A novel DC power flow controller for VSC-MTDC system

This paper proposes a novel dc power flow controller for multi-terminal HVDC (MTDC) system, which can be inserted in series on transmission lines to manage dc power flow of them. Its key features include: 1) simpler circuit topology, 2) fewer components and 3) elimination of external power supply and low-frequency high-voltage-insulation isolated transformer. A three-terminal HVDC system including the dc power flow controller is studied and its operation principle and characteristics are analyzed. A simulation mode is built to test the feasibility and effectiveness of the proposed dc power flow controller with cases of power injection step down, power loss of one terminal. The results show that the proposed dc power flow controller can enhance the performance and controllability of a MTDC system.