This addon for Immersive Engineering adds a new tier of wire: AF, or Alternating Flux. This acts as a sort of "Super High Voltage" line. Power transmitted over AF lines has very low power loss over distance, but cannot be connected to machines, and must be converted between other tiers of wire with special transformers.
Despite the special name, this mod does not actually add a new form of power and just uses Immersive Engineering's normal power system. So you don't have to worry about "yet another power system".
The properties of AF wire are configurable, so you can adjust it to your particular tastes, and all information on the mod is added to a section in the IE manual: see "Power, wire, generators/Alternating Flux"