What factors affect the voltage drop in a basic ac generator when an additional load is added in parallel
Since you are asking about an AC generator, you need to consider the generator's inductive reactance. That is responsible for most of the voltage drop that remains when the speed is maintained to provide the rated frequency. With a wound-field synchronous generator, the voltage can be more closely maintained by adjusting the field excitation. That is not an option with a permanent-magnet generator.