High Performance Unified Control for Interlinking Converter in Hybrid AC/DC Microgrid

The hybrid AC/DC microgrid features high flexibility and high efficiency due to reduced power conversion process. The key link between AC subgrid and DC subgrid in a hybrid AC/DC microgrid, is the interlinking converter (IC), which should not only achieve power dispatch between AC subgrid and DC subgrid but also support AC or DC voltage. The unified control strategy of IC can cope with different operating conditions without operation mode detection and controller switch. It consists of several control loops, such as power dispatch control, droop control of IC and voltage control, where the same control parameters are used in three different operation modes ( power control, AC voltage control and DC voltage control). As a result, the design of control parameters are vital for system stability. This paper presents parameters design method for unified controller. Moreover, a feedforward loop from the power dispatch loop to inner control loop is also proposed to improve the transient performance and stability. The analysis and proposed control strategy are verified by simulation and experimental results.