Applied Energy, Vol.239, 1-11, 2019
Hierarchical control of DC microgrid with dynamical load power sharing
The hierarchical control strategy is proposed for DC microgrid with distributed generators, energy storage systems and loads. In order to maintain power balance and smooth bus voltage fluctuation during system operation due to dynamic load and resource variation, the designed hierarchical control is divided into two layers. In the primary layer, the novel adaptive droop controller with voltage feedback compensation is constructed for distributed generators and energy storage systems by taking advantage of local electrical parameters, which can realize the dynamic load power sharing and reduce bus voltage deviation. The distributed generators may operate between maximum power point tracking mode and droop control mode by bus regulation units when power supply is larger than the loads demand and the charging capacity of energy storage systems. The state of charge can also be adjusted for energy storage through the designed adaptive droop scheme. On the other hand, the secondary supervisory control is designed to reduce power exchange and improve the system stability. Using the designed hierarchical control, the DC microgrid can operate in four different modes according to which source responsible for the bus voltage stabilization. Simulation and comparison results validate that the proposed strategy may smooth the bus voltage fluctuation and realize the dynamic power sharing.