the process by which inverter number 53 syncs itself to the other 52 on a local grid.
It's simple: it doesn't. It only syncs to the voltage it measures right where it is connected.
It can be as simple as measuring voltage, and controlling current controller's setpoint to be in direct relation with measured voltage.
It can work as simply as this:
* Measure instantaneous line voltage (e.g. 100V)
* Multiple this by a constant, say 0.1, to decide injected current. e.g. 100 * 0.1 = 10 (A)
* Set current controller loop to output 10A
* Current controller measures current through a shunt resistor and sees less than 10A going
* A transistor is turned on, and current through the inductor in the converter starts to rise
* Once 10A is flowing, transistor is turned off
Repeat this process thousands of times a second, and you have an inverter which "syncs to grid" and outputs power with PF1.0.
The above constant, 0.1 in this example, needs to be adjusted in a slowed control loop so that proper PV DC input voltage is maintained.
This is all electronic equivalent to what rotating machines do. They also sync themselves to the grid locally.
if you get your voltage to be different to the grid voltage then current will flow, somewhere.
By Ohm's law, yes. This small voltage difference is what "drives" current, in all power distribution systems, AC or DC. Or you can swap the thinking around and say that driving current into lines causes a small voltage drop; the same thing. It is just how it works. It is interesting how you find somehow the fact that there is current flowing in power grid somehow weird or problematic to mention it like this. I think to many, even complete laymen, it is obvious that current is flowing in power lines (grid or their home wiring).