Assessment of disturbance propagation between AC grids through VSC HVDC links using reduced Great Britain model

The growth in electricity demand, the low-carbon targets and the rising penetration of renewable energy sources are causing the electricity systems to work closer to their operational limits, therefore their reinforcement is becoming urgent. The construction of a European Super Grid, where existing AC systems are connected through High Voltage Direct Current (HVDC) corridors, is a valuable solution; the introduction of the HVDC links enhances system stability, improves power flow control and ensures protection from cascading disturbances. This paper investigates the ability of the HVDC links to act as a firewall against perturbations. Two reduced dynamic equivalent transmission systems resembling Great Britain are developed in DIgSILENT PowerFactory. A two-level Voltage Source Converter (VSC) HVDC link is designed for connecting the two grids. A variety of short-circuits fault were applied to the AC grids to test the extent to which faults in one grid propagate to the other. It was found that only minor power flow transients were caused in one grid by faults in the other. However, this is under the assumption that the HVDC converter stations are not called upon to provide post-fault damping services.