GENERATOR

Governor- :
Governor is a speed control system ,that acts on the turbine ,adjusting the inlet valves for the turbine.This is used to adjust the real power o/p from the generator or to regulate the frequency .Operation can adjust it's preset position for a direct change of real power o/p.

Exciter -:
Exciter is the unit that establishes DC current in the field winding .

AVR -:

AVR is a closed loop controller that fields control input of the exciter .

Real Power Control -:

Real power produced by the generator is approximately equal to the mechanical power received by the generator .
Governor is an inlet valve control mechanism activated through the opeartor . Real power o/p from a generator only be changed by adjusting the governor preset position.

Reactive power control -:

E - induced EMF phase voltage
Q- Reactive power

According to the expression of Q , we controll Q by adjusting induced emf E ,by adjusting induced emf E ,by adjusting excitation dc current (i)
Increase (i) to increase Q
Decrease (i) to decrease Q

change of (i) is activated via separate unit called AVR . This is closed loop voltage controlled adjustable preset .

If the reactive power of the busbar goes up , the terminal voltage is dropped .This drop is sensed by the AVR & send more (i) to the generator field . This boost up E & there by the reactive power generated in the process the terminal voltage (v) ,recovers it's drop & regains nominal value.
If we want to raise reactive power intentionally ; we should use preset input to raise internal emf E .