This conversion seems to be used to transfer 3D models saved in STL format (3d printing) to a MicroStation design format (.dgn). We do not know whenever MicroStation can import .stl files flawlessly, however you can find 3rd party software that supposedly support this type of conversion.
Convert Stereolithography CAD file to MicroStation drawing.
We found one software available in the database for this conversion.
Microsoft Windows software - convert stl to dgn on Windows
A 3D CAD translation softwate
Convert from stl file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.