> So now, DC current in some key AC lines is monitored continuously...
Can power lines have multiple currents in them at once? What would that mean for when the AC phase is moving opposite the DC direction?
Can power lines have multiple currents in them at once? What would that mean for when the AC phase is moving opposite the DC direction?
Tldr, DC is just like an offset to the voltage or current waveform which is itself a sine wave.
A wire is an essential one dimensional conductor; the electrons can move only backwards or forwards. Think of a narrow channel of water like a canal or river. A canal has no current, while a river has a direct current: it always flows one way. But a tidal inlet has an alternating current. The net flow of water is zero, but there is still a constant movement of water, backwards and forwards.
At a tidal estuary both things are happening: there's a DC component caused by net egress of water and an AC component caused by the tide.
The analogy doesn't really work because bodies of water also have capacitance. Wires are more like pipes. But hopefully you get the idea. Another way to think of it is like shouting in the wind, if you know how sound works.
Look into Fourier transforms if you're interested in learning more.