Applying power-synchronization control in a multi-terminal DC system

The performance of traditionally used converter control strategies in a multi-terminal dc system depends on the ac system conditions. One limiting factor for the converter controls to perform well is the short-circuit capacity of the ac system. This work is motivated by the rapid proliferation of high-voltage dc technology, which enables many converter stations being linked together by a dc transmission network. The dc network can be embedded in the conventional ac network and used to facilitate large power transfers across great distances between the interconnecting terminals. A previously proposed control method, power-synchronization control, has been demonstrated to perform well on a point-to-point high-voltage direct current link in connection to a weak ac system. In this paper, the potential of power-synchronization control is demonstrated in a multiterminal dc grid with one very weak ac system connection.