I'm working on a project to teach others about the oddball 3 phase services they may encounter. It would be helpful for others to review for technical accuracy:]
Your last circuit (corner grounded open delta) is workable, but it seems to me that grounding one end of the open delta V rather than the center point of the V is not the best practice.
Is there a particular reason that all of your open delta derivations show the two primaries on A-N and C-N rather than making use of the POCO-supplied wye by running primaries from A-B and B-C? Are both variations found "in the wild"?
It might be better if you explicitly indicate that what you are drawing are the POCO supply transformers and that the primary is some level of MV or HV.
All of your open delta circuits have corresponding full delta circuits, and the interesting features on the secondary side would remain exactly the same.
In your description of the corner grounded delta, you say that all phase-to-phase voltages are 480 (240) and that all phase-to-ground voltages are also 480 (240). That is clearly not true for phase B to ground. When discussing interesting (I will not make any statement about non-standard or oddball) circuits, I think it is important to make sure all of your statements are 100% accurate. Anything else will compromise the goal of your work.