This is simply this mod:
https://forums.factorio.com/viewtopic.php?f=93&t=20174&p=210042#p210042
updated for 0.14
Original author: Monty

Not sure if Monty is still developing things, but either way I really like this mod and haven't seen it available for new versions, so I wanted to make it available on the new mod portal. I'll also likely update the tooltips for each transformer to show the voltages that they're meant for, because right now I find myself looking back at the technology description periodically.

Original description by Monty:
This mod expands the control over the power grid and helps enhance the energy utilities.
It consists of a transformer,that does 3 jobs simultaneously
1)Act as a diode , dividing the energy grid into two.
2)Acts as an energy pump , lifting voltage from lower to higher voltage
3)Acts as an accumulator

They can further be grouped based upon the their range.
1)Low (1 MW inlet-10 MW outlet)
2)Medium(10 MW inlet-100 MW outlet)
3)High(100 MW inlet-1000 MW outlet)
4)Very High(500MW inlet- 5000MW outlet)

The aim is to have a more dynamic energy control.

Version 0.05:
Fixed a mistake in the code that resulted in a crash when using XL transformer.

Version 0.0.4:
More or less done with structuring and cleaning up the code, shaving it down to total 10kb from original 22kb control.lua file. #FeelingAccomplished
This should make it far easier for anyone to add/modify things in the mod. And maaaayyyybeeee it might use a tiny bit less cpu time since the amount of function calls is significantly reduced (Im talking nanoseconds here though, so not going to make a difference for the end-user).

Version 0.0.3:
Improved code structure and updated descriptions for the transformers to easily see their input/output limitations.
This also means that I might've made some errors while changing the code. It seems to work fine right now, but if you see any behavior that seems out of place - do leave a comment and I'll try to fix it.
(Updated the homepage for 0.0.2 for automatic updates to work on all versions.... I guess this note belongs here since that was done just now and 0.0.2 is re-uploaded?.. #Confuse)

Version 0.0.2:
Fixed for Factorio 0.14

Version 0.0.1:
Original by Monty
https://forums.factorio.com/viewtopic.php?f=93&t=20174&p=210042#p210042