Improvement of voltage stability by using VSC-HVdc

This paper analyzes and compares the stability of a power system when either a new ac transmission line or a dc link based on VSCs is connected in the grid. The location of the new transmission line is determined by the restrictions in the transfer of power. From the controllability point of view, this is not the most suitable location for a VSC-HVdc to provide damping. However the voltage support capability of the VSC-HVdc can be exploited to keep the system from losing synchronism due to voltage collapse.