There are two main methods of voltage regulation for generators:
Voltage regulator (AVR) control: This method automatically adjusts the excitation current based on voltage measurements to maintain a stable voltage output. The output voltage can be effectively controlled by changing the magnetic field strength of the generator.
Phase Shift Excitation: This method adjusts the excitation current according to the change in phase angle between voltage and current. A system that utilizes both methods is known as controlled phase shift excitation. If only phase shifting is used without a voltage regulator, it is called uncontrolled phase shifted excitation.