Exporting RDCH Files as IDVs
Choose the Buses you want to Export.
Make a Subsystem of the chosen Buses.
GoTo --> File/SaveAs...
Select Power Flow Raw Data --> Use with RDCH
Give the exported file a path and name with .idv Extentsion.
Hit Select... Verify the selected buses are listed.
OK and the .raw file will be output.

Given a .raw output File like this:
Save as .idv

Add three lines to top of File:
VERSION 33 (version used to export)
RDCH
1
add BAT commands:
example:
BAT_PURGBRN, iBUS, jBUS, ID
