Hi Lisa,
The AC power flow is implemented in
https://github.com/switch-hawaii/scuc. It unfortunately hasn't been maintained much as Switch and Pyomo have evolved over the years. But it has quite a lot of notes that may aid in updating it.
To use this, you would install Switch as normal, then download this repository and run the model stored there (or one similar to it). The key idea is that you would add "trans_branch_flow" to your modules.txt, which will load the module with that name from this repository. You would also create an iterate.txt with the same module in it. That module removes the normal zonal load balancing constraints, and instead uses an iterative AC power flow. It is fairly complicated -- it creates a DC power flow in Switch and then incrementally updates the loss and flow coefficients based on an AC power flow, until the DC flow matches the AC flow and there are no overloads even during line outages.
As I said, this is quite experimental. But it did work at one point, and if you'd like to use it, I could work with you to update it for the current versions of Pyomo and Switch.
About the DC power flow -- it should be fairly straightforward (certainly simpler than the scuc), which is why we promised it. But no one has needed it enough to implement it yet. Again, if you're interested in using it I could see about fast-tracking that.