Comparison with Opendss load flow and short circuit

[mrsilvabr]

Hi
I am trying to perform load flow and fault study in Pandapower. I have results from opendss studies for the same circuit. I have a bus "zero" connected to an external grid of known short circuit capacity (s_sc_max_mva=352 MVA).
After running the load flow, the result for this bus (slack bus) is v=1.00 pu. However, as I understand the situation, the system is not considering the voltage drop in the source impedance (about 5% in my case).
Running the same study in Opendss (EPRI), I get the correct result for bus "zero" which is then called "sourcebus".
In order to have comparable results I have to manually insert one impedance element after between bus "zero" and the main substation bus (bus "b1"). I found no reference in the documentation on how to tackle this issue.
Now, in the fault study, it seems that Pandapower accounts for the source/external grid impedance because the results are similar to those from Opendss.
Would someone help me ?