Power Factor and Load Angle in Synchronous Generator


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Recently I started going through the synchronous generator as I am following a module of Power and Generation. So Far I have a quite good understanding of how the synchronous generator works. For example the terminal voltage and frequency are constant as the grid synchronizes everything together of course unless you have a really huge generator that will make huge changes.

What I cannot visualize is how the power factor comes into play. So far i understand that the coil windings in the stator have an inductance. So every time the load increase slightly (so to keep current lagging) some Negative VAR is going to be produced, thus the need to increase the excitation field, since some voltage is dropping across the inductance.

Now let's say that the load increased slightly and we are supplying less voltage to the grid, because of the drop across the inductance of the coil. Also due to this drop, current is now lagging voltage.

In the so called phasor diagrams there are two angles, the angle of the power factor (i.e. the angle between the current and the voltage) and the load angle (this i have no idea what it due but so far i can only conclude that when the voltage in the stator windings decreases and since we have some reactive power, the rotor is at this "load angle" with the stator. Are these two angles correct the way i have described them?

Also one thing that is not so clear in my head is the magnetic field in the stator windings, when there is no reactive power, there will be no magnetic field since this will be suppressed by the field created by the rotor? .... with the same reasoning if the load increases more current will flow through the stator windings creating a slightly larger magnetic field which will again oppose the one created by the rotor and with this rise in the magnetic field the current starts to lag the voltage?

I hope i described the problem well, should some things need to be more clear just point them out