Enter the University of Kassel in Germany that has a demonstration project linking wind, solar, biomass and hydro generating stations into a 'Combined Power Plant'. Essentially, they've built a smarter generating infrastructure where each generating type provides at its ability and the whole is blended to meet demand. Not much different than how electric markets already work.
As a hurdle, however, this does show that integrated management of each station can be made to work, and makes it easier for scaling up as well as deployment elsewhere.
Take a look, including the video and system flow diagram on Gristmill.