Distributed Control for LCL DC Hub Enabling Reliable Energy Transfer in Future DC Grids

The multiport LCL dc hub is a high power electronic dc substation used to interconnect multiple dc systems in the future dc transmission grids. This paper proposes a distributed power balance controller for high power multiport LCL DC hub. The hub controller follows dispatcher demands for required power trading between the hub ports. In the proposed control method, each hub port (connected to local DC line or grid) equally contributes to manage the central capacitor voltage which ensures internal power balance in the hub. In presence of a fault at dispatcher communication or supervisory control, the proposed control strategy guaranties stability of the DC hub operation so that the active powers at ports are automatically balanced between the injecting and absorbing powers. The proposed control strategy is verified by detailed simulation of a 6-port LCL DC hub in PSCAD/EMTDC.