mhulbert,
Redundant medium voltage distribution is done in much the same way low voltage is distributed redundantly. You have to choose an overall philosophy, N+1 or 2N etc.
Then they are fed via main tie-tie main switchgear to other redundant switchgear. Don't forget that the gens are redundant too (or at least should be), and service the switchgear in redundant schemes with many fail over scenarios available with automatic and manual backups.
