I'm not too familiar with using a generator in this application, but typically with a generator that is paralleling (sourcing) into the grid, it's a big deal matching frequency and phase. With a generator operating as you describe, it sounds like you are more closely describing an alternator (ie: takes mechanical energy in, puts electrical energy out). In the parlance I'm familiar with, when you descibe a generator, you are describing not only the ability to take mechanical work and produce electrical work (alternator) but the ability to produce mechanical work in the first place --- for traditional 'generators' as I'm used to hearing, this usually means diesel fuel going into cyllinders, turning a rotor, etc.
I may be mincing words but long story short, yes you need protection, and yes, you need to ensure that the waveform produced by your 'generator' matches that on the grid. To do this, you often need some sort of controlling mechanism and the ability to 'lock out' your source until it reaches the rated voltage waveform.
As far as how EXACTLY this is accomplished in applications where you have a turbine, I look forward to some experts weighing in.