Theres a book cleverly titled 'Diesel Generation Handbook', I believe that its still available in print in some locations.
Some of the information is getting a bit dated (a lot of the smaller (high speed) engines that are truck derivatives are no longer mechanically governed) but its still quite a useful text to have.
I don't believe that it covers the latest load sharing systems either, Woodward used to have a number of publications that covered that.