High reliability Multiport Multiphase DC hub

A Multiphase Multiport DC hub concept is proposed in this paper. The DC hub is capable of connecting multiple DC transmission lines with different DC voltages. Multiphase LCL inner circuit is used to increase the power rating and reliability of each port. Adding a phase in the inner AC circuit increases power transfer and improves utilization of DC cables which have higher rating than the high power switches. When fault happens at the converter bridge of the hub, the faulted phase of the converter bridge is tripped and the inner LCL circuit is reconfigured to a balanced AC system with reduced number of phases. On permanent DC fault at any DC transmission line, the port connected to the faulted DC transmission line is tripped so that the DC fault will not affect normal operation of the other remaining DC transmission line. Simulation of a 3-port 4-phase DC hub in PSCAD/EMTDC demonstrated the high reliability of DC hub after tripping a port and after tripping a phase.