The Impact of Current Limiting on Voltage Support from Inverter-Based Resources

Grid-forming inverters (GFMIs) have emerged as a solution to declining system strength and inertia in modern power systems. Despite this, these devices often fail to improve transient stability due to their low fault current capability. New current limiting strategies have shown promise in overcoming this challenge. However, existing works often neglect the effect of neighbouring grid-following inverters (GFLIs) on performance. This paper proposes a simulation-based approach to explore the impact of GFLI penetration on voltage support capability. The model presented enables the responses of neighbouring grid-following and grid-forming inverter-based resources to be recorded during a large voltage dip. The data is used to compare three GFMI current limiting strategies against their ability to prevent GFLI tripping. GFLI penetrations that result in a violation of voltage limits are established for each case. The virtual power method was found to create large voltage drops at GFLI penetrations above $42 \%$ when used for voltage control grid-forming. The virtual impedance method resulted in excessive overcurrents at penetrations above $55 \%$. The findings reveal that significant barriers still exist for GFMIs towards improving transient stability.