Basically the AVR or Automatic Voltage Regulators function for generator is to ensure voltage generated from power generator running smooth to maintain the stable voltage in specified limit. It can stabilize the voltage value when suddenly change of load for power supply demand.
If the generator running in parallel condition,the AVR can controlled the voltage that it produce to ensure of equal value for reactive load sharing.
For the big system of interconnected power distribution with parallel design,it must have a full controlled and transient stability particular must added for requirement to the Automatic Voltage regulator for generator. read more