Control and dynamic performance evaluation of Multi-Terminal DC grid

In this paper, the operation of Voltage Source Converter (VSC) based Multi-Terminal DC (MTDC) transmission system consisting of three different power converter topologies is evaluated. The high frequency isolated modular converter is used as the VSC configuration for two terminals. The Modular Multi-level Converter (MMC) and three-phase AC/DC converters are also used as the VSC configuration for the other two terminals. In the high frequency isolated modular converter configuration, several H-bridge modules are connected in cascade. From the MTDC system control point of view, a droop control structure with dead-band controller is proposed for MTDC grid control. The dynamic performance of a four-terminal DC grid is further investigated in PSCAD/EMTDC environment. Simulation results are presented to verify the performance of multi-terminal DC grid based on the proposed control method.