Quantitative Comparison of Vulnerability Indicators for VSC-HVDC Site Selection to Improve Transient Voltage Response

The increasing penetration of variable renewable energy reduces the reactive power reserves and short-circuit capacity of power systems, raising concerns about transient voltage recovery following faults. Voltage Source Converter High Voltage Direct Current (VSC-HVDC) systems can mitigate these issues through fast reactive power support, but their voltage recovery effect strongly depends on installation location. While bus vulnerability indicators have traditionally been used for siting reactive power compensation devices, their applicability to VSC-HVDC site selection has not been quantitatively validated. This paper examines whether six conventional vulnerability indicators—two static (voltage sensitivity, short-circuit ratio) and four dynamic (comprehensive, self-recovery, victim, source types)—can effectively identify buses with large VSC-HVDC installation effects. Exhaustive dynamic simulations were performed on 109 buses of the IEEE 118-bus test system across 8 representative N-1 contingencies, and Spearman rank correlations and top-15 ranking comparisons were used to assess identification capability. The strongest indicator, voltage sensitivity R1, exhibited only a weak correlation (p=-0.244, p² ≈0.06), and the top-15 most effective buses showed an average R1 rank of 51. The largest installation effects were concentrated in two regions (Bus 1–13 and Bus 49–58) located in close electrical proximity to the representative fault buses, indicating that installation effect is determined primarily by the topological relationship between fault and installation buses rather than by individual bus properties alone. These results suggest that single vulnerability indicators are insufficient for VSC-HVDC site selection, and that fault scenario sets and fault–bus topological information must be jointly considered.