Improved DC voltage margin control method for DC grid based on VSCs

This paper addresses the problem of controlling the DC voltage in multi-terminal DC grid based on voltage source converter. Based on the basic inner and outer controller of VSC station, three traditional DC voltage control methods: constant voltage control, voltage margin control and voltage droop control are analyzed and the corresponding drawbacks of these control methods are studied. In order to overcome these weaknesses, an improved dc voltage margin control method for DC grid is proposed, which controls the steady-state power flow precisely and has good transient voltage response. Finally, simulations with the 5 terminal DC grid based on VSCs validates the proposed voltage control method.