I’m not getting it. For control power three options.
Option 1 is DC rectifiers on both busses. Only time you lose power is in a total outage.
Second option and usually recommended is a battery/UPS for substations with in this case dual chargers and blocking diodes so you can replace each UPS as needed although this is usually only done for very critical loads. Generators with ATS for instance don’t usually do this.
Third option is a capacitive trip device and/or a small battery. This gives you trip/close power for less than a minute.
In terms of switching the power side there are three options. First is two mains with open or closed transition. Second is main-tie-main or ideally double ties to work on one when needed. Third is ATS which is implemented as a double throw switch.