Operation and Control of HVDC Grids

Abstract: Meshed high-voltage direct current grids are becoming an increasingly important technology for integrating renewable energies into the power system. To control the grids in the best possible way, optimal converter and grid control strategies are needed. This project studies how a four-terminal high-voltage direct current grid is operated and controlled by implementing different grid and converter control strategies. The grid control strategies examined are centralized voltage control and distributed voltage control with and without deadband. Simulations are made in the software PSCAD. Different fault types on the grid are studied to investigate how the power flow and voltage level are affected. An optimal value for both the deadband width and droop constant has been identified. Moreover, the results indicate that centralized droop control is not a suitable grid control strategy, whereas distributed voltage control with and without deadband are. The fault study indicates no differences between distributed voltage control with and without deadband. The power flow and voltage levels are identical for all fault types.