The short-circuit current will not change in a simple, radial grid, no matter the impedance of the grid when fed only by a Full Size Converter (also fed by the External Grid which is needed to run the simulation, but with a negligible contribution of for e.g. 1e-6 kA). This is because, according to the IEC 60909 standard, the Full Size Converters are modelled as ideal current sources in the positive-sequence. This means that they do not partake in the impedance calculation, but their fault current contribution is simply superimposed on the pre-calculated short-circuit current (if any available).

Consequence of this is that for simple, radial grids with no intermediate infeed, there will be no change in the fault current, no matter the change in the grid impedance.

This can be observed in the example in the attachment.