Multiple objectives tertiary control strategy for solid state transformer interfaced DC microgrid

Abstract

This paper's investigation is based on a solid state transformer (SST) interfaced DC microgrid (MG) system. Correspondingly, a hierarchical power and energy management strategy is proposed for this system. The proposed power management strategy includes three control levels: 1) primary control, distributed control for system power balance without communication; 2) secondary control for system seamless switching from islanding mode to SST-enabled mode; 3) tertiary control for system energy management. Different from the previous methods, the multiple control objectives control is implemented in the tertiary control layer. Thus, the tertiary control can not only control the DC MG system output power, but manage the battery state (charge or discharge) in DC MG based on its state of charge (SOC). Lastly, several typical case studies are carried out and the simulation results verify the proposed power and energy management strategy.