Cascading-aware Criticality Assessment of Transmission Corridors in IBR-dominated Systems

Increasing the integration of Inverter-Based-Resources (IBRs) can introduce new dynamic behaviors into power grids, posing emerging challenges in power system resilience. One such challenge is the cascading phenomenon, well-documented in power systems, which can lead to potential system collapse due to voltage or frequency instability. Hence, updated methods are needed to assess the vulnerability of IBR-dominated grids to cascading failures. This paper introduces a methodology for assessing the cascading-driven vulnerability of hybrid AC/DC power grids, particularly IBR-dominated systems with RESs and HVDC links. It enables the identification of the most critical or influential components, including AC and DC transmission lines, that can trigger or propagate a cascading phenomenon by quantifying cascading impacts. The methodology leverages a DIgSILENT-aided tool for dynamic cascading failure analysis that fully captures voltage and frequency dynamics by modelling relevant controllers and protection mechanisms, such as under/over-voltage and frequency protective relays. The test system employed in this study is the 24-node simplified Northern Great Britain power grid, modelling the decarbonized generation and transmission background expected in the early 2030’s. The simulation results quantify the vulnerability of this IBR-dominated grid to cascading phenomena, highlighting how identified critical AC/DC transmission components contribute to grid degradation due to cascading events.