Yes it is possible. As new people come here we see these ideas come back.
The thing to remember is that you need to switch the low wind alternator out of circuit. If you leave it in parallel with the high wind one you will find that the low wind one becomes a source of high losses and even if it doesn't burn out it will rob you of a lot of power.
The switching is similar to a star delta scheme and for a lot of the time you will not be on the best load point for either alternator.
Usually you eventually realise that you can get the same effect from star/delta or series parallel reconnection of one alternator and you save duplicating magnets and coils.
If you want absolute simplicity and are not worried about the best possible efficiency then you can do something with the low wind pma to make it self protecting in high wind. That way you just don't need all the messy switching. A small iron cored pma with sufficient leakage reactance will limit to constant current and will not burn itself out. If you use an air cored machine for low winds to avoid iron losses then you need series inductors to get the limiting.
Either way the low wind machine will become rather inefficient and will rob power from the main high wind alternator but the effect may not be that noticeable.
I think I covered all of this and many other possibilities in the " matching the load" article I did long ago in a diary entry. I have used the 2 machine approach with a reactance limited pma for low winds and a dynamo for high winds many years ago and it was a considerable improvement on the dynamo alone. I have since found far better ways to do the same thing but if you want simplicity then yes give it a try.
Flux
