Back in the day all generators for stage productions were diesel-powered beasts, but options for smaller events and the times are changing.
An interesting and highly instructive thread from the AC Power and Grounding forum in the Live Audio Board (LAB) on ProSoundWeb.
Tutotial to focus on proper audio grounding techniques to keep systems quiet and problem-free
Finding and eliminating noise coupling where it actually happens
Audio Systems Group’s Jim Brown authors essential guide for consultants and integrators
Although hum and other problems are often blamed on “improper grounding,” in most cases there is actually nothing improper at all.