Multiterminal HVDC With Thyristor Power-Flow Controller

This paper presents the concept of a dc transmission controller integrated in a multiterminal HVDC system. The controller is based on a thyristor-based converter topology and it is inserted in series on a dc transmission line. A three-terminal voltage-source converter-based dc grid is modeled in PSCAD/EMTDC to demonstrate the operation and the stability of such a system. Simulation test cases include terminal loss and bidirectional ability of the thyristor power-flow controller. It is concluded that such a controller enhanced the performance and controllability of a dc grid.