achieve efficient utilization of energy. Simulations have been conducted to validate the proposed control approach. It shows that the proposed method is efficient in supplying stable energy to the DC microgrid.