Very interesting, thanks for this! Would you be interested in adding features from https://mods.factorio.com/mod/highvoltage ?
Basically, we could forge one-to-one transformer connections for high voltage - the script making sure that big poles don't branch off. Depending on the distance of the transformers we can easily calculate an energy loss on the sender side - make the transformer drop energy the higher the distance is. That would encourage localized builds.

Hmm that is a very interesting mod! It takes the 'other' way of restricting power to this mod (broadly, that mod limits flow whereas mine punishes you for not limiting it yourself). I think that the way it was done was very clever: it appears to work like my transformers, but splits up the 'input' and 'output' so that it only 'connects' them if there is a line of power poles (with red wires) joining them.

I'm not sure how well it would fit in this mod though? Would you actually want both the flow limiting and the overflow explosions at the same time? I guess there is an appeal there, but unfortunately I do not currently have the time to implement it. Maybe in a couple of months time if I'm still feeling like it :)

it appears to work like my transformers, but splits up the 'input' and 'output' so that it only 'connects' them if there is a line of power poles (with red wires) joining them.

Yeah, that's how it works. When one transformer is connected to another via big poles, they can teleport energy to each other. Of course the problem is, that you need red wire... But with current limitation like in your mod, you could actually use normal copper wire with big poles, just reduce the output of the step-up-transformer.

I'm not sure how well it would fit in this mod though? Would you actually want both the flow limiting and the overflow explosions at the same time?

Something like that, yes. AFAIK highvoltage doesn't limit flow, it just needs a bit of time until the transformers reach the required voltage. You should be able to pass infinitely high current through any pole though. But I think that charge up time gives it a nice challenge, since you can't just put hundreds of laser turrets down and have them work instantly, you need an energy buffer. That's what I am looking for, a bit more electric logistics.

Ok, so I'm seeing 2 feature requests here:
1. Some way to make long power lines lose energy
2. Add transformer ramp-up time

Neither of these are particularly inline with the rest of the mod (I'd class them both as "limiting flow" instead of "punishes you for not limiting it yourself'), but I wouldn't rule out adding them. In particular, 2 would be reasonable easy to add. They aren't my top priority.