Investigation of Constrained VSC-HVDC Tie Lines for Transient Stability Improvement of Interconnected Power Systems

Incorporation of a supplementary controller called Inter-Area Frequency Supplementary Controller (IAFSC) that monitors frequency deviations of the supporting area through a Phasor Measurement Unit (PMU). In the event of a severe transient fault in the supported area, the IAFSC will constrain the tie line power by modulating the active power through the VSC-HVDC link.