> So every point in the grid can't be perfectly in phase with every other point, right? Because we have both lightspeed delays and loops, so even if point A is

> So every point in the grid can't be perfectly in phase with every other point, right? Because we have both lightspeed delays and loops, so even if point A is receiving power from two substations in-phase, point B (with different lengths of wire to those two substations) should be receiving it out-of-phase, right? How do we balance that in the grid? As far as I know, in your example, one of the two circuits will be transmitting more power from the substations to point B than the other. There's a device called a phase-shifting transformer (https://en.wikipedia.org/wiki/Phase-shifting_transformer https://en.wikipedia.org/wiki/Phase-shifting_transformer) which can be used to adjust the phase angle of the circuits, and that way, adjust how much of the power is carried by each circuit. (The following sentence from that article probably goes to the core of the answer for your question: "For an alternating current transmission line, power flow through the line is proportional to the sine of the difference in the phase angle of the voltage between the transmitting end and the receiving end of the line.[1]")