If I am right and it is not (yet) available, I would suggest to allow adding an optional 'exception' list that will be taken into account in case of capitalization.
For instance: in case of changing to lower keys, one might wish to keep specific abbreviations unchanged.
Like DVD, USB, SATA, IBM, CD-ROM, etc.
Such items to be saved in a list that can be edited.
Within the rename panel users to tag/untag whether or not the list should be taken into account when renaming.